研究実績の概要 |
The principal investigator (PI) has collected daily time-series data of suicide and weather variables in 341 locations in 12 countries (Brazil, Canada, Japan, South Korea, the Philippines, Spain, South Africa, Switzerland, Taiwan, UK, USA, and Vietnam) ranging from 4 to 40 years. The PI also obtained consent to use the city-specific characteristics data for future suicide-temperature studies.
The database included a total of 1,320,148 suicides. The annual average temperature varied considerably from 6.7 °C in Canada to 28.5 °C in Vietnam. The seasonal patterns of the suicide showed high in warm seasons and low in cold seasons for the higher latitude countries of both northern and southern hemisphere. However, the seasonality in tropics was not observed. The statistical analyses showed the temperature-suicide associations were generally positive but showed nonlinearity in three northeast Asian countries (Japan, South Korea, and Taiwan), with the risk of suicide no longer increasing with temperature above a high threshold. In contrast, the associations estimated were nearly linear in Western countries (Canada, Spain, Switzerland, UK, and USA) and South Africa.
The evidence of this largest study ever investigating the short-term temperature-suicide associations gives a better understanding of suicide epidemiology and suggests a new perspective on how to implement suicide prevention programs given the high rates of suicide in young population. This study can also help in generating future projections of mortality burdens from suicide under climate change.
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