Relationship between annual household income and suicidal ideation: a cross-sectional study

Previous studies have shown that high income was associated with low risk of death by suicide; however, the extent to which household income reduces suicidal ideation remains unclear. We performed a survey to examine the relationship between annual household income and suicidal ideation and determine the level of annual household income at which suicidal ideation no longer decreased as income increased. In total, 94,131 members of Internet survey panels were recruited as participants by a major Japanese Internet survey company in 2016. The participants completed a self-administered questionnaire consisting of items pertaining to demographics, annual household income, and suicidal ideation. We performed logistic regression analysis with suicidal ideation as the dependent variable and income level as the independent variable. The results showed that odds ratios for suicidal ideation decreased as annual household incomes increased, with sex, age, educational level, marital status, and parenthood adjusted for; however, once annual household incomes exceeded 8 million JPY (approximately 77,700 USD), the risk of suicidal ideation no longer decreased. We conclude that suicidal ideation was negatively associated with annual household income and 8 million JPY (approximately 77,700 USD) is a threshold beyond which further increases in income no longer reduce individuals' suicidal ideation.