# All-cause mortality around the anniversary of a sibling’s death: findings from Swedish National Register Data

## TL;DR

This study found that sibling death anniversaries may not increase mortality risk overall, but effects vary by sex and age, with men under 50 showing higher risk before the anniversary.

## Contribution

The study provides novel insights into sex- and age-specific mortality patterns around sibling death anniversaries using nationwide data.

## Key findings

- Women had lower mortality risk on or just before the anniversary of a younger or same-age sibling's death.
- Men under 50 showed increased mortality risk 12 days before a sibling's anniversary, suggesting anticipatory stress.
- Overall, sibling death anniversaries were not linked to higher mortality, but patterns varied by demographic factors.

## Abstract

Death anniversaries may trigger stress responses that negatively affect health in bereaved individuals. Little is known about such reactions after adult sibling loss. This study examined whether mortality risk increases around the anniversary of a sibling's death. Using Swedish national register data (1990-2016), we conducted a time-stratified case-crossover study including 12 789 adults who experienced sibling loss and later died. Conditional logistic regression estimated associations between mortality and death anniversaries (including pre-anniversary and post-anniversary periods), adjusting for time-invariant confounders. Analyses were stratified by the bereaved's sex and age, the sibling's sex, sibling order, and whether ≥1 parent was alive at the bereaved's death. Among women, mortality risk was lower on the anniversary date (OR, 0.44; 95% CI, 0.21-0.93), and in the period from 1 day before and up to the anniversary date for women who lost a younger or same-age sibling (OR, 0.45; 95% CI, 0.20-1.00). In contrast, men bereaved before age 50 years had a heightened risk in the period ranging from 12 days before and up to the anniversary (OR, 1.40; 95 % CI, 1.05-1.86). Overall, sibling-death anniversaries were not associated with elevated mortality, though observed sex- and age-specific patterns merits further investigation.

Key messages:

Anniversaries following sibling death might not trigger anniversary reactions to the same extent as child and parental death. Women who experienced sibling death had lower mortality risk around the anniversary.Men who experienced sibling death before age 50 years had a heightened risk in the period ranging from 12 days before and up to the anniversary, consistent with an anticipatory anniversary reaction.Sibling bereavement can still affect health, but risks may emerge outside the immediate anniversary window and differ by sex and age.

Anniversaries following sibling death might not trigger anniversary reactions to the same extent as child and parental death. Women who experienced sibling death had lower mortality risk around the anniversary.

Men who experienced sibling death before age 50 years had a heightened risk in the period ranging from 12 days before and up to the anniversary, consistent with an anticipatory anniversary reaction.

Sibling bereavement can still affect health, but risks may emerge outside the immediate anniversary window and differ by sex and age.