OBJECTIVETo assess the association between heat wave and stroke mortality in Jiang'an District of Wuhan, China during 2003 to 2010.

METHODSDaily data of stroke mortality, meteorological factor and ambient pollution were collected from June to September during 2003 to 2010 in Jiang'an District of Wuhan.Quasi-Poisson regression in generalized additive model was applied to evaluate the impact of heat wave on stroke mortality on different lag days.

RESULTSDuring the study period, a total of 38 heat wave events and 191 heat wave days were registered. The total stroke death was 2 455 (1 182 women and 1 998 people aged 65 years old and over). Quasi-Poisson regression in generalized additive model showed that after controlling for long-term trend and seasonal trend, weekday, holiday, and relative humidity, heat wave was associated with stroke mortality on current day with relative risk of 1.15 (95%CI 1.01-1.30). Heat wave was not significantly associated with stroke mortality on current day among men (RR= 0.98, 95%CI 0.82-1.18, P=0.848) and people aged below 65 years old (RR=0.90, 95%CI 0.67-1.22, P=0.500), but relative risk increased to 1.34 (95%CI 1.12-1.62, P=0.002) and 1.20 (95%CI 1.04-1.39, P=0.002) for women and elderly (≥65 years old) people, respectively. When ambient pollutants (PM(10), sulfur dioxide and nitrogen dioxide) were involved into the models, the impacts of heat wave on stroke mortality almost remained unchanged. Lagged effects were found in the association between heat wave and stroke mortality, relative risks reached the highest on lag of 2 days and the effects of heat wave usually lasted for 3 to 5 days. Moreover, lagged patterns of the effects of heat wave on stroke mortality were different between female and male and people of different age groups.significantly increased relative risks were found on current day in the elderly (≥65 years old) people and women, while significant associations occurred on lag of 2 days for men and people aged below 65 years old.

CONCLUSIONSHeat wave increased the risk of stroke mortality in Jiang'an District of Wuhan. The effect of heat wave lasted for several days and lagged patterns of the effects of heat wave on stroke mortality were different between females and males and people of different age groups.