Impact Of Temperature On Outpatient Visits For Respiratory And Circulatory Diseases Among Residents In Rural Areas Of Ningxia: A Time-Series Study

Background Global warming is one of the biggest health threat to people at present and in the future.Therefore,the research on the influence of temperature on health has become an important field of concern.However,most studies focus on the relationship between temperature and mortality,and there are few studies on the temperature-outpatient visits.Objective This study was carried out in rural areas of Yanchi and Haiyuan county in Ningxia.Taking daily mean temperature as exposure factors and respiratory diseases(RD)and circulatory system diseases(CD)outpatient visits as health outcomes,using Distributed lag non-linear model(DLNM),the relationship between daily mean temperature(mT)and outpatient visits of RD and CD and its lag effects will be explored.The influence of m T on outpatient visits of RD and CD among different causes,sex and age will be evaluated and the susceptible population will be searched for.Methods The method of ecological study was adopted.Daily outpatient visits data of village-town levels and the meteorological data were collected from Yanchi County and Haiyuan County in Ningxia during the period of 2012-2015.A distributed lag non-linear model(DLNM)with Poisson link was used to assess the association between daily mean temperature and outpatient visits of RD and CD,after controlling for the effects of other confounding factors such as the long-term trends,seasonality,daily of the week,relative humidity,atmospheric Pressure and other meteorological factors.Results During the study period,there were 62653 and 289846 outpatient visits of RD and CD in Yanchi County,respectively,and the daily median outpatient visits of RD and CD were 41 and 185,respectively.There were 104870 and 1042527outpatient visits of RD and CD in Haiyuan County,respectively,and the daily median outpatient visits of RD and CD were 67 and 714,respectively.In the same period,the daily mean temperature(mT)in Yanchi county was 10.7°C(range:-14.5°C-29.4°C),and the daily temperature range was 13.6°C.The m T was 8.2°C(range-19°C and 27°C)in Haiyuan county,and the daily temperature range was 11.0°C.The temperature exposure response curves of outpatient visits were different in Yanchi County and Haiyuan County,but showed a nonlinear relationship with a "J" and "N" shape,in which the minimum outpatient visits risk on RD and CD was at 17°C and 23°C(Yanchi),13°C and 17°C(Haiyuan),respectively.The value was defined as the minimum outpatient temperature(MOT).Non-MOT will increase the risk of RD and CD outpatient visits.The effect of mT on outpatient visits varies among different diseases.There was a lag effect,and heat temperature lag effect was lasted longer than cold temperature.Taking MOT as the reference temperature,the total effect of mT at lag 28 days in RD and CD outpatients visits was discussed.For CD,When mT < MOT,the largest effect was achieved at-7°C(RR3.808(95% CI,2.847-5.093))in Yanchi,and was achieved at at-3°C(RR1.428(95% CI,1.247-1.636))in Haiyuan;When mT > MOT,the largest effect was achieved at 29°C(RR1.837(95% CI):(1.474-2.290))in Yanchi,and was achieved at 27°C(RR1.562(95% CI,1.281-1.905))in Haiyuan.For RD: When mT < MOT,the largest effect was achieved at-9°C(RR 5.055(95% CI,4.305-5.936))in Yanchi,and was achieved at at-5°C(RR 2.768(95% CI,2.615-2.930)in Haiyuan;When mT > MOT,the largest effect was achieved at 29°C(RR 1.230(95% CI,1.162-1.302))in Haiyuan.The cold effect of extreme temperature on outpatient visits for CD presented "V" shape,and there was a lag effect.In Yanchi,The largest effects(RR(95%CI)was 1.084(1.069-1.100)at lag 7 days,and the effects on males appear earlier than females,but females were more sensitive,?65 years old appeared earlier those aged <65,the older was more sensitive.In Haiyuan,The largest effects(RR(95% CI)was 1.027(1.019-1.035)at lag 9 days.The largest effects of extreme heat temperature was at lag 28 days(RR 1.027(95% CI,1.019-1.035)),the susceptible population was same as that of extreme cold temperature.The effects of extreme cold temperature on outpatient visits for RD were similar to that of CD in Yanchi,and with the largest effects at lag 7 days(RR 1.096(95% CI,1.088-1.103)).The largest lag effects on males and ?65 years old appear earlier,but the males and <65 years old were more sensitive.In Haiyuan,the effect of extreme cold temperature was gradually decreased with the lag time going on and its sensitive population was same as Yanchi.The ?65 years old were more sensitive to extreme heat temperature in Yanchi,and the females were more sensitive to extreme heat temperature in Haiyuan.In addition,we found that the cumulative effect of extreme heat temperature on CD and RD was higher than that of heat temperature.Extreme cold temperature and cold temperature could increase the risk of outpatient visits,its effect on the different causes and different regional were difference.For CD,there was a higher risk of cold temperature,the two areas showed a similar pattern;For RD,extreme cold temperature effect was greater for Yanchi,but cold temperature effect was greater for Haiyuan.Conclusion The mT has a nonlinear relationship with the CD and RD outpatient visits,and there is a lag effect.The minimum risk temperature for outpatient visits is different in the two regions,and the temperature is higher or lower than MOT can increase the risk of outpatient visits.The emergence of non MOT should be paid more attention to reducing the effect of temperature on the health of the population.In addition,the lag time of extreme heat temperature was longer than that of extreme cold temperature.There were differences in different regions.According to its specificity,the corresponding early warning measures should be put forward to prevent the influence of temperature.For patients with CD,females,<65 years old of Yanchi,and ?65 years old were more sensitive to extreme temperature.For patients with RD males and those aged <65 were more sensitive to extreme cold temperature;For ? 65 years old of Yanchi and females of Haiyuan were more sensitive to extreme temperature.The effects of extreme cold temperature and cold temperature on outpatient visits among CD and RD were more dangerous and should be paid attention to the influence of extreme weather,protect the sensitive people,and do a good job of coping strategies in time.