Rui Pan1, Yasushi Honda2,3,4, Emiko Minakuchi5,6, Satbyul Estella Kim2,3, Masahiro Hashizume4,7, Yoonhee Kim1. 1. Department of Global Environmental Health, Graduate School of Medicine, University of Tokyo, Tokyo, Japan. 2. Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan. 3. Center for Climate Change Adaptation, National Institute for Environmental Studies, Tsukuba, Japan. 4. School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan. 5. Graduate School of Medicine, Yokohama City University, Yokohama, Japan. 6. Department of International and Cultural Studies, Tsuda University, Kodaira, Japan. 7. Department of Global Health Policy, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
Abstract
BACKGROUND: Although substantial evidence suggests that high and low temperatures are adversely associated with nonaccidental mortality, few studies have focused on exploring the risks of temperature on external causes of death. OBJECTIVES: We investigated the short-term associations between temperature and external causes of death and four specific categories (suicide, transport, falls, and drowning) in 47 prefectures of Japan from 1979 to 2015. METHODS: We conducted a two-stage meta-regression analysis. First, we performed time-stratified case-crossover analyses with a distributed lag nonlinear model to examine the association between temperature and mortality due to external causes for each prefecture. We then used a multivariate meta-regression model to combine the association estimates across all prefectures in Japan. In addition, we performed stratified analyses for the associations by sex and age. RESULTS: A total of 2,416,707 external causes of death were included in the study. We found a J-shaped exposure-response curve for all external causes of death, in which the risks increased for mild cold temperatures [20th percentile; relative risk (RR)=1.09 (95% confidence interval [CI]: 1.05,1.12)] and extreme heat [99th percentile; RR=1.24 (95% CI: 1.20, 1.29)] compared with those for minimum mortality temperature (MMT). However, the shapes of the exposure-response curves varied according to four subcategories. The risks of suicide and transport monotonically increased as temperature increased, with RRs of 1.35 (95% CI: 1.26, 1.45) and 1.60 (95% CI: 1.35, 1.90), respectively, for heat, whereas J- and U-shaped curves were observed for falls and drowning, with RRs of 1.14 (95% CI: 1.03, 1.26) and 1.95 (95% CI: 1.70, 2.23) for heat and 1.13 (95% CI: 1.02, 1.26) and 2.33 (95% CI: 1.89, 2.88) for cold, respectively, compared with those for cause-specific MMTs. The sex- and age-specific associations varied considerably depending on the specific causes. DISCUSSION: Both low and high temperatures may be important drivers of increased risk of external causes of death. We suggest that preventive measures against external causes of death should be considered in adaptation policies. https://doi.org/10.1289/EHP9943.
BACKGROUND: Although substantial evidence suggests that high and low temperatures are adversely associated with nonaccidental mortality, few studies have focused on exploring the risks of temperature on external causes of death. OBJECTIVES: We investigated the short-term associations between temperature and external causes of death and four specific categories (suicide, transport, falls, and drowning) in 47 prefectures of Japan from 1979 to 2015. METHODS: We conducted a two-stage meta-regression analysis. First, we performed time-stratified case-crossover analyses with a distributed lag nonlinear model to examine the association between temperature and mortality due to external causes for each prefecture. We then used a multivariate meta-regression model to combine the association estimates across all prefectures in Japan. In addition, we performed stratified analyses for the associations by sex and age. RESULTS: A total of 2,416,707 external causes of death were included in the study. We found a J-shaped exposure-response curve for all external causes of death, in which the risks increased for mild cold temperatures [20th percentile; relative risk (RR)=1.09 (95% confidence interval [CI]: 1.05,1.12)] and extreme heat [99th percentile; RR=1.24 (95% CI: 1.20, 1.29)] compared with those for minimum mortality temperature (MMT). However, the shapes of the exposure-response curves varied according to four subcategories. The risks of suicide and transport monotonically increased as temperature increased, with RRs of 1.35 (95% CI: 1.26, 1.45) and 1.60 (95% CI: 1.35, 1.90), respectively, for heat, whereas J- and U-shaped curves were observed for falls and drowning, with RRs of 1.14 (95% CI: 1.03, 1.26) and 1.95 (95% CI: 1.70, 2.23) for heat and 1.13 (95% CI: 1.02, 1.26) and 2.33 (95% CI: 1.89, 2.88) for cold, respectively, compared with those for cause-specific MMTs. The sex- and age-specific associations varied considerably depending on the specific causes. DISCUSSION: Both low and high temperatures may be important drivers of increased risk of external causes of death. We suggest that preventive measures against external causes of death should be considered in adaptation policies. https://doi.org/10.1289/EHP9943.
Authors: Lauren Joe; Sumi Hoshiko; Dina Dobraca; Rebecca Jackson; Svetlana Smorodinsky; Daniel Smith; Martha Harnly Journal: Int J Environ Res Public Health Date: 2016-03-09 Impact factor: 3.390