Effects of extreme high/low air temperature on mortality of cardio and cerebrovascular disease

Objective To understand the association between air temperature and cardio and cerebrovascular disease mortality in the urban area of Taizhou, Zhejiang province.

Methods Poisson regression model in a distributed lag nonlinear model framework was used to analyze the effect of air temperature on mortality rates of cardiovascular disease (CVD) and cerebrovascular disease (CBD) and related lag effects.

Results U-shaped curves on relationships between air temperature and the mortality rates of CBD and CVD were observed. The cold and heat thresholds were 12 °C and 25 °C for CBD, 12 °C and 26 °C for CVD, respectively. The cold effects increased gradually with the lag days. The peak of cold effects appeared on lag 0–27 days for CBD (RR＝1.068, 95% CI: 1.052–1.084) and CVD (RR＝1.111, 95% CI: 1.078–1.145). As for heat effects, the peak was observed on the current day (lag 0) for CBD (RR＝1.017, 95% CI: 1.004–1.030) and CVD (RR＝1.036, 95% CI: 1.012–1.061).

Conclusion Both extreme high air temperature and low air temperature are associated with an increased risk of cardio and cerebrovascular mortality in the urban area of Taizhou. The effect of heat is immediate while the effect of cold has longer time lags.