Variation in under-5 mortality attributable to anomalous precipitation during El Niño–Southern Oscillation cycles: Assessment of the intertemporal inequality in child health

Abstract

ObjectiveTo explore the health effect of anomalous precipitation on deaths among children younger than 5 years (under-5 deaths) in low- and middle-income countries (LMICs). MethodsBased on a sample of 1.6 million children from 56 LMICs, we conducted a sibling-matched Cox regression model to examine the association between under-5 deaths and anomalous precipitation in annual average. We established a nonlinear exposure–response function to characterize heterogeneity in the association, and checked its robustness by conducting a few sensitivity analyses. To illustrate absolute risks embedded in the complex climate-health linkage, across 100 LMICs, we calculated burden of under-5 deaths attributable to anomalous precipitation, and showed how the burden varied with the El Niño–Southern Oscillation (ENSO), a well-known predictable climate pattern affecting the rainfall cycle. We focused on the intertemporal inequality in the attributable burden. ResultsThe epidemiological analyses showed a robust negative association between anomalous precipitation and under-5 deaths for arid areas, and a potentially positive association for humid areas. The anomalous precipitation was significantly associated to an intertemporal inequality in under-5 mortality. Across the 100 LMICs, 26.7% or 134 million under-5 children lived in ENSO-sensitive areas. Among them, anomalous rainfall decreased under-5 deaths by 46,246 (CI: 24,599–68,703) during an El Niño year (October 2015 to September 2016), and increased under-5 deaths by 77,505 (CI: 55,890–99,815) during a La Niña year (March 2008 to February 2009) across the 100 LMICs. ConclusionAnomalous precipitation can lead to intertemporal inequality in child health. Healthcare resources should be allocated according to predicted variability in precipitation, such as ENSO-mediated extreme rainfall.