Following a hypertensive disorder of pregnancy, hypertension can worsen in the postpartum period following hospital discharge. Risk factors for hypertension exacerbation and associated outcomes have not been well characterized.We sought to identify risk factors and characterize outcomes for individuals requiring initiation of anti-hypertensive medication following hospital discharge postpartum through our hospital system’s remote blood pressure management program.We performed a cohort study of individuals delivered between 9/2019–6/2021 and enrolled in our remote blood pressure monitoring program, which utilizes standardized protocols for anti-hypertensive medication initiation postpartum.Postpartum unit at a referral hospitalPopulation-based sample of individuals with a hypertensive disorder of pregnancy  and no pre-pregnancy hypertension.Anti-hypertensive medication initiation timing: no anti-hypertensive medications, initiation prior to hospital discharge postpartum, and initiation after hospital discharge postpartumPostpartum readmission and emergency room visitsOf 2,705 individuals in our cohort, 1,458 (54%) required no anti-hypertensive medications postpartum, 637 individuals (24%) were discharged on anti-hypertensive medications, and 610 (23%) required initiation of anti-hypertensive agents after discharge. Utilizing an inpatient threshold of ≥ 150/100 mmHg in line with current obstetric guidelines for medication initiation postpartum fails to identify 385 (63%) of individuals who required medication initiation after discharge. These individuals had higher home blood pressures, increased odds of Emergency Room visits [aOR 2.22 (95%CI 1.65–2.98)] and hospital readmissions postpartum [aOR 5.73 (95%CI 3.72–8.82)] compared with individuals discharged on no medications.Over 20% of individuals with hypertensive disorders of pregnancy required initiation of anti-hypertensive medications after hospital discharge. Current blood pressure guidelines for medication initiation fail to identify the majority of these individuals during delivery hospitalization. These data support the critical role of remote blood pressure monitoring programs and highlight the need for improved tools for risk strati cation and liberalization of thresholds for medication initiation postpartum. There are no clear guidelines on optimal blood pressure management in the postpartum period, resulting in variation by provider and institution.6 ACOG suggests that treatment be initiated for persistent blood pressure ≥ 150/100 mmHg; however, these recommendations do not address the expected exacerbation of hypertension that is seen at days 4–7 postpartum.8 Severe hypertension (≥ 160/110mmHg) is associated with a higher risk of severe maternal morbidity postpartum, particularly stroke, heart failure, and seizure.10The American College of Obstetricians and Gynecologists (ACOG) recommends a single blood pressure check between 3–10 days postpartum for individuals with a hypertensive disorder of pregnancy.Our objectives were to, first, identify risk factors for initiation of anti-hypertensive medication following hospital discharge postpartum; second, to characterize associated outcomes for individuals initiated on anti-hypertensive medications following hospital discharge and, third, to interrogate the performance of various blood pressure thresholds for identifying inpatient individuals ultimately requiring anti-hypertensive medications within a remote blood pressure monitoring program.4 Regardless of diagnosis, hypertension in pregnancy is defined as blood pressure ≥ 140 mmHg systolic or 90 mmHg diastolic. Maternal, obstetrical and sociodemographic data are obtained from the electronic medical record and subsequently the Clinical Data Warehouse (CDW) at UPMC. The program was approved by the University of Pittsburgh Medical Center Quality Improvement Review Committee and the University of Pittsburgh Institutional Review Board. The data collection and analysis was approved as an exempt study posing no greater than minimal risk, thus written informed consent was not required. The reporting followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines.This study is part an ongoing quality improvement project that included postpartum individuals admitted to the postpartum unit of a hospital system  between September 2019 and June 2021. Eligible individuals have one of the following hypertension-related diagnoses: gestational hypertension, preeclampsia, eclampsia, or new onset postpartum hypertension. As our focus was on new-onset hypertensive disorders of pregnancy, postpartum individuals with pre-pregnancy chronic hypertension were excluded from this analysis. To be included in the program, individuals must be English-speaking and have access to a text messaging-enabled mobile device. Diagnoses of HDP are made by the clinical care team according to ACOG criteria.11 Briefly, we created a remote patient monitoring platform that leveraged Vivify Health® as its vendor. The monitoring platform is integrated with electronic health records and the CDW for both ordering and results. Individuals are enrolled in the program by their primary obstetric provider while inpatient on the postpartum unit or after a readmission postpartum. For this analysis, we included only individuals enrolled during the delivery admission. After identification and verification of eligibility, the provider places an order in the electronic medical record with the patient’s phone number which automatically generates a text message to enroll the patient. We utilize the A&D UA-651  automatic upper arm blood pressure monitor. The patient is trained on use of the blood pressure device by a program-specific nurse educator prior to discharge from the hospital. During program enrollment, bedside nursing staff record blood pressure on both the home blood pressure monitoring device and the hospital device to confirm accuracy. The program is managed through a nurse-staffed UPMC call center with documentation of calls and blood pressures directly into the electronic medical record.A description of the remote monitoring program has been previously described.12 Following discharge from the hospital, individuals are prompted to check their blood pressure at least daily for the first two weeks of the program and between 3–5 times per week for the remainder of the program through six weeks postpartum. Blood pressures are reported utilizing text messaging. The initial choice of anti-hypertensive agent is dictated by the inpatient clinical care team. Following hospital discharge, titration of medication or, in the case of medication initiation, selection of the anti-hypertensive agent is based on clinical judgment from the call center physician. There are currently no standardized management guidelines for specific anti-hypertensive agents or parameters for medication titration in the postpartum period.6 Individuals with symptoms including chest pain, severe headache, blurry vision or vision disturbances, shortness of breath or blood pressures ≥ 180 mmHg systolic or 120 mmHg diastolic are referred to the emergency room (ER) for further evaluation.We designed nursing call center-driven blood pressure management and treatment algorithms that were developed by local expert stakeholders, consistent with national guidelines on goals for hypertension management postpartum.For the first objective, we compared demographic, clinical characteristics, inpatient and outpatient blood pressure and care utilization among three groups of postpartum individuals: (1) those who never required anti-hypertensive agents, (2) those initiated on anti-hypertensive agents during the delivery hospitalization prior to discharge and (3) those who were initiated on anti-hypertensive agents through the remote blood pressure management program after hospital discharge. Across group comparisons were performed using chi-squared for categorical data, one-way ANOVA for normally distributed data and Kruskall-Wallis for non-parametric data. Between group comparisons  were performed using chi-squared for categorical data, two sample t-test for normally distributed data and Wilcoxon rank sum test for non-parametric data. We utilized logistic regression to model odds of ER visits and postpartum readmission within the UPMC Hospital system. Models were adjusted for predefined covariates known to be associated with blood pressure, postpartum ER visits and readmissions including maternal age, pre-pregnancy body mass index (BMI), self-reported race , type of hypertensive disorder, postpartum length of stay following delivery and delivery type. All postpartum hospital readmissions and ER visits within the UPMC Hospital System were captured, regardless of whether the ER visit or readmission were primarily related to hypertension given that there may be multiple reasons for hospital readmission or ER visits and our primary objective was to assess healthcare utilization in the postpartum period. We performed a sensitivity analysis limiting the analysis to hospitalizations that occurred after initiation of anti-hypertensive medications.Additionally, we compared outpatient blood pressure trajectories in the first two weeks postpartum utilizing mixed-effects regression models with weeks postpartum as the timescale for all analyses. We used repeated blood pressure measures to fit mixed-effects linear regression models with each blood pressure measure as the outcome, participant identifier as random intercepts and weeks postpartum as a fixed effect expressed using restricted cubic splines with three knots positioned at 3, 8 and 13 days postpartum. The optimal number of knots were chosen comparing AIC and BIC between models. Mixed effects regression models were further adjusted for predefined covariates known to be associated with blood pressure including early pregnancy body mass index (BMI), maternal age and type of hypertensive disorder. Differences between the groups were tested via likelihood ratio test between models. There were 10% of individuals missing information on early pre-pregnancy BMI and missing data was handled with multiple imputation.In our second objective, we interrogated the ability of the ACOG ≥ 150/100 mmHg BP threshold for medication initiation applied inpatient to identify individuals ultimately requiring anti-hypertensive agents. We categorized individuals with persistent postpartum inpatient systolic BP ≥ 150 mmHg or diastolic ≥ 100mmHg (2 or more BPs ≥ 4 hours apart) as “meeting ACOG criteria for medication initiation”. We compared the proportion of individuals who met ACOG criteria applied inpatient within each of the three groups. Finally, we assessed whether lower BP thresholds applied inpatient would more accurately identify (1) individuals ultimately requiring anti-hypertensive agents or (2) those who had severe hypertension (≥ 160/110 mmHg) after hospital discharge reported through our remote monitoring program. Given that the American College of Cardiology / American Heart Association (ACC/AHA) threshold for initiation of anti-hypertensive agents outside of pregnancy or postpartum in the absence of a known history of chronic hypertension is 140/90 mmHg, we utilized cutoffs between 140–150 mmHg systolic and 90–100mmHg diastolic in our analyses.All analyses were performed using Stata IC 16 software package . All p-values were 2-sided with a significance level of 0.05.2. Most individuals in our cohort, 1,458 (53.9%), required no anti-hypertensive medications postpartum, 637 (23.5%) were discharged on anti-hypertensive medications, and 610 (22.6%) required initiation of anti-hypertensive medications after discharge. Among those requiring initiation of medications after hospital discharge, the median time of initiation of anti-hypertensive medication was postpartum day 7 [IQR 5–9]. We first compared demographic and clinical characteristics between individuals who never required anti-hypertensive agents to those requiring medication initiation after hospital discharge to determine whether clinical or demographic characteristics could differentiate the groups. When compared to those who never required anti-hypertensive medications, those who were initiated on medications after hospital discharge were older, had a higher early pregnancy BMI and were more likely to self-identify as Black race. The groups were similar in terms of mode of delivery, type of hypertensive disorder and length of stay postpartum. As expected, the group started on anti-hypertensives during the delivery hospitalization were more likely to have a diagnosis of preeclampsia, have a preterm delivery, lower infant birthweight, were more likely to receive magnesium and had a longer length of stay postpartum when compared to the other two groups  and a postpartum hospital readmission  when compared with those who never required anti-hypertensive agents and, respectively. In adjusted analyses, compared to those who never required anti-hypertensive medications, individuals initiated on anti-hypertensive agents after hospital discharge had increased odds of an ER visit [aOR 2.22 (95%CI 1.65–2.98)] and increased odds of postpartum hospital readmission [aOR 5.73 (95%CI 3.72–8.82)] . These rFor our second objective, we assessed the ability of the ACOG antihypertensive medication initiation guidelines, when applied to inpatient BPs, to identify individuals who (1) ultimately required anti-hypertensive agents and (2) had severe hypertension after hospital discharge. Of those who never required medications, 364 (25%) met the persistent 150/100 mmHg threshold inpatient, compared with 225 (37%) of those who were initiated on medications after hospital discharge and 478 (75%) of those who were treated with medications while inpatient (p < 0.001). Overall, the ACOG 150/100 mmHg threshold, when applied inpatient, identified 56% of individuals who ever needed medications and 51% of those who had severe hypertension after hospital discharge. In our cohort, using a threshold of 140/90 mmHg inpatient for initiation of anti-hypertensives would have identified 84% of those who ever required anti-hypertensive agents and 85% of those who had severe hypertension after hospital discharge but would have potentially overtreated 69% of those who never required medications .In our remote monitored population, over 20% of individuals required initiation of anti-hypertensive agents after discharge from the delivery hospitalization. Despite having clinical evidence of less severe disease at the time of delivery, individuals requiring initiation of anti-hypertensive medications after discharge were the most likely to have severe hypertension postpartum and had the highest rates of ER visits and hospital readmissions when compared to individuals who never required medications or those initiated on medications during the delivery hospitalization. These findings persisted when we limited our analysis to the hospital encounters that occurred after initiation of anti-hypertensive medication, suggesting that ER visit or hospital readmission was not the only factor driving initiation of medication. Further, current ACOG guidelines fail to identify over 60% of postpartum individuals who required medication initiation after discharge. However, lowering blood pressure thresholds for initiation of medication to align with guidelines in a non-pregnant or postpartum population may overtreat nearly 70% of individuals who never required anti-hypertensive agents postpartum.15 Prior small, randomized trials have shown a reduction in hospital readmission and increased adherence to ACOG recommendations surrounding BP assessment in the postpartum period.17 Even more notably, prior studies have also demonstrated a reduction in racial disparities in blood pressure measurement in the postpartum period.18 Despite this, few institutions have implemented system-level remote monitoring programs in the postpartum period. This is likely due to the significant barriers of implementing such programs, including technological barriers, lack of infrastructure, cost of the devices and lack of reimbursement.19 These cost-related barriers are likely exacerbated by the lack of insurance coverage in many states for telehealth and remote monitoring programs.20Our findings demonstrate that individuals requiring medication initiation after hospital discharge have the highest rates of ER visits and hospital readmission even in the setting of a robust remote blood pressure management program, rates that may be even higher at institutions without such programs. These data support the critical role of remote BP monitoring and BP management programs in the postpartum period for detection of hypertension, particularly severe hypertension, after hospital discharge that requires anti-hypertensive medication initiation. Multiple studies have demonstrated the feasibility and acceptability of home blood pressure monitoring and management in the postpartum period.21 For example, for individuals with blood pressures in the upper 140s systolic or upper 90s diastolic in the immediate postpartum period, providers should expect that exacerbation of hypertension after hospital discharge may result in blood pressures that fall in a range where ACOG would recommend medication initiation (≥ 150/100 mmHg) or even into the severe range . This severe hypertension in the postpartum period has been associated with an increased risk of stroke, seizure and heart failure.22 Thus, our findings raise the question of whether a lower threshold for anti-hypertensive medication initiation ought to be considered in populations where home blood pressure monitoring and management is not utilized. On the contrary, universally employing a lower threshold, such as the 140/90 mmHg threshold that is now used for treatment of chronic hypertension in pregnancy based on the recently published Chronic Hypertension in Pregnancy (CHAP) trial may lead to overtreatment and potential adverse effects.23 While this is a widely accepted threshold for medication initiation outside of the postpartum period, obstetric guidelines use a higher threshold of 150/100 mmHg, possibly related to theoretical concerns regarding the risks of hypotension in the postpartum period. However, these guidelines were created prior to the use of remote monitoring and management of blood pressures after hospital discharge. The optimal threshold for initiation of anti-hypertensive medication initiation inpatient in the postpartum period is still unclear and future trials should address this important question. Our findings overall support the need for improved tools for risk stratification to predict which individuals may have significant worsening of hypertension postpartum. Despite the significant contribution of postpartum hypertension to severe maternal morbidity and hospital readmission, to date, few studies have developed risk prediction models or biomarkers specifically to predict which individuals might have worsening of hypertension after hospital discharge. Goel et al demonstrated that a high sFlt1/PlGF ratio was associated with an increased odds of persistent hypertension while inpatient postpartum, however, did not address blood pressure patterns after hospital discharge.24 Finally, it is worth noting that despite this study being performed in a large, tertiary care center with a delivery volume of 10,000 deliveries per year, over 20% of individuals in our study were not started on anti-hypertensive medications despite meeting ACOG criteria during the delivery hospitalization. This is certainly an area for future quality improvement.Our findings regarding blood pressure trajectories in the immediate postpartum period are similar to those from smaller studies in this population, which suggest an exacerbation of hypertension after hospital discharge. These findings reinforce the importance of blood pressure monitoring after hospital discharge and consideration for lower thresholds for medication initiation in the postpartum period.11 Our study has limited generalizability given that our data are from a single institution and findings may not be the same among institutions without a remote blood pressure monitoring and management program. Furthermore, we are limited to evaluating postpartum care utilization only within our health system. All blood pressures are self-reported and we were unable to assess medication adherence during our study period. In our primary analysis, we assessed all ER visits and hospital readmissions regardless of the timing in relation to medication initiation, however, our findings were unchanged when we limited our analysis to hospital readmission after medication initiation, suggesting that it was not solely the interaction with the healthcare system that prompted initiation of anti-hypertensive medication. Additionally, we included all ER visits and rehospitalizations, not just those primarily related to hypertension in an effort to characterize care utilization for other reasons that may indirectly be related to hypertension (such as headache or heart failure). Given our limited sample size, we are unable to perform predictive modeling to assess risk factors and blood pressure thresholds for initiation of anti-hypertensive medications in the immediate postpartum period. Future study should attempt to identify the ideal thresholds for medication initiation postpartum, which may require a large-scale randomized controlled trial to address.Our study is strengthened by the large sample size and ability to compare risk factors across three different groups. Additionally, we used real-time home blood pressure measures instead of in-office measures that may be limited in this population. Our remote monitoring program incorporates standardized protocols, minimizing variation in practice. Our program has been robustly implemented at our institution, such that we have captured > 80% of the eligible population who delivered during the target time period. However, it is possible that our findings may be biased by not including those who did not participate in the program.In summary, we found that nearly half of individuals treated with oral anti-hypertensive medication postpartum required initiation after discharge from the delivery hospitalization. In our cohort, individuals who required initiation of anti-hypertensive medications after discharge had the highest rates of ER visits and hospital readmission, despite clinical evidence of less severe disease during the delivery hospitalization. Importantly, current ACOG guidelines fail to identify the majority of individuals who require post-discharge medication initiation, reinforcing the critical role of remote BP monitoring in the postpartum period. Our findings also suggest the need for further research to develop effective blood pressure thresholds for anti-hypertensive medication initiation in the postpartum period.


To report a rare case of pulmonary and ocular complications with visual loss due to bilateral Purtscher-like retinopathy and paracentral acute middle maculopathy (PAMM) following a hyaluronic acid (HA) filler injection to the breast. Systemic and visual recovery was attained following corticosteroid therapy.A 27-year-old lady presented with painless blurring of vision in both eyes for 2 weeks following hyaluronic acid breast filler injections by a non-medical practitioner. She was initially admitted to the medical ward for diffuse alveolar haemorrhage and altered sensorium. The presenting visual acuity was counting fingers in both eyes. Bilateral dilated fundus examination showed hyperaemic discs, concentric rim of retinal whitening around macula with patches of polygonal-shaped retinal whitening, generalised cotton-wool spots, tortuous veins, and flame-shaped haemorrhages. Spectral-domain optical coherence tomography (SD-OCT) macula revealed hyper-reflective bands at the inner nuclear layer (INL). Fluorescein angiography demonstrated hot discs, delayed arm-to-retina time, arterial filling, and arterio-venous transit time with staining of the vessels at the posterior pole. She was managed with a tapering dose of systemic corticosteroids. The visual acuity improved to 6/12 over 8 weeks with significant anatomical and functional improvement. Dilated fundus examination showed resolution of initial funduscopy findings. The hyper-reflective bands on the OCT had resolved with subsequent thinning of the INL and disorganisation of retinal inner layers.Filler injections are in increasing demand and are frequently being performed by non-medical practitioners. Visual loss from non-facial HA fillers is rare. Inadvertent entry of HA into a blood vessel may potentially cause systemic and sight-threatening ocular complications. Good anatomical knowledge and proper injection technique are vital in preventing this unfortunate sequela. There are limited reports on successful visual recovery following various treatment approaches and we hope this case provides valuable insights. Cosmetic filler injection is a common aesthetic procedure to increase dermal tissue volume. It has gained popularity as a minimally invasive procedure to increase tissue volume for enhancement of appearance. The composition of these fillers can be collagen, hyaluronic acid (HA), polylactic acid, calcium hydroxyapatite and polymethylmethacrylate (PMMA) . The AmeFiller injections rarely cause sight-related adverse events but if they do occur, they are frequently irreversible resulting in catastrophic complications. The mechanism for this is inadvertent retrograde embolisation with the entrance of filler materials into the ophthalmic circulation and central retinal artery through the external carotid-internal carotid anastomoses . In a syIn contrast, non-facial fillers have a lower incidence of blinding ocular complications. As HA injected into the subdermal region is usually a blind procedure, the direction and angle of the needle during injection are hence crucial as there is a possibility of inadvertent entry of the needle into a blood vessel, causing an intraluminal inoculation of HA .There are several reported cases of filler-associated visual loss, and almost all cases involved injection into facial tissues. To our best knowledge, visual loss following filler injection to breast tissue has yet to be reported. We report a rare case of systemic complications and visual loss secondary to bilateral Purtscher-like retinopathy and PAMM following a HA filler injection to the breast. Systemic and visual recovery was achieved with corticosteroid therapy.3/µL with otherwise normal haemoglobin and platelet counts. The erythrocyte sedimentation rate was 18 mm/hour. Other blood investigations including renal profile, liver function, coagulation profile, serology for syphilis, hepatitis B & C and HIV, and autoimmune panel were all unremarkable.A 27-year-old healthy female was admitted to the medical ward for sudden onset of shortness of breath and reduced responsiveness immediately after undergoing an HA filler injection to her right breast by a non-medical practitioner. The estimated volume of injection was around 500 millilitres. She was diagnosed with acute respiratory distress syndrome. Initial laboratory investigations upon admission showed leukocytosis at 13.7 × 10The contrast-enhanced computed tomography (CECT) thorax showed multiple imperceptible tiny nodular-like lesions in both breasts, diffuse bilateral ground-glass opacification, and consolidative changes in both lungs predominantly at the upper lobes and at the periphery. Bronchoscopy and bronchoalveolar lavage confirmed features of diffuse alveolar haemorrhage. An echocardiography was attempted but there was limited visualisation due to poor penetration. She was also noted to have altered sensorium and CECT brain showed a left corona radiata infarct with no radiographic evidence of intracranial haemorrhage. There were intermittent generalised rhythmic delta waves suggestive of diffuse cerebral encephalopathy on the electroencephalography suggestive of toxic encephalopathy. The patient did not consent to a lumbar puncture. She was managed with intravenous ceftriaxone and hydrocortisone by the physicians after which her condition stabilised, and she was discharged well after two weeks with a tapering dose of oral corticosteroids.Although she had also experienced sudden bilateral painless visual loss within 24 h after the procedure, she was only referred to the Ophthalmologist two weeks later upon discharge from the medical ward. She denied eye redness, discomfort, seeing floaters or flashes. Upon presentation to the Ophthalmologist, the visual acuity was counting fingers in both eyes. There was no relative afferent pupillary defect. She could not perceive any numbers on Ishihara’s colour vision plates. Anterior segment examination was unremarkable. Dilated fundus examination of the right eye showed a pink optic disc and multiple small to large cotton wool spots distributed mainly at the posterior pole. The superotemporal and inferotemporal veins appeared tortuous with few flame-shaped haemorrhages seen. A concentric rim of retinal whitening was seen around the macula, extending temporally and inferiorly, giving rise to a pseudo-cherry-red spot. A few patches of polygonal-shaped retinal whitening were noted. The left fundus showed a hyperaemic optic disc and had similar findings as the right fundus Fig. A, B.Fig.Spectral domain-optical coherent tomography (SD-OCT) revealed hyper-reflective bands mainly at the level of the inner nuclear layer (INL). At the maculopapular region of the right OCT, these bands extended up to the nerve fibre layer. The outer retinal layers and ellipsoid layers were intact Fig. . Fundus She was diagnosed with bilateral Purtscher-like retinopathy and PAMM secondary to HA breast filler injection. The oral corticosteroids prescribed by the physician were increased to an anti-inflammatory dose and gradually tapered over 8 weeks. Oral acetylsalicyclic acid 150 mg daily was also prescribed.Three weeks later, the visual acuity improved from counting fingers to 6/18 in both eyes. At 8 weeks, the best corrected visual acuities further improved to 6/12. Serial fundus photography thereafter showed the resolution of the cotton wool spots and patchy areas of retinal whitening. OCT macula showed thinning of the INL and disorganisation of the inner retinal layers Fig. .Fig. 3FuWe believe this case is the first reported Purtscher-like retinopathy and PAMM following HA fillers involving breast tissue. We postulate that there was an inadvertent inoculation of HA into the artery supplying the breast which then passed on to the subclavian artery, the brachiocephalic trunk and onward to the arch of aorta, ascending to both common carotid arteries and to the internal carotid arteries. HA particles then passed through the ophthalmic arteries, the distal branches of the central retinal artery and finally reached the capillaries and caused occlusion Fig. . The tenIn view of the high content of fat in breast tissue, the other possible explanation for this patient's pulmonary and ocular complications could be fat embolism. Fat embolism could result from mechanical obstruction from fragments of fatty tissue causing obstruction in the pulmonary microvascular system. Alternatively, a paradoxical embolism whereby the embolus passes from a patent foramen ovale and enters the arterial circulation, or a microembolism where small emboli pass through the pulmonary artery into the pulmonary and systemic circulation are possible mechanisms. This patient's CECT thorax findings with bilateral ground-glass opacification have also previously been reported in other similar cases of fat embolism syndrome .Although the patient had presented to the ophthalmologist only two weeks later, the clinical features of Purtscher’s retinopathy were apparent in both fundi, mainly the haemorrhages and cotton wool spots in the posterior pole. Small patches of polygonal-shaped retinal whitening also known as Purtscher’s fleckens Fig. A and B wPAMM is believed to occur when there is ischemia of the intermediate and deep capillary plexus. The inner nuclear layer and outer plexiform layer may act as a watershed zone being more susceptible to ischaemia. The secondary inflammation provoked by this mechanical occlusion may cause perivascular oedema and further exacerbate hypoperfusion by vaso-compression . NemirofThere were four previous case reports on PAMM following non-facial filler injection. Khatibi reported a case after PMMA injection into buttock muscles, with good visual improvement after a course of systemic steroid therapy ; Bruno eThere is no standard evidence-based management for visual loss secondary to filler. However, early and prompt intervention may be potentially sight-saving . HyaluroSystemic corticosteroids in the form of intravenous or oral steroids have been used in the management to reduce inflammation which may further compromise blood flow. Although our patient presented only after two weeks, she had already received systemic hydrocortisone and oral steroids for the pulmonary involvement. While the visual acuity was still poor at counting fingers, there was gradual visual recovery noted with the continuation of an anti-inflammatory dose of oral corticosteroids. The possibility of this being part of the natural course of PAMM which may be self-limiting cannot be ruled out.This patient first developed shortness of breath soon after the breast filler procedure and was initially managed by the physicians for life-threatening respiratory distress syndrome. This delayed her referral to the ophthalmologist. Pulmonary complications following HA injections are less common and usually related to non-thrombotic pulmonary embolisms (NTPEs) , 19. VerIn summary, we present a case of pulmonary and ocular complications with visual loss due to bilateral Purtscher-like retinopathy and PAMM following HA filler injection to the breast. Systemic and visual recovery was attained following corticosteroid therapy. Practitioners performing filler injections should have good anatomical knowledge and be aware of possible risks to prevent the associated life-threatening and sight-threatening complications.


Gains in malaria control are threatened by widespread pyrethroid resistance in malaria vectors across sub-Saharan Africa. New long-lasting insecticidal nets (LLINs) containing two active ingredients  have been developed to interrupt transmission in areas of pyrethroid resistance. We aimed to evaluate the effectiveness of three dual active-ingredient LLINs compared with standard pyrethroid LLINs against pyrethroid-resistant malaria vectors in rural Tanzania.Anopheles vectors were then tested for malaria parasites and identified at species level, to distinguish between sibling species of the Anopheles gambiae and Anopheles funestus groups, using molecular laboratory techniques. The primary outcomes were density of different malaria vector species measured as the number of female Anopheles collected per household per night, the entomological inoculation rate (EIR), an indicator of malaria transmission, and sporozoite rate. Entomological outcomes were assessed on the basis of intention to treat, and the effect of the three dual active-ingredient LLINs was compared with the standard pyrethroid LLINs at household level.In this study, we did a secondary analysis of entomological data from a four-group, 3 year, single-blind, cluster-randomised controlled trial carried out between Feb 18, 2019, and Dec 6, 2021. We conducted quarterly indoor mosquito collections using the Centers for Disease Control and Prevention light trap, in eight houses in each of the 84 study clusters in the Misungwi district, northwestern Tanzania. Anopheles funestus sl, the most efficient vector in the study area, with comparatively weak effect on An arabiensis. An funestus density was 3∙1 per house per night in the pyrethroid LLIN group, 1∙2 in the chlorfenapyr pyrethroid LLIN group , 1∙4 in the piperonyl-butoxide pyrethroid LLIN group , and 3∙0 in the pyriproxyfen pyrethroid LLIN group . Malaria transmission intensity was also significantly lower in the chlorfenapyr pyrethroid group, with 0∙01 versus 0∙06 infective bites per household per night in the pyrethroid LLIN group . Ecological niche models indicated that vector-species distribution was stable following LLIN intervention despite the reductions observed in An funestus sl density.Dual active-ingredient LLINs had the greatest effect on An funestus sl over 3 years of community use, whereas the effect of piperonyl-butoxide pyrethroid LLIN was sustained for 2 years. The other vector, An arabiensis, was not controlled by any of the dual active-ingredient LLINs. Additional vector control tools and strategies targeted to locally prevalent vector species evading dual active-ingredient LLINs should be deployed to further reduce malaria transmission and achieve elimination.Chlorfenapyr pyrethroid LLINs were the most effective intervention against the main malaria vector The Department for International Development, UK Medical Research Council, Wellcome Trust, the Department of Health and Social Care, and The Bill & Melinda Gates Foundation via the Innovative Vector Control Consortium. The primary malaria-vector control tools, consisting of pyrethroid long-lasting insecticidal nets (LLINs) and indoor residual spraying, have substantially reduced malaria morbidity and mortality across sub-Saharan Africa.Anopheles vector species composition might also change following intervention deployment, a phenomenon that has been reported previously.To address the biological challenge of insecticide resistance while sustaining malaria control gains, novel next-generation dual active-ingredient LLINs are under evaluation; some have received provisional recommendation by WHO.Evidence before this studyAnopheles gambiae complex”, “Anopheles arabiensis”, or “the Anopheles funestus group”, and “malaria”, “entomological inoculation rate”, “randomised controlled trial”, “village trials”, and “long lasting insecticidal net” or net in combination with “chlorfenapyr”, piperonyl butoxide”, or “pyriproxyfen”. We found five cRCTs, one in Burkina Faso, one in Uganda, two in Tanzania, and one village trial in Mali, assessing the effectiveness of dual active ingredient LLINs with some entomological outcomes. In Burkina Faso, the entomological inoculation rate (EIR) was 51% lower in the pyriproxyfen pyrethroid LLIN group compared with the standard LLIN group (standard pyrethroid LLIN). In Uganda, at 25 months follow-up, reduction in density of malaria vectors was 62% in the piperonyl-butoxide pyrethroid LLINs compared with standard pyrethroid LLIN. The Tanzanian study showed that the indoor overall vector density and EIR were significantly reduced in the chlorfenapyr pyrethroid LLIN group by 57% and 85%, respectively, after 2 years of community use, and by 58% and 73%, respectively, in the piperonyl-butoxide PY group only in year 1, compared with the standard pyrethroid LLIN group. In the Tanzanian cRCT, the pyriproxyfen pyrethroid LLIN did not have a significant impact on entomological outcomes when compared with the pyrethroid LLIN. In Mali, the piperonyl-butoxide pyrethroid LLINs did not show any improved control on indoor Anopheles arabiensis population density when compared with standard permethrin LLINs; however, sporozoite rates were lower in the piperonyl-butoxide pyrethroid LLIN group than in the the permethrin LLIN group only during the rainy and high-malaria-transmission seasons. Here, we report the effect of dual active-ingredient LLINs on each of the main vector species and associated malaria transmission, over 3 years of net use.Insecticide resistance in malaria vectors is widespread in many endemic settings, thus presenting a serious threat to the efficacy of vector-control tools, mainly long-lasting insecticidal nets (LLINs) and indoor residual spraying. To sustain the progress made against malaria and to improve vector-control tools, WHO recommends the development of new insecticidal products with different modes of action against resistant vectors. Piperonyl butoxide LLINs received interim WHO recommendation as a novel malaria vector-control tool after showing better protection than standard pyrethroid LLINs against malaria infection and transmission in two cluster randomised controlled trials (cRCTs) in Tanzania and Uganda. The current study is a follow-up of the recently published large-scale cRCT assessing the effectiveness and cost-effectiveness against malaria of three types of dual active-ingredient LLINs, compared with pyrethroid-only LLINs in Tanzania. We searched for published papers in English in PubMed on Feb 10, 2022, without restrictions on the date, using the terms “mosquito” or “vectors” and “Added value of this studyAnopheles coluzzii, An gambiae ss, and An funestus, with An funestus becoming the most important in eastern and southern Africa. A fourth vector, An arabiensis, a secondary vector, is involved in residual malaria transmission because of its outdoor biting behaviour and considerable behavioural plasticity, allowing it to feed on both animal and human hosts. Anopheles mosquito species diversity and malaria-transmission dynamics have implications during the deployment of effective malaria vector-control strategies. In this study, we observed differential effects of dual active-ingredient LLINs on different malaria-vector species. Two dual active-ingredient LLINs, chlorfenapyr pyrethroid LLINs and piperonyl-butoxide pyrethroid LLINs, were most effective compared with standard pyrethroid LLINs at controlling An funestus population density in the southern part of the study area with no impact on An arabiensis, suggesting that targeted control could be optimised to specific species focusing on high-burden settings to ensure sustained malaria control. This study's entomological findings provide additional insights to understand the epidemiological results observed in the trial, but might also explain some differences between trials done in other sites where vector-species composition differed. Chlorfenapyr pyrethroid LLINs were the most effective dual active-ingredient LLINs, and the effect was sustained for 3 years.This is to our knowledge one of the few large-scale community trials looking at the effectiveness of next-generation dual active-ingredient LLINs on the density of different vector species. Malaria in sub-Saharan Africa is highly heterogeneous due to ecological and climatic variations. Currently, the three main vectors are Implications of all the available evidenceAn funestus, An gambiae, and Culex quinquefasciatus. A Cochrane review reported a significant impact of piperonyl-butoxide pyrethroid LLINs mainly on An gambiae ss. One large community trial showed improved efficacy of pyriproxyfen pyrethroid LLINs against An gambiae ss. The current cRCT contributes to previous evidence, as the first community trial assessing differential impacts of dual active-ingredient LLINs on the major malaria-vector species in sub-Saharan Africa. It reveals a superior impact of dual active-ingredient LLINs containing chlorfenapyr and piperonyl butoxide, compared with standard pyrethroid LLINs, in reducing population density of the major malaria vector An funestus, thereby preventing human infectious bites. The protective efficacy of chlorfenapyr pyrethroid LLINs were sustained for 3 years, whereas piperonyl-butoxide pyrethroid LLINs lasted for 12 months. These dual active-ingredient LLINs, however, could not control An arabiensis, suggesting that additional targeted control tools should be tailored to reduce secondary vectors responsible for residual malaria transmission.Previous randomised controlled field trials supported by small-scale experimental hut trials have demonstrated the improved effectiveness of dual active-ingredient LLINs compared with standard pyrethroid LLINs on entomological indices. In hut trials, chlorfenapyr pyrethroid LLINs were found effective against several vector species, including A Cochrane review reported that piperonyl-butoxide pyrethroid LLINs had a greater effect on malaria prevalence and mosquito population density than pyrethroid-only LLINs, in areas with high pyrethroid resistance.An gambiae sl and An funestus sl. In addition, we also report on the effects of dual active-ingredient LLINs on entomological outcomes during the third year of follow-up. Finally, we complement the entomological indicators by using an ecological niche model to investigate potential shifts in malaria-vector species distribution following the introduction of these interventions.In this Article, we detailed a secondary analysis from a large cRCT in Tanzania. The primary outcomes reporting the effectiveness of the dual active-ingredient LLINs on malaria indicators and overall vector density over 2 years follow-up have already been published.An arabiensis and An funestus, with An funestus being the leading malaria-vector species responsible for more than 90% of ongoing malaria transmission.13In this secondary analysis, entomological surveillance was done in 84 clusters formed from 72 villages, as part of a 3 year, single-blind, four parallel arm cRCT in the Misungwi district of north-western Tanzania.Study LLINs were distributed in January, 2019. 13 households were selected for entomological monitoring, eight main households and five additional households were randomly selected from the core area of each cluster from a census list generated during baseline enumeration. At the beginning of the household visit, we sought consent from the household heads or adult members of each household. Adult mosquitoes were collected quarterly using Centers for Disease Control and Prevention (CDC) light traps . CDC light traps were installed in a room, preferably with a single sleeping place, at the foot end, and the net found was replaced with a new standard Interceptor LLIN. Household information including net coverage and information related to household characteristics such as roofing and wall materials, type of eaves, and total number of residences were collected and recorded in an electronic form in Open Data Kit. Because of the SARS-CoV-2 pandemic, mosquito collections were suspended between March and May, 2020, thus one extra survey was carried out in year 2 and year 3 after intervention, to compensate. We provided an outline of the study design .Figure 1Anopheles from other mosquito genera, and then separated to species level, separating An funestus sensu lato sl from An gambiae complex. Up to ten An funestus sl and ten An gambiae sl per house collection were randomly selected for Plasmodium falciparum sporozoite detection using circumsporozoite-protein ELISA.An funestus sl or An gambiae sl per cluster, to distinguish sibling species in An gambiaeAn funestus complexes.Wild-collected adult female malaria vectors were morphologically identified, separating Anopheles collected per household per night; entomological inoculation rate (EIR), an indicator of malaria transmission, defined as the average number of sporozoite-positive mosquitoes per night per household and weighted to account for the proportion of collected Anopheles to be processed for sporozoite analysis; and sporozoite rate, defined as the proportion of Anopheles found infected with malaria parasites. All entomological endpoints were analysed at 12 months, 24 months, and 36 months after distribution and compared between the interventional group and reference group. Secondary outcome was vector-species composition. Preintervention species-distribution models were used to assess changes after intervention in the geographical distribution of major malaria-vector species in each intervention group. We also did exploratory secondary analyses to assess the effect of the interventions on vector density at two geographical locations (northern and southern clusters) of the study area with varying epidemiological and ecological characteristics.The primary outcomes were as follows: density of different malaria-vector species measured as the number of female An funestus, An gambiae sl, or Culex species density, and EIR at different study points. The relative proportion of Anopheles species between study groups and study period were modelled using logistic regression. Sporozoite rates were compared between groups using mixed-effect logistic regression. The models accounted for clustering effect and were adjusted for baseline malaria prevalence, net usage, and vector density. The intervention groups, year, and their interaction, as well as baseline covariates, were fitted in the model as fixed effects, with collection round and cluster as random effects. The interaction was added to estimate time-specific effects of the individual interventions by reference to the standard pyrethroid LLIN during the 3 survey years after intervention. Average Anopheles caught per night per household, density ratios, and 95% CIs were presented. The same analysis was also done for the northern and southern clusters separately. All statistical analysis was done using Stata version 15.1. As the study net usage was low in the third year, a post-hoc per-protocol analysis was done for vector density and included only households that actually used the allocated study nets in the room in which the CDC light traps were installed.The trial was designed to provide adequate power for the primary analysis. In this Article, the secondary analysis followed a preplanned analytical plan on the basis of a published protocol .Anopheles species was determined using an ecological niche modelling approach, on the basis of a maximum entropy (MaxEnt version 3.4.1) algorithm.To complement entomological collections, species-distribution models were initially constructed and validated before the randomisation of study clusters to intervention groups, to predict the geographical extent of different malaria-vector species across the study area.An arabiensis and An funestus sl using pilot survey-occurrence records (n=69 for An arabiensis and n=51 for An funestus sl). Bioclimatic variables for model development at a 1 km resolution were obtained from the WorldClim database, including temperature seasonality, annual precipitation, precipitation of wettest month, precipitation of driest month, precipitation seasonality, and elevation. These variables were selected for their association with malaria-vector species in Tanzania.An arabiensis and AUC of 0·90 for An funestus. Species-specific models were further validated using independently-collected occurrence data from baseline entomological monitoring in all study clusters between August and November, 2018 (n=141 for An funestus and n=79 for An arabiensis); models had high external validity using the baseline occurrence data as test data (AUC=0·79 for An funestus and AUC=0·80 for An arabiensis).A pilot entomological survey was done in May, 2018, before the start of the cRCT. A total of 202 households across 92 villages were sampled for one night each using a CDC light trap. Separate niche models were constructed for Species-occurrence data from the 2 years following LLIN distribution were used as test records for external validation of preintervention niche models to assess changes after intervention in the geographical distribution of major malaria-vector species in the different study groups. The test AUC value was compared with initial model accuracy metrics obtained using baseline test data, whereby no change in AUC values indicated stability in species occurrence , whereas a decrease in AUC values indicated a shift or contraction in species occurrence after intervention relative to the predicted preintervention niche. A threshold was then applied to dichotomise the predicted habitat suitability into presence or absence and the test omission rate was calculated for each model.The funders of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report.An funestus ss, accounting for 4700 (95%) of 4973 Anopheles vectors collected, and was responsible for more than 90% of malaria transmission in the study area.At baseline, household characteristics, LLIN coverage, and entomological and epidemiological indicators were similar in the four study groups.An funestus sl and An gambiae sl. 110 246 samples were culicines and the remaining were other mosquitoes, including male mosquitoes.A total of 146 936 mosquitoes were collected over the 3 successive years, of which 34 605 (23·6%) were female anophelines, principally An funestus. Over the full trial period, mean An funestus sl density was 3∙1 per house per night in the standard pyrethroid LLIN group and significantly lower in the chlorfenapyr pyrethroid LLIN group (mean density 1∙2 per house per night). There was consistently significantly lower densities of An funestus sampled in the chlorfenapyr pyrethroid LLIN group than in the standard pyrethroid LLIN group at year 1, at year 2, and at year 3 . The strongest effect of piperonyl-butoxide pyrethroid LLINs against An funestus density was seen in year 1 and year 2, with weak evidence in year 3 after net distribution.We observed differential effects of the dual active-ingredient LLINs on separate vector species, with the greatest effect on t year 3  after inAn funestus population density in the pyriproxyfen pyrethroid LLIN group, compared with the standard pyrethroid LLIN group. There was variation in indoor An funestus population density across the survey period (An arabiensis (There was weak evidence of a difference in y period . None ofabiensis . Per-proabiensis .An funestus EIR (per night per household) being significantly lower in the chlorfenapyr pyrethroid LLINs group than in the standard pyrethroid LLINs group throughout the study period . Overall, chlorfenapyr pyrethroid LLINs significantly reduced the density of all indoor mosquitoes by 54% , compared with standard pyrethroid LLINs during 3 years of community use  across the four study groups. Other species found at lower proportions included An rivulorium  and An parensis . Of the An gambiae sl analysed to species level (n=2945), most individuals were An arabiensis ; the remaining species were An gambiae ss . We reported Anopheles sibling-species composition per study group over 2 survey years  compared with the standard pyrethroid LLIN group  and we found borderline weak evidence of reductions of An funestus in the piperonyl-butoxide pyrethroid LLIN group relative to the standard pyrethroid LLIN group in the second year. A non-significant difference in species composition was also observed in the pyriproxyfen pyrethroid LLIN group compared with the standard pyrethroid LLIN group  and close to 80% loss in chlorfenapyr content after 24 months,An funestus, reducing density and EIR up to the third year of follow-up, which is probably because of An funestus being susceptible to chlorfenapyr even at low dosage or carry-over effects from the net use in previous years. Previous small-scale semi-field experimental hut trials in Tanzania showed consistently higher mortality against Anopheles gambiae ss and An funestus in chlorfenapyr pyrethroid LLINs compared with pyrethroid-only LLINs, demonstrating no loss of efficacy of the chlorfenapyr component in the nets even after being washed 20 times.An coluzzii, An gambiae ss, and An arabiensis in west Africa.21In clusters provided with chlorfenapyr pyrethroid LLINs, Culex species and other Anopheles. In this study, female Culex species contributed to 69% of the indoor mosquito population density. Overall, there was a statistically significant decrease in Culex species density by 48% and all mosquitoes by 54% in clusters given chlorfenapyr pyrethroid LLINs compared with pyrethroid LLINs. Previous hut trials have demonstrated the effectiveness of chlorfenapyr on Culex species,Community acceptance of interventions relies on reductions in biting nuisance from all mosquitoes, in addition to an effect on malaria transmission. In the present trial, the chlorfenapyr pyrethroid LLINs were effective in reducing the biting nuisance of non-malaria mosquitoes such as An funestus density by 51%, with the strongest effect (67% reduction) observed in year 1 and year 2; this reduction declined over time and was not sustained up to the third year after intervention. The shorter effect of piperonyl-butoxide pyrethroid LLINs is inconsistent with previous studies in which the intervention effectiveness was sustained for 2 years in TanzaniaAn gambiae ss, the main malaria vector found in these two trials,An funestus predominated.An gambiae ss metabolic resistance is mediated by overexpression of cytochrome P450, whereas resistance mechanisms other than those that are P450 based,An funestus resistance.An funestus were lower in the piperonyl-butoxide pyrethroid LLIN group, compared with the standard pyrethroid LLIN group over the study period, these reductions were not statistically different.Overall, piperonyl-butoxide pyrethroid LLINs were more effective than standard pyrethroid LLINs and reduced An funestus population density compared with standard-pyrethroid LLINs in year 1, however the effect was not statistically significant; this finding is in contrast to a 1 year cRCT done in Burkina Faso in which pyriproxyfen pyrethroid LLINs reduced vector density by 22% and EIR by 51% compared with standard LLINs.An funestus could explain the low effectiveness of this LLIN in the study setting. Yunta and colleaguesAnopheles, thereby reducing the bioefficacy of pyriproxyfen pyrethroid LLINs. In addition to inducing vector mortality, pyriproxyfen pyrethroid LLINs have a sterilising effect in female mosquitoes;An funestus mosquitoes were sterilised.There was some indication that pyriproxyfen pyrethroid LLINs reduced the An arabiensis has also been described in previous studies in which standard pyrethroid LLINs did not control this species,An funestus within all malaria vectors was 40·4% in the chlorfenapyr pyrethroid LLIN group after 3 years, corresponding to a 72% significant decrease when compared with the standard pyrethroid LLIN group; although relative proportions of An arabiensis significantly increased by four times in the chlorfenapyr pyrethroid LLIN group. It is likely that An arabiensis can maintain residual transmission especially when there is a shift in sibling-species composition and elimination of primary malaria vectors An funestus, An gambiae ss, or both by indoor interventions, as reported previously;An funestus to rebound if high coverage of chlorfenapyr pyrethroid LLINs is removed. It also highlights the importance of using ecological modelling to identify geographical differences in vector-species distributions that can be used to inform cRCT designs, and to guide the deployment of different targeted interventions to improve the effectiveness of malaria control in areas with diverse vector species.The absence of an impact of indoor interventions on Anopheles vector mosquitoes in the study area, with higher vector densities in the southern clusters than in the northern clusters;An funestus was the most abundant vector in the southern part of the study area, whereas An arabiensis was uniformly distributed across both north and south clusters,An funestus was the leading and most important malaria vector, responsible for more than 90% of malaria transmission, because of its anthropophagical and endophagical behaviour.Consistent with baseline entomological findings and the ecological niche, we observed microgeographical differences in species composition and density of An funestus, with chlorfenapyr pyrethroid LLINs being the most effective over 3 years of community use. Dual active-ingredient LLINs were not effective in controlling An arabiensis. The highest effect was observed in the southern part of the study area, with recommendations for targeted species-specific control in high-burden areas to sustain gains in malaria control.In conclusion, this study confirmed the superiority of two dual active-ingredient LLINs, containing either chlorfenapyr or piperonyl butoxide, compared with standard pyrethroid LLINs, against the major malaria vector species, The datasets generated or analysed during this study are presented within the Article and its supporting appendix.We declare no competing interests.


Outpatient Parenteral Antibiotic Therapy (OPAT) provides coordinated services to deliver parenteral antibiotics outside of the acute care setting. However, the reduction in monitoring and supervision may impact the risks of readmission to the hospital. While identifying those at greatest risk of hospital readmission through use of computer decision support systems could aid in its prevention, validation of such tools in this patient population is lacking.The primary aim of this study is to determine the ability of the electronic health record-embedded EPIC Unplanned Readmission Model 1 to predict all-cause 30-day hospital unplanned readmissions in discharged patients receiving OPAT through the Duke University Heath System (DUHS) OPAT program. We then explored the impact of OPAT-specific variables on model performance.This retrospective cohort study included patients ≥ 18 years of age discharged to home or skilled nursing facility between July 1, 2019 –February 1, 2020 with OPAT care initiated inpatient and coordinated by the DUHS OPAT program and with at least one Epic readmission score during the index hospitalization. Those with a planned duration of OPAT < 7 days, receiving OPAT administered in a long-term acute care facility (LTAC), or ongoing renal replacement therapy were excluded. The relationship between the primary outcome (unplanned readmission during 30-day post-index discharge) and Epic readmission scores during the index admission (discharge and maximum) was examined using multivariable logistic regression models adjusted for additional predictors. The performance of the models was assessed with the scaled Brier score for overall model performance, the area under the receiver operating characteristics curve (C-index) for discrimination ability, calibration plot for calibration, and Hosmer-Lemeshow goodness-of-fit test for model fit.The models incorporating maximum or discharge Epic readmission scores showed poor discrimination ability  in predicting 30-day unplanned readmission in the Duke OPAT cohort. Incorporating additional OPAT-specific variables did not improve the discrimination ability . Although models for predicting 30-day unplanned OPAT-related readmission performed slightly better, discrimination ability was still poor .EPIC Unplanned Readmission Model 1 scores were not useful in predicting either all-cause or OPAT-related 30-day unplanned readmission in the DUHS OPAT cohort. Further research is required to assess other predictors that can distinguish patients with higher risks of 30-day unplanned readmission in the DUHS OPAT patients. Administration of parenteral antibiotics outside an institution-based setting is greatly facilitated by structured multidisciplinary programs known as Outpatient Antibiotic Therapy (OPAT). However, up to 25% of OPAT patients require hospital readmission within 30 days. This highlights the need for decision support tools that would facilitate the identification of patients at the highest risk of hospital readmission. One such tool widely available and evaluated in various patient cohorts is the EPIC Unplanned Readmission Model. However, its ability to predict hospital readmission among OPAT patients has not been previously reported. This retrospective cohort study included adult patients discharged with OPAT care with at least one Epic readmission score during the index hospitalization. We found the model was not useful in predicting either all-cause or OPAT-related 30-day unplanned readmission. Our study highlights the need for further research to identify data tools that can identify the OPAT patients at the highest risk of increased healthcare utilization. Outpatient Antibiotic Therapy (OPAT) is a structured program that coordinates the administration of parenteral antibiotics outside of the acute care setting. The OPAT program at our institution was established in 2016, and has grown to include a core group of pharmacists, nurses, and infectious diseases providers. OPAT nurses and pharmacists review weekly laboratory work and adjust medications. OPAT patients are seen by infectious diseases providers during their OPAT course. The intended result is to save hospital resources and alleviate patient inconvenience and cost. However, there are risks of increased treatment-related adverse effects and hospital readmission due to reduction in direct patient monitoring  9) and 16.9 (SD 8.5), respectively.EPIC scores in patients with and without 30-day unplanned readmission are summarized in Table 3 summarizes the admission-related clinical outcomes. Of the 467 unique admissions, 94 (20.1%) encountered unplanned readmission during the 30-days post-discharge, and 56 (12%) were OPAT-related. Among the 56 unplanned OPAT-related admissions, infection-related and antibiotic-related adverse effects accounted for 30 (53.6%) and 17 (30.4%), respectively. shows the boxplots of the maximum and discharge readmission scores by 30-day unplanned readmission, respectively. From univariable logistic regression, neither the maximum Epic risk score nor the discharge Epic risk score was associated with 30-day unplanned readmission . Table 4 summarizes the multivariable logistic regression for 30-day unplanned readmission, using the maximum and discharge Epic readmission scores as the primary predictor. None of the predictors included  was associated with 30-day unplanned readmission.Table 5. The C-indices were all very close to 0.5, indicating poor discrimination ability. Adding other predictors only slightly improved performance. The Hosmer-Lemeshow tests were all above 0.05, suggesting no evidence of the lack of fit of the models. We also observed zero or close to zero scaled Brier scores, indicating the forecast was not more accurate than predicting using the average probability of the outcome.The performance of the four Epic readmission score models for predicting 30-day unplanned readmission are summarized in Fig 2, which showed no discrimination ability among any of the models. Calibration plots of the four models utilizing Epic readmission scores to predict 30-day unplanned readmission are provided in  which showed poor agreement between the predicted (from the models) and observed numbers of unplanned readmission.Receiver operating curves (ROCs) of the four models utilizing Epic readmission scores to predict 30-day unplanned readmission are provided in In contrast to previous reports evaluating the utility of the EPIC Unplanned Readmission Model 1 in predicting 30-day unplanned hospital readmissions conducted within DUHS on a variety of clinical service cohorts, we found poor discrimination ability among models utilizing maximum and discharge Epic readmission scores in predicting both all-cause and OPAT-related 30-day unplanned readmission in the DUHS OPAT cohort ,11. We bWhile the present study included one score per day, the Epic Readmission Risk Model V.1 calculates a readmission risk score every 4 hours for the hospitals within DUHS. The model variables include patient age, clinical diagnoses, laboratory values, medication numbers and classes, order types, and other healthcare use variables ,15. The Differences in patient cohorts between studies make comparisons difficult, even within OPAT populations . Such diThe fixed model and factor weighting may limit the utility of the EPIC model in predicting readmission in selected cohorts. Previous studies evaluating readmission risk models within the OPAT patient population have used prior hospitalizations in the preceding 12 months, concurrent IV antimicrobial therapy, type of infection and mode of OPAT treatment , 7, 8. WOther differences exist between the present study and prior reports. In the prior studies, the percentage of patients receiving OPAT was not specifically reported. Rates of 30- day hospital readmission may further be characterized by cause  and as planned or unplanned. Similar to several other studies and consistent with the application of the score, we first sought to characterize 30-day  unplanned readmission rates. Others have reported 7, 14, and 30 days and that the utility of the model declined after 7 days post-discharge . In addiThere are limitations to our evaluation worth discussion. The single-center nature of the study may limit generalizability to institutions without comparable OPAT populations. As previously discussed, we limited our characterization of the EPIC score to discharge and maximum Epic readmission scores in the predictive models. There could be other important predictors for unplanned readmission that we did not include in the study, such as service line . While hospital readmission data was limited to hospitals within the DUHS system, we feel the close patient follow-up provided by the OPAT service would have detected the unlikely admission to other healthcare facilities. Attribution of the readmission reason as related or unrelated to OPAT was made by the investigators. Since we intentionally chose the timing of the cohort selection to provide data free of the potential influence of the COVID19 pandemic on hospital admission and readmission rates, it is unknown whether such findings would be impacted by such extraordinary circumstances. Other investigators have reported EHR-based tools to predict hospital readmission risk in patients admitted due to COVID19 infection with similar or superior performance characteristics [The models incorporating maximum or discharge Epic readmission scores showed poor discrimination ability in predicting 30-day unplanned readmission in the DUHS OPAT cohort. Incorporating additional DUHS-specific variables, including age, vancomycin use before index discharge, IV drug abuse, and mode of OPAT delivery in a skilled nursing facility did not improve the discrimination ability. The models for predicting 30-day unplanned OPAT-related readmission performed slightly better but the discrimination ability was still poor. There remains something unique in the OPAT population influencing readmissions that is not captured in the standard readmission risk model (such as the Epic model) despite our attempts to improve the model’s discriminating ability by adding variables identified by other investigators. This may include factors such as such as the patients’ subjective needs and/or cost-of-care reimbursement. We believe that more research needs to be done to investigate what unique socioeconomic or clinical factors may be responsible for readmissions in the OPAT population.


Céline Bournonville, Kentaro Mori, and colleagues  found that ascorbate synthesis in tomato (Solanum lycopersicum) is regulated by a flavin-dependent photoreceptor named PAS/LOV Protein (PLP), which inhibits a key step in the pathway except when blue light is present (see Ascorbate (vitamin C) is an antioxidant found in fresh fruits and vegetables that is an essential nutrient in the human diet. The content of ascorbate fluctuates with environmental changes and can influence reactive oxygen species production. The high antioxidant capacity of ascorbate makes it a good target for breeding nutrition-dense fruits. Although the L-galactose pathway of ascorbate synthesis in plants is well established, little is known about how the pathway is regulated. In this issue, sent see ..Arabidopsis thaliana) display a dramatic decrease in ascorbate content and are unable to grow without exogenous application of ascorbate , a key enzyme of the ascorbate biosynthesis pathway . GGP-relscorbate . In addiPLP gene. By generating a plp mutant in wild-type tomato using CRISPR/Cas9, the authors established that the mutant shows high ascorbate content in all organs compared with wild-type plants, and PLP genetically functions as a repressor of ascorbate accumulation in tomato throughout multiple developmental stages. To address the mechanism of this regulation, the authors tested the possibility that PLP and GGP proteins interact first by examining their subcellular localization using transient expression in tobacco (Nicotiana - benthamiana) leaves. Confocal microscopy images showed that both proteins possess a dual residency pattern that marks both the nucleus and cytosol. Secondly, using the Bimolecular Fluorescence Complementation assay, they found that indeed PLP interacts with GGP in both the nucleus and cytosol. Moreover, this interaction was abolished using a truncated version of the PLP protein that lacks the blue light–sensing domain, suggesting that the PLP-GGP protein-protein interaction might be blue light dependent.Using a previously identified EMS mutant with increased ascorbate content , the autTo further investigate how the blue light–sensing LOV domain in PLP participates in this PLP-GGP interaction, the authors used a heterologous system in mammalian cells. Unlike the truncated PLP, a strong interaction was detected between full-length PLP and GGP in the dark, whereas the blue light exposure minimized the interaction. The use of this heterologous system suggested that no additional factor is required for the PLP-GGP interaction, providing evidence for the blue light–mediated interaction of the PLP and GGP. Further, using the activity assay in vitro, the authors showed that the blue light–mediated interaction inhibits GGP enzyme activity.Together,


The neuronal circuit disturbances that drive interictal and ictal epileptiform discharges remains elusive. Using a combination of extraoperative macro- and micro-electrode interictal recordings in six presurgical patients during non-rapid eye movement (REM) sleep we found that, exclusively in the seizure onset zone, fast ripples , but not ripples (80–200 Hz), frequently occur <300 msec before an interictal intracranial EEG (iEEG) spike with a probability exceeding chance . Such FR events are associated with higher spectral power (p<1e-10) and correlated with more vigorous neuronal firing than solitary FR  irrespective of FR power. During the iEEG spike that follows a FR, action potential firing is lower than during a iEEG spike alone , reflecting an inhibitory restraint of iEEG spike initiation. In contrast, ripples do not appear to prime epileptiform spikes. We next investigated the clinical significance of pre-spike FR in a separate cohort of 23 patients implanted with stereo EEG electrodes who underwent resections. In non-REM sleep recordings, sites containing a high proportion of FR preceding iEEG spikes correlate with brain areas where seizures begin more than solitary FR (p<1e-5). Despite this correlation, removal of these sites does not guarantee seizure freedom. These results are consistent with the hypothesis that FR preceding EEG spikes reflect an increase in local excitability that primes EEG spike discharges preferentially in the seizure onset zone and that epileptogenic brain regions are necessary, but not sufficient, for initiating interictal epileptiform discharges. Spikes are of primary importance in the diagnosis of epilepsy2, but also disrupt cognition3, and may, in some cases, promote the development of spontaneous seizures6. Epileptiform spikes, and their underlying neuronal correlates, are not uniform7. Moreover, spikes propagate as traveling waves9. Recent data suggests that epileptogenic brain regions may be identified by characterizing the spike initiation zone (SIZ) using precise source localization algorithms in intracranial EEG (iEEG)9. Little is known about what distinguishes spikes in the SIZ and what neuronal or macroscale neuronal network activity may prime an epileptiform discharge to occur next there.Spontaneous interictal epileptiform spikes  and ripples (80–200 Hz). Like spikes FR, recorded by macroelectrodes, do not generally occur in healthy brain tissue11, but unlike spikes FR are thought to better predict the development of chronic seizures in chemoconvulsant exposed animals12, and better identify the epileptogenic zone (EZ), that is necessary and sufficient for seizure generation in patients undergoing evaluation for epilepsy surgery13. The physiological counterpart to FR is ripples that play a role in normal brain function, and specifically the sharp-wave ripple complex in area CA1 of the hippocampus has been found to be essential for memory consolidation during non-REM sleep14. However, in chemoconvulsant animal models and in patients with epilepsy, ripples are generated at increased rates in and around the EZ15. HFOs can occur superimposed on the background EEG  or superimposed on an interictal epileptiform spike 17 and both are associated with ictogenesis in animal models19 and in vitro6 and in vivo20 recordings from epilepsy patients. However, fRonS and RonS may have increased accuracy for predicting epileptogenesis and localizing epileptogenic regions24. Recently, we reported that fRonO can also spatially propagate in epileptogenic regions within a range <30 mm at a velocity of ~1.54 mm/ms26 and interestingly, propagation increased the probability a fRonO was immediately followed by a spike. These data suggest excitability associated with fRonO could help generate spikes, but the neuronal activity contributing to fRonO and ensuing spike has not been studied.High-frequency oscillations (HFOs) also are considered biomarkers of epileptogenic brainTo better understand and possibly establish a link between fRonO events and after-going spike probability we investigated the neuronal and network activity associated with these events in patients with medically refractory focal epilepsy undergoing pre-surgical evaluation with paired macro- and microelectrode implants. We compared neuronal action potentials (AP) with the properties of HFOs and corresponding local iEEG spikes, as well as HFO-spike temporal coincidence . Our res28. Sleep studies were conducted in the epilepsy monitoring unit 48–72 hr after surgery and lasted 7 hr on average, and sleep-wake stages were scored according to established guidelines. The montage included two EOG electrodes; two EMG electrodes scalp electrodes at C3, C4 Pz, and Fz; two earlobe electrodes used for reference; and continuous video monitoring. In each patient, 8–12 depth electrodes were implanted targeting medial brain areas. Both scalp and depth interictal intracranial EEG (iEEG) data, from the most medial depth electrode macroelectrode contact, were continuously recorded, during slow wave sleep, with a Stellate amplifier at a sampling rate of 2 kHz, bandpass-filtered between 0.1 and 500 Hz, and re-referenced offline to the mean signal recorded from the earlobes. Each electrode terminated in eight 40-μm platinum-iridium microwires from which extracellular signals were continuously recorded  at a sampling rate of 28 kHz using a Neuralynx Cheetah amplifier and bandpass-filtered between 1 and 6000 Hz.All data were acquired with approval from the local institutional review board (IRB) at University of California Los Angeles (UCLA) and Thomas Jefferson University (TJU). The paired macroelectrode-microelectrode recording cohort was recorded from six patients with focal epilepsy at UCLA who were implanted for the purpose of localization of the SOZ in 2009–201029. Inclusion criteria for this cohort included pre-surgical MRI for MRI-guided stereotactic electrode implantation, as well as a post-implant CT scan to localize the electrodes, and stereo EEG recordings during non-rapid eye movement (REM) sleep at a 2 kHz sampling rate, and a post-resection/ablation MRI. Patients with no adequate post-operative clinical follow up, or a failure to record at least ten minutes of artifact free iEEG during non-REM sleep were excluded. Eligible patients were identified through queries of preexisting clinical databases. Post-implantation CT scans were co-registered and normalized with the pre-implant and post-resection MRIs using Advanced Neuroimaging Tools (ANTs) (https://picsl.upenn.edu/software/ants/) with neuroradiologist supervision, using an in-house pipeline31. The position of each electrode contact was localized to normalized MNI coordinates. For each patient, in the resection cohort clinical interictal iEEG  was recorded from 8 to 16 depth electrodes, each with 7–15 contacts, using a Nihon-Kohden 256-channel JE-120 long-term monitoring system  during epochs containing mostly high amplitude slow and delta oscillations. A larger number of electrodes with more contacts were implanted at TJU. The reference signal used for the recordings performed at UCLA was a scalp electrode position at Fz in the International 10–20 System. The reference signal used for the TJU recordings was an electrode in white matter.The retrospective resection cohort used consecutive recordings selected from 8 patients who underwent intracranial monitoring with depth electrodes between 2014 and 2018 at UCLA and from 15 patients at the Thomas Jefferson University (TJU) in 2016–2018 for the purpose of localization of the SOZ32. Unit stability throughout sleep recordings was confirmed by verifying that spike waveforms and inter-spike-interval distributions were consistent and distinct throughout the night. HFOs and sharp-spikes were detected in the non-REM sleep iEEG using previously published methods34 (https://github.com/shenweiss). HFOs in the microwire LFP recording were not subject to analysis, minimizing the chance that high-frequency events such as fast ripples may be influenced by leakage from action potential events35. A two-stage algorithm first used a custom Hilbert based detector implemented in Matlab with artifact rejection features to identify transient elevations in ripple (80–200 Hz) and fast ripple (200–600 Hz) amplitude33. In the second stage, the different HFO types: (1) ripples on oscillations (RonO); (2) ripples on spikes (RonS); (3) fast ripples on oscillations (fRonO); (4) fast ripples on spikes (fRonS), and (5) sharp-spikes without a HFO were distinguished using the topographical analysis of the wavelet convolution36. In brief, this method distinguished HFOs on spikes by comparing onset of the outermost closed-loop isopower contour of the HFO in the time-frequency spectrogram with onset of the outermost open-loop isopower contour of the spike and determining if the latter occurred earlier. Open-loop contours without closed loop contours were designated sharp-spikes without HFOs. This method also identified the spectral content, power, and duration of each HFO. Ripples and fast ripples were distinguished by the mean frequency of the closed-loop contour group, and peak spectral content and power from the largest isopower contour value in the closed-loop contour group. Duration was computed from the onset and set of the outermost contour in the closed-loop contour group. Compared to visual analysis of two reviewers, HFO and spike detection sensitivity and accuracy of event detection, using this method, was typically 80–90%34. Following automatic detection of HFO and sharp-spikes, false detections of clear muscle and mechanical artifact were deleted by visual review in Micromed Brainquick. This methodology did not detect bluntly contoured spikes, with no corresponding power signature >80 Hz, and sharp-waves.Action potentials were detected by high-pass filtering the local field potential (LFP) recordings above 300 Hz and applying a threshold at 5 SD above the median noise level. Detected events were further categorized as noise, single-unit, or multiunit events using superparamagnetic clusteringTo calculate the latency, within individual iEEG channels, between HFOs on oscillations and after-going epileptiform spikes, the onset times of all spikes, or a subtype of spikes, were subtracted from the onset time of each individual HFO on oscillation to find the minimum latency greater than zero. To determine if the distribution of these latencies exceeded chance, the number of HFO on oscillations were kept constant but the onset times of the HFOs on oscillations across the recording time were uniformly randomized within artifact free epochs and resampled 500 times within each individual iEEG channel and across all iEEG channels.i.e., bl-fr). The mean was used, as opposed to the median, to avoid bias towards the isolated single units with low firing rates. The peak HFO-unit firing rate was defined as the maximum of the Gaussian smoothed AP train rate during the duration of the HFO event , and another value hfodiff-fr was defined as hfofr minus bl-fr. During RonS and fRonS the peak firing rate during the epileptiform spike was invariably during the superimposed HFO17. Since we wished to examine the factors that reliably modulate AP firing during HFO events, we excluded units from the model that did not significantly change in firing rates during the HFO events. Often this occurred because few HFO events were detected in the unit’s corresponding macroelectrode recording. Thus, a paired t-test was used to compare the bl-fr with the hfo-fr for each type of HFO event, across all trials, but within units. If the p value exceeded 0.001 after controlling for the Holms-Bonferroni false-discovery rate (f.d.r.) the unit was excluded from the generalized linear mixed-effects models (GLMMs) analysis.All the RonO, fRonO, RonS, or fRonS events detected in a single macroelectrode contact’s recording were individually compared with the corresponding action potentials (APs) from each individual unit isolated from the LFPs recorded from the bundle of microelectrodes distal to that macroelectrode (within <~4mm). Within each individual unit, for each macroelectrode HFO event, a trial was generated consisting of a two second raster centered at the onset of the HFO event with a resolution of 1 ms ,2A. Thisi.e., unit numbers did not repeat across different macro-microelectrode pairs). Fixed effect included the log10 recorded in the macroelectrode, and whether the RonO or fRonO preceded (<300 ms) an epileptiform spike or whether a RonS or fRonS followed (<300 ms) a RonO or fRonO in the macroelectrode recording. At most, each GLMM included only two fixed effects, including HFO power, with a single interaction term. The categorical neuroanatomical location of the unit was not used as a fixed effect because the unit identifier was included as a random effect.The data for the GLMMs consisted of all the combined HFO event-unit AP train trials across all units, macroelectrodes, and patients. For each category of HFO, the GLMMs fit the bl-fr or the hfodiff-fr using a Gaussian distribution, a log link, a fixed intercept, and the maximum quasi-likelihood method in Matlab using the fitglme.m function. Random effects included the unit identifier, macroelectrode contact identifier, and patient identifier. All these identifiers were distinct (https://itk-snap.org) prior to performing calculations29. The SOZ and resected ratio was calculated, within patients, as the number of HFO events detected from the SOZ or resected contacts, respectively, divided by the total number of detected HFO events. The fast ripple rate-distance radius difference was calculated by first deriving the rate (events/min) of all fRonS events and the fRonO events with a peak spectral frequency > 350 Hz per contact and then computing an adjacency matrix as the average rate between contact pairs multiplied by the Euclidian distance (mm) between the contact pairs. A second adjacency matrix was computed using only contacts in the resection margins. The charpath.m function  was used to calculate the radius of these scaled distance graphs and the radius difference was defined as the √ 29.With respect to seizure outcome following surgery, Engel class 1 refers to freedom from disabling seizures, Engel class 2 to rare disabling seizures, Engel class 3 to worthwhile improvement in seizures, and Engel class 4 to no worthwhile improvement. The epileptologist defined SOZ contacts were aggregated across all seizures during the entire iEEG evaluation for each patient. The identification of the named electrode contacts in the resection cavity was performed manually in itk-SNAP  from 217 units in 175.95 iEEG contact-hours of synchronized macroelectrode and microelectrode recordings during N2/N3 sleep , one with MTLE and neocortical epilepsy, one with neocortical epilepsy, and one with an unknown site of seizure onset. Each of the depth electrodes in these patients contained a bundle of 8 microelectrodes extending beyond the distal tip that was positioned in mesial temporal lobe or medial neocortical structures 27. We isN3 sleep . Second,N3 sleep 29. Many ure free .26. We defined iEEG spikes as either fRonS, RonS, or sharp-spikes (no fast ripple or ripple) which accounted for 19.8, 71.5, and 8.7% of all spikes, respectively. We compared peak firing during the fRonO and RonO events to a baseline epoch defined as beginning 750 ms before the events. We then asked if there was differential AP firing accompanying fRonO and RonO that preceded spikes versus solitary fRonO and RonO, i.e., without subsequent spike. Based on results from our prior investigation of fRonO and epileptiform spikes we defined fRonO and RonO preceding spikes as occurring within <300 msOf the 217 units, 80 and 174 increased their firing rate during the fRonO and RonO , respectively, irrespective of coincidence with spikes, and no units decreased their firing rate during either HFO. Among the aforementioned units that increased firing during HFO with respect to baseline, we found higher peak firing rates, with respect to baseline, correlated with higher HFO power  of all fRonO  a iEEG spikes . BaselinWhen a RonO preceded a spike, the RonO spectral power was higher than the power for a solitary RonO, but the effect size was smaller than fRonO preceding a spike  aligned trials  of fRonS . We assumed that if fRonO prime fRonS or RonS, then rate of fRonO should exceed the rate of fRonS or RonS in the SIZ. To test this we calculated the ratio of fRonS to fRonO and RonS to fRonO occurrences in one-minute bins in the SOZ. We found the ratio fRonS to fRonO was less than one, but RonS to fRonO was greater than one . We next37.Extending the results from the preceding paragraph we assessed fRonO preceding all spikes  in relation to the clinical SOZ and seizure outcome in a separate cohort of 23 patients who underwent resections. For each patient we computed the SOZ ratio defined as the proportion of fRonO preceding spikes on macroelectrode contacts in the SOZ contacts to the total macroelectrode contacts in SOZ and non-SOZ. The SOZ ratio of fRonO preceding spikes was greater than the SOZ ratio of solitary fRonO  and weights them by the spatial distance between the generator sites. Using this measure we found significantly lower residual fast ripple rate-distance in the 10 seizure free patients  spikes is statistically more common than chance, and that fRonO preceding spikes correspond with increase neuronal excitability, which could help generate an ensuing spike. We also found during the spike, neuronal firing was reduced, which could associate with an inhibitory restraint that has been demonstrated in preventing interictal spike propagation42. We extrapolated on these mechanistic findings in a larger cohort of patients who underwent resections and found that fRonO preceding spikes were generated in regions defined as the epileptogenic SOZ by the clinician that were subsequently resected, which supports fRonO preceding spikes demarcating a SIZ37. However, resecting the SIZ did not correlate with seizure free post-operative seizure outcome which suggests that epileptogenic regions are necessary but not sufficient for spike generation.Bridging prior work demonstrating that HFOs preceding spikes have increased neuronal firing rates43, although measurements of spectral power are confounded by differences in the distance from the generator to the electrode contact44. The fRonO preceding spikes exhibited higher associated firing rates than solitary fRonO while the corresponding spectral power of these fRonO events was much greater than solitary fRonO events. This suggests that a network effect involving macroscale neuronal recruitment is partly responsible. However, after controlling for increased fRonO power, the firing rates associated with pre-spike fRonO were still increased as compared to solitary fRonO. We also found that baseline firing rate was negatively correlated7 with the power of most forthcoming HFO types. A plausible explanation is that excitatory and inhibitory balance changes in neuronal ensemble activity, perhaps related to the UP and DOWN states, may also be predictive of a forthcoming HFO. We did not distinguish putative excitatory from inhibitory single units in this study but a prior investigation of the single unit correlates of epileptiform discharges found no difference in the firing properties of excitatory and inhibitory single units7. Together, these findings may help better explain the changes in network properties responsible for HFO and spike generation17 and spike priming by fRonO.A novel finding of our study was the strong correlation between increased spectral power of HFO and corresponding peak unit firing rates during the HFO. The HFO spectral power can reflect the recruitment of a larger pool of neurons for HFO generation in pathological regions17. The most likely explanation is our use of a Gaussian kernel and a peak firing measure to estimate AP trains, which may also explain why we did not identify units that decreased in firing during HFO spike17. Importantly all the studies of the firing rate during interictal discharges measured from in vivo recordings in patients show that they are substantially less than that reported in human cortical slices45, and much less than in chemoconvulsant treated animals47.We observed that the mean firing rate of the grand average of all fRonS and RonS event-unit AP trains more than doubled from baseline during the fRonS/ RonS. However, the overall firing rates were lower than that reported in similar investigations48. Thus, it is possible that decreased excitability during a fRonS/RonS is a result of the preceding fRonO or RonO alone. However, when RonS followed RonO decreased excitability was not observed in the baseline firing rate but was observed only during the RonS. This dissociation suggests that the decreased firing rate could not have resulted exclusively from RonO generation. Also, the decreased excitability during the fRonS following fRonO was more statistically significant than the decreased excitability seen during the baseline epoch preceding the fRonS. One interpretation is that decreased excitability during HFO spikes following RonO and fRonO results from an inhibitory restraint mechanism initiated during or just after priming. Inhibitory restraint of spike propagation has already been well established in animal models42, but its importance in spike initiation is less clear.In our study, when an fRonS/RonS followed a fRonO it exhibited decreased baseline AP firing before the event and decreased AP peak firing at the time of the event. We also observed, but did not quantify, that following the generation of all the HFO types, unit firing rate decreased for at least 500 msec. A recent study found that following fRonS generation a decreased in firing rates is seen even spatially far from the generatorAlthough evidence for inhibitory restraints was seen for RonS followed by a RonO, we think it is more likely that fRonO prime spikes and less often RonO, because RonO preceded spikes less than chance, and exhibited no associated changes in excitability when they preceded spikes. Together, the results imply that HFO spikes that follow fRonO exhibit decreased excitability due to an inhibitory restraint mechanism functioning to prevent spike initiation.26. Here we could not relate fRonO propagation to unit firing activity because iEEG recordings were only available from the mesial most electrodes. However, we found that fRonO that precede epileptiform spikes by <10 ms may be distinct from fRonO that precede spikes by 10–300 ms neration 29 and su37, although this was not the case in another study utilizing microelectrode arrays instead of macroelectrodes8. It will be necessary in the future to combine fRonO and spike coincidence analysis with iEEG spike source localization analysis to determine if the location of the SIZ is agreed upon.A limitation of our study is that source localization, employing the temporal ordering of discharges, was not used to identify the SIZ because it required distinct methods for isolating bluntly contoured discharges. Two studies implementing this method similarly localized the SIZ to epileptogenic regionsWe show that the generation of a fRonO, reflecting increased neuronal excitability, primes the generationof an after-going spike within an epileptogenic region. Additionally, during the initiation of this subsequent spike, excitability is reduced relative to solitary spikes. This likely reflects an inhibitory restraint that is well established for preventing the spatial propagation of spikes. In a clinical context, our results show that epileptogenic regions are necessary but not sufficient for spike generation. This is important in current practice because strategies to localize and resect just the SIZ or SOZ alone may not always succeed because of the possibility of a residual EZ. In future practice it may be possible to prevent both spikes and seizures by pharmacologically or electrically inhibiting the occurrence of fRonO.Supplement 1