Causes of death in individuals exposed to spousal, parental, and child suicide: a nationwide population-based cohort comparison study

Exposure to suicide is associated with higher mortality, and the health impact varies depending on the types of kinship. However, the moderating role of kinship remains unclear. Therefore, this study aimed to compare causes of death between individuals exposed to spousal, parental, and child suicide to those exposed to natural or unnatural death. In this study, 1,929,872 individuals were enrolled, of whom 1,726,846 individuals were exposed to natural death, 141,206 individuals were exposed to unnatural death, and 61,820 individuals were exposed to suicide. To compare causes of death between kinship, stratified analysis and moderation analysis were conducted by using the Cox proportional hazard model and the cause-specific hazard model. Although higher mortality from specific causes, such as suicide, homicide, and vascular and unspecified dementia, was observed in individuals exposed to suicide compared to those exposed to natural and unnatural death (adjusted hazard ratio: 1.69 to 23.26), we did not observe higher all-cause mortality when compared to those exposed to unnatural death. Some causes of death were moderated by kinship. When compared to unnatural death, parental or spousal suicide was associated with higher mortality from suicide and homicide than child suicide (adjusted hazard ratio: 1.70 to 15.67), and parental suicide was associated with higher mortality from accidents than spousal suicide (adjusted hazard ratio: 1.81). These findings provide an integral understanding of the role of kinship in the impacts of suicide exposure on causes of death.