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BackgroundEvidence for association between heat and child morbidity is limited. We aimed to estimate the association of heat with cause-specific emergency department (ED) visits and quantify burden attributable to heat among children in a large network of US children’s hospitals.
MethodsWe calculated daily numbers of ED visits from 47 US children’s hospitals and estimated daily maximum ambient temperature at the population-weighted centroid of the county in which the hospital is based using the Parameter-elevation Relationships on Independent Slopes Model from May to September 2016 to 2018. We first used a distributed lag non-linear model to estimate the association between heat and cause-specific ED visits to each hospital, and subsequently pooled hospital-specific results using random-effect meta-analyses regression. We calculated the relative risk (RR) for extreme heat, estimated by comparing the risk for the 95^th percentile versus the temperature of minimum morbidity (MMT), and attributable fraction (AF) for heat, defined as all days with temperatures above the MMT.
Results There were 3,812,395 ED visits to 47 US Children’s hospitals during the study period. A day of extreme heat was associated with higher RRs of ED visits for multiple specific causes and for all-causes combined. For example, we observed RRs of 1.83 (95% CI: 1.48, 2.28) for heat, light, and volume depletion, 1.21 (95% CI: 1.15, 1.28) for injuries and poisonings, and 1.17 (95% CI: 1.09, 1.25) for all-causes. If causal, the corresponding AFs for these three disease categories were 31.0%, 17.7%, and 11.8%, respectively. RRs were more pronounced among non-white patients [RR: 1.21 (95% CI: 1.17, 1.26)] and hospitals located in US Northeast [RR: 1.34 (95% CI: 1.16, 1.54)].
ConclusionsDays of extreme heat are associated with higher relative risk for ED visits for all-cause and various cause-specific diseases and are responsible for a substantial fraction of summertime ED visits in US children.