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Environ Health Perspect. 2019 Nov;127(11):117007. doi: 10.1289/EHP4898. Epub 2019 Nov 26.

Suicide and Ambient Temperature: A Multi-Country Multi-City Study.

Author information

1
Department of Global Environmental Health, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
2
Graduate School of Public Health, Seoul National University, Seoul, Republic of Korea.
3
Department of Public Health, Environments and Society, London School of Hygiene and Tropical Medicine, London, United Kingdom.
4
Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan.
5
Department of Mathematical Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea.
6
School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan.
7
Institute of Environmental Assessment and Water Research, Spanish Council for Scientific Research, Barcelona, Spain.
8
Department of Statistics and Computational Research, Universitat de València, Spain.
9
CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain.
10
School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada.
11
Air Health Science Division, Health Canada, Ottawa, Ontario, Canada.
12
Department of Epidemiology and Public Health, Environmental Exposures and Health Unit, Swiss Tropical and Public Health Institute, Basel, Switzerland.
13
University of Basel, Basel, Switzerland.
14
Department of Environmental Health, Emory Rollins School of Public Health, Emory University, Atlanta, Georgia, USA.
15
Department of Earth Sciences, University of Turin, Turin, Italy.
16
Department of Environmental and Occupational Medicine, National Taiwan University College of Medicine and National Taiwan University Hospital, Taipei, Taiwan.
17
National Institute of Environmental Health Sciences, National Health Research Institutes, Zhunan, Taiwan.
18
Department of Environmental Engineering, Kyoto University, Kyoto, Japan.
19
Institute of Research and Development, Duy Tan University, Da Nang, Vietnam.
20
Faculty of Public Health, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, Vietnam.
21
Institute of Advanced Studies, University of São Paulo, São Paulo, Brazil.
22
Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.
23
School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, USA.
24
Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.

Abstract

BACKGROUND:

Previous literature suggests that higher ambient temperature may play a role in increasing the risk of suicide. However, no multi-country study has explored the shape of the association and the role of moderate and extreme heat across different locations.

OBJECTIVES:

We examined the short-term temperature-suicide relationship using daily time-series data collected for 341 locations in 12 countries for periods ranging from 4 to 40 y.

METHODS:

We conducted a two-stage meta-analysis. First, we performed location-specific time-stratified case-crossover analyses to examine the temperature-suicide association for each location. Then, we used a multivariate meta-regression to combine the location-specific lag-cumulative nonlinear associations across all locations and by country.

RESULTS:

A total of 1,320,148 suicides were included in this study. Higher ambient temperature was associated with an increased risk of suicide in general, and we observed a nonlinear association (inverted J-shaped curve) with the highest risk at 27°C. The relative risk (RR) for the highest risk was 1.33 (95% CI: 1.30, 1.36) compared with the risk at the first percentile. Country-specific results showed that the nonlinear associations were more obvious in northeast Asia (Japan, South Korea, and Taiwan). The temperature with the highest risk of suicide ranged from the 87th to 88th percentiles in the northeast Asian countries, whereas this value was the 99th percentile in Western countries (Canada, Spain, Switzerland, the UK, and the United States) and South Africa, where nearly linear associations were estimated. The country-specific RRs ranged from 1.31 (95% CI: 1.19, 1.44) in the United States to 1.65 (95% CI: 1.40, 1.93) in Taiwan, excluding countries where the results were substantially uncertain.

DISCUSSION:

Our findings showed that the risk of suicide increased with increasing ambient temperature in many countries, but to varying extents and not necessarily linearly. This temperature-suicide association should be interpreted cautiously, and further evidence of the relationship and modifying factors is needed. https://doi.org/10.1289/EHP4898.

PMID:
31769300
DOI:
10.1289/EHP4898
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