Is suicide underreported? Evidence from Japan

Purpose: The underreporting of suicides has been a serious global concern among scholars and policymakers. Several studies have sought to detect the prevalence of underreporting by examining whether suicide mortality rates are negatively correlated with those due to unknown intent or causes. This study adds to the literature by examining the potential underreporting of suicides in Japan, where suicide rates have greatly declined in the recent years. Methods: We compiled subnational data from 47 prefectures between 1995 and 2016, obtained from Vital Statistics of Japan. We examined whether (1) mortality rates due to unknown intent or causes increased as suicide rates decreased; and (2) major socioeconomic causes of suicide (unemployment and divorce rates) had any relationship with the deaths due to unknown intent or causes. Results: Our analysis indicates that mortality rates due to unknown intent or causes were uncorrelated with suicide rates and the above socioeconomic indicators. Conclusions: In Japan, the frequency of suicides has no systematic relationship with deaths due to unknown intent or causes, suggesting the accuracy of suicide statistics.