BACKGROUND

The aim of this study was to evaluate the association between extreme heat waves and age adjusted cardio-kidney-metabolic (CKM) all-cause mortality rate in the US.

METHODS

In this cross-sectional study, the county level age adjusted CKM premature (age < 65 years) all-cause mortality rate (CKM aaMR) was collected from the Center for Diseases Control (CDC) WONDER (Wide-ranging Online Data for Epidemiologic Research) (2010-2019). The primary exposure was the 2023 US Federal Emergency Management Agency heat wave risk index (HWRI), a marker of extreme heat event frequency. Counties were grouped by the quartile (Q) of their HWRI. Generalized linear models with a Poisson rate regression were fitted to evaluate the association between CKM aaMR and HWRI quartiles adjusting for county-level median age, percentage of ethnic minorities, prevalence of hypertension, diabetes, obesity, coronary artery disease, and stroke; results were reported as incident rate ratios (IRR) and 95 % confidence intervals.

RESULTS

Out of 3243, we included data from 2834 (90 %) counties. The median (25th - 75th percentile) CKM aaMR was 64 (47 -85) 15 deaths per 100 000 residents. The county-level median HWRI was 56.4 (32.0, 78.1). Nationwide, compared to counties in HWRI Q1, those in Q2 [IRR 1.03(0.99, 1.06); < 0.1], Q3 [IRR 1.05 (1.01, 1.08); < 0.01], and Q4 [(IRR 1.09 1.05, 1.12); < 0.001] were associated with higher for CKM aaMR.

CONCLUSIONS AND RELEVANCE

In the US, counties at more risk to experience extreme heat events were noted to have higher rates of age adjusted cardio-kidney-metabolic syndrome all-cause mortality rates.