Date Published: May 31, 2018
Publisher: Public Library of Science
Author(s): Nathan C. Lo, Jedidiah Snyder, David G. Addiss, Sam Heft-Neal, Jason R. Andrews, Eran Bendavid, Roger K. Prichard. http://doi.org/10.1371/journal.pntd.0006500
Abstract: BackgroundThere is debate over the effectiveness of deworming children against soil-transmitted helminthiasis (STH) to improve health outcomes, and current evidence may be limited in study design and generalizability. However, programmatic deworming continues throughout low and middle-income countries.Methodology and principal findingsWe performed an empirical evaluation of the relationship between deworming in pre-school age children (ages 1–4 years) within the previous 6 months, as proxy-reported by the mother, and health outcomes of weight, height, and hemoglobin. We used nationally representative cross-sectional data from 45 countries using the Demographic and Health Surveys (DHS) during the period 2005–2016. We used logistic regression with coarsened exact matching, fixed effects for survey and year, and person-level covariates. We included data on 325,115 children in 45 STH-endemic countries from 66 DHS surveys. Globally in STH-endemic countries, children who received deworming treatment were less likely to be stunted (1.2 percentage point decline from mean of 36%; 95% CI [-1.9, -0.5%]; p<0.001), but we did not detect consistent associations between deworming and anemia or weight. In sub-Saharan Africa, we found that children who received deworming treatment were less likely to be stunted (1.1 percentage point decline from mean of 36%; 95% CI [-2.1, -0.2%]; p = 0.01) and less likely to have anemia (1.8 percentage point decline from mean of 58%; 95% CI [-2.8, -0.7%]; p<0.001), but we did not detect consistent associations between deworming and weight. These findings were robust across multiple statistical models, and we did not find consistently measurable associations with data from non-endemic settings.Conclusions and significanceAmong pre-school age children, we detected a robust and consistent association between deworming and reduced stunting, with additional evidence for reduced anemia in sub-Saharan Africa. We did not find a consistent relationship between deworming and improved weight. This global empirical analysis provides evidence to support the deworming of pre-school age children.
Partial Text: The large-scale empiric treatment of children for soil-transmitted helminthiasis (STH), commonly known as “deworming”, has become controversial [1–4]. This strategy of regular deworming (also known as ‘preventive chemotherapy’) with albendazole or mebendazole has been the main STH control strategy recommended by the World Health Organization (WHO) for over a decade . While deworming continues to be implemented throughout low and middle-income countries for the estimated 1.5 billion people with STH (caused by infection with Ascaris lumbricoides, hookworm species of Ancylostoma duodenale and Necator americanus, and Trichuris trichiura), the evidence linking real-world experience of deworming with health outcomes is mixed .
We examined the relationship between reported deworming and the pre-specified health outcomes of malnutrition (underweight, stunting) and anemia among pre-school age children (ages 1–4 years, selected based on WHO classification of this age group) in 45 low- and middle-income STH-endemic countries in Africa, the Americas, Asia, and Europe using cross-sectional data during the period 2005–2016. We also performed an analysis for sub-Saharan Africa alone given the substantial STH burden and scale of ongoing deworming .
Drawing upon data from more than 320,000 pre-school age children in 45 countries, this empirical analysis provides evidence for a global-level association between deworming and reduced stunting, with additional evidence for reduced anemia in sub-Saharan Africa for pre-school age children. We do not find a consistent relationship between deworming and improved weight. While the evidence to support the benefit of mass deworming has recently been questioned [1–4], this study aims to bring new data and study design to better understand the relationship between deworming and health outcomes in the population of pre-school age children. We addressed potential limitations of past studies by examining across diverse settings for generalizability and increasing sample size and focusing on children who received treatment to improve statistical power. Importantly, while a mother’s recall of deworming may be imperfect, any recall bias is unlikely to be unique to the dewormed group so this would bias our overall study findings towards no association and would not be a threat to the validity of our findings. The study results from our global empirical analysis provide evidence to support the deworming of pre-school age children.