Mortality around the anniversary of a sibling's death. Findings from Swedish register-data

Abstract Background Studies have found that the death of a sibling is associated with adverse health in bereaved siblings. Anniversaries may trigger grief reactions and contribute to an acute deterioration of health and are exogenous to shared intergenerational characteristics and may provide an indication of a causal effect of bereavement. Previous studies have found anniversary effects following the loss of a child and parent. We examined whether mortality increases among adult siblings around the anniversary following sibling death. Methods This case-crossover study used Swedish register-based longitudinal data from 1990 to 2016, based on the entire population. Participants included all adults aged 18 to 65 years who experienced sibling death and subsequently died. Conditional logistic regression was used to quantify the association between the anniversary (or preanniversary and postanniversary periods) and mortality, controlling for time-invariant confounding. All analyses were stratified by sex of the bereaved. Further analyses will also be stratified by socio-demographic characteristics such as the sex of the deceased sibling, time since sibling death, age, marital status and cause of sibling death. Results The results show that the anniversary of a siblings’ death is not associated with an increased mortality risk in bereaved siblings. We rather found somewhat reduced mortality risks around the anniversary dates in men (OR 0.78 95% CI 0.55-1.10 for the period ranging from 2 days before up to the anniversary) and women (OR 0.44 95% CI 0.20-0.97 for the anniversary). Further analysis will scrutinize whether anniversary effects are found when the analysis are stratified by socio-demographic characteristics and cause of sibling death. Conclusions Anniversaries following sibling death might not trigger grief to the same extent as anniversaries following the death of a parent or child. Sibling bereavement may still have health consequences although not during anniversaries. Key messages • Anniversaries following sibling death might not trigger grief to the same extent as child and parental bereavement. • Sibling bereavement may still have health consequences although not around anniversaries.