Temperature fluctuations associated with cardiovascular admissions in older adults

Researchers used inpatient records from Henan Province, China, covering 2019–2024, in a time-stratified case-crossover study of adults aged 65 years or older. The primary analysis included 2,598,149 cardiovascular disease admission events and more than 11.4 million case-day and control-day records. Temperature exposures were assigned using locations of participants’ affiliated primary healthcare institutions as proxies; distributed lag non-linear models assessed associations over 14 days.

The temperature-admission relationship was non-linear. Compared with 28.5 °C, where the fitted cumulative association was lowest, odds were higher at −3.6 °C (OR 1.032, 95% CI 1.009–1.056) and 0.2 °C (OR 1.064, 95% CI 1.045–1.084). The fitted maximum was around 14.2 °C (OR 1.194, 95% CI 1.177–1.213). At 0.2 °C, the association emerged after about two days and persisted through day 14; the association at 32.0 °C was smaller and more immediate. Directional warming was also associated with admissions after adjustment for concurrent mean temperature (OR 1.030 per +8.5 °C, 95% CI 1.023–1.038).

The findings are observational and may not translate directly into individual risk. Exposure locations were proxies, and the study did not estimate absolute admission risk or attributable burden. The authors characterize the warming association as small and hypothesis-generating.