Locust outbreaks around the world regularly affect vast areas and millions of people. Mapping and monitoring locust habitats, as well as prediction of locust outbreaks is essential to minimize the damage on crops and pasture. In this context, remote sensing has become one of the most important data sources for effective locust management. This review paper summarizes remote sensing-based studies for locust management and research over the past four decades and reveals progress made and gaps for further research. We quantify which locust species, regions of interest, sensor data and variables were mainly used and which thematic foci were of interest. Our review shows that most studies were conducted for the desert locust, the migratory locust and Australian plague locust and corresponding areas of interest. Remote sensing studies for other destructive locust species are rather rare. Most studies utilized data from optical sensors to derive NDVI and land cover for mapping and monitoring the locust habitats. Furthermore, temperature, precipitation and soil moisture are derived from thermal infrared, passive and active radar sensors. Applications of the European Sentinel fleet, entire Landsat archive or very-high-spatial-resolution data are rare. Implementing new methods  and additional data sources could provide new insights for locust research and management.Schistocerca gregaria) and lack of monitoring due to political conflicts or inaccessibility of those habitats lead to massive desert locust outbreaks and swarms migrating over the Arabian Peninsula, East Africa, India and Pakistan. At the same time, swarms of the Moroccan locust (Dociostaurus maroccanus) in some Central Asian countries and swarms of the Italian locust  in Russia and China destroyed crops despite developed and ongoing monitoring and control measurements. These recent events underline that the risk and damage caused by locust pests is as present as ever and affects 100 million of human lives despite technical progress in locust monitoring, prediction and control approaches. Remote sensing has become one of the most important data sources in locust management. Since the 1980s, remote sensing data and applications have accompanied many locust management activities and contributed to an improved and more effective control of locust outbreaks and plagues. Recently, open-access remote sensing data archives as well as progress in cloud computing provide unprecedented opportunity for remote sensing-based locust management and research. Additionally, unmanned aerial vehicle (UAV) systems bring up new prospects for a more effective and faster locust control. Nevertheless, the full capacity of available remote sensing applications and possibilities have not been exploited yet. This review paper provides a comprehensive and quantitative overview of international research articles focusing on remote sensing application for locust management and research. We reviewed 110 articles published over the last four decades, and categorized them into different aspects and main research topics to summarize achievements and gaps for further research and application development. The results reveal a strong focus on three species—the desert locust, the migratory locust (Locusta migratoria), and the Australian plague locust (Chortoicetes terminifera)—and corresponding regions of interest. There is still a lack of international studies for other pest species such as the Italian locust, the Moroccan locust, the Central American locust (Schistocerca piceifrons), the South American locust (Schistocerca cancellata), the brown locust  and the red locust (Nomadacris septemfasciata). In terms of applied sensors, most studies utilized Advanced Very-High-Resolution Radiometer (AVHRR), Satellite Pour l’Observation de la Terre VEGETATION (SPOT-VGT), Moderate-Resolution Imaging Spectroradiometer (MODIS) as well as Landsat data focusing mainly on vegetation monitoring or land cover mapping. Application of geomorphological metrics as well as radar-based soil moisture data is comparably rare despite previous acknowledgement of their importance for locust outbreaks. Despite great advance and usage of available remote sensing resources, we identify several gaps and potential for future research to further improve the understanding and capacities of the use of remote sensing in supporting locust outbreak- research and management.Recently, locust outbreaks around the world have destroyed agricultural and natural vegetation and caused massive damage endangering food security. Unusual heavy rainfalls in habitats of the desert locust ( Locust and grasshopper pests have been destroying agriculture and affecting human lives by causing major food security challenges since ancient times and serious outbreaks are documented both in historical sources and modern literature ,2,3,4. TSchistocerca gregaria), is responsible for the most dramatic and sudden outbreaks and plagues in the 20th and 21st centuries [2, stretching from West Africa to Southwest Asia [Dociostaurus maroccanus) in parts of Central Asia, the Italian locust  in parts of East Russia, the South American locust (Schistocerca cancellata) in parts of Paraguay and Argentina, the African migratory locust (Locusta migratoria migratorioides) in Botswana, Namibia, Zambia and Zimbabwe as well as Yellow-spined bamboo locust (Ceracris kiangsu) in parts of Vietnam, Laos and China [One of the most destructive species, the desert locust  or episodic, with alternating periods of invasion and recession  . Locust Due to the size of the impact, locust management and control are essential. Locust management is complex and requires a multi-disciplinary approach including entomology, biology, and ecology, with aspects of spatial distribution modelling, climate analysis, weather prediction, organism behavior and interaction with other species , control using chemical insecticides or bio-agents as well as remote sensing applications. The latter has become one of the most important sources providing valuable information within locust management. Meanwhile, there is a wide range of existing passive  and active (emit a controlled beam of energy and detect the amount of energy reflected back to the sensor) Earth Observation (EO) sensor systems. For a detailed introduction to remote sensing, we refer the reader to ,22,23. TRemote sensing-based research and case study applications were important drivers to improve our understanding of locust-relevant ecological and environmental conditions. Since the 1980s, information acquired from remote sensing data has accompanied many locust management activities and contributed to improved and more effective control of locust outbreaks and plagues around the world. Nevertheless, locust outbreaks still cause devastation and hunger, despite technological progress and improvement in monitoring and control. One of the reasons is the ineffective monitoring, management or population control in some locust habitats, e.g., due to lack of available resources and technology . EnvironMapping and monitoring the locust habitat state and environmental conditions which promote the transition process between the solitarious and gregarious phases.Prediction of hatching time and possible outbreaks based on historical information, present vegetation monitoring and weather forecast.Locust nymph bands and swarm monitoring with airborne or UAV-based sensors.Post outbreak crop and vegetation damage assessment.In addition to EO remote sensing, direct radar (X-band) observations of ‘migration in progress’ have been used for research on the migration systems of locusts and migratory grasshoppers, particularly for the Australian Plague locust and the Senegalese grasshopper . Insect-The Food and Agriculture Organization (FAO) has been successfully introducing standardized monitoring methods and data collection when remote sensing data and applications play an essential role. Remote sensing data related to locust outbreaks was first introduced by Pedgley  and HielThis review aims to provide a comprehensive and quantitative overview on ‘satellite-based’ remote sensing applications and research within critical phases for locust management. Due to high potential for locust management, as well as similar principles in image interpretation and processing, we also included UAV and airborne-based studies. We aim to summarize past and present developments and identify topics which still require further research and scientific attention. This review is structured as follows: in Orthoptera: Acrididae). Therefore, additional excluding keywords were applied. In a final step, we screened the resulting publications based on the following inclusion criteria which are relevant for this review:Orthoptera: Acrididae).Articles are related to locust and grasshopper species  including Science Citation Index (SCI) journals and full-text conference contributions . For theThe literature review workflow and number of studies for each step are summarized in The total selected 110 studies were analyzed to extract relevant information for this review in two main aspects. The first aspect includes publication-specific information about “species of interest”, “region of interest”, “applied remote sensing sensor” and “derived variables from remote sensing data”. Additionally, we extracted involved authors’ affiliation to investigate where main research is based compared to regions of interest. The second aspect includes thematical foci which were categorized into “habitat mapping”, “habitat monitoring”, “forecast of hatching/outbreak”, “damage assessment” as well as “review and general articles” without a specific data analyzing part . Oedaleus senegalensis) [In this section, we recap the historical development of studies related to locust research and management applying remote sensing data . The firalensis) ,47,48, talensis) , and thealensis) .At the beginning of the new millennia, there was a slight increase in publications and a trend towards more specific studies related to outbreaks between 1999 and 2001 in Central Asia, Russia, China, Australia as well as desert locust outbreak in 2003–2005 in West Africa. This increase is visible in a first significant accumulation of studies from 2004 with the peak in 2008. The second peak of studies in 2013/2014 is related to a special issue “Advances in Remote Sensing Applications for Locust Habitat Monitoring and Management in the Journal of Applied Remote Sensing” with a total of 14 studies. The peaks in 2018 and 2020 can be related to an open source policy and accessibility of different satellite data archives and following new approaches , as well as overall increased public and research interest and available funding probably related to recent severe outbreaks.In general, it is clear that remote sensing application studies, at least those published in the English language, were rather rare until the start of the new millennium, mostly driven by research developments in collaboration between research centers and universities with FAO and APLC for monitoring and prediction service for the desert locust and the Australian plague locust. Afterwards, the academic interest involving EO data increased in the past two decades. Nevertheless, a significant development observed in other disciplines, e.g., related to new available EO data sources  or opening long term archives  is not evident. The observed accumulation of studies is related to locust outbreaks rather than technological advances and availability of remote sensing data. However, recent analysis related to soil moisture ,52,53,54In terms of the investigated temporal scale, 18% of all studies were conducted only for one image representing the conditions at the time of overfly . A total of 71% of studies were conducted for several images representing several states at different time steps or temporal development . Studies for other destructive species such as the Central and South American locusts (1%), the Moroccan locust (1%) and the red locust (1%) are rare. The category General (5%) does not focus on specific species but rather summarizes review papers including several species or general research which is relevant for more than one species .Two species dominate the publications, i.e., the desert locust (33%) and the migratory locust (27%) . The migIn this section, we would like to pay attention to countries and regions of interest which were in focus of reviewed publications . ObviousMost studies focused on study areas in China (26%), followed by Australia (13%), Mauritania (12%), Uzbekistan (7%) and Kazakhstan (5%). There are no studies for the Arabian Peninsula, Pakistan and only one for India, although those regions are highly vulnerable, e.g., to desert locust outbreaks. English-language publications using remote sensing for locust research or management were barely found for North and South America, South-East Asia and Europe. This may be due to minor risk of locust outbreaks  or that applications use data sources apart from remote sensing, e.g., field and station measurements  ,60,61.In this section, we quantify the studies based on different sensor types, derived variables and metrics. The reviewed publications show a distinct dominance with 57% of using optical instruments only . This doThe category of sensors including thermal infrared (TIR) is related to temperature estimation which is, together with rainfall, important for monitoring as well as for hatching and outbreak prediction. In combination, there were 16% of studies using TIR . There were no studies using satellite-based hyperspectral sensors and only two studies (2%) referring to data from airborne and UAV cameras. Among variables, parameters and metrics, we found that vegetation indices (39%), precipitation (14%), land cover classification (13%), temperature (11%) and soil moisture (9%) are dominant . Within Habitat mapping and ecological niche modeling as static state description of potential habitat where locust might breed.Habitat monitoring as temporal description focusing on variable environmental parameters relevant for locust development.Outbreak and hatching prediction as forecast component for future.Damage and loss assessment as post outbreak evaluation.Overarching review and general research papers.As described in the introduction, remote sensing can add valuable information at different critical time steps of the locust life cycle . This deThe thematic categorization of reviewed studies was performed by examining the major objectives and presented results. If the objective of a study was to map or describe habitat or ecological niche of a locust species, it is grouped into the category “habitat mapping”. The major result can be categorical habitat maps for a certain time or time period, as well as probability assessment about which areas are more prone to locust breeding. Studies which focus on monitoring or detecting changes of ecological parameters over time are grouped in “habitat monitoring”. Here, the focus is on analyses at high temporal frequency or operational monitoring of ecological parameters which affects locust life cycle and potentially contribute to early warning. Studies focusing on forecast are grouped in “outbreak and hatching prediction”. For these three categories, there are studies which might include components in line with two or even three described categories. For example, most studies grouped into “outbreak and hatching prediction” also contain monitoring aspects because it is an important tool to predict outbreaks and many forecast approaches are constructed based on statistical relationship between historical field data and relevant ecological and meteorological parameters. In these cases, we categorize based on the most important outcome. The grouping into “damage assessment” and “review and general” was more straight forward due to none intersecting objectives.Identifying habitat and possible breeding sites is one of the most important tasks for implementing cost- and time effective pest control . Since tPhragmites australis). These habitats are highly dynamic in terms of inundation, which defines the locust population density and therefore triggers outbreaks. Sivanpillai et al. [The first approach utilizes land cover classification methods. The outcome of land cover-based mapping are usually categorical maps of land cover or vegetation classes, which also might be converted into risk or habitat suitability classes . At the beginning, researchers, e.g., McCulloch and Hunter , classifi et al.  applied i et al.  and Sivai et al.  for selei et al.  the authi et al.  applied i et al.  analyzedAdditionally, research efforts on habitat mapping have been conducted for the migratory locust in several study sites in China. Q. Liu et al.  applied Hammatocerus schistocercoides) in Mato Grosso, Brazil. Dreiser [On the contrary to reed vegetation for the migratory locust, the detection of plant species which are favored by other locust species is more challenging due to the spectral characteristics of most optical sensors. Therefore, studies for other locust species rather focus on the general state of vegetation as a proxy for favorable breeding or invasion areas. For example, Bryceson  utilized Dreiser  and Voss Dreiser  produced Dreiser , who int Dreiser  suggesteArtemisia spp.) which also grows on fallow and abandoned fields, overgrazed pastures, as well as along roads and other man made structure [A unique human-locust species inter-connection example can be found by examining the Italian locust. The Italian locust prefers sagebrush  or ecological niche models (ENM) by combining locust presence locations (derived from ground surveys) and different sets of environmental variables. ENM are usually based on machine learning algorithms to correlate a set of environmental conditions to species presence and absence records and thus predict its suitable habitats . The outOedaleus decorus asiaticus) in the Inner Mongolia steppe. Relevant climate variables influencing oviposition, overwintering and incubation were considered within a fuzzy evaluation model (multi-objective linear weighted function).Aragón et al.  estimateMalakhov et al.  pointed Recently, Kimathi et al.  used maxIn the following, we summarize studies which focused on the temporal monitoring of environmental conditions, which determine the phase change as well as the timing of hatching. In this way, those studies focus on information about temporal dynamics rather than a static habitat status or potential species distribution as described in the previous section. Another main difference to previous section is that following studies potentially contribute to operative service or enable immediate decisions as part of early warning system . The majority of habitat monitoring studies were focusing on precipitation and soil moisture monitoring as well as assessing vegetation change.Early research conducted by Cherlet et al., Hielkema et al., Hielkema, Hielkema and Snijders, Tucker et al. ,45,86,87Recent research to monitor (i) vegetation, (ii) soil moisture, and (iii) studies which investigate combination of several ecological import variables are summarized in following three subsections.In the last 15 years, there was increased development in monitoring vegetation. Major focus was placed on temporal scale and relation of vegetation indices variability to locust development.Ceccato  combinedTratalos and Cheke  found th2 = 0.9). Therefore, the MODIS spatial resolution is still too coarse to resolve complex landscape patterns, which were responsible for 60% of the error [In Pekel et al. , the authe error . In thishe error  further he error  tested tAdditionally, Deveson  reportedSoil moisture plays a crucial role for locust development. Early studies on soil moisture showed its potential, but also the restrictions of applying satellite-based radar data to operational services due to low spatial and temporal resolution . Liu et Escorihuela et al.  presenteIn this subsection, we summarize studies which presented monitoring strategies combining several variables of importance. Han et al.  presenteAnother alternative monitoring approach was presented by Propastin ,105 combLi et al.  presenteGómez et al.  applied Chen et al.  used mulIn this section, we focus on studies which specifically target prediction of locust outbreaks or the beginning of hatching. Compared to monitoring studies from previous sections, the focus is on the future, although historical data, past measurements and monitoring are essential part of those studies. According to Rosenberg , the focFirst of all, Healey et al.  introducTodd et al.  analyzedVallebona et al.  analyzedPiou et al.  presenteCressman  presenteFor the Italian locust, Tronin et al.  introducFor eastern Australia, Veran et al.  used MOD3/cm3) and followed by consecutive decrease. Hereafter, the random-forest forecast model combining soil moisture data with NDVI showed promising results with high AUC value of 0.761 and out of the box error of 23.7%. The model validation for years between 2010 and 2016 reached AUC between 0.583 and 0.709 and error between 27.6% and 39.7%.Apart from using rainfall and vegetation as variables for locust forecast, soil moisture is another critical variable to be considered. For brown locust life cycle modelling, Crooks and Cheke  assessed2 = 0.6474). Ji et al. [Heiroglyphus nigrorepletus on sorghum. Furthermore, Song et al. [Stressed or damaged vegetation is characterized by a difference in reflectance compared to healthy vegetation. Due to loss of chlorophyll stressed vegetation can be detected in red edge spectrum. Extreme loss of green vegetation is visible in VI  as well as in high-resolution SAR (change in canopy cover and structure). Studies focusing on damage assessment were conducted mainly for migratory locusts in China. These studies assessed vegetation patterns before and after a specific outbreak and thus identified affected areas. The information on whether there is a causal relation between damaged vegetation and locust swarms was mostly based on a priori knowledge and assumptions of the authors that no other factors contributed to the damage. All following reviewed vegetation damage studies can be considered as case studies at local scale and therefore with limited spatial coverage. For the East Asian migratory plague locust, Ma et al. ,125 perfi et al.  used MODi et al.  analyzedi et al.  and Tiani et al.  calculati et al.  introduci et al.  conducteg et al.  estimateWeiss  also invAdditional to satellite-based studies it is interesting to note that Hunter et al.  analyzedIn our literature search, we found six review and four general discussion publications dealing with locust pests and remote sensing applications. Cracknell  discusseLatchininsky and Sivanpillai  presenteHuang  providedThe review paper of Zhang et al.  covered Recently, Abd El-Ghany et al.  publisheIn this section, we reflect on the main remote sensing contribution for improved locust management and recent trends. First of all, in regards to habitat mapping, recent approach has been shifted from single image land cover analyses ,65,79 toSecondly, in terms of habitat monitoring, there was a district development. In 1991, Cracknell  discusseMoreover, applications of remote sensing-based soil moisture data has been comparably rare despite the acknowledged fact that it is one of the most important variables defining the survival of locust eggs as well as for the timing of hatching. In 2014, Crooks and Cheke  stated tIn terms of prediction, recent progress utilizes machine learning approaches and establishes statistical relationship between all available and important variables ,54,56. FFormer studies using coarse satellite data stated that there was no significant relation between locust and vegetation indices. Rosenberg  mentioneFurthermore, using Landsat, and eventually Sentinel data, the detection of damage assessment has been proven to be feasible. Nevertheless, economical loss assessment caused by locust plagues and outbreaks from remote sensing data is still rare . The LanFinally, the potential and possible benefits of VHR satellites are basically unexplored. Additional studies need to provide a better understanding of how VHR data can be exploited for early warning and detection of early instar activity  and damage assessment. EO data and archives provide the required specifications to tackle these challenges and investigate benefits and restrictions.The majority of publications focus on the desert locust and migratory locusts affecting large parts of the African continent, the Arabian Peninsula, India and Pakistan. The third foremost species is the Australian plague locust. For the migratory locust and the Australian plague locust, we found a clear relation between investigated regions of interest and the countries of affiliation of the authors . HoweverDespite the progress been made for the desert locust, the migratory locust and the Australian plague locust , there is a lack of studies for other pest locust species . This laFurther research on geomorphological variables for the desert locust as suggested by Lazar et al. .Application of sensor fusion/combination to minimize restrictions of sensor characteristics ,137.Application of hyperspectral data to enable more detailed classification of vegetation types, stressed vegetation or damage ,139.Time-series analysis focusing on phenology ,141,142.Other indices and metrics, e.g., Soil Adjusted Vegetation Index (SAVI)  or PerpeAs shown by Propastin ,105 altiSystematic and large-scale detection of damage and remote sensing-based economical loss assessment studies to evaluate economic impact and production loss on large scale. Remote sensing applications have received comparable little attention . Red edgUsage of VHR resolution imagery and machine learning approaches ,148,149 Further inclusion of remote sensing in ENM and HSI modelling, where all important static and dynamic environmental parameters are combined with species specific preferences ,151,152.The importance and potential of UAV-based systems for locust management supporting ground teams requires standardized analysis and investigation for automatic image processing. The advantages of UAV-based monitoring are promising ,154. HowFinally, locusts and grasshoppers strongly depend on climate conditions such as temperature, precipitation and humidity . FurtherRecent studies focus on comprehensive analysis of several essential ecological variables. This is due to the availability of more and more ARD. In this way, scientist can focus on the relation and individual importance of variables rather than dealing with extensive raw data preprocessing. Reviewed studies have been applying mostly NDVI to assess the risk of gregarization, to predict hatching and outbreaks, or simply use the technique as a metric for land cover classification. However, the capacity of NDVI in arid areas has been controversial. Therefore, at the background of new options and cloud computing possibilities, the benefit of additional indices or variables can be explored and compared. For example, Cherlet et al.  concludeMentioned suggestions for further research have to prove their benefit and outline practical contribution towards locust management. Therefore, from a locust management perspective, one has to consider all important factors within operational services  and contrast it with possible improvements.(i) Investigated species: The majority of studies focused on the desert locust (33%), the migratory locust (27%) and the Australian plague locust (14%). Remote sensing applications for other harmful locust species such as the brown locust (4%), the Central and South American locusts (1%), the Italian locust (5%), the Moroccan locust (1%) or the red locust (1%) are still very rare.(ii) Areas of interest: Areas of interest were mostly located in China (24%), Australia (14%) and Mauritania (11%). Despite a high risk of outbreaks from different species, there is a lack of English-speaking studies for the Arabian Peninsula (none), the Middle East and Pakistan (none), India (1%), South-East Asia (1%), North and South America (2%) and Russia (2%).(iii) Employed sensor types: Optical EO data were most frequently used. Here, 57% of all studies solely used optical data. Whereas, AVHRR, MODIS, SPOT-VGT and Landsat sensors were mostly employed. Following optical sensors, radar (6%) and TIR (3%) were the second and third most used sensor types, respectively. However, both were mostly applied in combination with others . No peer-reviewed publication was found using VHR  or Sentinel-2 data; only one study is available using Sentinel-1 SAR data.(iv) Used variables: The majority of studies applied NDVI, land cover information, LAI or fCover for analysis , referring to the importance of vegetation as a key parameter affecting population density and phase change of locusts. Despite the high importance of soil moisture for locust development, there are only few studies focusing on EO-based soil moisture retrieval (9%). However, recent development indicates that remote sensing-based soil moisture data will be an essential part in further research and eventually in desert locust management.Research foci: The majority of studies focused on habitat monitoring (39%), followed by habitat mapping (25%), outbreak/hatching prediction (17%) and general review publications (10%). Few damage assessment studies were conducted (9%); most of these studies are feasibility cases carried out for the migratory locust in selected geographic areas.Most articles reveal test case studies covering small study regions and short time periods. Overall, only 18 studies were long-term covering ten or more years.Furthermore, we found fewer English-speaking, peer-reviewed literature and studies conducted by organizations or universities located in locust-affected regions .In this review, we provided an extensive overview of 110 English-speaking, EO-related research articles with respect to destructive locust/grasshopper pest species. On the one hand, our focus was to quantify different aspects of reviewed studies. Therefore, we categorized the studies covering (i) investigated species, (ii) areas of interest, (iii) sensor types employed, and (iv) variables used. On the other hand, we aimed to point out main research foci and reflect on the development. We categorized specific research foci, namely (A) habitat mapping, (B) habitat monitoring, (C) outbreak/hatching prediction, (D) damage and loss assessment, and (E) review and general studies. By looking at the quantified results and methodological progress, the following findings can be summarized:The role of remote sensing for locust management and research has increased over the past 40 years and nowadays can be considered as irreplaceable. Well-operating monitoring and prediction systems for the desert locust (by FAO) and the Australian plague locust (by APLC) document the success and the advantage of implementing EO data to save time and resources once outbreaks occur. Summarizing, most EO applications focus on the monitoring of vegetation changes and precipitation patterns in locust habitat areas to determine potential gregarization, to stratify field surveys and to assess the risk of locust population increase . In rece


Ovarian cancer (OC) is one of the deadliest gynecological cancers worldwide. Previous observational epidemiological studies have revealed associations between modifiable environmental risk factors and OC risk. However, these studies are prone to confounding, measurement error, and reverse causation, undermining robust causal inference. Mendelian randomization (MR) analysis has been established as a reliable method to investigate the causal relationship between risk factors and diseases using genetic variants to proxy modifiable exposures. Over recent years, MR analysis in OC research has received extensive attention, providing valuable insights into the etiology of OC as well as holding promise for identifying potential therapeutic interventions. This review provides a comprehensive overview of the key principles and assumptions of MR analysis. Published MR studies focusing on the causality between different risk factors and OC risk are summarized, along with comprehensive analysis of the method and its future applications. The results of MR studies on OC showed that higher BMI and height, earlier age at menarche, endometriosis, schizophrenia, and higher circulating β-carotene and circulating zinc levels are associated with an increased risk of OC. In contrast, polycystic ovary syndrome; vitiligo; higher circulating vitamin D, magnesium, and testosterone levels; and HMG-CoA reductase inhibition are associated with a reduced risk of OC. MR analysis presents a2 valuable approach to understanding the causality between different risk factors and OC after full consideration of its inherent assumptions and limitations. Ovarian cancer (OC), the eighth most common type and eighth leading cause of cancer-related mortality in women, is considered the deadliest gynecological cancer. Three main types of OC have been identified, specifically epithelial, germ cell, and sex cord-stromal, with epithelial tumors comprising about 95% of OC cases . EpithelOC is a multifactorial disorder influenced by both genetic predisposition and modifiable exposures. Identification of causative risk factors amenable to modification is thus essential for prevention of this disease. Randomized controlled trials (RCTs) can be uniformly applied to determine whether certain exposures are causal factors for diseases of public health interest. While RCTs remain the gold standard research design for inferring causality, they are extremely expensive, time-consuming, and associated with a high failure rate (>50% due to lack of efficacy) , 5. In aTo overcome the limitations of observational design, genetic variants have been proposed as potential instrumental variables (IV), usually single-nucleotide polymorphisms (SNPs), to simulate the effects of modifiable environmental exposures on disease susceptibility, referred to as Mendelian randomization (MR) . MR offeMR uses germline genetic variants as instruments  for exposures  to examine the causal effects of these exposures on health outcomes (disease incidence or progression) . ExposurI. IVs (SNPs being used) should be clearly and quantifiably linked to the exposure(s) in question.II. IVs should not be linked in any way to confounding variables.III. IVs should be linked to outcomes only through the exposure(s) in question.To estimate a causal effect with IV analysis, additional assumptions are required. One such assumption is that:IV. The associations are linear and not affected by statistical interactions .p = 5×10−8) and subsequently evaluate the relationship between these SNPs and outcomes to obtain odds ratios (OR) and mean differences  have made an important contribution to the identification of genetic variants associated with numerous potential risk factors for health-related outcomes. GWAS results have facilitated the application of MR in evaluating causal relationships between modifiable exposures and outcomes. During recent years, numerous MR studies focusing on OC have been conducted . In addiOriginal studies were identified by searching for relevant articles up to February 2, 2021, in the PubMed database. The search algorithms for PubMed database were as follows: “Mendelian randomization” or “genetic instrumental variable” or a related term  and “Ovarian Cancer” or “Ovarian Neoplasm” or “Ovary Cancer” or “Ovary Neoplasm” or “Cancer, Ovary” or “Neoplasm, Ovary”, with no restriction on subheadings. All retrieved articles were checked for relevant citations and studies not included in the above electronic sources were searched manually. We included studies based on the following criteria: (1) those using MR methodology and instrumental variable analysis to evaluate risk factors of OC and (2) those performed on the basis of observational study design. The search strategy and selection criteria have been checked by two independent authors and, if necessary, the inconsistent part would be judged by third authors. A total of 30 articles were finally included and classified according to type of exposure  and then to acetate by acetaldehyde dehydrogenase (ALDH2). Carriers of the A-allele of ADH1B rs1229984 consumed less alcohol per week . TherefoA number of epidemiological studies on epithelial OC have shown that smoking increases risk of OC, but only for the mucinous subtype. Significantly increased risk of invasive mucinous and borderline mucinous OC among current smokers has been reported , shown tAn MR study using 115 SNPs from participants of European ancestry recruited from 14 countries reported that lifetime smoking exposure was associated with increased risk of invasive epithelial OC. In subtype-specific analyses, evidence for association of smoking with high grade serous cancer (HGSC), but not the mucinous subtype, was obtained . AnotherCoffee consumption is suggested to be associated with decreased estrogen circulation in pre- and postmenopausal women. Its intake is linked with obesity, metabolic syndrome, and type 2 diabetes as well as liver fibrosis, cirrhosis, and specific types of cancer, including breast, colorectal, lung, endometrial, and prostate cancer. Given that elevated estrogen has been long suspected to increase the risk for OC, coffee consumption may decrease this risk . AdditioIn 2018, Ong et al.  conductePrevious studies suggest that anthropometric characteristics are related to OC risk and prognosis . While sObservational studies have revealed an association between BMI and various cancer types. In 2014, fat index was identified as a potential risk factor for OC by World Cancer Research Fund/American Institute for Cancer Research . ConversBRCA1 and BRCA2 mutation carriers revealed a positive association between BMI and OC risk in premenopausal BRCA1/2 mutation carriers  from FOCI and large-scale GWAS of adiposity-related traits comprehensively analyzed the causal relationship between adiposity at different life stages and OC risk. The group reported potential associations of genetic scores for higher adult BMI with increased risk of overall OC but failed to show strong evidence of associations between genetically predicted birth weight, childhood BMI or WHR, and OC risk . In 2016carriers . Subsequcarriers .Changes in sex hormones in females during their 20s and 30s are important in the pathogenesis of epithelial OC. Height is strongly influenced by the peripubertal hormonal milieu and reflects pubertal hormonal levels. Observational studies support an association of increased height in adults with higher risk of OC . ReportsBRCA1/2 mutation carriers, no causal relationship between height and OC risk was observed  show changes during childhood and adolescence, which are thought to play an important role in the etiology of OC. In 2013, a meta-analysis including 22 case–control and 5 cohort studies on age at menarche and OC risk supporting an inverse relationship between menarche and risk of OC was published. An inverse association between menarche age and OC risk has been reported in the majority of subgroups, but limited to invasive and borderline serous OC , 67.Another article showed evidence for association of earlier age at menarche with risk of invasive epithelial OC in inverse-variance-weighted (IVW) models. However, horizontal pleiotropy may bias the IVW estimate. In studies examining invasive epithelial OC histotypes and low malignant potential tumors, evidence for association of earlier age at menarche with endometrioid carcinoma was obtained, which was robust in MR-Egger, weighted median, weighted mode, and leave-one-out analyses . MR analMenopause is permanent cessation of the menstrual cycle, marking the end of female reproductive life. In addition to changes in related sex hormone levels, the timing of menopause can also be applied to predict future health outcomes, such as risk of hormone-related cancers. Earlier menopause may be related to increased risk of OC. This theory is based on the gonadotropin hypothesis for pathogenesis of OC, which predicts that ovarian aging, accompanied by higher concentrations of follicle-stimulating and luteinizing hormones, increases the risk of OC . PreviouPast epidemiological studies have shown that parity is associated with the occurrence of ovarian cancer. Nulliparity and low parity are associated with an increased risk of ovarian cancer. Parous women have a 30%–40% lower risk of developing ovarian cancer, and an additional protective effect is seen with increasing parity . StudiesEndometriosis is a chronic, estrogen-dependent progressive disease characterized by the presence of endometrioid tissue, glands, and interstitium outside the uterine cavity. In addition to serious adverse effects on female health and wellbeing, increased risk of OC development cannot be overlooked. Endometriosis, in particular, ovarian endometriosis, is suggested to increase the risk of malignant tumors. Two main pathways have been proposed to describe the potential association between OC and endometriosis: (1) the two diseases coexist and are the result of common risk factors and their effects and (2) endometriotic cells gradually transform into cancer cells . NumerouOur MR analysis include reports that endometriosis is associated with risk of OC. Strong evidence of an association of genetic liability to endometriosis with increased risk of invasive epithelial OC was obtained in these studies. Subtype-specific analyses further confirmed significant association with clear-cell carcinoma and potential association with endometrioid carcinoma, low malignant potential tumors and HGSC. Findings on invasive epithelial OC and clear-cell carcinoma were reported based on sensitivity analyses examining horizontal pleiotropy whereas somewhat inconsistent effect estimates were found for endometrioid carcinoma, low malignant potential tumors, and HGSC. Analyses employing Steiger filtering provided strong evidence that the causal direction was from genetic liability to endometriosis to invasive epithelial OC whereas the causal direction could not be clearly established for clear-cell carcinoma .Polycystic ovary syndrome (PCOS) is a common hormonal disorder affecting 5%–8% women of reproductive age. A population-based case–control study highlighted the possibility of risk of OC in women with PCOS, which was not supported by other studies . RecentlTwo recent MR analyses on PCOS and OC risk may contribute to clarification of this issue. The first article provided little evidence that genetic susceptibility to PCOS affects the risk of invasive epithelial OC . FurtherFor more than 100 years, the debate on whether schizophrenia can reduce the risk of cancer has continued. A number of previous studies indicate that schizophrenia contributes to prevention of cancer. Genetic research additionally supports an inverse correlation between schizophrenia and cancer, including evidence of common protein transcription pathways of the two diseases . HoweverCholine metabolism disorders in association with schizophrenia and epithelial OC are documented. A bidirectional MR analysis of epithelial OC (data from six OCAC and two Consortium of CIMBA projects) and schizophrenia [Schizophrenia Working Group of the Psychiatric Genomics ] highligVitiligo is an autoimmune disease characterized by selective destruction of melanocytes leading to depigmentation of skin. The association between vitiligo and skin cancer has been discussed previously, but findings to date are inconsistent. The potential correlation between vitiligo and risk of other cancer types has received limited research attention. A recently published MR analysis of vitiligo and cancer risk in European populations suggests a protective role of vitiligo against development of OC .Several epidemiological studies support an association between type 2 diabetes and increased risk of some types of gynecologic neoplasms, such as endometrial, cervical, ovarian, and vulvar cancer. Insulin resistance, chronic inflammation, and high levels of free ovarian steroid hormones may be among the potential mechanisms underlying this complex relationship . In the Nutritional factors are related to OC, and improper lifestyle choices can exacerbate disease progression. Therefore, assessment of the impact of diet on risk of OC is of critical importance to the public, clinicians, and research and health institutions . MR reseVitamin A activity is important for normal control of cellular differentiation and proliferation and hypothesized to modify cancer risk. Interestingly, a previous study exploring the correlation between vitamin A levels and risk of OC demonstrated no association while a subsequent meta-analysis reached the opposite conclusion , 80. A fVitamin E, also designated tocopherol, has strong antioxidant activity that protects cells against oxidative DNA damage and mutagenesis, thereby preventing the onset of specific tumors. Vitamin E also contains putative anti-cancer and anti-mutant compounds and were suggested to play a role in the prevention of cancer. However, conflicting data have been reported showing that vitamin E is not related to OC , 81. An B vitamins  are essential micronutrients purported to influence carcinogenesis through regulation of one-carbon metabolism. Women in the highest quintile of folate and vitamin 6 intake were shown to have lower risk of OC than those in the lowest quintile , 82. Howin vitro and animal model studies support anti-tumor effects of vitamin D  is a highly sensitive and widely used systemic marker of inflammation. The protein is mainly produced by liver cells, together with other acute phase proteins, and released into the circulatory system in response to tissue damage and inflammation. Systematic reviews and meta-analyses have validated the utility of serum CRP levels as an effective indicator of risk of OC . HoweverMR analysis conducted on a European population showed that despite no evidence that C-reactive protein affects risk of invasive epithelial OC, analyses examining histotypes and low malignant potential tumors suggested an inverse association of C-reactive protein with endometrioid carcinoma. C-reactive protein was not clearly associated with other histotypes or low malignant potential tumors .in vitro studies as well as epidemiological observations, available evidence that sex steroids play a role in OC is mainly indirect and the precise relationship between circulating levels of sex steroids and risk of OC is yet to be established (The sex hormone binding globulin (SHBG) gene regulates its effect by regulating the bioavailability of sex steroid hormones in target tissues (such as ovary). Hormone stimulation of ovarian epithelial cells is proposed as a mechanism underlying the development of OC. According to animal and ablished . An earlablished . In 2020ablished .in vitro and in vivo studies have shown that statins inhibit cancer cell growth by inducing apoptosis and inhibiting cell cycle progression through multiple cell signaling pathways (Statins are widely used to treat hypercholesterolemia. These drugs inhibit 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR), an enzyme necessary for synthesis of mevalonate . HMGCR ipathways . MR studpathways .Due to the increase in cardiovascular, endocrine, and metabolic diseases, such as metabolic syndrome, diabetes and polycystic ovary syndrome, the prevalence of insulin resistance continues to increase. Several studies support a link between insulin resistance and OC. Insulin resistance is reported to be related to ovarian steroid hormone imbalance and inflammation in diabetic patients and gynecological malignancies. Effective control of insulin resistance could therefore prevent various gynecological cancers. However, contrary to these findings, no association between insulin-like growth factor 1 (IGF-1) or binding protein 3 (IGFBP-3) and OC was identified in other studies . The cauTestosterone is also a key hormone in women. In addition to being an essential precursor for estradiol biosynthesis, testosterone directly acts as an androgen and exerts physiological effects on both reproductive and nonreproductive tissues in women. The role of endogenous androgens in ovarian carcinogenesis is not well understood at present. A number of reports have shown no correlation between androgens and overall risk of invasive epithelial OC while other studies suggest that androgens are both protective and carcinogenic , 102. MRArachidonic acid (AA) is metabolized by cyclooxygenases and lipoxygenases to proinflammatory eicosanoids that modulate tumor cell proliferation, differentiation, and apoptosis according to experimental research. AA is a polyunsaturated fatty acid present at high concentrations in the OC microenvironment and associated with poor clinical outcomes. Several studies support its utility as a therapeutic target for intervention and prognostic indicator of OC . HoweverObesity is considered a chronic inflammatory state characterized by continued infiltration of adipose tissue by macrophages and other immune cells leading to increased or decreased adipose secretion of adipokines  that may be linked to cancer development , 105. WhTelomeres, which protect the physical integrity of linear chromosomes, are shortened with each cell division, a process that may be accelerated by damage incurred by oxidative stress. Tissue-based studies have revealed a pattern of telomere shortening, genomic instability, and upregulated telomerase expression in many tumor types, including OC. As cells progress from noninvasive precursor lesions to cancer, telomere shortening is a common phenomenon of the early stage of malignant transformation. Prospective studies suggest that greater circulating leukocyte telomere length is associated with lower risk of OC, especially for non-serous and rapid death cases. However, no evidence showing that overall telomere length is causally related to the risk of OC is currently available . In 2015MR is effective in reducing reverse causality and confounding variables and has gradually become an increasingly useful tool in epidemiological research. Moreover, MR analysis can be effectively used to analyze exposures that are not easy to investigate in some RCT and observational studies (such as height and BMI) , 16. TheA straightforward and common way of performing MR is called the ratio of coefficients or Wald method. The causal effect is triangulated by dividing the coefficients of regression of the outcome on the IV by the regression of the exposure on the IV . This mepriori , the LiaoNing Revitalization Talents Program (No. XLYC1907102 to Q-JW), the Shenyang High Level Innovative Talents Support Program (No. RC190484 to Q-JW), and the 345 Talent Program to Q-JW (No. M0268).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


The Ontario government implemented a regulatory change to mandate the collection of socio-demographic (SD) data for individuals who tested positive for COVID-19. This change was informed by evidence of COVID-19’s disproportionate impact on marginalized communities and calls for broader collection of SD data. Given the scarcity of similar efforts, there is a significant knowledge gap around implementing standardized SD data collection in public health settings.Public Health Ontario provided collaborative support for the implementation of SD data collection, grounded in health equity principles, evidence, and best practices. We supported the addition of SD fields in Ontario’s COVID-19 data collection systems, issued data entry guidance, hosted webinars for training and learning exchange, and published a resource to support the data collection process. The current focus is on building sustainability and quality improvement through continued engagement of public health units.By November 28, 2020, almost 80% of COVID-19 cases had information recorded for at least one SD question . We hosted three webinars for the field, and the data collection resource was viewed almost 650 times. Practitioners continue to express needs for support on applying equity principles to data analysis and interpretation, and community engagement on data collection and use.Sharing knowledge on responsive implementation supports in collaboration with the field and using current evidence and guidance will strengthen public health practice for SD data collection. Laying this groundwork will also improve the likelihood of success and sustainability of these equity-focused efforts. Areas with highest ethnic diversity had higher hospitalization rates (4× higher), higher intensive care unit (ICU) admission rates (4× higher), and higher death rates (2× higher) compared with those with the lowest ethnic diversity , ICU admission (2× higher), and death rates (52% higher) compared with those with lowest material deprivation  collection infrastructures, particularly around race-based data  project started in 2007 in Interior Health; since then, a few reports have used the data in health strategies and planning  provides strategic leadership for the health system and is responsible for health legislation and regulations. Within the MOH, the Office of the Chief Medical Officer of Health develops public health strategies and policies, and sets the standards for local Boards of Health and PHUs. This includes standards with respect to health equity, and communicable disease prevention and control programs and surveillance. Public Health Ontario (PHO) provides scientific and technical information, advice, and support to the MOH and PHUs to inform decisions and action, with an explicit aim to help reduce health inequities  to support the introduction of data collection and build skills around data collection practices. The session covered core equity principles driving this work, including historical and current inequities. Attendees also learned about the SD questions , scripts, and data entry guidelines.Data collection resource document to support case managers in navigating the new SD data fields. The resource included a sample script that may be used during data collection, tips for case managers, frequently asked questions, and background information. This document was intended for use in conjunction with PHO’s technical data entry guide.Data analysis advice, organized into three parts: (1) data quality, (2) data summaries, (3) description of COVID-19 outcomes . This included the application of an intersectional lens in the analysis. For specific guidance on interpretation and messaging, we defer to the work of existing groups , recognizing that this area of work should centre the perspectives of impacted communities rather than organizations holding the data. This approach would also help mitigate the harm and stigma that can result from sharing data about disproportionately impacted communities.We also held two online learning exchanges that brought together PHUs to discuss emerging experiences, opportunities, and concerns. Following short PHU presentations, attendees participated in an interactive discussion with each other and the panelists. The first learning exchange (June 2020) focused on preparing and familiarizing PHUs with the process of implementing SD data collection. We invited three PHUs that started local SD data collection ahead of the provincial roll-out. Presenters shared their strategies for successful data collection, including training, workflows, engagement, and sustainability planning. The second learning exchange in December addressed the progress on data collection since early implementation. Reflecting a shift in focus from collection to analysis, three health units shared their experiences with improving data quality , integrating an equity lens in this work, and initial efforts in analyzing the data to identify inequities in their regions. In the case of both events, PHO facilitated the discussion and collated questions for future use in training and support. Upon evaluation, discussion components were rated as one of the strongest elements of the events. In addition to events, the PHO team has prepared resources, including:In the first full week of data collection, more than 50% of cases had information recorded for at least one of the SD questions see Fig. . FollowiTable The target audience for our webinars have been Ontario PHUs 34 in total). Within that group, we have seen representation from diverse professional roles , as well as geographies , learning exchanges between PHUs, training for data collectors, and other resources. During this period, we continued to engage practitioners across the province and in various roles in PHUs, community health, data expertise, and others. We continue to explore key support needs and engage PHUs to build sustainable, equitable, and impactful data collection systems to inform program and policy decisions to address health equity.We provided scientific advice and knowledge translation activities to support the introduction of COVID-19 socio-demographic (SD) data collection by adapting resources from other Canadian health settings.This work contributes to filling gaps in SD collection infrastructures in the provincial and national health systems, particularly around race-based data.The collection and use of robust and reliable data on race, household size, income, and additional SD variables sets the foundation for building accountable and responsive policy and programs.What are the burning research questions for this innovation?There is a need for research and evaluation on tools and methods used in supporting SD data collection in public health nationally and internationally, applying an implementation framework.Further study is needed on implementation supports and knowledge exchange methods for teaching and skill development in SD data collection and use, driven by equity-centred evidence and community perspectives.There is also a need to understand interventions to support practice in addressing health equity through data use, including its use to inform public health efforts, SD data in program planning and implementation, and resource redistribution, tailored programs, and policy change.What are the innovations in this policy or program?


Experience of care is a pillar of quality care; positive experiences are essential during health care encounters and integral to quality health service delivery. Yet, we lack synthesised knowledge of how private sector delivery of quality care affects experiences of care amongst mothers, newborns, and children. To fill this gap, we conducted a systematic review that examined quantitative, qualitative, and mixed-methods studies on the provision of maternal, newborn, and child health (MNCH) care by private providers in low- and middle-income countries (LMICs). This manuscript focuses on experience of care, including respectful care, and satisfaction with care.Our protocol followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Searches were conducted in eight electronic databases  and two websites and supplemented with hand-searches and expert recommendations. For inclusion, studies examining private sector delivery of quality care amongst mothers, newborns, and children in LMICs must have examined maternal, newborn, and/or child morbidity or mortality; quality of care; experience of care; and/or service utilisation. Data were extracted for descriptive statistics and thematic analysis.Of the 139 studies included, 45 studies reported data on experience of care. Most studies reporting experience of care were conducted in India, Bangladesh, and Uganda. Experiences of private care amongst mothers, newborns, and children aligned with four components of quality of care: patient-centeredness, timeliness, effectiveness, and equity. Interpersonal relationships with health care workers were essential to experience of care, in particular staff friendliness, positive attitudes, and time spent with health care providers. Experience of care can be a stronger determining factor in MNCH-related decision-making than the quality of services provided.Positive experiences of care in private facilities can be linked more broadly to privileges of private care that allow for shorter waiting times and more provider time spent with mothers, newborns, and children. Little is known about experiences of private sector care amongst children.CRD42019143383).This systematic review was registered with the PROSPERO international prospective register of systematic reviews (registration number The online version contains supplementary material available at 10.1186/s12913-021-06905-3. Increasing access to and provision of care without an explicit focus on quality of care limited improvements in maternal, child, and newborn health (MNCH) care during the course of the Millennium Development Goals 2000–2015) [5 [1]. ReComprised of six intersecting components, quality of care is care that is safe, effective, patient-centred, timely, efficient, and equitable , 9. PosiExperience of care is rarely included as a measure in large-scale facility-assessment tools , in partWith regards to MNCH, the World Health Organization (WHO) recognises the complex relationship between experience of care and health outcomes , 18. ExpAs a pillar of quality of care, experience of care appears in the WHO framework for quality of maternal and newborn health care, where it is disaggregated into three critical components: effective communication, respect and dignity, and emotional support . The fraThe private sector, which includes individuals and organizations that are neither owned nor directly controlled by governments and are involved in the provision of health services  , plays aHow does the provision of quality health care by the private sector affect morbidity and mortality among mothers, newborns, and children?How does provision of quality health care by the private sector affect utilization of services by mothers, newborns, and children?How effective and efficient is the private sector at delivering quality of care?Among mothers, newborns, and children utilizing health care provided by the private sector, what are their experiences of care? The Network for Improving Quality of Care for Maternal, Newborn and Child Health (the Network), a partnership of 11 countries  and their technical partners, was launched in 2017 with the aim of halving maternal and newborn deaths and stillbirths in participating health facilities in 5 years’ time . NetworkThis study is part of that larger systematic review. Given the extensive amount of data and studies in the entire systematic review, our aim in this article is to answer the fourth research question by systematically assessing the evidence from studies reporting outcome data on experiences of private sector quality MNCH care. Results from complementary analyses on the first three research questions will be presented in separate companion articles.We conducted a systematic review following guidance in the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) Statement for clear and transparent reporting of systematic reviews and meta-analyses , 28. As We searched journals from eight electronic databases  and two websites . We supplemented these searches with hand searching of reference lists and expert-recommended articles. The searches, application of inclusion/exclusion criteria, screening, and data extraction were conducted using a published protocol and data extraction tools . The seaBackground information Intervention background information Intervention details ◦ Maternal morbidity◦ Maternal mortality◦ Newborn morbidity◦ Newborn mortality◦ Child morbidity◦ Child mortality◦ Service utilization◦ Experience of care, including respectful care◦ Components of quality care Critical outcomes :Evaluation/study details Study quality Quantitative and qualitative data were extracted on the following categories:JS and SRL extracted and quality assessed studies in duplicate. Quantitative studies were assessed using the Effective Public Health Practice Project quality assessment tool , and quaQualitative data were thematically analysed using a three-stage approach, appropriate for systematic reviews . All datGiven the heterogeneity between the studies in terms of study designs and interventions, it was not possible to conduct a meta-analysis for the outcome experience of care. Quantitative findings are presented using a narrative synthesis with tables of descriptive statistics. More detailed summary tables, including quality scores, appear in Additional File As shown in Fig. n = 110) followed by experience of care (n = 45)  Table . The totMost studies reporting outcome data on experience of care were conducted in India 24.4%), Bangladesh (11.1%), Uganda (11.1%), and Kenya (6.7%)  implemented a specific intervention . These interventions were most often single interventions and focused on supply-side factors  [n = 3) [Amongst studies reporting data on experience of care, one-third of studies e n = 1)  or moder [n = 3) , 36. Add  or modeAmong studies reporting experience of quality MNCH care in the private sector, four key themes emerged: (1) comparative studies between public and private health facilities illustrate the relative importance of interactions with health care workers and timeliness in overall experience, and they provide opportunities for shared learning between facilities; (2) mothers’, newborns’, and children’s interactions with health care workers and staff in private clinics most frequently impacted their reported experience of care; (3) timeliness was an essential component of care and associated with both experiences of care and satisfaction with care; and (4) few studies presented findings on contextual inequalities and experiences of private health care beyond affordability. Studies reporting on experiences of care amongst children and newborns did so from the perspective of parents, caregivers, or through clinical observations, rather than from the newborns or children themselves. Thus, the results for newborns and children are experiences of care by proxy.Comparative studies of the private and public sectors highlighted that experience of care was not uniformly better in private or public facilities. Rather, both private and public facilities could provide important lessons for quality improvement. In the private sector, women valued their experiences of care for being efficient, timely, clean, and patient-centred. In particular, women obtaining care in the private sector experienced reduced wait times. Women at private antenatal clinics in Pakistan were able to spend an average of 8 min with their health care provider, whereas women at public facilities spent an average of 3 min with their health care provider . For preResults assessing the provision of care in private facilities showed mixed results. While private hospitals delivering maternal and child health services in Nairobi, Kenya provided good staff interactions, public facilities had more experienced staff and higher quality services . SimilarStudies frequently reported interpersonal communications and interactions that intersected all four domains within experience of care: support, effective communication, respect and dignity, and user-centred health systems. These interactions most often involved the behaviours of health care workers towards mothers, newborns, and children receiving care, including experiences of care during treatment , staff attitudes , and experiences of counselling , 45–48. Qualitative and observational studies corroborated the significance of interpersonal communications between health care workers and care seekers. Among women accessing reproductive and child health services from franchises in Ghana, positive experiences of care were linked to staff being “sociable” and to staff giving clients space for questions and answers in case of confusion . An obseWomen’s ability to communicate with health care staff during consultation, treatment, and provision of care was critical in determining positive or negative experiences. A mixed-methods evaluation of a social franchise programme in India, which included a telemedical intervention, found that poor communication lines led to women reporting negative experiences of care . Among wInteractions with health care providers and other staff members also influenced women’s care seeking decisions, particularly the experiences of dis/respectful care and dignity. These interactions shaped where women sought out care, illustrating that real and perceived experiences can significantly influence care trajectories. Women attending private facilities in Nairobi, Kenya cited real and perceived negative treatment from staff, including abuse and ostracism, as a reason to avoid public facilities . As one Respondents in multiple studies reported privacy and confidentiality of services as essential components of experience of care. A survey of women receiving first-tier public and private antenatal care in Tanzania emphasised the relationship between privacy and positive experiences of care in both facility models . Two difWithin the user-centred health systems domain of experience of care, evidence from India indicated room for improvement. Clinical observations of 275 mother-neonate pairs at 26 public and private hospitals in Uttar Pradesh, India, found that health care workers avoided harmful or unnecessary interventions for the mother in only 6.6% of observations in public facilities and 1.5% of observations in private facilities . Health Effective quality of care also emerged as a sizeable clinical component of experience of care within the user-centred health systems domain. The provision of care that is effective, or perceived to be effective, shaped the expectations and satisfaction of care-seekers, including the provision of quality counselling, provision of essential equipment, and choice to avoid overmedicalized care. Women valued knowledge of available options and choices. In Dhaka, Bangladesh, women who had caesareans in the private sector reported that a lack of medical counselling, overmedicalization of birth, and presentation of birth options prior to care had negative implications: “I think, the doctor did not say anything, because it involves a lot of money. In private clinics, there is hardly any normal delivery. Now I think, if I had a normal delivery, it would have been better.”  ObservatIn addition to linking to experience of care, interpersonal communications and staff treatment also impacted satisfaction with care. In an intervention aimed at improving quality of post-abortion family planning provision, women reported higher satisfaction due to their improved experiences of counselling and time spent with provider: 69% of women reported being given clear care instructions post-intervention compared to 58% of women at baseline . In publNumerous studies used “time” as a measure corresponding to user-centred health system indicators and also to broader aspects of experiences of care. Timeliness was conceptualised differently across studies, including the time that mothers, newborns, and children spent waiting and receiving care in facilities; the associated time costs in accessing care ; and time-based accessibility .Wait times directly affected experiences of care with longer waiting times resulting in poorer experiences of care. In Uttar Pradesh, India, women reported waiting “a number of hours” before being able to attend a telemedical consultation with a health care worker, leading to significantly negative experiences of care . In privConversely, shorter wait times generally led to higher satisfaction and positive experiences of care. Women accessing abortion services in Istanbul, Turkey, reported positive experiences of short wait times; most women obtained an abortion within 1 to 10 days, whereas women seeking abortions from a public hospital had to wait at least a week . In westInsufficient time with health providers generally resulted in poorer experiences of care and even poorer health outcomes. Not being allowed “enough time” with doctors negatively impacted women’s experiences, as reported by women who had caesarean sections in Dhaka, Bangladesh . These wA facility’s opening hours, an important component of “timeliness,” also influenced decisions to seek care in the private sector. Women in Kenya reported better experiences accessing MNCH services in a private facility “since it operates all the time”; in addition, the facility’s hours influenced women’s decision-making about where to obtain services .Inequalities were present in women’s experiences accessing their choice of care as well as women’s experiences receiving care. These inequalities reflected contextual structural hierarchies of discrimination, with studies reporting differences in experience due to income, ethnicity (particularly for Indigenous women), and mobile/internet connectivity. Inequalities primarily occurred at point of access. In private prenatal clinics in Mexico, lower-income and Indigenous women were treated differently in private facilities than higher-income and non-Indigenous women, whereas in public facilities there was no difference . This trMost research focused on affordability and its associated impact on experiences of private health care. Affordability is an essential component of user-centred health systems and was a consistent barrier for women seeking care in private facilities. Experiences of care among women seeking caesarean sections in Dhaka, Bangladesh were better in private than public facilities; private facilities were only available to higher income women who had the necessary resources to exercise choice . StudiesThe experiences of women in informal settlements in Nairobi, Kenya who sought MNCH services highlighted the extent of this variation in cost. While some women could take advantage of payment schemes in private hospitals , others found private health care prohibitively expensive . An analBy systematically reviewing the evidence of mothers’, newborns’, and children’s experiences of care in the private sector, this article provides insights into best practices for delivering high quality experiences of care. The findings illustrate the importance of interpersonal relationships with health care workers, in particular staff friendliness, positive attitudes including non-judgement, time spent listening to women, and responsive counselling. The relationship between mothers, newborns, and children and health care workers is essential and cannot be underestimated, as it impacts person-centred care, timeliness, and equity. Timeliness of care, privacy, and affordability were also important aspects of women’s experiences of care in the private sector and by extension, women’s health outcomes. These components of positive experiences of care emerged as noteworthy in both quantitative and qualitative studies. Researchers frequently mixed experience of care and satisfaction with care in their studies, emphasising the complexity of these measures and their variation across contexts as well as their subjective nature amongst people seeking care.Beyond “affordability” as a socioeconomic measure of inequality, there is a paucity of evidence on inequalities and experiences of private health care among women, children, and newborns. Parents and caregivers may or may not judge care provided to themselves and that provided to their children differently . Experiences in private facilities raise important questions on the affordability and by extension, the choice of care that women, children, and newborns may obtain. Compared to public health systems, private health systems may both directly and indirectly exacerbate socio-demographic inequalities. People seeking private health care may experience prohibitive costs at point of care; Indigenous and lower-income women may experience lower quality services. These inequalities and the continued marginalisation of certain populations have been identified as challenges across mixed health systems, regardless of the sector (public or private) in which people seek and receive care.The context of private sector delivery of quality MNCH care is essential to consider. Studies highlight the varied and complex roles that the private sector has in different settings, for example, facilitating MNCH care delivery in areas where public sector infrastructure and capacity is weaker  or proviThis systematic review contributes to previous reviews on the public and private health sectors in low- and middle-income countries , 63. It Due to language restrictions, relevant studies may have been excluded from this systematic review, particularly studies from Latin American and the Caribbean. We were also unable to locate 108 texts, despite our best efforts to locate authors and library assistance. The majority of these missing texts appear to be grey literature, particularly abstracts from the Popline database that closed in September 2019. Moreover, publication bias, particular in intervention research, may have resulted in an increased proportion of negative or neutral findings being rejected for publication . This poIn conducting this systematic review, we observed that studies and reports largely do not consider the delivery of MNCH care in the mixed health system. Thus, the design, analysis, and reporting of studies are often not organized in a way that captures mixed health system data or presents disaggregated findings. As a result, this oversight leads to cherry picking of findings or conclusions, poor comprehension of the actual situation, and at times, the politicization of private sector service delivery.Insights from this systematic review confirm that experience of care is fundamental for people seeking quality MNCH care in the private sector. The private sector is varied, complex, and context specific. While inaccessibility amongst some private services allows for privileged experiences of care, this is not inevitable. Meaningful engagement with, and regulation of, private sector service delivery can support efforts to achieve universal health coverage with quality. Of course, providing quality MNCH care and ensuring positive experiences of care in mixed health systems require the existence of basic prerequisites like the availability of clean water, sanitation, and hygiene; essential equipment; medications; and enabling environments for health care workers.Policymakers, programme implementers, and private sector stakeholders must recognise that experience of care can be a stronger determining factor in health-related decision making than the quality of care available in public and private facilities. In addition to influencing care outcomes, experiences of care amongst mothers, newborns, and children influence their future decision-making and choice of both health providers and health facilities. Poor experiences of care lead people and their caregivers to seek care elsewhere, thus encouraging private providers to prioritise experience of care to ensure market competitiveness and future revenue.Experience of care is frequently only a small component of studies on quality of care. Additional research should centre experience of care as a key focus, explore the relationship between experience of private sector quality care and socioeconomic inequalities, and fill in gaps around mothers’ experiences of private health care for childbirth.Experience of care should not be an outcome limited to adults. The experiences of children, newborns, and parents or carers seeking care for their children can also add value to studies investigating quality of care.Establishing criteria for understanding experience of care would help reduce variations within qualitative and quantitative data. Satisfaction and experience of care are important but separate constructs. Criteria more clearly presenting the differences between experience of care and satisfaction with care are required, as is the centring of inequalities in experiences of care.This systematic review excluded 64 studies that presented aggregated findings on the public and private sectors and 45 studies that did not specify whether the health facilities were public and/or private. To better understand experiences of care in the private sector, we encourage researchers to specify what types of health facilities are included in the study and to disaggregate their data on the public and private sectors when conducting analyses. Had we been able to draw upon this work and knowledge, we might have been able to generate more conclusive evidence on experiences of quality MNCH care provided by the private and public sectors.The private sector is heterogenous, so having additional details about the types of private facilities included in a study  could show valuable differences.Findings from this systematic review support recommendations aimed at strengthening the evidence base on experiences of private sector MNCH care and recommendations for improving experiences of private sector MNCH care. In order to better understand experiences of quality MNCH care within the private health sector, the following recommendations are made for researchers:Patients seeking MNCH care may switch between the public and private sectors, obtaining private antenatal care but choosing to deliver in a public facility, for example. Improving experience of care requires approaching the entire mixed health system and also strengthening case referrals between the public and private sectors.In certain settings, a lack of economic incentives to establish and operate private health facilities delivering MNCH care in rural areas means that private health facilities are likelier to deliver MNCH care in urban areas and to people from higher socioeconomic groups. Expanding access to low-interest loans and providing economic incentives to private health facilities can help facilitate the entry of private MNCH providers in hard-to-reach and rural areas as well as amongst lower socioeconomic groups, thus expanding access to affordable quality care and helping deliver universal health coverage.Even if mothers, newborns, and children report positive experiences of care, poor dissemination of updated guidelines and standards to private health providers means that the quality of MNCH care delivered may not always align with national standards. Greater dissemination and outreach to private facilities and providers is warranted as is the inclusion of stakeholders from the private sector in developing national policies, standards, and strategies. Additional resources and easier access to financing can also help facilitate greater compliance with national quality standards.Comparative studies of experiences of quality MNCH care in public and private health facilities provide opportunities for shared learning between facilities; however, this cross-learning is rarely instutionalised. We encourage Ministries of Health to strengthen and operationalise a mechanism for public-private dialogue in order to foster relationships, create open and transparent communication, and co-develop and co-implement an agenda to strengthen quality of MNCH care.In order to improve experiences of MNCH care within the private health sector, the following recommendations are made for policymakers and programme implementers:Additional file 1.Additional file 2.


Objective: To report on the role of nature in outdoor therapies through review and summary of existing systematic and meta-analytic reviews in an effort to articulate a theoretical framework for practice. Materials and methods: An umbrella review was conducted following systematic protocols PRISMA guidelines. Results: Fourteen studies met the inclusion criteria and represented five self-identified approaches: nature-based therapies, forest therapy, horticultural therapy, wilderness therapy, and adventure therapy. Clear and comprehensive descriptions of theory, program structure, and activity details with causal links to outcomes were mostly absent. Conclusions: A rigorous and determined program of research is required in order to explicit in-depth theories of change in outdoor therapies. Conversely, or maybe concurrently, a holistic theory of integrated relatedness may be developed as a parallel expression of support for nature in therapy while the explanatory science catches up. Understanding therapeutic values of human contact with nature is a topic of growing interest across health promotion and treatment fields . A commoOutdoor therapies are intentional therapeutic processes that are (1) place-based, (2) feature active bodily engagement, and (3) recognize nature-human kinship . SignifiUnderstanding and describing mediators (relationships between intervention and outcomes), moderators (characteristics that influence direction or magnitude between the intervention and outcomes), and mechanisms of change (the steps or effects—described with specificity—that produce change) in therapy is complicated. A concerted and systematic effort is required to understand how and why change is taking place in practices within outdoor therapies ,21. An uThe overall objective of this umbrella review is to report on the role of nature in outdoor therapies through a summative review of existing published systematic reviews and meta-analyses. Our specific objectives were to identify: (1) theories explaining nature’s role in outdoor therapies, (2) nature’s mechanisms of change in outdoor therapies, and (3) recommendations for practice and research within the field of outdoor therapies.An umbrella review was conducted following systematic protocols set out by Aromataris et al.  and follStudies were identified by systematically searching electronic databases selected to represent three distinct fields of study related to our knowledge of the outdoor therapies literature: PsychINFO (psychology), Medline (medicine), and Academic Search Premier (education and multi-disciplinary). Each database provided adequate control over filters to utilize consistent and strict search terms, which would return meaningful results. Search terms were proposed by the first author using PsycINFO thesaurus to identify possible key word for studies investigating outdoor therapies. Search terms were then agreed upon by all authors through exploratory searches, appraisals of other review findings, reduction of terms through testing , and open dialog prior to running the database search. Further, consistent search criteria details included that studies had to be published in English and were peer-reviewed. No publication date restrictions were applied and the final comprehensive search was conducted 15 August 2020. All studies were imported into Covidence software  to managThe first screening was completed (by NJH & LEG) at the level of title and abstract only and resulted in an exclusion of 81 studies for not meeting the PICOS criteria. At this point in the study, two umbrella reviews in specific outdoor therapies were located in a sperate search; one in animal-assisted interventions  and one Processes and criteria for data extraction, guided by our PICOS statement, were agreed upon a priori by all researchers. Two researchers (NJH & CRF) independently completed extraction utilizing the following categories: populations, context, theory, mechanisms of change, recommendations for practice, and recommendations for research. Conflicts on data extractions were resolved through dialog and inclusion of a third researcher (LEG).Ten of the studies included youth participants, eleven included adults (one specific to 60+ year olds), and only two studies included children. A range of contexts were identified across the 14 studies including studies assessing mental and physical health, specific diagnosed health issues, and wellbeing.Of the 14 studies in this review, seven were located in the discipline of public health ,35,36,38Studies were evaluated for quality using the Joanna Briggs Institute’s (JBI)  criticalCritical appraisal of the studies resulted in maintaining the inclusion of all 14 papers. Most papers included necessary elements required of a systematic review as suggested by the JBI checklist. Three areas of weakness in about a third of the papers was a lack of recommendations for research, recommendations for practice, and a thorough explanation of how data extraction errors may have been minimized. It is worth reminding readers that a quality rating for an umbrella review is not a quality assessment of the individual studies within each review, but rather how well the systematic reviews and meta-analyses were conducted and reported. Overall, while some weaknesses were present, these papers were consistent in reporting according to protocols established for umbrella reviews .The primary objective of this review was to identify clear expressions of nature’s role in outdoor therapeutic practices. While included reviews shared some conceptual arguments in their respective literature review sections, we were searching for theories of change reported in the results and discussion sections of each included review. In other words, we were seeking to identify operationalized theoretical frameworks explaining nature’s role in therapy, however we found little.Direct reference to theories other than allusions to specific activities and therapeutic approaches was limited to Attention Restoration Theory (ART)  and StreAnnerstedt and Währborg  suggest “From the included articles it is also difficult to draw any conclusion of what are the underlying explanatory mechanisms behind NAT’s [nature-assisted therapies] functionality and why certain programmes or therapies are more efficient than others. This is often rather vaguely discussed and no determined explanations are given.”  (p. 383)Annerstedt and Währborg  set the Kotera et al.  also spoA few correlations (postulating possible mechanisms of change) were identified in this review, including the role and impact of the facilitator, a person-in-environment or bodily-felt experience, and the ‘five senses’ approach. The role and potential need of a trained facilitator was discussed as likely linked to processes ,36 and sThis primary objective of this review was to identify theories and mechanisms of change guiding outdoor therapies. With scant theory and causal mechanisms identified, there exists a considerable gap in knowledge as to how outcomes in outdoor therapies are achieved. Clinical and practical outcomes reported in each of the 14 papers we reviewed suggest positive benefits from “moderately positive” to “effective.” The reviews of nature-based therapies suggest some improvements in mental health and psycho-social wellbeing , psycholIn sum, the evidence of treatment outcomes across outdoor therapies is mostly positive. The breadth of interventions were diverse and all were comprised of being place-based/outdoors, with active engagement of bodies-in-environments, and often focused on increasing one’s connection to nature. While populations served and issues addressed varied, the approaches all included direct contact with nature and other species. Still, we were unable to identify clear articulations of nature’s contribution to the specific therapy undertaken. ART and SRT were both presented in an explanatory manner but fall short of explaining outcomes. Descriptive models of change in these therapies is sorely lacking and in need of development, along with clear descriptions of practice for future researchers to design and plan research by. Echoing these needs, Britton et al.  stated “Public health authorities are beginning to recognize the value of proximity to, and contact with, natural environments as upstream health promoting interventions for the population on the whole . A term Thus far, theoretical models, on which to base both practice and research, are not concisely defined, nor utilized for testing and implementation. Annerstedt and Währborg’s  observatUnfortunately, while nature + therapy seems to be beneficial, the knowledge base within outdoor therapies to date remains a conditional basis for effect inferences and the heterogeneity within the field makes it premature to formulate specific recommendations for practice at this stage . In ordeOutdoor therapies present certain core challenges for the conduct of high-quality research, where the complex interaction between individual subjective experience, activities, pedagogies, and places are difficult to operationalize and measure in quantitative terms . The praThrough this umbrella review, we have elicited a number of recommendations for outdoor therapy research: (1) The use of validated psychometric assessment tools ,28 and pWhen it comes to the latter request for randomized controlled designs (RCT), randomization is not always feasible, ethical, or acceptable, acknowledging the difficulty in designing controlled or clinical interventions in outdoor, natural, and/or water settings compared to more controllable environments, typically indoors . When apFurther areas for research include a request for investigating ethical implications for outdoor therapies and evaluating the impact of nature-based solutions on public health . Kotera Outdoor therapy studies are dominated by the use of self-referred subjects, who might be expected to have an interest in nature and natural environments, which again could cause a potential “nature-positive” bias . Not allOutdoor therapeutic practices may serve as accessible and affordable upstream health promotion with the potential to enhance mental, physical, and social wellbeing for various populations. In general, activities, pedagogies, and types and qualities of the natural environments of the outdoor practices under investigation were not presented in sufficient detail. Furthermore, given that practices are culturally and geographically bounded, descriptions of local conditions should be considered and described carefully in future research. While systematic reviews to date have synthesized the wealth of predominantly correlational literature exploring nature contact and health benefits across highly heterogeneous interventions, the current evidence is both diverse and dispersed, leaving us with simplified conclusions, reduced interpretational value, and potentially inappropriate recommendations .To the best of our knowledge, this is the first umbrella review of outdoor therapies: horticultural, nature-based, forest, wilderness, and adventure therapies combined. As further systematic and meta-analytic reviews are completed in each of these areas, a specific umbrella review will be of benefit to further capture the volume and quality of the evidence within each approach. We hope that the progression of research in these specific areas of practice will contribute towards further defining theory and mechanisms of change. Two recent studies have utilized a realist methodology to attempt to capture the complexity and make theoretical progress within the field of outdoor therapies. Fernee et al.  set out We recognize growing and now heightened interest  in these approaches as active practitioners and researchers. Guidelines have recently been put forth for the use of talking therapy outdoors from the British Psychological Society and the statement for good practice for outdoor mental health intervention and outdoor therapy from the Institute of Outdoor Learning . Other pIn closing, we found the causal approach (theory—mechanisms—outcomes) to our review unfruitful, and while echoing others’ calls for more specific research, we also conclude that it may be difficult to find what we seek: nature’s role in outdoor therapies. Outdoor therapies take place in complex social and environmental contexts with almost infinite mediating and moderating variables . A rigor