Prognostic Factors in Heat Wave-Related Deaths

Background:Although identifying individuals who are at increased risk of dying during heat waves and institutingprotectivemeasuresrepresentanestablishedstrategy,theevidencesupportingthecomponentsofthisstrategy and their strengths has yet to be evaluated. We conductedameta-analysisofobservationalstudiesonrisk and protective factors in heat wave–related deaths. Methods: Using the OVID interface, we searched Medline (1966-2006) and CINHAL (1982-2006) databases. The Web sites of the World Health Organization, Institut National de Veille Sanitaire, and Centers for Disease ControlandPreventionwerealsovisited.Thesearchterms includedheatwave,heatstroke,heatstroke,sunstroke,and heatstressdisorders.Eligiblestudieswerecase-controlor cohort studies. Odds ratios (ORs) and information on study quality were abstracted by 2 investigators independently. Six case-control studies involving 1065 heat wave–related deaths were identified. Results: Being confined to bed (OR, 6.44; 95% confidence interval [CI], 4.5-9.2), not leaving home daily (OR, 3.35; 95% CI, 1.6-6.9), and being unable to care for oneself (OR, 2.97; 95% CI, 1.8-4.8) were associated with the highest risk of death during heat waves. Preexisting psychiatricillness(OR,3.61;95%CI,1.3-9.8)tripledtherisk of death, followed by cardiovascular (OR, 2.48; 95% CI, 1.3-4.8) and pulmonary (OR, 1.61; 95% CI, 1.2-2.1) illness. Working home air-conditioning (OR, 0.23; 95% CI, 0.1-0.6),visitingcoolenvironments(OR,0.34;95%CI,0.20.5),andincreasingsocialcontact(OR,0.40;95%CI,0.20.8) were strongly associated with better outcomes. Takingextrashowersorbaths(OR,0.32;95%CI,0.1-1.1)and usingfans(OR,0.60;95%CI,0.4-1.1)wereassociatedwith a trend toward lower risk of death. Conclusion: The present study identified several prognostic factors that could help to detect those individuals who are at highest risk during heat waves and to provide a basis for potential risk-reducing interventions in the setting of heat waves.