2017 Fiscal Year Research-status Report
Global Perspectives of Seasonal Changes of Suicide and Associations between Suicide and Weather
| Project/Area Number |
16K19773
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| Research Institution | Nagasaki University |
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Principal Investigator |
金 允姫 長崎大学, 熱帯医学研究所, 助教 (40746020)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | suicide / temperature / seasonality of suicide / multi-country |
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| Outline of Annual Research Achievements |
We conducted a statistical analysis using the daily time-series data of suicide counts and weather variables covering 299 locations in 10 countries (Brazil, Canada, Japan, South Korea, Philippines, Spain, Taiwan, UK, USA, and Vietnam) ranging from 4 to 40 years. Specifically, we investigated a seasonal pattern of suicide for each country and conducted a two-stage meta-analysis including a location-specific regression and a multivariate meta-regression to estimate the association between suicide and temperature for each location and each country and identify a range of temperature with the highest risk of suicide.
The results showed that higher temperature was associated with the increased risk of suicide in general. However, the suicide risk decreased rather than increased during extremely high temperatures (inverted J-shaped curve) in some locations, particularly for northeast Asian countries. The temperature with the highest risk of suicide for each country ranged from 91st to 99th percentile except the Philippines and the USA.
This study based on the large-scale data is promising to give a better understanding of nature of the suicide-weather association.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
In addition to the data collection and descriptive analyses in the 1st year, we have examined the nonlinear association between suicide and temperature using the large-scale daily time-series data covering multiple countries in this year, which is the primary goal of this project. We applied the conditional Poisson regression model, that was found to be more flexible approach than the two statistical methods initially planned, followed by the meta-regression analysis as planned. Also, we investigated a critical range of temperature with the highest risk of suicide. Sensitivity analyses were also conducted to examine the robustness of the results. The quantified relative risks for the temperature were fairly consistent across countries, except for Vietnam with large uncertainty.
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| Strategy for Future Research Activity |
In the final year, we will expand the application of the analytical methods we have built in the 2nd year to the subgroup analysis by sex (for all countries) and age groups (for 9 countries except Taiwan) and the additional analysis to examine the association between suicide and other weather factors available (relative humidity and sunshine duration for 7 and 5 countries, respectively). Despite the small variations in the suicide-temperature association across countries, we will collect some regional characteristics to incorporate them into the meta-regression model.
Besides, we will review literature about suicide prevention programs and suggest a conceptual model for suicide prevention that would embed the suicide-weather associations together with the existing potential risk factors.
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