Method-specific suicide trends from 1979 to 2016 among Japanese adolescents

In 2015 the Japanese government set a target of a 30% reduction in the total suicide rate by 2025, but deaths among adolescents have been rising since. In 2018 the overall suicide rate increased by 33% among Japanese students, as a part of a continued trend of rising suicide among adolescents. This study analysed the trends in method-specific suicide among Japanese adolescents from 1979 to 2016.

We conducted a cross-sectional study using data obtained from the vital statistics registration of the Ministry of Health, Labour and Welfare Japan. Poisson regression analysis was performed among 10-20-year-olds separately by sex, with year, age category, suicide method and a 1998 step variable as covariates.

There was a sharp increase in suicide rates among boys (Incidence Rate Ratio (IRR), 1.68; 95% CI, 1.58-1.77) and girls (IRR, 1.69; 95% CI, 1.56-1.84) aged 10-20 years in 1998 when the overall suicide rate in Japan was at its peak. The commonly used method of suicide, hanging, has increased rapidly among high school and university-level aged adolescents since 1998.

The computed mortality rates may have been affected by the shift in mortality coding from ICD-9 to ICD-10 in 1995.

Suicide among adolescents has been rising since the early 1990s. Several cultural factors such as notoriety of internet suicide and detergent suicide could have influenced the increase in suicide among adolescents. There is an urgent need to address suicide by hanging and gas among high school and university-aged adolescents.