Background: Coinfection with hepatitis C virus (HCV) is a poor prognostic factor for human immunodeficiency virus (HIV)-infected patients. We examined whether the increased mortality in these patients is partly explained by a familial excess risk of death.
Methods: Danish HIV-infected patients who had had at least 1 HCV test were included (n=3531). In addition, 336,652 population control subjects matched for sex, age, and residency were identified from the Danish Civil Registration System. For both HIV-infected patients and population control subjects, we identified all siblings born after 1951, with dates of death or emigration. Siblings of HIV-infected patients were classified according to the patients' HCV serostatus. Survival after age 20 years was compared among the groups of siblings.
Results: We identified 437 siblings of HIV/HCV-coinfected patients, 1856 siblings of HIV-monoinfected patients, and 285,509 siblings of population control subjects. Mortality was substantially higher in siblings of HIV/HCV-coinfected patients than in either siblings of HIV-monoinfected patients (mortality rate ratio [MRR], 2.97 [95% confidence interval {CI}, 1.98-4.45]) or siblings of control subjects (MRR, 4.23 [95% CI, 3.09-5.79]). Siblings of HIV-monoinfected patients had slightly higher mortality (MRR, 1.43 [95% CI, 1.10-1.85]) than siblings of control subjects.
Conclusions: HCV infection is a marker of familial factors that affect the survival of HIV-infected patients independently of the pathogenicity of HCV.