Hello winter! Cardiovascular risks associated with cold

Extremely hot and extremely cold temperatures were associated with a greater risk of cardiovascular mortality in an analysis of data from countries around the world.

The study, published online December 12 in Circulation, showed that for every 1000 all-cause cardiovascular disease (CVD) deaths, 2.2 excess deaths were attributed to extremely hot days and 9.1 CVD deaths to extremely cold days. Across cities, sample temperature ranges varied from −30° C in Helsinki, Finland, to 44° C in Kuwait City, Kuwait.

The researchers used data from the Multi-Country Multi-City Collaborative Network to create a database of daily counts of cardiovascular causes of death from 567 cities in 27 countries across five continents in overlapping periods ranging from 1979 to 2019.

The analyses included deaths from any cardiovascular cause (32,154,935); ischemic heart disease (11,745,880); stroke (9,351,312); heart failure (3,673,723); and arrhythmia (670,859).

City-specific daily ambient temperatures were obtained from weather stations and climate reanalysis models, the authors note.

The pooled RRs of death associated with extreme cold (1st percentile vs MMT) from ischemic heart disease, ischemic stroke, and heart failure were 1.33, 1.32, and 1.37, respectively.

Overall, a range of extreme temperatures, defined as hot days above the 97.5th percentile and cold days below 2.5th percentile, accounted for 2.2 and 9.1 excess deaths for every 1000 cardiovascular deaths, respectively.