Heat-wave Definitions Based On Mortality Risk And The Mortality Burden From Heat-wave In Different Regions Of China

Objective To offer the framework for health risk-based heat wave early warning systems and heat wave risk management.We explored the relationship between extreme heat and mortality in seven regions of China to build up the regional definitions of heat wave,as different regions have different climate characteristics,socioeconomic conditions,and climate adaptability.Method Daily mortality and meteorological variables from 66 Chinese communities were collected for the years 2006-2011.Taking climate type and administrative division into account,we classified seven regions in China.We first used a Distributed Lag Non-linear Model(DLNM)to estimate community-specific effects of temperature on non-accidental mortality.A multivariate meta-analysis was then applied to pool the estimates of community-specific effects to explore region-specific temperature index,threshold,and duration for definition of heat wave.After building up the region-specific definition of heat wave,we further estimated the mortality burden attributable to heat wave,stratified by cause of death,age,gender,and educational level in the seven regions.Results For each region,we found a positive non-linear association between extreme high temperature and mortality,with the effects appearing from 2 to 5 days of extreme heat event onset.Specifically,we defined regional heat wave of Northeast,North,Northwest,East,Central and Southwest China as being two or more consecutive days with daily mean temperature exceeding the 64 th,71st,85 th,67th,75 th and 77 th percentile of warm season temperature,respectively,and South China heat wave as five or more consecutive days with daily mean temperature higher than the 93 rd percentile of warm season temperature.According to our regional definition of heat wave,we observed the highest mortality burden in Northeast China,with an estimated 1,520(95%CI: 1116,1876)cases on non-accidental mortality which accounted for 2.35%(95%CI: 1.72%,2.90%)in total mortality.North China,Central China,East China,Southwest China,and South China,with estimated 861(95%CI: 549,1155),1,933(95%CI: 1390,2430),2,140(95%CI: 1624,2561),1,470(95%CI: 1155,1772),194(95%CI: 127,253)cases on non-accidental mortality which accounted for 1.79%(95%CI: 1.14%,2.40%),1.76%(95%CI: 1.27%,2.22%),1.64%(95%CI: 1.25%,1.96%),1.27%(95%CI: 1.00%,1.54%),0.24%(95%CI: 0.15%,0.31%)in total mortality during the study period.There was no significant difference in mortality burden due to heat wave in Northwest China.Conclusions The region-specific definition of heat wave developed in our study may provide guidance for establishment and implementation of early heat-health response systems for local government to address the projected negative health outcomes due to heat wave.