Temperature and mortality on the roof of the world: a time-series analysis in three Tibetan counties, China.
BACKGROUND
Tibet, with an average altitude of more than 4,000 meters, is warming faster than anywhere else in China. However, there have been no studies in Tibet of the relation between ambient temperature and mortality.


METHODS
We examined mean temperature and daily mortality in three Tibetan counties (Chengguan, Jiangzi and Naidong) using a distributed lag non-linear model (DLNM) based on 5,610 deaths that occurred in 2008-2012. We separately investigated hot and cold effects on non-accidental deaths, cardiovascular deaths, out-of-hospital deaths and vulnerability factors including age, sex and education.


RESULTS
In all three counties, the effect of heat tended to be immediate, while the impact of cold lasted longer. The effects were consistent but modest in size and not statistically significant except for cumulative cold effects in Jiangzi (lag=0-14, RR=2.251, 95% CI=1.054-4.849). Those who were more vulnerable to temperature extremes tended to be men, the elderly (over 65 years) and illiterate persons. We found stronger temperature effects on cardiovascular deaths than on all-cause mortality, and we also observed an increase in out-of-hospital mortality in one county.


CONCLUSIONS
This is the first study to investigate the temperature-mortality relationship in Tibet, and the findings may guide public health programs and other interventions to protect the population against extreme temperatures in a developing Tibet.
State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 155 Changbai Road, Changping District, Beijing 102206, PR China. Electronic address: baili_ChinaCDC@163.com.
Li
L
Bai
Tibet Autonomous Region Center for Disease Control and Prevention, 21 Linkuo North Road, Lhasa 850000, Tibet, PR China. Electronic address: cirendunzhuok@126.com.
Cirendunzhu
School of Population Health, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Electronic address: a.woodward@auckland.ac.nz.
Alistair
A
Woodward
Tibet Autonomous Region Center for Disease Control and Prevention, 21 Linkuo North Road, Lhasa 850000, Tibet, PR China. Electronic address: xzcdcdawa@sina.com.
Dawa
Tibet Autonomous Region Center for Disease Control and Prevention, 21 Linkuo North Road, Lhasa 850000, Tibet, PR China. Electronic address: xzcdc-xr@163.com.
Xiraoruodeng
State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 155 Changbai Road, Changping District, Beijing 102206, PR China; Shandong University Climate Change and Health Center, 44 WenHua Road, JiNan, Shangdong 250012, PR China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou 310003, PR China. Electronic address: liuqiyong@icdc.cn.
Qiyong
Q
Liu
D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000401:mortality; D005260:Female; D057232:Global Warming; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D009026:Mortality / Q000639:trends*; D017711:Nonlinear Dynamics; D012621:Seasons; D013696:Temperature; D018609:Tibet / Q000453:epidemiology
Cold; Heat; Mortality; Temperature; Tibet; Vulnerability