A case-crossover study in China suggests that hourly heat exposure is associated with increased risk of acute ischemic stroke (AIS). The time-stratified case-crossover study used a nationwide registry and included 82 455 adult AIS patients (mean age, 65.8 years; males 63.4%) hospitalized in the warm seasons (from April 1 to September 30) between January 1, 2019, and December 31, 2021. A monotonically increasing risk of AIS onset was associated with higher temperatures. The excess AIS risk occurred immediately at lag 0 hours and persisted for 10 hours. Compared with the reference temperature (12.1 °C), the cumulative odds ratio (OR) over lag 0 to 10 hours of AIS onset associated with extremely high temperature (33.3 °C) was 1.88 nationwide. The exposure-response curve was steeper in the north than in the south (OR 1.80 vs 1.57). The ORs were greater for males and patients with a history of dyslipidemia or atrial fibrillation, although the differences were not significant. The findings suggest that a transient exposure to high temperature be an important risk factor in AIS onset, with the association occurring at the concurrent hour and lasting for up to 10 hours. Source: https://jamanetwork.com/
