Causal link between humid heatwaves and ischemic heart disease: assessing hospitalizations and economic burden across 955 Chinese counties.

Abstract

Background: Humid heatwaves might cause more massive destruction to human health systems, especially the cardiovascular system. However, there is no systematic approach for identifying humid heatwaves and assessing their impacts on human health and health-related economic burden. This study aims to elucidate the relationship between short-term exposure to humid heatwaves and the relative risk of hospitalization for ischemic heart disease (IHD) and the hospitalization-related economic burdens.

Methods: This study utilizes hospitalization data from the Chinese Multiple-County (CMC) Hospital Network with 6,843,511 IHD cases across 1309 counties from 2016 to 2022. We employed a pre-post analysis and a causal inferential propensity score matching aided difference-in-differences (PSM-DID) approach to assess the causal effect of each type of humid heatwaves on IHD hospitalization rate changes.

Results: IHD hospitalizations increased by 2.92% (95% CI, 1.17%, 4.66%), 2.76% (95% CI, 1.07%, 4.45%), and 1.60% (95% CI, 0.08%, 3.12%) following independent humid heatwaves, light precipitation involved-, and moderate precipitation involved-humid heatwaves, with annual hospitalization-related economic burden reached $154 million (95% CI, $20, $249 million), $75 million (95% CI, $14, $136 million), and $81 million (95% CI, $31, $131 million), respectively. Chronic IHD and Angina were the most sensitive subtypes. Moreover, middle-to-old and male populations were afforded the most burdens.

Conclusions: As humid heatwaves become more intense, older populations with IHD should be provided with more care and medical resources. Identifying strategies and implementing actionable adaptation measures to minimize disruptions in healthcare delivery following these extremely hot and humid events is crucial to reducing IHD hospitalizations.