title: Characterizing the relationship between temperature and mortality in tropical and subtropical cities: a distributed lag non-linear model analysis in Hue, Viet Nam, 2009-2013.
abstract: The relationship between temperature and mortality has been found to be U-, V-, or J-shaped in developed temperate countries; however, in developing tropical/subtropical cities, it remains unclear.
  
  
  
  Our goal was to investigate the relationship between temperature and mortality in Hue, a subtropical city in Viet Nam.
  
  
  
  We collected daily mortality data from the Vietnamese A6 mortality reporting system for 6,214 deceased persons between 2009 and 2013. A distributed lag non-linear model was used to examine the temperature effects on all-cause and cause-specific mortality by assuming negative binomial distribution for count data. We developed an objective-oriented model selection with four steps following the Akaike information criterion (AIC) rule (i.e. a smaller AIC value indicates a better model).
  
  
  
  High temperature-related mortality was more strongly associated with short lags, whereas low temperature-related mortality was more strongly associated with long lags. The low temperatures increased risk in all-category mortality compared to high temperatures. We observed elevated temperature-mortality risk in vulnerable groups: elderly people (high temperature effect, relative risk [RR]=1.42, 95% confidence interval [CI]=1.11-1.83; low temperature effect, RR=2.0, 95% CI=1.13-3.52), females (low temperature effect, RR=2.19, 95% CI=1.14-4.21), people with respiratory disease (high temperature effect, RR=2.45, 95% CI=0.91-6.63), and those with cardiovascular disease (high temperature effect, RR=1.6, 95% CI=1.15-2.22; low temperature effect, RR=1.99, 95% CI=0.92-4.28).
  
  
  
  In Hue, the temperature significantly increased the risk of mortality, especially in vulnerable groups (i.e. elderly, female, people with respiratory and cardiovascular diseases). These findings may provide a foundation for developing adequate policies to address the effects of temperature on health in Hue City.
authors.affiliation: Department of Health Care Policy and Management, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.|Department of Environmental Health, Faculty of Public Health, University of Medicine and Pharmacy, Ho Chi Minh City, Viet Nam; ngocdangytcc@gmail.com.
authors.forename: Tran Ngoc
authors.initials: TN
authors.lastname: Dang
authors.affiliation: Department of Health Care Policy and Management, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.
authors.forename: Xerxes T
authors.initials: XT
authors.lastname: Seposo
authors.affiliation: Department of Global Health Promotion, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.|Department of Pediatrics, Hue University of Medicine and Pharmacy, Hue City, Viet Nam.
authors.forename: Nguyen Huu Chau
authors.initials: NH
authors.lastname: Duc
authors.affiliation: Institute for Community Heath Research, Hue University of Medicine and Pharmacy, Hue City, Viet Nam.
authors.forename: Tran Binh
authors.initials: TB
authors.lastname: Thang
authors.affiliation: Department of International Cooperation, Ministry of Health, Hanoi, Viet Nam.
authors.forename: Do Dang
authors.initials: DD
authors.lastname: An
authors.affiliation: Department of Epidemiology and Preventive Medicine, Graduate School of Medical and Dental Sciences, University of Kagoshima, Kagoshima, Japan.
authors.forename: Lai Thi Minh
authors.initials: LT
authors.lastname: Hang
authors.affiliation: Department of Epidemiology and Preventive Medicine, Graduate School of Medical and Dental Sciences, University of Kagoshima, Kagoshima, Japan.
authors.forename: Tran Thanh
authors.initials: TT
authors.lastname: Long
authors.affiliation: Department of Global Public Health, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.
authors.forename: Bui Thi Hong
authors.initials: BT
authors.lastname: Loan
authors.affiliation: Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Honda
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D002648:Child; D002675:Child, Preschool; D002947:Cities; D005260:Female; D014943:Global Health; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009026:Mortality; D017711:Nonlinear Dynamics; D012307:Risk Factors; D017678:Sex Distribution; D013696:Temperature; D014744:Vietnam / Q000453:epidemiology; D014887:Weather; D055815:Young Adult
keywords: cold effects; high temperature effects; hot effects; low temperature effects; time-series regression