Comorbid injection drug use (IDU) with hepatitis C (HCV) infection increases epigenetic age acceleration (EAA) among patients with HIV, with epigenetic age partially mediating the relationship between IDU+HCV and all-cause mortality, according to results published in Epigenetics. Ke Xu, MD, and colleagues analyzed data from the Veterans Aging Cohort Study (n=927) and employed four established epigenetic clocks to estimate DNA methylation age. Compared with those without IDU or HCV (IDU-HCV-), people with both IDU and HCV (IDU+HCV) exhibited a 2.23- fold higher mortality risk. IDU+HCV was associated with a significant increase in EAA according to three out of four epigenetic clocks examined. Epigenetic age partly mediated the connection between IDU+HCV and all-cause mortality, with a mediation proportion of up to 13.67%. “Our results suggest that comorbid IDU with HCV increases EAA in [people with HIV] that partially mediates the increased mortality risk,” Dr. Xu and colleagues wrote.