Association between mean temperature and hospital admissions for acute ischemic stroke: a time-series study

Abstract

Ambient temperature has been associated with cardiovascular and cerebrovascular outcomes, but its short-term relationship with acute ischemic stroke (AIS) admissions remains heterogeneous across regions. This study evaluated the association between mean temperature (MT) and AIS admissions in a subtropical city in China. Daily AIS admissions from July 1, 2017, to June 30, 2020, were collected from a tertiary hospital in Nanning, China. A quasi-Poisson generalized linear model combined with a distributed lag nonlinear model was used to assess the nonlinear and lagged associations between MT and AIS admissions over lag days 0–7. Sensitivity analyses were conducted by varying temporal adjustment, air-pollutant adjustment, maximum lag periods, excluding 2020, and adjusting for the Spring Festival window. Among 2,382 AIS admissions, the mean daily number of admissions was 2.17. Compared with the median MT of 23.30 °C, higher MT (29.60 °C) was associated with increased AIS admissions over early cumulative lag periods, with relative risks of 1.347 (95% CI: 1.058–1.714) for lag0-1 and 1.396 (95% CI: 1.085–1.797) for lag0-2. The association attenuated over longer lag periods. Lower MT (10.50 °C) showed a lower same-day estimate but less consistent cumulative associations. The main findings were generally robust in sensitivity analyses. Higher MT was associated with a short-term increase in AIS admissions in this subtropical setting, with the association concentrated within the early lag period. The low-MT association was less consistent and requires cautious interpretation.