Extreme temperature contributes to CV mortality

Nonoptimal temperatures appear to be the cause of several cardiovascular (CV) deaths worldwide, according to a study.

A total of 1,801,513 (95 percent empirical confidence interval [CI], 1,526,632‒2,202,831) CV deaths occurred annually across the globe. Nonoptimal temperatures contributed 8.86 percent (95 percent empirical CI, 7.51‒12.32) of the total CV mortality, equivalent to 26 deaths per 100,000 population.

Of these deaths, 8.20 percent (95 percent empirical CI, 6.74‒11.57) were cold-related, while 0.66 percent (95 percent empirical CI, 0.49‒0.98) were heat-related. The mortality burden varied significantly across regions, with Central Asia and Eastern Europe recording the highest excess mortality rates.

From 2000 to 2019, heat-related death ratios increased, and cold-related ratios decreased. This led to an overall decline in temperature-related deaths. Regions with the greatest reduction were Southeastern Asia, Sub-Saharan Africa, and Oceania, whereas Southern Asia had an increase. On the other hand, the Americas and other regions in Asia and Europe showed fluctuating temporal patterns.

“Nonoptimal temperatures substantially contribute to cardiovascular mortality, with heterogeneous spatiotemporal patterns,” the investigators said. “Effective mitigation and adaptation strategies are crucial, especially given the increasing heat-related cardiovascular deaths amid climate change.”

This study applied a 3-stage analytical approach using daily cardiovascular deaths and temperature data from 32 countries. In stage 1, the investigators estimated location-specific temperature‒mortality associations, with considerations for nonlinearity and delayed effects.

Stage 2 used a multivariate meta-regression model developed between location-specific effect estimates and five meta-predictors. In stage 3, the investigators examined CV deaths associated with nonoptimal, cold, and hot temperatures for each global grid. They also assessed temporal trends from 2000 to 2019.