Deworming Children for Soil-Transmitted Helminths in Low and Middle Income Countries: Systematic Review and Individual Participant Data Network Meta-Analysis

Background: Mass deworming affects millions of children afflicted by intestinal parasites.We aimed to assess differences in effects of deworming on nutritional and cognitive outcomes across potential effect modifiers. Methods: For this systematic review and network meta-analysis of individual participant data (IPD), we searched MEDLINE, CINAHL, LILACS, EMBASE, the Cochrane Library, Econlit, Internet Documents in Economics Access Service, Public Affairs Information Service, Social Services Abstracts, Global Health CABI and CAB Abstracts to March 27, 2018. We searched grey literature, contacted authors and screened reviews. We included randomized and quasi randomized trials of deworming children compared to placebo or other nutritional or deworming interventions with data on baseline infection. We used a frequentist approach for random-effects network meta-analysis with IPD using General Linear Mixed Models, assessed Cochrane Risk of Bias and GRADE for overall quality, following a pre-specified protocol. The main outcomes were weight, height, haemoglobin and cognition. Findings: We received IPD from 19 RCTs of STH deworming with 31,945 participants. For deworming for schistosomiasis alone, we received too few studies. Overall risk of bias was low. STH deworming vs. placebo effect on weight was 0.01 kg (95%CI: -0.08 to 0.11), height 0.09 cm (95%CI: -0.08, to 0.27) (moderate certainty), and haemoglobin 0.32 g/L (95%CI: -0.63 to 1.26) (low certainty). No study showed important effects on cognition (low certainty). There were no statistically significant subgroup effects across age, sex, nutritional status or infection intensity. Confidence limits included important effects on weight and haemoglobin for children with higher intensity infections. Interpretation: Deworming for STH alone is insufficient to improve child nutrition and cognition at population level in areas with light intensity infections. Funding Statement: Bill and Melinda Gates Foundation Declaration of Interests: Dr. Friis reports grants from ARLA Food for Health Center, grants from Danish Dairy Research Foundation, grants from Nutriset, outside the submitted work. Dr. Elliott reports grants from Wellcome Trust, during the conduct of the study. Dr. King reports grants from World Health Organization for work included in the study. Dr. LIU reports grants from International Initiative for Impact Evaluation, grants from National Natural Science Foundation of China, during the conduct of the study. All other authors state they have nothing to disclose. Ethics Approval Statement: This study was approved by the Bruyere Research Institute and SickKids research ethics boards.