Objectives: The death of a sibling can trigger grief and depression. Sibling deaths from external causes may be particularly detrimental, since they are often sudden. We aimed to examine the association between the death of an adult sibling from external causes and the risk of suicide among surviving siblings up to 18 years after bereavement. We adjusted for intrafamily correlation in death risks, which might occur because of shared genetics and shared early-life experiences of siblings in the same family.

Design: A follow-up study between 1981 and 2002 based on the total population.

Setting: Sweden.

Participants: Swedes aged 25–64 years (n=1 748 069).

Primary and secondary outcome measures: Suicide from the Swedish cause of death register.

Results: An increased risk of mortality from suicide was found among persons who had experienced the death of a sibling. In women, the suicide risk was 1.55 times that of non-bereaved persons (95% CI 0.99 to 2.44), and in men it was 1.28 times higher (95% CI 0.93 to 1.77). If one sibling committed suicide, the risk of the remaining sibling also committing suicide was 3.19 (95% CI 1.23 to 8.25) among women and 2.44 (95% CI 1.34 to 4.45) among men. Associations with other main causes of death—such as external other than suicide, cardiovascular diseases or cancer—were generally much smaller and statistically not significant in either sex. We found no clear support for a specific time pattern according to time since a sibling's death.

Conclusions: Our study provided evidence for suicide risk associated with the death of a sibling at adult age, revealing that bereaved persons’ risk of suicide is higher when siblings die from suicide, even when adjusting for intrafamily correlation in death risks.