Global warming boosts heat-related cardiovascular hospitalizations, study finds

The impact of high temperatures on hospitalizations due to cardiovascular diseases has increased over the past two decades in Queensland, Australia, according to a new study published this week in PLOS Medicine by Shanshan Li and Yuming Guo of Monash University, Australia, and colleagues.

Extreme temperatures—both cold and hot—are known risk factors for cardiovascular morbidity and mortality. Global climate change is increasing the duration and intensity of such extreme temperatures. Previous studies have found a decrease in the association between hot temperatures and cardiovascular deaths, suggesting that people may have adapted to the warming climate. In the new study, researchers used data on 1,855,717 cardiovascular hospitalizations in Queensland, Australia between 1995 and 2016 to study the association between temperature and hospitalizations.

Between 1995 and 2016, the daily mean temperature in Queensland increased from 20.9°C to 21.7°C and the annual number of cardiovascular hospitalizations increased from 46,730 to 123,477. In all ages, sexes and climate zones, the relative risk of cardiovascular hospitalizations associated with high temperatures increased over time but the impact of cold temperatures decreased over time. The increasing magnitude of heat impacts was larger in men than in women (p=0.002) and larger in people aged less than 70 years compared to people aged 70 years and over (p<0.001).

"Given the increased associations between hot temperatures and cardiovascular hospitalization and the acceleration of global warming, we highlight a worrying trend that the burden of cardiovascular healthcare facilities is to increase over time on high temperature days," the authors say.