Familial Mortality Risks in Patients With Ischemic Stroke: A Swedish Sibling Study

Abstract

Background: The influence of familial factors on the prognosis of ischemic stroke (IS) is unknown. This nationwide follow-up study evaluated familial mortality risks of IS among Swedish sibling pairs hospitalized for IS. Methods: We linked Swedish nationwide registers for the identification of 1380 Swedish born sibling pairs (2760 cases), where both siblings were hospitalized for first-time IS between 1991 and 2010. Median age was 62 years (range, 26–78 years). Sibling pairs with cancer were excluded. Familial hazard ratios (FHRs) for mortality after first IS hospitalization were determined with Cox regression. The influence of proband survival after IS was categorized as short sibling survival (<1, 2, 3, 4, or 5 years) or long sibling survival (≥1, 2, 3, 4, or 5 years) after IS. FHRs were adjusted for age at onset, sex, education, county, year of diagnosis, days of hospitalization, and comorbidities. Results: Short sibling survival (ie, <3 or <4 years) after IS was associated with an adjusted FHR of 1.29 (95% CI, 1.05–1.58) and 1.24 (95% CI, 1.02–1.51), respectively, for overall mortality after IS. Stratified analysis showed that short sibling survival (ie, <2—<5 years) was stronger and significant only among younger individuals (<62 years) and males. Highest FHR for short sibling survival (ie, <4 years) was 1.42 (95% CI, 1.08–1.88) for younger individuals and 1.50 (95% CI, 1.21–1.87) for males. For young male subjects, FHR was 1.80 (95% CI, 1.33–2.46). In the adjusted model, mortality was also associated with sex, education, age at onset, year of diagnosis, days of hospitalization, coronary heart disease, diabetes, dementia, heart failure, obesity, alcoholism, and hyperlipidemia. Conclusions: Our results suggest that family history of short survival in siblings after IS is associated with mortality after IS for younger male subjects. Additional studies are needed to characterize possible genetic and nongenetic familial environmental causes of this association.