Time-Regular pattern analysis on effect of extreme temperature to the death of cerebrovascular and cardiovascular diseases in Chongqing

Objective: To explore the relationship between extreme temperature and death from cardiovascular and cerebrovascular diseases in Chongqing, a “furnace city”, and its time regularity. Methods the death data of cardiovascular and cerebrovascular diseases, meteorological and environmental protection data from 2011 to 2013 in Chongqing were collected. The confounding factors such as air pollution, long-term and short-term trends were controlled. The distributed lag nonlinear model (dlnm) was used to analyze the lag effect and cumulative effect of extreme temperature on the death of cardiovascular and cerebrovascular diseases. Results for cerebrovascular disease death, the effect of high temperature was the greatest on the same day (rr= 166, 95% CI: 119–233) for 2 days; the influence of low temperature lags 4 days and lasts for 12 days. The maximum RR value appears on the 6th day (lag 6) and is 122 (95% CI: 106–141). For ischemic heart disease deaths, the effect of high temperature was greatest on the same day (rr= 188, 95% CI: 112–315) for 7 days; the influence of low temperature lags behind for 1 D and lasts for 27 D. The maximum RR value appears on the second day (lag 2) and is 205 (95% CI: 132–320). The cumulative risk of extreme high temperature (34 ℃) on death from cerebrovascular disease and ischemic heart disease was 208 (95% CI: 149–290) and 263 (95% CI: 127~542), and the cumulative effects of extreme low temperature (2 ℃) on them were 461 (95% CI: 185–115) and 120 (95% CI: 372–463). Conclusion the lag effect of extreme high temperature and low temperature on the death of the two diseases is different; the cumulative effect of extreme low temperature is higher than that of extreme high temperature, especially on the death of ischemic heart disease.