Global State of Deworming Coverage and Inequity in Low-Income and Middle- Income Countries: a Spatiotemporal Study of Household Health Surveys
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bioRxiv preprint doi: https://doi.org/10.1101/589127; this version posted March 28, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Global state of deworming coverage and inequity in low-income and middle- income countries: a spatiotemporal study of household health surveys Nathan C. Lo1, Sam Heft-Neal2, Jean T. Coulibaly3,4,5,6, Leslie Leonard7, Eran Bendavid8,9*, and David G. Addiss7* 1Division of Epidemiology, Stanford University School of Medicine, Stanford, CA, USA 2Department of Earth System Science, Stanford University, Stanford, CA, USA 3Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland 4University of Basel, Basel, Switzerland 5Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoire 6Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, Côte d'Ivoire 7Task Force for Global Health, Decatur, GA, USA 8Primary Care and Population Health, Stanford University, Stanford, CA, USA 9Center for Health Policy and the Center for Primary Care and Outcomes Research, Stanford University, Stanford, CA, USA *Indicates co-senior authorship Abstract Word Count: 391 Main Text Word Count: 3,561 Figures: 3 Tables: 2 Keywords: soil-transmitted helminthiasis, deworming, equity, neglected tropical diseases, mass drug administration, preventive chemotherapy Correspondence: Nathan C. Lo Division of Epidemiology Stanford University School of Medicine 300 Pasteur Drive Stanford, CA 94305 USA [email protected] bioRxiv preprint doi: https://doi.org/10.1101/589127; this version posted March 28, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Abstract Introduction: Mass deworming against soil-transmitted helminthiasis (STH) is a hallmark program in the neglected tropical diseases portfolio that is designed to be equitable and “pro- poor”. However, the extent to which current deworming treatment programs achieve equitable coverage across wealth class and gender remains unclear, and the current public health metric of national deworming coverage does not include representation of inequity. This study develops a framework to measure both coverage and equity in global deworming to guide future programmatic evaluation, investment, and metric design. Methods: We used nationally representative, geospatial household survey data that measured mother-reported deworming receipt in pre-school age children (age 1-4 years) in the previous 6 months. We estimated global deworming coverage disaggregated by geography, wealth quintile and gender and computed an equity index. We examined trends in coverage and equity index across countries, within countries, and over time. We used a regression model to compute the household correlates of deworming receipt and ecological correlates of equitable deworming. Findings: Our study included 820,883 pre-school age children living in 50 STH-endemic countries between 2004 and 2017. Globally, the mean global deworming coverage in pre-school children was estimated at 36%. The sub-national coverage ranged from 0·5% to 87·5%, and within-country variation was greater than between-country variation in coverage. The equity index was undesirable (deworming was consistently concentrated in the wealthier populations) in every endemic region of 12 countries. Of the 31 study countries that WHO reported achieving the goal of 75% national coverage, 26 had persistent inequity in deworming as defined by the mean equity index. Deworming equity modestly improved over time, and within-country variation in inequity decreased over time. We did not detect differences in deworming equity by bioRxiv preprint doi: https://doi.org/10.1101/589127; this version posted March 28, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. gender. We found the strongest household correlates of deworming to be vitamin A supplementation and receipt of three doses of diphtheria-tetanus-pertussis vaccine (DTP3), while the strongest ecological predictors of equitable deworming were regions with higher coverage of health services such as DTP3 and vitamin A supplementation. Interpretation: Although mass deworming is considered to be “pro-poor”, we find substantial inequities by wealth, despite often high reported national coverage. These inequities appear to be geographically heterogeneous, modestly improving over time, and we found no evidence of gender differences in inequity. Future reporting of deworming coverage should consider disaggregation by geography, wealth, and gender with incorporation of an equity index to complement national deworming coverage. Funding: Bill and Melinda Gates Foundation, Stanford University Medical Scientist Training Program 3 bioRxiv preprint doi: https://doi.org/10.1101/589127; this version posted March 28, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Background Soil-transmitted helminthiasis (STH) is the most prevalent neglected tropical disease of poverty with an estimated prevalence of 1·5 billion people.1,2 STH affects the most vulnerable people, helps to drives the cycle of poverty, and contributes to health inequities.3,4 STH is caused by infection with Ascaris lumbricoides, hookworm species of Ancylostoma duodenale and Necator americanus, and Trichuris trichiura, and is associated with a range of sequelae, including anemia, micronutrient deficiency, chronic abdominal pain, and stunting, some of which may be reversible with treatment.5-8 To address the public health burden of STH, the World Health Organization (WHO) recommends preventive chemotherapy (often referred to as mass “deworming”), which is a large-scale intervention that provides periodic administration of medications for empiric treatment of at-risk populations. In 2012, WHO broadened its school- based deworming program to include at-risk preschool-age children (1-4 years), in recognition of the significant disease burden in this age group that was otherwise not accessing treatment.9 During the past 15 years, deworming programs have made tremendous strides in scaling up coverage to reaching almost 600 million children annually, which makes it one of the largest public health programs in the world.10,11 While STH affects the most economically and socially disadvantaged, the degree to which current deworming treatment programs reach those most in need remains unclear. Equitable deworming would include all at-risk individuals, with coverage that is generally proportional to risk of STH and at least equal by economic and educational status, gender, and geographic zone. In some cases, equitable deworming may even be “pro-poor” given the higher risk of STH in more impoverished populations.3,4 Historically, the conventional metric for deworming has been bioRxiv preprint doi: https://doi.org/10.1101/589127; this version posted March 28, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. national deworming coverage, which is used to track progress of country programs and to set the WHO goal of achieving 75% national coverage or greater by 2020.4 However, national deworming coverage does not necessarily reflect equity by economic status, gender, or geography.12 Specifically, national deworming coverage may be subject to “tyranny of averages” which can obscure low coverage in significant geographic regions, economically disadvantaged populations, or other key subgroups.12 As a result, our understanding of the key correlates of deworming receipt that may be related to inequity remains less clear. While the goal of equity lies at the foundation of global health, emphasis on measuring and tracking equity in public health programs has increased with the Sustainable Development Goals.13 There is an abundant literature on simple metrics to estimate equity for various public health programs (e.g. concentration indices, ratios) and case examples on their use, such as with child mortality,14,15 yet their application to routine measurement and evaluation of programs in global health is limited. WHO recently provided guidance to public health programs on simple equity metrics and disaggregating programmatic data by geography, wealth, and gender.15 Mass deworming has been promoted as an example of an equitable and even “pro-poor” intervention in global health, yet the degree to which this is true remains unclear given limited programmatic monitoring of equity with disaggregation of data or incorporation of equity measures. To empirically test the degree to which deworming for STH is equitable and “pro- poor”, the aim of this study was to estimate the global status and trends in sub-national deworming coverage and equity by wealth and gender. 5 bioRxiv preprint doi: https://doi.org/10.1101/589127; this version posted March 28, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Methods We used nationally representative, geospatial household survey data from the Demographic and Health