The socioeconomic status (SES) gradient in hospital and emergency room utilization among adults with type 2 diabetes (T2DM) is partially driven by cost-related non-adherence.To test the impact of the Diabetes Health Plan (DHP), a diabetes-specific health plan incorporating value-based insurance design principles on healthcare utilization among low-income adults with T2DM.To examine the impact of the DHP on healthcare utilization, we employed a difference-in-differences (DID) study design with a propensity-matched comparison group. We modeled count and dichotomous outcomes using Poisson and logit models, respectively.Cohort of adults (18–64) with T2DM, with an annual household income <$ 30,000, and who were continuously enrolled in an employer-sponsored UnitedHealthcare plan for at least 2 years between 2009 and 2014.The DHP reduces or eliminates out-of-pocket costs for disease management visits, diabetes-related medicines, and diabetes self-monitoring supplies. The DHP also provides access to diabetes-specific telephone case management as well as other online resources.N = 1732), any emergency room utilization (N = 1758), and any hospitalization (N = 1733), within the year.Number of disease management visits (p < 0.001), on average, than comparison beneficiaries. Models for emergency room  and hospital utilization  did not demonstrate statistically significant changes associated with DHP exposure.DID models predicting disease management visits suggested that DHP-exposed beneficiaries had 1.7 fewer in-person disease management visits per year (− 1.70 , While no relationship between DHP exposure and high-cost utilization was observed in the short term, fewer in-person disease management visits were observed. Future studies are needed to determine the clinical implications of these findings. Cross-sectional studies have demonstrated a negative relationship between medication adherence, emergency room utilization, and hospitalizations.7The prevalence of diabetes has increased over the past two decades in the USA, disproportionately affecting populations with low incomes. Between 2011 and 2014, compared with persons with high income, the relative percentage increase in diabetes prevalence was 40.0%, 74.1%, and 100.4% for those classified as middle income, near poor, and poor, respectively.8 Observational studies of the utilization implications of health insurance plans incorporating VBID principles among the broader patient population have demonstrated reductions in emergency room utilization and hospitalization among these beneficiaries; however, it is not clear that these findings can be extrapolated to populations with low SES.9 There may be differences in health literacy, self-management knowledge, access to primary care, and other social determinants of health that translate into different healthcare utilization implications of these types of health insurance plans among the subpopulation with low socioeconomic status.10 Given the upfront costs to insurers of incorporating VBID principles into health insurance plans and associated costs due to increases in medication adherence, it will be important to have information regarding how healthcare utilization may be impacted among one of the most affected subpopulations of beneficiaries. The objective of this study is to examine the impact of the Diabetes Health Plan (DHP), , on healthcare utilization among beneficiaries with low household incomes .Methodologically rigorous studies suggest that health insurance plans that incorporate value-based insurance design (VBID) principles such as lowering out-of-pocket costs for medications used to treat chronic disease may be particularly effective for improving medication adherence among patients with low SES, but few studies have evaluated the healthcare utilization effects of such plans among this subpopulation. Choudhry et al. found that a randomized control trial in which patients with a recent myocardial infarction were randomized to either a health insurance plan that eliminated co-insurance, copayments for disease management visits, and copayments for secondary prevention medications, or usual health insurance coverage, reduced racial/ethnic disparities in major vascular events or revascularization among the intervention group.12 The DHP also provides access to diabetes-specific telephone case management as well as other online resources. Additionally, the DHP provides scorecards with reminders to complete health maintenance activities, such as biannual hemoglobin A1C and cholesterol screening and an annual retinal eye exam. Overall, the DHP provides between $150 and 500 in annual out-of-pocket savings for enrollees.13 The DHP standard benefit design can be modified by purchasing employers to better suit the needs of beneficiaries, which include both employees and their dependents. Uptake of the DHP, across employers, has spanned the years since 2009 and varied across years. Some employers use an opt-in enrollment strategy (employees must choose to participate) while others use an opt-out strategy . Studies have shown that DHP uptake can range from a low of 8% among opt-in plans to a high of 85% for opt-out plans.14 Additionally, studies have shown variability in the demographic characteristics of DHP participants as a consequence of the enrollment strategy. Specifically, Kimbro et al. found that DHP participants enrolled in an opt-out plan were more likely to be dependents, were more racially and ethnically diverse, and had a broader range of incomes and educational backgrounds relative to participants enrolled in opt-in plans, who tended to have higher incomes and more education and who were less likely to be Hispanic.12 Studies have previously demonstrated the beneficial impact of the DHP on medication adherence and emergency room utilization among the broader cohort of beneficiaries.15 However, the results of studies examining the effects of the DHP among low-income beneficiaries have been mixed. Huang et al. found no relationship between the DHP and medication adherence among beneficiaries with household incomes of $50,000 or less.16 While Narain et al. found that the DHP was associated with improved adherence to oral hypoglycemic medications among beneficiaries with household incomes $30,000 or less and low baseline medication adherence.17In 2009, UnitedHealthCare (UHC) introduced the DHP which includes financial incentives to encourage patient engagement in evidence-based diabetes care, including reduced or eliminated out-of-pocket patient expenses for disease management visits; free diabetes self-monitoring training and supplies; and reduced or eliminated out-of-pocket expenses for diabetes-related medicines Table .11,12 ThThe analytic data set is limited to 26 large employer groups that purchased the DHP and standard benefit plans from UHC (2009–2014) that have (1) internal pharmacy contracts, (2) complete pharmacy claims data, (3) sufficient medical claims and lab data to identify employees with type 2 diabetes (T2DM), and (4) fewer than 15% of employees enrolled in high deductible health plans. In addition to the above-mentioned criteria, the DHP employer groups must have at least 1 year of standard benefit plan data, prior to the purchase of the DHP, and comparison employer groups are further limited to those that have overlapping propensity scores with DHP employers after employer-level matching (described further below) and who have at least 2 years of continuous enrollment in the standard benefit plan during the duration of the match to the DHP employer.AmeriLINK data.18 This data source incorporates consumer financial survey responses, publicly available information , and zip-code-level information from the Internal Revenue Service to generate individual-level estimates of household income. The sample size flow chart for the unique DHP and comparison beneficiaries are shown in Figures A diabetes diagnosis was defined as having any of the following prior to the implementation of the DHP: 1) at least one 250.X ICD-9 diagnosis code from an inpatient, outpatient, or emergency department claim; (2) hemoglobin A1C laboratory value of 6.5% or greater or a 2-h value on an oral glucose tolerance test of greater than 200 mg/dl; or (3) at least one prescription fill for an oral hypoglycemic medication other than metformin or insulin. Estimated household income is obtained from the  at least19 The employer and beneficiary matching was done using PROC PSMATCH in SAS version 9.4.Matching criteria for both the DHP and comparison employers were derived with respect to the 12-month period preceding the date of DHP adoption for the DHP employers or standard insurance plan contract renewal (the index date). The matching criteria included the following as reported by UHC: average employee salary, geographic region, number of employees, % female, % in each racial/ethnic category , health benefit plan generosity, % of employees with a HDHP, and % of beneficiaries with each one of the following claims-based co-morbidities  as well as the index date. A single comparison employer could be matched to more than one DHP employer. Individual-level matching criteria were based on the following pre-index date criteria: race and ethnicity, age, gender, Charlson Comorbidity Index, insulin use status, presence of any diabetes complication , and baseline healthcare utilization. Nearest-neighbor matching was conducted with replacement using a caliper equal to 25% of the propensity score standard deviation, in an effort to get 3 comparison matches for each DHP beneficiary.20 We treated emergency room and hospital utilization as dichotomous variables. Both variables were indicators coded as “1” if the utilization was present during the post-period year and coded as “0” if the utilization was not present. These utilization outcomes were not restricted to those exclusively related to diabetes.We coded “disease management visits” as a count variable based on the composite number of outpatient visits with providers who may perform diabetes management during the course of a visit . Patients with an unusually high number of disease management appointments in the baseline year were excluded from this analysis prior to matching using the 1.5 interquartile range heuristic for identifying outliers.21 If the parallel trend assumption is met, any difference in the pre-post intervention change in slope across treatment and comparison groups is attributed to intervention effects. We use the propensity-matched sample to increase the likelihood that the DHP and comparison groups have a similar trend of utilization during the pre-intervention time period.22 Non-linear statistical models were run for each of the utilization outcomes using the PROC GENMOD procedure in SAS. The model used for disease management visits employed a Poisson distribution with a log link function, and binomial logit models were used to model emergency room and hospital utilization. These models include an indicator for time (post-index vs. pre-index) that was coded as “1” if the observation was from the post-index year and coded as “0” if the observation was from the pre-index (baseline) year, and an indicator for group (DHP group vs. comparison group) that was coded as “1” if the observation was from the DHP group and coded as “0” if the observation was from the comparison group and the interaction between time and group, among our matched samples. Specifically, the between-group differences in the change of the outcome variables, post-index, were estimated by the interaction effects.We used a DID study to examine the impact of the DHP on utilization. The key assumption of the DID study is the parallel trends assumption which necessitates that the pre-intervention trends for outcome measures across the treatment and comparison groups are the same.12We conducted an additional test to assess the sensitivity of our results to selection bias by repeating the above-mentioned analyses with DHP employers that use an opt-out enrollment strategy as the sole source of the treatment population. This methodological change should allow for evaluation of the DHP utilization effects among a less motivated subset of beneficiaries than the subset including individuals that proactively enrolled in the DHP.19The final analytic samples were 1732, 1758, and 1733 matches with replacement for disease management visits, emergency room use, and hospitalizations, respectively. Across all three samples, prior to matching, the DHP sample was older, had a higher proportion of females, was more likely to be non-Hispanic Black, was more likely to have a diabetes complication, and had a higher Charleston Co-morbidity Index Tables . Post-map < 0.001; Table p = 0.966) and hospital utilization  did not demonstrate statistically significant changes associated with DHP exposure. In sensitivity analyses including only employers enrolling DHP beneficiaries using an opt-out strategy as the treatment population, once again, we find a negative association between DHP exposure and disease management visits, with DHP beneficiaries visiting providers 2.0 fewer times, on average, 1 year after exposure compared to controls , but no association with emergency room  or hospital utilization  and low baseline medication adherence found by Narain et al. makes this explanation less likely.15 These differences may stem from differences in the study designs. Specifically, differences between the study populations used in the Moin et al. study and this study include analysis of beneficiaries of all income levels rather than an emphasis on beneficiaries with low household incomes and inclusion of beneficiaries with both pre-diabetes and diabetes while we restrict our sample to beneficiaries with diabetes. Additionally, the Moin et al. study findings are based on an employer-level analysis rather than an individual-level one. As such, they propensity score match at the employer level while we propensity score match at both the employer and individual levels.Our results for ER utilization diverge from that of the Moin et al. study which find reductions in ER utilization associated with DHP exposure.The study results must be viewed in the context of some important limitations. A key underlying assumption of the DID approach is that secular time trends for the DHP-exposed and comparison beneficiaries do not differ in the pre-treatment time period. We use propensity score matching in an effort to ensure similarity of pre-treatment secular time trends across the DHP-exposed and comparison beneficiaries, but this strategy does not account for differences in unmeasurable factors. Our study approach also reflects an intent-to-treat design which may result in beneficiaries without DHP insurance coverage being included in the treatment population. Consequently, DHP effect estimates may be biased towards the null. However, this intent-to-treat design reduces the risk of selection bias being a plausible explanation for our results. Additionally, given that our data source is claims data, we lack data on health outcomes that could be valuable for providing context to the study results. Lastly, our results also reflect average effect estimates for the DHP. As such, effects may vary across DHP implementation strategies.9 In light of the DHP-associated benefits for medication adherence found by Narain et al., studies with a larger sample size, which can stratify populations across co-morbidity level and which can follow DHP-exposed and comparison beneficiaries over a longer time horizon, may find more favorable results.17 Nonetheless, we do find a negative association between DHP exposure and reduced disease management visits which may engender some cost savings that can be used to offset the cost of implementing the program. Additionally, fewer in-person disease management visits may translate into less missed work and higher levels of employee productivity, potentially leading to indirect cost savings for employers associated with the DHP in a relatively short time frame.24We do not find changes in emergency room and hospital utilization among DHP-exposed beneficiaries with low household incomes. These null findings may be attributable to a relatively healthy and young study population in addition to a relatively short duration of follow-up.We used strong quasi-experimental studies and administrative/pharmacy claims data to evaluate the effect of the Diabetes Health Plan  on healthcare utilization among beneficiaries with household income ≤ $30,000 and found a negative association between DHP exposure and disease management visits but no relationship with emergency room or hospital utilization. Future studies are needed to determine if the associated reduction in disease management visits reflects improved diabetes management or reduced access to care.


Excess mortality is an indicator of the impact of the coronavirus disease (COVID-19) pandemic. This study aims to describe excess mortality in the Philippines from January 2020 to December 2021 using an online all-cause mortality and excess mortality calculator.All-cause mortality data sets from 2015 to 2021 from the Philippine Statistics Authority were obtained and analysed using the World Health Organization Western Pacific Regional Office All-Cause Mortality Calculator. Expected mortality, excess mortality and P-scores were obtained using two models, 5-year averages and negative binomial regression, for total deaths and by administrative region.Reported national all-cause mortality exceeded the expected mortality in August 2020 and from January to November 2021, peaking in September 2021 at 104 per 100 000. Total excess mortality using negative binomial regression was −13 900 deaths in 2020 and 212 000 deaths in 2021, peaking in September 2021. P-scores were −2% in 2020 and 33% in 2021, again peaking in September 2021 at 114%. Reported COVID-19 deaths accounted for 20% of excess deaths in 2021. In 2020, consistently high P-scores were recorded in the National Capital Region from July to September and in the Bangsamoro Autonomous Region in Muslim Mindanao from June to July. In 2021, most regions recorded high P-scores from June to October.Tracking excess mortality using a robust, accessible and standardized online tool provided a comprehensive assessment of the direct and indirect impacts of the COVID-19 pandemic in the Philippines. Furthermore, analysis by administrative region highlighted the key regions disproportionately affected by the pandemic, information that may not have been fully captured from routine COVID-19 surveillance. The coronavirus disease (COVID-19) pandemic has been ongoing since March 2020 and, as of early January 2023, there have been more than 666 million reported cases and more than 6.7 million reported deaths globally. . Country data on mortality are available from both the Philippine Statistics Authority (PSA) and the Department of Health (DOH). The PSA data are obtained from death certificates, whereas the DOH data are obtained from mortality reports sent to the DOH Epidemiology Bureau.  is an open-source online tool developed to calculate expected all-cause mortality, excess mortality and P-scores from mortality data. All-cause mortality can also be calculated by age, sex and administrative state or region if the disaggregated mortality data are indexed in the calculator. The results can then be displayed using tables and graphs. The ACM Calculator estimates excess mortality and P-scores using two approaches: historical 5-year averages (5YA) and a non-parametric negative binomial regression (NBR) model.  using data generated by the ACM Calculator.Mortality data from publicly available PSA reports  for the counts is modelled asc(t) is the annual cycle in all-cause mortality, modelled as a piecewise cyclic cubic spline function, trend(t) is the non-cyclic cubic spline function of all-cause mortality over time, and Xt is for arbitrary time-varying covariates.where Excess mortality. Excess mortality was calculated using the formulaand values were calculated per region and per month for 2020 and 2021. Excess mortality counts were computed using both 5YA and NBR expected mortality.P-scores of excess mortality. P-score was calculated using the formulaand is expressed as percentages. These values were calculated per region and per month for 2020 and 2021 and were also computed using both 5YA and NBR expected mortality.Total excess mortality and P-scores were calculated using both 5YA and NBR expected mortality. However, only NBR was used to calculate excess mortality and P-scores per administrative region due to its increased accuracy and adoption by WHO.Reported COVID-19 deaths per month for 2020 and 2021 were also extracted from the WHO coronavirus (COVID-19) dashboard. . The reported mortality for the Philippines exceeded the upper bound of the expected mortality in August 2020 and from January to November 2021, while mortality was lower than expected in March and April 2020 and in December 2021 .In 2020, reported mortality in the Philippines peaked during August at 52 per 100 000 population, with the lowest mortality rate reported in April at 41 per 100 000. In 2021, the peak occurred in September at 104 per 100 000, with the lowest rate observed for December at 44 per 100 000 .The ratio of reported COVID-19 deaths to calculated excess mortality was −66% in 2020 and 20% in 2021, the latter suggesting that reported COVID-19 deaths in the country only accounted for about 20% of excess mortality in 2021. Monthly ratios ranged from −360% in October to 142% in September of 2020 (interquartile range = 56%) and from −44% in December to 159% in November of 2021 (interquartile range = 15%)  reported positive excess mortality of 14 100 deaths or 105 per 100 000 in 2020, while all administrative regions reported positive excess mortality in 2021  averages and NBR. NBR models can be used for data with low or zero counts, and can account for overdispersion, seasonal fluctuations within a given year, secular trends in data, reporting delays and other time-sensitive covariates, such as internal and external movement of populations or periods with low reporting activities .  was closer to the estimate (184 000) from a 2022 global study (There were several limitations to this study. Mortality reporting systems do not cover all deaths, especially in low-resource settings, with civil registration of deaths noted to be as low as 20% in some low- and middle-income countries. (Analysing excess mortality provided a more comprehensive picture of the direct and indirect impacts of the COVID-19 pandemic in the Philippines. While the pattern of excess mortality was similar to reported COVID-19 deaths, the reported COVID-19 deaths only accounted for a small proportion of excess deaths. We therefore recommend incorporating excess mortality analysis during surveillance of similar events such as outbreaks and pandemics. Our analysis by administrative region highlighted the key regions disproportionately affected by the pandemic, which is information that may not have been fully captured from national COVID-19 surveillance. We recommend that excess mortality be calculated using age- and sex-disaggregated data, as well as other studies on the indirect factors that may contribute to excess mortality. Standardizing the methods of analysing and reporting excess mortality would assist in contextualizing information from different sources. We also recommend the use of open-source tools such as the ACM Calculator to monitor excess mortality especially in low-resource countries, as these tools can provide standardized and timely information that may help decision-makers to optimize the use of health resources and subsequently contribute to the achievement of Sustainable Development Goals in strengthening the capacity of developing countries for early warning, risk reduction and management of national and global health risks.


Bamboo fiber is a natural and environmentally friendly material made from cheap and widely available resources and is commonly selected as the reinforcement material for steel-wire-mesh BFRPbar concrete beams. In this work, the effects of various fiber lengths and fiber volume rates on the shear properties of bamboo-fiber-reinforced steel-wire-mesh basalt fiber composite reinforcement concrete beams were studied through a combination of shear tests and numerical simulations. The findings demonstrate that the addition of bamboo fiber improves the cracking performance of the beam. The improvement effect of 45 mm bamboo fiber mixed with a 1% volume rate was the most obvious at about 31%. Additionally, the test beam’s total stiffness was increased, and the deflection was decreased. However, the use of bamboo fiber was found to decrease the concrete’s compressive strength, lowering the final shear capacity for the majority of beams. A method for estimating the shear capacity of the bamboo-fiber-reinforced steel-wire-mesh BFRPbar concrete beams is provided and lays the foundation for engineering practice, in accordance with the impact of bamboo fiber and steel wire mesh on beams that suffer shear breaks. In the construction industry, a basalt fiber-reinforced polymer (BFRP) bar is a high-performance reinforcement material made by pulling, squeezing, and coiling basalt fiber materials and bonding them to the outer surface with epoxy resin. The fiber content of a BFRP bar usually ranges from 75% to 90% with tensile strength between 600 and 1500 MPa. Natural basalt fiber is corrosion resistant, non-toxic, environmentally safe, stable under high temperatures, and has insulating properties. Additionally, steel bars in concrete structures can be replaced with BFRP bars, which solves the corrosion problem ,3,4. TheFiber-reinforced concrete has many characteristics, such as strong earthquake resistance, excellent flexural and shear performance and the ability to improve the ductility and toughness of the components ,14,15,16Bamboo fiber composite materials are strong, wear-resistant, shock absorbing, heat insulating, environmentally friendly, lightweight, energy-saving, and cost-effective. Global forest cover and resource storage have decreased in recent years. However, bamboo area shows a stable growth trend, giving this material undeniably broad development prospects . ConsequThe test was conducted using concrete with a standard compressive strength of 40 MPa in cubic blocks and a strength rating of 42.5 for regular silicate cement. For coarse-grain material, we selected 5~10 mm continuous-graded gravel to facilitate passage through the wire mesh, improving the performance of the concrete. Medium sand was selected as the fine-grain material, as shown in 0 = 262 mm. To achieve shear failure of the test beam’s intended purpose, the test beam was reinforced longitudinally using three BFRP bars 20 mm in diameter, and two pieces of hot-rolled steel bars with a standard tensile strength of 300 MPa and a diameter of 8 mm were provided near the top of the beam as erection bars. The hot-rolled steel bars used for the hoops were 8 mm in diameter with a specified tensile strength of 300 MPa. They were evenly spaced at a distance of 100 mm along the whole beam. The section reinforcement is shown in The test was designed with eight test beams using the fiber length and fiber volume rate as variation parameters, as shown in Steel strain gauges were arranged in the middle of the span of the three basalt fiber composite bars at the bottom, as well as in the shear span area where the line between the support and the loading point intersected with the corresponding hoop reinforcement. The concrete strain gauge was arranged at the connection between the shear span support at both ends of each beam and the loading point. A DH3818Y strain tester was used to collect strain data. For monitoring the overall deformation of the beam, a displacement meter was placed in the middle span above the support and below the loading point.The test loading apparatus was chosen to be a model ZHP-300B 500 kN uniaxial electro-hydraulic servo loading system, as illustrated in All eight test beams presented shear compression damage. In the process of graded loading, under loading to the ultimate bearing capacity of 9~16% of the span in the tensioned area, there first appeared small vertical bending cracks .To a certain extent, the inclusion of bamboo fiber was found to improve the cracking load of steel-wire-mesh BFRP-bar concrete beams compared to L-0-0, as illustrated in Comparing specimens L-15-1, L-30-1, L-45-1, and L-60-1  is given by GB50010-2010 “Code for Design of Concrete Structures” [The shear capacity of stirrups Vfc=VThe longitudinal tensile steel bars are high-performance FRP bars made of basalt fiber, which have a different influence than ordinary steel bars on the shear capacity of the flexural members. The calculation formula for the inclined section shear capacity of FRP-bar concrete beams without abdominal bars, given by our specification GB50608-2010 “Application Technical Specification for Construction of Fiber Reinforced Composite Materials” , is as fVu of the bamboo fiber reinforced steel-wire-mesh BFRP-bar concrete beam can be obtained as follows:By substituting Formulas (8) into (7) and then substituting (5), (6), and (7) into (4), the final calculation formula of the oblique section shear capacity fλ as the horizontal axis and vβ as the vertical axis. The corresponding values of fλ and vβ when the oblique section of each specimen was damaged by shear were placed in the coordinate system, as shown in vβ = −1.972 under the packet line can be determined as the vβ value.The coordinate system was established with A comparison of the experimental and theoretical results of the shear ultimate bearing capacity of each test beam is presented in The ratio between the test value and estimated value, as shown in (1)After the bamboo fiber is added to the concrete, it functions as a reinforcement able to withstand tensile stress alongside the concrete, thereby postponing the onset of the concrete beam’s initial crack and enhancing cracking load. The improvement effect of 45 mm bamboo fiber mixed with a 1% volume rate was the most obvious at about 31%.(2)The inclusion of bamboo fiber can stop the crack from spreading further, lower the specimen’s stress at the crack point on the BFRP bar, and increase the beam’s overall stiffness, all of which work to lessen the deflection of the beam.(3)As bamboo fiber reduces the compressive strength of fiber-reinforced concrete, it has a slightly negative impact on the ultimate load of the beams. The largest drop, roughly 8.3%, was observed under a 1.5% volume ratio with the 45 mm bamboo fiber beam.(4)The findings of the numerical simulation are essentially in line with the outcomes of the experiments, which validates the accuracy of the numerical analysis methodology and establishes a basis for the simulation study of bamboo-fiber-reinforced steel-wire-mesh BFRP-bar concrete beams.(5)A formula was established to determine the shear load capacity of the bamboo-fiber-reinforced steel-wire-mesh BFRP bar and concrete beam oblique sections. The shear capacity of this type of member can be accurately predicted using this formula, which is straightforward in form and has excellent agreement with the experimental results. This formula also serves as a theoretical foundation for actual engineering work.This study examined concrete beams made of bamboo-fiber-reinforced steel-wire-mesh BFRP bar using shear testing and numerical modeling. The conclusions are as follows:(1)This study only considered long thin rod-type bamboo fibers. However, the bonding effects between different fiber shapes and substrate may be different, so more bamboo fiber shapes, such as bamboo filament types, bamboo piece types, and other shapes should be considered for future research.(2)Although plant fiber material is easy to obtain, it is also easy for it to become corroded in the concrete environment, so future research should be carried out based on two aspects: the processing of bamboo fiber surface and the modification of cement.(3)Wire mesh was woven from vertical and longitudinal wires, and the vertical wire portion more obviously improved shear performance. The effect of the wire mesh as a variable on the shear performance of the test beam, however, was not considered in this paper, so the improvement effects on shear performance after changing the size and material of the wire mesh could be considered in future work.Based on this paper, a few areas remain to be studied in depth:


Virtual libraries from external sources, however,may be associated with long delivery time and high cost. In this study,we present a Do-It-Yourself (DIY) combinatorial chemistry librarycontaining over 14 million almost completely novel products builtfrom 1000 low-cost building blocks based on robust reactions frequentlyapplied at medicinal chemistry laboratories. The applicability ofthe DIY library for various drug discovery approaches is demonstratedby extensive physicochemical property, structural diversity profiling,and the generation of focused libraries. We found that internallybuilt DIY chemical libraries present a viable alternative of externalvirtual catalogs by providing access to a large number of low-costand quickly accessible potential chemical starting points for drugdiscovery.The advancement of  The application of novel, diverse,and quickly accessible chemical screening libraries in early phasedrug discovery is essential for the identification of suitable chemicalstarting points and for effective hit-to-lead optimization. A largevariety of compound libraries exists for drug discovery. Some of themost important aspects that a drug discovery group should considerwhen selecting chemical libraries are novelty, cost, and acquisitiontime of the molecules.Pharmaceutical companies frequently buildan in-house inventoryof screening compounds. While this approach provides the shortestsample preparation time for physical screening and the highest availabilityrate , the large upfront investment and ongoing costs of acquiring,maintaining, and managing physical libraries of 100,000 or millionmembers makes this approach less feasible and sustainable for academicresearch groups and startups. Furthermore, the novelty of the librarymay be low if the samples are acquired from public supplier catalogs,or it is expensive to maintain if they are sourced from contract researchorganizations on an exclusive basis.2A different strategy isto acquire compounds from chemical supplierin-stock screening catalogs just before experimental screening. Thecompounds to be purchased can be selected based on virtual screeningresults; thereby, only the most promising virtual hits are acquired.Since the number of obtained samples is low, this approach is muchmore cost-effective. It does not require an upfront investment oflarge libraries, and the maintenance costs are marginal. Nevertheless,the lack of novelty in suppliers’ public catalogs presentsa risk in intellectual property management. The acquisition time ofthe samples may also highly vary due to the different locations ofthe supplier warehouses. Furthermore, the availability rate may alsodiverge by suppliers and catalogs. The management of multiple supplierscan also present a challenge, additional cost, and time; however,these may be overcome by the application of a chemical marketplaceproviding a one-stop-shop of all supplier catalogs.3 where the molecules are formed by up to 17 non-hydrogen atoms andare connected in accordance with their valence restrictions. Thereare other—yet smaller—databases that focus on the collectionof structures that were physically available once; hence, their syntheticfeasibility has been confirmed.5 The application of suchlibraries for screening purposes, however, is less practical, as whenresearchers find an interesting hit, it has to be decomposed withretrosynthetic tools6 or custom syntheticpaths have to be developed to acquire a physical sample; plus, thereis a chance to run into very complex, low-yield synthetic routes.The application of combinatorial chemistry,8 onthe other hand, has the potential to generate enormously large chemicallibraries10 based on predefined synthetic routes andavailable, in-stock building blocks. Numerous combinatorial approachesexist that combine building blocks with reaction rules to form newmolecules , designedby either academic and commercial groups, that differ primarily intheir accuracy of prediction, speed, and validation.12 Potential hits of such combinatorial libraries can be assigned toa robust, few-step synthetic route, and thus their synthesis can beexecuted on demand, costs can be precalculated, and the lead timecan be kept in an acceptable time frame due to the limited numberof applied robust reaction types/steps and to the high availabilityrate of the reagents. Such virtual libraries typically provide notablyhigher novelty than in-stock ones simply due to their size (some ofthe largest of such type libraries can reach the multihundred millionor even billion size of unique molecules), exemplified by Mcule ULTIMATE,11 WuXi GalaXi,14 orEnamine REAL.15Alternatively, one may rely on external suppliers’ virtualscreening libraries. Some virtual libraries can be highly valuablefor theoretical studies, such as GDB-17,Such external suppliervirtual catalogs earned significant attentionrecently as their provided novelty is exceptional, and their deliverysuccess rate and timeline improved significantly compared to earlierreleased virtual catalogs. Nevertheless their delivery times are stilllonger, and their pricing is also significantly higher than thoseof in-stock compounds.These drawbacks of external virtual librariesmight be overcomeby building the libraries internally in research groups with syntheticcapacity. The design of a relatively large and novel internal virtualchemical library may be built on a small number of low-cost buildingblocks that can be combined in 1–2 robust reaction steps. Thepotential advantage of such an approach is that it requires only asmall initial investment of low-cost reagents. Due to the low numberof necessary chemicals, the associated storage and maintenance costsare marginal compared to those of an internal stock library. The leadtime to produce the physical samples of the hits can be kept shortif only a few steps of robust reactions are applied. The concept ofsuch internal virtual libraries can be particularly interesting foracademic medicinal chemistry research groups with internal syntheticcapacity as well as for industrial members who can build up the libraryeither in-house or at an external synthetic partner.In thepresent study, we intended to demonstrate the viabilityof the above concept of building an internal virtual library basedon a limited number of low-cost reagents combined by robust reactionrules and the applicability of the library to various drug discoveryapproaches. The results demonstrate that large, exceptionally novel,and pharmaceutically relevant virtual chemical libraries can be builtup from simple reagents. The resulting virtual chemical library mightprovide an excellent starting point and a useful strategy to thosewho would like to start a general or a focused drug discovery programsee 1 involvi16 Structural errors can have a large negativeimpact on the results of in silico studies; thus,it can be beneficial to use a curated data set, such as the Mculedatabase, where registered compounds are already rigorously checked,standardized, and corrected.18 Commercially availablebuilding blocks at a price of less than 10 USD per 1 g were firstselected (4448 molecules). To generate the virtual chemical library,we applied two reaction steps using Mcule’s enumeration algorithmARCHIE11 with standard settings. The potentialchemical reactions were handed over to the enumerator algorithm asreaction SMARTS (SMIRKS)19 patterns. The algorithmthen checked whether any of the favored main reaction SMIRKS patterns and none of the unfavored side reaction patterns match . Finally,the SMILES20 representation of the productwas generated. In the first reaction step, both reagents were selectedfrom the original reagents set. In the subsequent second reactionstep, all the intermediates generated by the first step were allowedto react with any of the original reagents. This process yielded productsformed by three reagents in two consecutive reaction steps. Initialevaluation of the DIY building block set revealed that some of themost common reactive functions of the building blocks include amino-,hydroxy-, aryl halide, and carboxylic acid groups. Consequently, fourmain reaction categories were selected for the library enumerationthat are frequently applied by medicinal and synthetic chemistry laboratories21 and utilize the above functionalities.28 the most commonreaction type for which several mild reaction conditions are available.amide bond formation,24 which utilizes coupling agents and conditions similar to amide bondformation.ester formation between acids and alcohols,NAr—requiringan aromatic ring substituted by a halogen at an electron-poor location,25 with a simple base for the reaction; or Buchwald-Hartwig-typereaction that require catalytic systems28).reactions of heteroaromatichalides and nucleophiles,such as amines, alcohols, or thiols ,19 patterns whichwere being matched pairwise. If a match was found, it was furtherchecked against more than 100 other so-called “side reaction”patterns to avoid competitive reactions and byproducts. If only onematch was found and that was among our main reactions, the two moleculeswere allowed to form the product by the algorithm. Cases were allowedwhere the different conditions and additives  required for the reaction typesexcluded the possibility for the side reaction to occur, as a built-infunctionality of the ARCHIE algorithm. For example, in the case ofamidation as a main reaction, Suzuki coupling is not considered asa side reaction , while aliphatichalides are capable of forming byproducts. Similarly, some labilesubstructures are defined to avoid, for example, the decompositionof some esters.The required characteristics of the reagentsfor the above reactionswere defined as SMARTS2061 reagents out of the 4448 have turned outto be reactive inat least one of the selected reaction types. To identify the 1000most efficient reagents yielding the highest number of products atthe lowest total price, we used an iterative method. At each iteration,the “Reaction score” of each building block was calculatedas the number of potential end-products derived from the buildingblock divided by its price. The reagent with the lowest score wasexcluded after each iteration. The iterative process was carried outby a python script starting with the above selected 2061 buildingblocks yielding over 21 million synthesizable products. After thelast iteration, the best scoring 1000 building blocks were kept associatedwith 14,020,690 synthetically feasible products. The cheapest buildingblock had the price of 4.5 USD while the average and median priceswere 8.5 and 9.0 USD, respectively. Depending on the price of thebuilding blocks and the number of applicable synthesis steps, thetotal building block costs range from 9 to 30 USD.36 relevant to classification of drug discovery application using Openbabel37 on a 24/48 core machine with AMD EPYC 7401PCPU for 358 min: molar mass, log P, polar surfacearea (PSA), number of H-bond acceptors and donors , number of rotatablebonds (Nrotb), heavy atom count (HAC),number of rings, fraction of sp3 carbons, refractivity,number of aromatic rings, number of aliphatic rings, number of chiralcenters, acidic group count, basic group count, acidic plus basicgroup count, noncyclic amide count, O and N atom count, heteroatomratio.For the14 million synthetically accessible products generatedabove, we calculated the following physicochemical properties38 SMARTS matching tools.During the generation of custom libraries the reactivesites andsubstructures were identified using custom written SMARTS patternsof the respective formulas and matched using Openbabel and Indigo17 molecules was carriedout based on the InChI39 representationsof the products.Exact matching of DIY in-house productsagainst ChEMBL40 covalentwarheads,42 fragment-based drug discovery43 (FBDD), bioactive compounds suitable for phenotypic screening,44 or various derivatives of nucleotides46 or amino acids.48 In the case of the amino acidderivative subset, glycine derivatives were excluded since they wouldhave outnumbered every other derivative due to their simple substructure.The detailed criteria on physicochemical properties, desired functionalgroups, and substructures are collected in Supporting Information Tables S1 and S2, respectively.DIY in-house products were classified intoappropriate librariesbased on their property profiles, reactive functionalities, and specialsubstructures. The assigned focused libraries included molecules forDNA encoded library (DEL) design,49 The molecules were described with their extended-connectivity fingerprints(ECFP4)50 using the Chemplot python library.51 The t-SNE algorithm defines a probabilisticdistribution of the molecules in the high-dimensional fingerprintspace and then defines a similar probability distribution in the low-dimensionalspace. In the last step, it minimizes the Kullback–Leiblerdivergence between the two distributions and results in a two-dimensional(2D) projection of the high-dimensional space. In that projection,we can state that structurally similar objects of the high-dimensionalspace will appear close to each other in the low-dimensional space.The algorithm was initialized with random parameters, and perplexitywas set to 70.The t-distributedstochastic neighbor embedding (t-SNE) algorithmwas used for clustering and visualization.24 catalytic C–C couplings,31 and SNAr25 or Buchwald-Hartwig-type reactions28 that are easily performed in any organic chemistry laboratories;thus, hits derived from the library can be obtained in a “Do-It-Yourself”(DIY) fashion. The ARCHIE11 enumeratoralgorithm applied in this study already implements the synthetic rulesof the above robust chemical reactions as well as various side-reactionrules.In the present study, only a small portion ofthe most common androbust reaction types was used which do not require extreme reactionconditions, extensive optimization, or rare and expensive additives.These reactions included amide and ester bond formation protocols,The building block set of the DIY in-house library, derivedfromthe Mcule database, contains 4448 potential reagents priced below10 USD/1 g. Only 2061 out of the 4448 building blocks have shown reactivityin at least one of the reactions. 349,948 synthetically accessibleproducts were generated in the first reaction step using the aforementionedreaction types, while the second reaction step resulted in 21,823,447additional products.To further optimize the cost of the buildingblocks, the top 1000reagents with the highest number of end-products per USD were iterativelyselected. As the building blocks with the lowest reactivity scoreswere excluded, the number of products and the overall budget was reduced.This selection method was effective for eliminating the most expensivebuilding blocks with low combinatorial chemistry potential, as shownin The best-scoring 1000 building blocks yielded 14,020,690products,comparable in size to the currently available full in-stock chemicalspace, for an estimated building block price of 8576 USD. The estimatedcost of a 2-step synthesis product includes the price of the buildingblocks (3 times 8.6 USD), coupling agents or catalysts , and solvents(∼1 USD). Altogether, the overall direct costs fall well shortof the price of the virtual compounds.The contribution of theapplied reaction types to the first andsecond reaction steps are summarized in 31 Mcule, Enamine,ZINC,5 ChEMBL,17 and SureChEMBL52 databases), nor are they currentlyavailable from commercial sources like Mcule, Enamine, and ZINC.5 The unexpectedly small overlap between the DIYin-house library and the currently available public databases suggestsa large gap between the available and already exploited parts of thesynthetically feasible chemical spaces. Thus, there is great potentialto exploit such portions of the chemical space for drug discovery.Analyzing the novelty of the database we found that13,774,903products (98.2%) have not been published in patents or research articlesyet .A short overview of the validated compounds is shown in To validate our forward-predicting synthetic rules and the methodologyused for the generation of the DIY in-house library, example productswere synthesized for each of our four main reaction types . From the various reaction conditionsavailable in the literature, we selected those that are robust andcommonly applied and that do not require expensive or custom-madeadditives. The detailed protocols and results are reported in the 34Additionally, to investigate whether the identifiedsyntheticallyfeasible products are suitable for various drug discovery applications,we characterized them by their most common physicochemical properties.Ruleofthree compliant53 molecules, lead-likemolecules according to Oprea et al.,54 and drug-likemolecules based on Lipinski’s Rule of five.33 We found that 86.4% of the DIY in-houselibrary meets drug-like property limits and 31.6% fulfills leadlikecriteria. A rather small portion (0.1%) of the DIY in-house libraryis suitable for fragment-based screening, which might be reasonedby the fact that fragment chemical space is much smaller than lead-likeand drug-like chemical spaces but provides a better sampling. Additionally,the combinatorial design may result in fewer fragment-sized products.The physicochemical characteristics of the DIY in-house virtual chemicallibrary are shown in in vitro high-throughput screening: (i) DNA-encoded library synthesis-compatiblebuilding blocks, (ii) covalent binders; (iii) nucleotide derivatives,(iv) amino acid derivatives, and (v) bioactive molecules for phenotypicscreening. Surprisingly, we found that a significantly larger portionof the DIY in-house library (11.9%) could be applied for the analyzeddrug discovery approaches than that of the commercially available compounds of over 100 suppliers’in-stock catalogs (5.6%) (At first glance we set up three subcategories: s (5.6%) 2.These results are mainly attributed to the high numberof aminoacid derivatives and DEL applicable building blocks found in the DIYin-house library. The smaller-sized phenotypic subset can be explainedby the exceptionally high novelty rate of the DIY library; thus, thereis only limited or no information available on these compounds yet.Nevertheless, 115 products of the DIY in-house library already haveChEMBL annotations with sub-micromolar activity. Targets of thesebioactivities span kinases, receptors, oxidoreductases, dehydrogenases,and several other substrates.58The subset of products with variouscovalent warheads was furthersplit into drug-like and fragment-sized categories. The most commonfunctions in these subsets were cyanide, carbamate, and boronic acidfunctions. Products of the DIY in-house library that can be appliedin DNA encoded library (DEL) synthesis can be divided into three subcategoriesbased on the number of reactive functionalities therein . Products with only one reactive functionality (capping buildingblocks) are omitted in the current classification due to their highprevalence. In addition to the above focused libraries, a general-purposescreening library was prepared—filtered against unwanted reactivesites and PAINS motifs.50 with ECFP451 fingerprint descriptorsdepicted on An overview and visualization of 1000 randommolecules from eachof the various subsets was generated using t-SNE algorithm59 to see how these reference databases compareto the DIY library. The analysis revealed that the DIY library coversa larger portion of the chemical space, and only smaller parts overlapwith the Mcule In Stock database (To further analyze the structural characteristicsof the DIY in-houselibrary we extended this approach on the Mcule In Stock database aswell as on the collection of approved drugs from Drugbankdatabase 6. On theIn this study we showed that a virtual chemicallibrary consistingof 14 million, almost completely novel, synthetically accessible end-productscan be built up from only 1000 low-cost building blocks that wereselected by an iterative process of maximizing end-product numberper cost. Each of these building blocks is available for less than10 USD in 1 g amount. The application of maximum 2-step, robust reactionsensures quick synthesis and high availability rate. The syntheticfeasibility of the DIY in-house library has been demonstrated by synthesizingexamples of each applied reaction type. The library has been characterizedby the most commonly used physicochemical descriptors with high medicinalchemistry relevance. The property distributions suggested that themajority of the DIY in-house library falls within the drug-like chemicalspace. Furthermore, based on these descriptors and additional filteringcriteria, special focused subsets of the DIY in-house library havebeen created that are applicable to various drug discovery approachesincluding DEL, covalent ligand design, and phenotypic screening usingbioactive compounds. The DIY in-house library approach offers a comprehensiveand easily available cost-effective alternative to medicinal chemistryresearch groups entering the field of drug discovery or broadeningtheir toolkits to construct their desired focused set of differentdrug discovery strategies. The DIY in-house virtual chemical libraryis a low-cost, quickly accessible alternative of in-house and externalstock chemical libraries to identify novel, intellectual propertyfree chemical starting points for drug discovery.


Point of care ultrasound (POCUS) is becoming a major extension of patient care. From diagnostic efficacy to its widespread accessibility, POCUS has expanded beyond emergency departments to be a tool utilized by many specialties. With the expansion of its use, medical education has begun to implement ultrasound education earlier in curricula. However, at institutions without a formal ultrasound fellowship or curriculum, these students lack the fundamental knowledge of ultrasound. At our institution, we set out to incorporate an ultrasound curriculum, into undergraduate medical education utilizing a single faculty member and minimal curricular time.Our stepwise implementation began with the development of a 3-hour fourth-year (M4) Emergency Medicine clerkship ultrasound teaching session, which included pre- and post-tests as well as a survey. The success with this session progressed to the development of a designated fourth-year ultrasound elective, which was evaluated with narrative feedback. Finally, we developed six 1-hour ultrasound sessions that correlated with first-year (M1) gross anatomy and physiology. A single faculty member was responsible for this curriculum and other instructors included residents, M4 students, and second-year (M2) near-peer tutors. These sessions also included pre- and post-tests and a survey. Due to curricular time limitations, all but the M4 Emergency Medicine clerkship session were optional.87 students participated in the emergency medicine clerkship ultrasound session and 166 M1 students participated in the voluntary anatomy and physiology ultrasound sessions. All participants agreed or strongly agreed that they would like more ultrasound training, that ultrasound training should be integrated into all four years of undergraduate medical education. Students were in strong agreement that the ultrasound sessions helped increase understanding of anatomy and anatomical identification with ultrasound.We describe the stepwise addition of ultrasound into the undergraduate medical education curriculum of an institution with limited faculty and curricular time.The online version contains supplementary material available at 10.1186/s12909-023-04227-y. Point of care ultrasound (POCUS) is becoming increasingly common in medical practice across a variety of specialties. As a brief, targeted, and clinician-directed imaging study performed at the patient’s bedside, POCUS is favored for its accessibility and ease of use as a diagnostic tool allowing the clinician to rapidly answer specific clinical questions, optimize patient care, and expedite management . First bMedical schools have responded to these trends by incorporating ultrasound into undergraduate medical education with the breadth of these programs varying from fully integrated, four-year programs to limited integration of ultrasound into preexisting courses – 19. StuRecommended curricula and educational strategies for medical schools have been previously published in Europe and the United States; however, a 2012 survey of US medical schools showed that only 62% of survey participants reported focused ultrasound education in their UME curricula (Beeson 2013) with a subsequent survey from 2014 indicating that only 27.7% of schools had a formal curriculum , 24−27. At our institution, medical students were exposed to ultrasound intermittently during clinical rotations; however, there was no formal ultrasound instruction within our curriculum. We sought to take steps to introduce ultrasound instruction in the undergraduate medical curriculum using a single faculty member and minimal curricular time. Our stepwise implementation included the development of an fourth-year (M4) Emergency Medicine clerkship session, a designated M4 ultrasound elective, and an adjunct ultrasound curriculum correlating with first-year (M1) gross anatomy and physiology.The Brody School of Medicine at East Carolina University, United States, admits 90 students per year and has a traditional four-year medical school (M1-M4) curriculum. The medical school is associated with a 974-bed tertiary-care teaching hospital that supports many residency and fellowship training programs. There is an emergency medicine residency, but no emergency ultrasound fellowship. The emergency medicine residency curriculum includes an ultrasound rotation during the intern year.Because the Emergency Medicine clerkship is required for all students and ultrasound is covered on the clerkship shelf exam, it was selected as the initial target for introductory medical student ultrasound education. In coordination with the emergency medicine clerkship director and executive curriculum committee, a 3-hour block of educational time was designated for ultrasound education. The sessions were held in the simulation center which provided lecture space with equipment, ultrasound machines with appropriate probes, and standardized patients. The sessions began with a 30-minute presentation by an Ultrasound faculty member discussing basic machine operation and the physics of ultrasound. Then, students viewed instructional videos made by the Society of Academic Emergency Medicine (SAEM) Academy of Emergency Ultrasound (AEUS) Narrated Lecture Series covering the extended focused assessment with sonography for trauma (eFAST), biliary ultrasound, and aortic ultrasound. Each video was followed by hands-on practice of that ultrasound examination on a standardized patient. Instructors included emergency medicine faculty and residents. The maximum number of students per group was seven. If necessary, the students were split into two groups for the hands-on practice. The students each completed a seven-item, five-point Likert Scale survey evaluating the effectiveness of the session. They also completed a pre-test and post-test that consisted of multiple-choice questions assessing ultrasound knowledge related to the session subject material and a free-response section assessing the ability to identify anatomical structures on ultrasound images.Once the emergency medicine clerkship ultrasound session was established and running smoothly, the creation of a four-week fourth-year medical student ultrasound elective was launched as the second phase of the project. The goal of this elective was to expose fourth-year medical students to the core ultrasound applications used in daily practice by emergency medicine physicians. This elective allowed students to develop hands-on skills in image acquisition and bedside interpretation of images, improving competency in Focused Assessment with Sonography for Trauma (FAST), Abdominal Aorta, Cardiac, Biliary, Renal, Thoracic, and Soft tissue/Abscess imaging. Students were also exposed to more advanced emergency ultrasound applications including ocular, advanced cardiac, deep vein thrombosis, testicular, and procedural applications. Course requirements included online didactics and 14 scanning shifts in the Emergency Department. Enrollment in the elective was limited to 10 students per academic year due to the faculty time required to complete the hands-on component. Preference was given to students planning to pursue residency in Emergency Medicine, Surgery, Radiology, or other ultrasound-intensive specialty. This course was evaluated by narrative feedback from students at the end of the academic year.The final phase of ultrasound integration was the creation of an ultrasound curriculum that correlated with the M1 anatomy and physiology courses. This ultrasound series consisted of 6 separate sessions: cardiac, aorta, upper abdominal, renal, pelvic, and ocular. The sessions were scheduled immediately following coverage of corresponding material in M1 anatomy and physiology. Due to limited curricular time, these sessions were voluntary for students. The second-year medical student leaders coordinated the timing of the sessions and notified M1 students of upcoming sessions. The sessions were held in the simulation center, which provided lecture space with equipment and ultrasound machines with appropriate probes. Each session was designed to last no more than 1 h and consisted of an introductory lecture created by the faculty member followed by hands-on ultrasound practice. For the hands-on component of the session, group sizes were limited to 5 students to one instructor and students practiced scans on each other. The sessions were created and led by one emergency medicine faculty member. Instructors included emergency medicine interns on their ultrasound rotation, M4 students enrolled in the ultrasound elective, and M2 student leaders who were selected to facilitate the sessions. Mirroring the emergency medicine clerkship ultrasound session, pre-module and post-module assessments were used that consisted of two parts: a session-specific multiple-choice section assessing related ultrasound knowledge and a free-response section assessing ability to identify anatomical structures on ultrasound images. Additionally, the students completed a seven-item, five-point Likert Scale survey regarding the usefulness of the session and whether it should be incorporated into the curriculum.During one academic year, 87 students participated in the emergency medicine clerkship ultrasound session. The mean percent correct on the pre-tests and post-tests were 53.5% (median 58.3%) and 80.3% correct (median 83.3%), respectively p < 0.01) . Due to the COVID-19 pandemic, the pelvis ultrasound session was unable to be held during the second year. When comparing pre-module and post-module scores, students demonstrated a statistically significant  increase in the basic ultrasound anatomical knowledge assessed through the multiple-choice section (Table In this educational intervention, we describe the stepwise integration of ultrasound into undergraduate medical education in an institution with limited faculty and curricular time. Point-of-care ultrasound, due to its effectiveness as a cost-friendly diagnostic tool, is becoming increasingly relevant in medical practice and medical education. There is extensive literature demonstrating the utility of incorporating ultrasound education early in residency and fellowship training, and that the assimilation early into the medical school curriculum was associated with higher scores on image interpretation tests –11, 23. The introduction of ultrasound to the undergraduate medical student curriculum was initially implemented as a three-hour session during the M4 Emergency Medicine clerkship. Similar incorporation of ultrasound at the M3/M4 level has been attempted in the past with only a few specifically targeting emergency medicine –32. ThisAfter the fourth-year EM clerkship ultrasound session was established, a 4-week EM ultrasound elective was created to provide a more in-depth ultrasound experience for interested M4 students. Similar courses have been established at other medical schools –34]. Th. Th34]. Following the successful implementation of the fourth-year ultrasound elective and the growing demand for ultrasound education, we sought to incorporate ultrasound earlier in the undergraduate medical curriculum. Because of the technology’s ability to demonstrate structural relationships, anatomy courses have become the natural target for incorporating ultrasound into pre-clinical undergraduate medical education. Previous research shows that students who participate in similar sessions believed the sessions improved their understanding of human anatomy and these feelings were objectively supported by improved test scores following instruction , 29, 35.While full curricula exist for the incorporation of ultrasound into the medical school curriculum, limitations include lack of financial resources and faculty availability with the current curricula focused on faculty-led initiatives , 24–29. The main limitation to our study is the lack of long-term outcomes. Specifically, whether ultrasound sessions improved knowledge long-term and resulted in better test performance and graduates who were better prepared for residency. Additionally, we describe the addition of ultrasound to the undergraduate medical curriculum at a single institution; each institution has its own unique challenges that might not be addressed by our study.The are many barriers an institution may face when attempting to incorporate ultrasound education into the undergraduate medical curriculum. In this manuscript, we illustrate a stepwise approach to incorporating ultrasound into undergraduate medical education in a setting that lacks faculty and curricular time. Students found these sessions relevant and informative and felt ultrasound was a useful tool for reinforcing basic science concepts. These results suggest that the next step at our institution should be adding the first-year medical student ultrasound sessions to the formal curriculum.Below is the link to the electronic supplementary material.Supplementary Material 1Supplementary Material 2Supplementary Material 3Supplementary Material 4


Aim: The primary goal of this study was to evaluate the reduction in non-perfusion area and improvement in blood flow as well as the reduction in retinal edema on optical coherence tomography angiography (OCT-A) in patients with retinal vein occlusion treated with 2 mg intravitreal injections of aflibercept. Material and methods: Fifty eyes of nine patients with central retinal vein occlusion (CRVO) and sixteen patients with branch retinal vein occlusion (BRVO), aged 50 to 75 years, were collectively analyzed as retinal vein occlusion (RVO). The following parameters were analyzed: superficial vessel density (VDSF), deep vessel density (VDD), flow area in the outer retina (FAOR), choriocapillaris flow area (FACC), non-flow area (NFA) and the foveal avascular zone (FAZ). Results: OCT-A revealed a reduction in macular edema. The most significant change in central retinal thickness (CRT) was observed between measurement timepoint “5” and the baseline (46%). The non-flow area was also reduced. Following a significant decrease in superficial vessel density 30 days after the first dose of aflibercept, a non-significant increase was noted at the subsequent timepoints. An increase was also found in deep vessel density and choriocapillaris flow area. Improvements in the above OCT-A parameters resulted in increased retinal blood flow and improved visual acuity. Conclusions: Patients with retinal vein occlusion treated with 2 mg aflibercept exhibited reduced macular edema and FAZ, increased vessel density, improved blood flow, and better visual acuity. Retinal vein occlusion (RVO) is the second most common retinal vascular disease after diabetic retinopathy, which can cause irreversible deterioration of visual acuity related to ischemia and resultant macular edema ,2,3,4,5.Proper treatment of occlusion sequelae is based on timely and accurate diagnosis of the retinal condition. There have been significant changes in the approach to retinal disorders related, among others, to the rapid development of modern diagnostic imaging techniques. These include Optical Coherent Tomography (OCT) and, above all, Optical Coherent Tomography Angiography (OCT-A), a non-invasive imaging modality that visualizes the individual layers of the retina . DespiteCurrently, there are several modern therapeutic options for retinal vein occlusion. Vascular endothelial growth factor (anti-VEGF) inhibitors and corticosteroids such as dexamethasone drug delivery system or triamcinolone acetate are commonly used. Systemic preparations, including low-molecular-weight heparin, niacin, and acetylsalicylic acid, have also been administered. Anti-VEGF is currently the standard of care for macular edema secondary to RVO. The efficacy of anti-VEGF has been shown in numerous studies, such as COPERNICUS, GALILEO, and HORIZON .The goal of this study was to evaluate the reduction in the non-perfusion area and improvement in blood flow on optical coherence tomography angiography (OCT-A) as well as the reduction in retinal edema on OCT in patients with thrombotic occlusion of retinal veins treated with 2 mg aflibercept intravitreal injections. In addition, to determine the effectiveness of this treatment based on the examination of retinal vessels, visual field, and visual acuity of the treated and control eyes.We hypothesized that anti-VEGF treatment in RVO patients would result in detectable changes in central retinal thickness (CRT) and hemodynamic changes within the macula.Fifty eyes of 25 patients with central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO), aged between 50 and 75 years, were included in this study. Based on our own experience and the findings of Balaratnasingam et al. , we deciThe inclusion criteria were as follows: central retinal vein trunk or branch occlusion of no more than one month duration, cystoid macular edema confirmed on OCT, best corrected visual acuity (BCVA) ≤ 5/10 (0.5) determined on the Snellen chart, intraocular pressure ≤ 21 mmHg, no previous treatment for RVO, OCT-A scan quality index of 8/10 or higher, age 50 to 75 years, written informed consent for drug administration (2 mg aflibercept) and venous blood collection for testing.Exclusion criteria included hypersensitivity to the drug, advanced glaucoma resistant to pharmacotherapy, infection of the eye or its area, vitreous hemorrhage, vitreoretinal traction, ocular media opacity affecting the quality of OCT-A scans), age below 50 years or above 75 years, systemic bacterial, viral or parasitic infection, and lack of written informed consent.Intravitreal injections of 2 mg aflibercept were given three times at 30-day intervals.Follow-up examinations were conducted 30 days after each intravitreal injection of anti-VEGF and at monthly intervals for two months after the last aflibercept injection. A total of six measurements were made, includingpre-therapy measurement, i.e., timepoint 0 (hereafter referred to as the baseline);three intra-therapy timepoints, i.e., timepoint 1 (30 days after the first anti-VEGF injection), timepoint 2 (30 days after the second injection), and timepoint 3 (30 days after the third injection);two post-therapy timepoints, i.e., timepoint 4 (60 days after the third injection) and timepoint 5 (90 days after the third injection).p < 0.05. The determination of qualitative variables distribution included calculating their individual values.Descriptive and analytical statistics were used to analyze these data. Descriptive statistics show the distributions of individual variables. The mean value, standard deviation, middle value (median), and value range (minimum-maximum) were calculated for quantitative variables. The normality of the distribution of quantitative variables was tested using the Shapiro–Wilk test; the level of significance was set at t-test was used when the distribution of variables did not deviate from a normal distribution and the non-parametric Kruskal–Wallis test when the distribution of variables was non-normal. A paired samples t-test was used to assess paired differences when the distribution of variables was normal, and the non-parametric Wilcoxon Signed Rank test was used when the distribution of variables was other than normal. Data analysis was based on variables reflecting the measured values and transformed variables.Analytical statistics allowed the determination of the statistical significance of differences. Differences between the distributions of quantitative variables in two independent groups were assessed. A Student’s A series of measurements taken at the following timepoints were analyzed: the pre-therapy timepoint (point 0) and five monitoring points at designated intervals (points 1–5).p < 0.05.The dynamics of changes in the results of the ophthalmic examination were evaluated by analyzing the absolute values and transformed variables. Variables were transformed using standardization of repeated measurement results against the initial measurement . Relative values (%) of changes in the study parameters were calculated for each measurement timepoint . The results of difference and correlation analyses were interpreted using the statistical significance level of OCT and OCT-A were performed using the Angiovue optical coherence tomography angiography (OCTA) software of the RTVue XR Avanti .vessel density (VD) of the superficial capillary plexus (VD-SF) and deep capillary plexus (VD-D),flow area in the outer retina (FAOR) and choriocapillaris flow area (FACC),superficial non-flow area (NFA),foveal avascular zone (FAZ).OCT-A images of the 6 × 6 mm central macular area were used for analysis. The following parameters were analyzed: Central retinal thickness (CRT) was determined based on OCT images and ETDRS grids.Automated measurement was used for OCT and OCT-A parameters, except for NFA, which was measured manually by one examiner.Below are samples of macular OCT images with the macular thickness map—ETDRS grids before and after the treatment .Standard care for retinal vein occlusion with secondary cystoid macular edema consists of intravitreal administration of a VEGF inhibitor .The analysis of the relative differences at five follow-up measurement timepoints showed a statistically significant decrease in CRT in the eyes with RVO treated with an anti-VEGF (aflibercept). The most remarkable relative CRT decrease (37%) was noted at measurement timepoint 1, i.e., 30 days after the first anti-VEGF injection. These changes were less pronounced at subsequent timepoints but still significant compared with the baseline. The comparison with standardized CRT values was intended to enrich these currently available data with some insight into the dynamics of the processes under study.The most significant decrease in CRT was observed between timepoint 5 and the baseline (46%). The change in CRT values between timepoints 5 and 3 was the lowest (4%). The therapeutic effect  continued until measurement timepoint 3 (30 days after the third anti-VEGF injection). This was followed by stabilization until measurement timepoint 5, i.e., 90 days after the last dose of aflibercept . In the Thirty days after the first anti-VEGF injection (measurement timepoint 1), a 31% increase in NFA was observed in the treated eye, followed by a decrease at all subsequent measurement timepoints. This might be accounted for by the high likelihood of baseline measurement inaccuracy due to increased congestion of the examined area, retinal edema, and venous dilatation partially masking the NFA surface in this phase of the disease. With the therapeutic effect of anti-VEGF treatment, the NFA decreased significantly .The mean NFA change in this study’s eyes reached 30%.Another parameter studied was vessel density (VD) in the superficial and deep plexuses. OCT-A showed VD reduction in the study eyes compared with the control.An analysis of this study’s eyes absolute and relative VDSF values confirmed a significant reduction in this parameter at timepoint 1. A non-significant increase was found at timepoints 2 through 4. Ultimately, i.e., at timepoint 5 (90 days after the third anti-VEGF injection), VDSF returned to the baseline value.In this study’s eyes, a statistically significant reduction in VDD was only observed between the baseline and timepoint 1. The values obtained at subsequent measurements did not differ significantly compared with the baseline. In the control group, statistical significance was only found at timepoint 1. Statistical analysis showed no statistically significant differences between pre- and post-therapy VDSF or VDD, indicating anti-VEGF therapy for RVO did not significantly affect this parameter. However, observation of the retina after the first injection, when its swelling becomes reduced, and the actual vascularization of the retina is revealed, showed an increasing trend at timepoints 2 through 5 .An analysis of the percentage change in VDSF revealed little change (0% to 1% in this study’s eyes and 0% to 3% in the control eyes), indicating the insensitive nature of this parameter for assessing and documenting the effects of therapy. Changes in VDD were delayed beyond the therapy phase but then persisted until the end of the observation period . Notably, in the control eyes, small changes in VDSF and VDD were seen at timepoint 1 and persisted until the end of the follow-up period.To extend our analysis of RVO-related changes in retinal hemodynamics, the flow area in the outer retina (FAOR) and choriocapillaris flow area (FACC) were also assessed.An analysis of FACC change in this study group revealed a statistically significant increase at all measurement timepoints compared with the baseline. Comparisons with standardized data show a substantial increase in FACC at timepoints 1 and 2, each by 10%.The profiles of change in absolute and relative FAOR values in the study and control groups demonstrate a statistically significant reduction in this study group for all measurement timepoints relative to the baseline. The most remarkable reduction in FAOR values (23%) was observed 30 days after the first anti-VEGF injection, i.e., at timepoint 1. Following a decline in retinal congestion, an increase in perfusion was revealed at all subsequent timepoints, documenting the effectiveness of the therapy.An analysis of FAOR change in this study’s eyes revealed a non-unidirectional trend. The change in FACC values was the lowest between timepoints 5 and 3. The greatest therapeutic effect of anti-VEGF was already apparent at measurement timepoint 3 and persisted until timepoint 5 . In the An interesting and important OCT-A parameter to assess the severity of hemodynamic changes in RVO is the foveal avascular zone (FAZ). The profile of FAZ change in this study group showed a gradual and statistically significant increase at successive measurement timepoints compared with the baseline. FAZ values were higher in the treated than in the control eye except for the baseline and timepoint 1. This might be accounted for by the likelihood of OCT-A measurement inaccuracy due to macular edema still present at these two timepoints. No significant differences between successive measurements were noted in the control group.The most remarkable change in FAZ was seen between timepoint 3 and the baseline. The percentage change between timepoints 5 and 3 was the lowest. The most noticeable therapeutic effect of anti-VEGF was already apparent at measurement timepoint 3 and persisted until timepoint 5 . In the Best Corrected Visual Acuity (BCVA) is the clinical result of all the hemodynamic variables described above. In this study’s eyes, significantly higher BCVA values were observed throughout the observation period compared with the baseline. Significant differences were also noted for the control eyes. We therefore conclude that the anti-VEGF therapy improved BCVA .The last parameter evaluated in this study was the visual field expressed as the mean defect (MD). The study group’s absolute and relative MD values were significantly reduced at successive measurement timepoints, indicating visual field improvement. Similar changes were found in the fellow, i.e., control eyes. Visual field testing performed after consecutive anti-VEGF injections made us conclude that three injections over 90 days stabilized the visual field area in patients with RVO. It should be emphasized that, in the case of other study parameters, sustained response and stability of treatment results were observed after the last aflibercept administration. MD, on the other hand, continued to decrease, indicating further improvement in the visual field .The present study covers a 5-month follow-up period of 25 eyes with RVO, treated with a monthly intravitreal injection of 2 mg aflibercept (three injections were administered to each eye), and of the same number of fellow eyes of the same patients. The therapy was found to be highly effective.Our results indicate that the effectiveness of anti-VEGF therapies is most accurately measured with CRT, FAOR, FACC, and FAZ. It should also be noted CRT, FACC, and FAZ showed the highest differentiating ability . The analysis of the 2-month post-therapy follow-up revealed a statistically significant difference between post-therapy changes in CRT, NFA, VDD, FACC, and MD for the diseased vs. fellow eye. An important practical observation indirectly derived from this study is that measurements assessing hemodynamic changes in the retina should be taken after retinal edema has resolved.The presented study had several limitations, most notably a small number of study eyes and the lack of a suitable control group, i.e., untreated RVO patients. Other significant limitations of this study were a short follow-up period and the small number of therapeutic interventions, i.e., only three intravitreal injections. However, despite these drawbacks, we demonstrated some therapy effects. In addition, the changes observed during therapy are consistent with other authors’ observations from analogous clinical trials.The pathomechanism of retinal vein occlusion and its diagnosis and treatment are still controversial. The increasing number of these patients, new diagnostic techniques, and therapeutic approaches are raising the ophthalmologists’ and patients’ expectations. Further research into, among others, the size of the perfusion zones and the topography of the non-perfusion field, depending on the type and stage of therapy for retinal vein occlusion, is therefore well warranted.An analysis of relative differences at measurement points 1 through 5 showed a statistically significant decrease in CRT in treated eyes. The therapeutic efficacy of aflibercept was apparent at timepoint 2 and persisted throughout the follow-up period. Huang et al.  and SuzuIn this study group, a significant reduction was found in the NFA’s absolute and relative values starting at timepoint 2. Subsequent anti-VEGF injections caused a reduction in the non-perfusion area and an improvement in regional blood flow. Similar results were obtained by Suzuki et al. , who assNon-invasive microcirculation imaging with OCT-A showed a reduction in retinal vessel density in the superficial and deep plexuses of RVO eyes compared with the control.VDSF and VDD showed no statistically significant difference during the entire follow-up period and returned to the baseline at the last measurement timepoint. However, the observation of the retina after the first injection, when edema was reduced, and the actual retinal vascularisation was revealed, showed a favorable trend toward increasing vessel density at subsequent measurement timepoints until the end of this study.OCT-A images have demonstrated that RVO can be associated with decreases in superficial and/or deep perifoveal vessel density ,21. AntiThis might be the reason why the effects of anti-VEGF therapies cannot be conclusively interpreted. Suzuki et al.  observedFAZ changes in this study’s eyes at successive measurement points were characterized by a gradual and statistically significant increase compared with the baseline. A comparison of the FAZ in the RVO eyes with that of the fellow eyes during the 5-month follow-up revealed that FAZ values were higher in the diseased eyes. Again, several researchers believe this parameter should only be assessed when macular edema masking the actual area of the FAZ has subsided ,28,29,30The BCVA values recorded for the treated eye at each follow-up timepoint were significantly higher than at the baseline. The therapy used in the study protocol resulted in visual acuity improvement. A significant improvement in BCVA occurred solely in the treated eye and was already apparent during treatment. Several studies indicated that visual acuity was strongly related to the FAZ size in the superficial plexus , maximump < 0.001). Interestingly, changes in all parameters were independent of the number of anti-VEGF injections. MD in the visual field was shown to re-increase, which could be associated with edema recurring between injections.In this study group, a statistically significant reduction in the visual field’s absolute and relative MD values was noted at successive measurement timepoints. Similar changes were found in the control eyes. We, therefore, concluded that a total of three intravitreal anti-VEGF injections (administered during three consecutive months) stabilized the visual field in patients with RVO. Similar results were observed by other researchers. Papadia et al.  found noIn the present study, covering a five-month observation period, the effectiveness of the applied therapy was high. The results have shown that the most accurate indicators of therapy effectiveness were CRT, FAOR, FACC, and FAZ. It should be emphasized that CRT, FAZ, and FACC showed the highest differentiating ability, diseased vs. fellow eye.Patients with retinal vein occlusion treated with intravitreal injections of 2 mg aflibercept exhibited reduced macular edema and FAZ, increased vessel density, improved blood flow, and better visual acuity.