Ischemic Stroke Hospital Admission Associated with Ambient Temperature in Jinan, China

BACKGROUND This study estimated the effects of ambient temperature and relative humidity on hospital admissions for ischemic stroke during 1990-2009 in Jinan, China. METHODS To account for possible delayed effects and harvesting effect, we examined the impact of meteorological factors up to 30 days before each admission using a distributed lag non-linear model; we controlled for season, long-term trend, day of week and public holidays in the analysis. Stratified analyses were also done for summer and winter. RESULTS A total of 1,908 ischemic stroke hospital admissions were observed between 1990 and 2009. We found a strong non-linear acute effect of daily temperatures on ischemic stroke hospital admission. With the mean temperature 15°C as the reference, the relative risk (RR) was 1.43 (95% confidence interval (CI): 1.10-1.85) for 0°C daily temperature on the same day, and 0.43 (95% CI: 0.31-0.59) for 30°C daily temperature on the same day, respectively. The effect of ambient temperature was similar in summer and winter. No significant association was observed between relative humidity and ischemic stroke hospitalization. CONCLUSIONS Low temperature might be a risk factor for ischemic stroke, and high temperature might be protective factor of ischemic stroke occurrence in Jinan, China.