Changes to how reasons for suicide are tallied starting in January 2022
Our Research Letter has been published in JAMA Network Open.
Following the January 2022 change in how reasons for suicide are tallied, we examined the actual impact of this revision.
First, researchers working in this field should note that simple comparisons of reasons for suicide before and after 2022 are no longer possible.
Below, I provide a brief overview in the comments along with a Supplementary Figure that could not be included in the paper due to limits on the number of figures.
Following the January 2022 change in how reasons for suicide are tallied, we examined the actual impact of this revision.
"Regarding causes and motives for suicide, up through 2021 (Reiwa 3), up to three reasons could be recorded per person, and only when backed by materials confirming the person's words or actions before death, such as a suicide note. Starting in 2022 (Reiwa 4), up to four reasons can be recorded per person, including plausible reasons inferred from testimony by family members and others. Because of this, simple comparisons cannot be made."
Reference: Office for Suicide Countermeasures, Ministry of Health, Labour and Welfare; Community Safety Planning Division, Community Safety Bureau, National Police Agency. Status of Suicides in 2022 (PDF file) https://www.npa.go.jp/safetylife/seianki/jisatsu/R05/R4jisatsunojoukyou.pdf
The analysis uses a piecewise linear regression model. Using data from January 2010 through 2021, we generated simulation plots showing what would have happened if the tallying method had not changed.
The impact of the methodological change is evident starting in January 2022, demonstrating that reasons for suicide can no longer be directly compared before and after 2022.
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2812888
This is the Supplementary Figure that we could not include due to limits on the number of figures and tables. The subcategories also show a level change in January 2022, reflecting the same pattern.
While simple comparisons before and after 2022 are no longer possible, the number of cases categorized as "reason unknown" has decreased. Over the medium to long term, this change should prove useful for examining the reasons behind suicide today. I hope this revision to the tallying method will help further clarify the contributing factors in the future.
Harada N, Koda M, Nomura S. Early Outcomes of Changes to Collection of Suicide Data in Japan. JAMA Netw Open. 2023;6(12):e2347543. doi: https://doi.org/10.1001/jamanetworkopen.2023.47543