A systematic review and meta-analysis comparing the health burden of extreme heat and cold on mortality and urgent care utilization.

Abstract

<h4>Background</h4>Globally, extreme temperature events are expected to increase in frequency and intensity, yet the evidence on the impact of extreme temperatures on urgent care indicators is not extensively documented.<h4>Methods</h4>Relevant observational quantitative studies from 2000 to 2024 were searched. We applied MeSH search approach to construct the search terms and included studies meeting the PECOS (Population, Exposure, Comparator, Outcome and Study design) criteria. Urgent care utilization included hospitalization, emergency department visits (EDVs), length of stay (LoS), and medical costs. A meta-analysis was performed to obtain pooled results.<h4>Results</h4>From 3411 screened papers, 58 studies were included. The pooled RR for all-cause mortality was 1.478 (95% CI:1.219-1.792) for extreme cold, 1.145 (95% CI:1.103-1.189) for extreme heat, and 1.280 (95% CI:1.155-1.418) for heatwaves. Furthermore, the pooled RR for hospitalization was 1.060 (95%CI:1.018-1.104) for heatwaves. The pooled RR for EDVs was 1.047 (95% CI:1.022-1.072) for heatwave. Limited studies have shown that extreme cold and heat increase the RR for stays longer than 24 h, and the economic losses could amount to €25.5 billion.<h4>Conclusions</h4>Extreme cold is the most hazardous temperature event, with mortality being the most sensitive indicator. Limited studies have assessed LoS using factors other than extreme heat, and extreme temperature may lead to a higher workday losses and economic burden.