Mortality From Myocardial Infarction After the Death of a Sibling: A Nationwide Follow-up Study From Sweden

Background-Death of a sibling represents a stressful life event and could be a potential trigger of myocardial infarction (MI). We studied the association between loss of an adult sibling and mortality from MI up to 18 years after bereavement. Methods and Results-We conducted a follow-up study for Swedes aged 40 to 69 years between 1981 and 2002, based on register data covering the total population (N=1 617 010). Sibling deaths could be observed from 1981 and on. An increased mortality rate from MI was found among women (1.25 CI 1.02 to 1.54) and men (1.15 CI 1.03 to 1.28) who had experienced death of an adult sibling. An elevated rate some years after bereavement was found among both women (during the fourth to sixth half-years after the death) and men (during the second to sixth half-years after the death), whereas limited support for a short-term elevation in the rate was found (during the first few months since bereavement). External causes of sibling death were associated with increased MI mortality among women (1.54 CI 1.07 to 2.22), whereas nonexternal causes showed associations in men (1.23 CI 1.09 to 1.38). However, further analyses showed that if the sibling also died from MI, associations were primarily found among both women (1.62 CI 1.00 to 2.61) and men (1.98 CI 1.59 to 2.48). Conclusions-Our study provided the first large-scale evidence for mortality from MI associated with the death of a sibling at an adult age. The fact that findings suggested associations primarily between concordant causes of death (both died of MI) could indicate genetic resemblance or shared risk factors during childhood. Future studies on bereavement should carefully deal with the possibility of residual confounding.