Drivers of Decline in Diarrhea Mortality between GEMS and VIDA Studies

Background: Statistical modeling suggests that decreasing diarrhea-Associated mortality rates in recent decades are largely attributed to improved case management, rotavirus vaccine, and economic development. Methods: We examined data collected in 2 multisite population-based diarrhea case-control studies, both conducted in The Gambia, Kenya, and Mali: The Global Enteric Multicenter Study (GEMS; 2008-2011) and Vaccine Impact on Diarrhea in Africa (VIDA; 2015-2018). Population-level diarrhea mortality and risk factor prevalence, estimated using these study data, were used to calculate the attribution of risk factors and interventions for diarrhea mortality using a counterfactual framework. We performed a decomposition of the effects of the changes in exposure to each risk factor between GEMS and VIDA on diarrhea mortality for each site. Results: Diarrhea mortality among children under 5 in our African sites decreased by 65.3% (95% confidence interval [CI]:-80.0%,-45.0%) from GEMS to VIDA. Kenya and Mali had large relative declines in diarrhea mortality between the 2 periods with 85.9% (95% CI:-95.1%,-71.5%) and 78.0% (95% CI:-96.0%, 36.3%) reductions, respectively. Among the risk factors considered, the largest declines in diarrhea mortality between the 2 study periods were attributed to reduction in childhood wasting (27.2%; 95% CI:-39.3%,-16.8%) and an increased rotavirus vaccine coverage (23.1%; 95% CI:-28.4%,-19.4%), zinc for diarrhea treatment (12.1%; 95% CI:-16.0%,-8.9%), and oral rehydration salts (ORS) for diarrhea treatment (10.2%). Conclusions: The VIDA study sites demonstrated exceptional reduction in diarrhea mortality over the last decade. Site-specific differences highlight an opportunity for implementation science in collaboration with policymakers to improve the equitable coverage of these interventions globally.