Impact Of Temperature Changes On Mortality In Ningxia From 2010 To 2015

ObjectivesIn this study we analyzed the associations of daily mean temperature and diurnal temperature range(DTR)with mortality in 5 cities of Ningxia.We aimed to explore the effects of daily mean temperature and DTR on mortality in different cities and regions(Yellow-River irrigation area and non-irrigation area).Further,we evaluated the relationship between daily mean temperature and mortality in different genders and ages,in order to find susceptible population to temperature changes in Ningxia and to provide a theoretical basis in prevention of extreme weather.MethodsA quasi-poisson regression with distributed lag non-linear model(DLNM)was used to analyze the associations of daily mean temperature and DTR with different mortalities(included non-accidental death(NAD),deaths from cardiovascular disease(CD)and respiratory disease(RD))in 5 cities of Ningxia during 2010~2015.Then we estimated the associations of daily mean temperature with different mortality in Yellow-River irrigation area and non-irrigation area of Ningxia.Finally,a meta-regression analysis was applied to pool the estimates of city-specific effects with different genders and ages.Results1 The relationship between daily mean temperature and mortality1.1 Cumulative lag effectsThe effects of daily mean temperature on mortality were varied in different cities with non-linearity.Both extreme hot and cold temperatures were risk factors.Extreme hot could do more harm to NAD and CD of residents in Yinchuan(RR_N=1.106(95%CI:1.037~1.179),RR_C=1.124(95%CI:1.026~1.230))and Guyuan(RR_N=1.094(95%CI:1.006~1.190)).Extreme cold could increase the risk of mortality in Yinchuan(RR_N=1.144(95%CI:1.027~1.274),RR_C=1.260(95%CI:1.093~1.453)),Wuzhong(RR_N=1.140(95%CI:1.006~1.290),RR_C=1.181,(95%CI:1.016~1.373)),and Guyuan(RR_N=1.211(95%CI:1.068~1.373),RR_C=1.410(95%CI:1.162~2.712)),.All cities did not find the significant associations except Shizuishan,with a protective cold effect(RR_R=RR:0.551(95%CI:0.054~0.887))between daily mean temperature and respiratory mortality.1.2 Lag effects at single daysThe effects on hot days in most cities were found almost during the first three days.Hot effects on NAD were found in Yinchuan and Shizuishan at lag 1 day,in Guyuan at the current day,with the relative risks reaching 1.031(95%CI:1.005~1.057),1.037(95%CI:1.003~1.072)and 1.107(95%CI:1.022~1.199),respectively.Hot effects on CD were found in Yinchuan at lag 3 day and Guyuan at lag 5 day,with the relative risks reaching 1.023(95%CI:1.000~1.047)and 1.026(95%CI:1.000~1.053),respectively.The effects on cold days in most cities were found nearly after 5 days.For example,extreme cold could increase the risks of NAD of residents in Yinchuan(RR_N=1.017,95%CI:1.001~1.033),Wuzhong(RR_N=1.026,95%CI:1.002~1.051)and Guyuan(RR_N=1.033,95%CI:1.008~1.059)at lag 7 day,and the risks of CD of residents in Yinchuan(RR_C=1.032,95%CI:1.002~1.063),wuzhong(RR_C=1.004,95%CI:1.002~1.088),and Guyuan(RR_C=1.041,95%CI:1.001~1.083)at lag 5day.The cold effects were later in Shizuishan on NAD at about lag 11 day(RR_N=1.026,95%CI:1.004~1.048),and on CD at about lag 9 day(RR_C=1.047,95%CI:1.022~1.073),compared with other cities.Specially,extreme cold had adverse effects on RD in Zhongwei and protective effects on RD in Shizuishan,with the relative risks reaching 1.102(95%CI:1.008~1.204)and 0.923(95%CI:0.869~0.981)respectively.2 The relationship between DTR and mortality2.1 Cumulative lag effectsCompared with daily mean temperature,the effects of DTR on mortality were lighter.The strongest effects of extreme DTR on NAD and RD were found in Yinchuan,with the relative risks reaching 1.181(95%CI:1.050~1.329)and 1.238(95%CI:1.049~1.462),respectively.We also found the adverse effects on RD in Zhongwei(RR_R=1.292(95%CI:1.001~1.668)).2.2 Lag effects at single daysExtreme DTR could increase the risks of NAD and RD of residents(RR_N=1.046(95%CI:1.001~1.094)and RR_R=1.145(95%CI:1.034~1.269),respectively)in Yinchuan at the current day,but decrease the risk of NAD and RD of residents(RR_N=0.971(95%CI:0.950~0.993)and RR_R=0.963(95%CI:0.930~0.997),respectively)in Wuzhong at lag 7 day.3 The effects of daily mean temperature on mortality in regionsBoth extreme hot and cold temperatures were linked with NAD risks in Yellow-River irrigation district and non-irrigation district in Ningxia.There were longer hot effects on CD in irrigation district,but extreme cold could do more harm to residents with respiratory disease(RR_R=1.271(95%CI:1.040~1.554)).4 Pooled effectsThe pooled estimated effects suggested that people in Ningxia were more susceptible to extreme cold weather,and the extreme cold temperature mainly caused NAD and CD.After stratifying by ages,people aged less than 65 years were more sensitive to hot weather(RR_N=1.284(95%CI:1.019~1.618)),while people aged up to 65 years were sensitive to both hot(RR_N=1.233(95%CI:1.005~1.512))and cold weather(RR_N=1.039(95%CI:1.075~1.594)and RR_C=1.440(95%CI:1.106~1.875),respectively).Conclusions1 Extreme daily mean temperatures could increase the mortality in Ningxia,with heterogeneity in different areas.Generally,daily mean temperature had higher effects on non-accidental mortality and cardiovascular mortality than respiratory mortality.2 Mortality were influenced by both extreme daily mean temperatures and DTR.Compared with DTR,people in Ningxia were more susceptible to daily mean temperature.3 People in non-irrigation were more susceptible to daily mean temperature,especially on respiratory mortality.4 We found no gender differences in temperature related death.5 Compared with people aged less than 65 years,people aged up to 65 years were more easily influenced by extreme temperatures.