Objective: To assess the impact of HIV and hepatitis C virus (HCV) infection on long-term mortality in injecting drug users (IDU).
Design: Community-based prospective cohort study.
Methods: Mortality data from follow-up in clinical sites and the Mortality Registry by December 2002 were collected for 3247 IDU who attended three centres for voluntary counselling and testing for HIV/AIDS, HCV and hepatitis B virus (HBV) in 1990-1996. Mortality rates by Poisson regression were adjusting for age, sex, duration of drug use, education, HBV and calendar period (1990-1997 and 1998-2002).
Results: Overall, 11.2% were HIV/HCV negative, 43.7% positive only for HCV and 45.1% positive for both. During 26 772 person-years of follow-up, 585 deaths were detected (2.19/100 person-years). Before 1997, HIV/HCV-positive subjects had a five-fold increase in risk of death [relative risk (RR), 5.4; 95% confidence interval (CI), 2.5-11.4] compared with those negative for both; after 1997, a three-fold increase was observed (RR, 2.7; 95% CI, 1.7-4.2). Being HCV positive/HIV negative was not associated with an increase in the risk of death either before (RR, 1.3; 95% CI, 0.6-2.9) or after (RR, 1.2; 95% CI, 0.8-1.9) 1997 compared with HCV/HIV negative. While increases in mortality were seen in those HCV/HIV negative (RR, 1.6; 95% CI, 0.7-3.7) and those only positive for HCV (RR, 1.5; 95% CI, 1.0-2.1), a 20% reduction among coinfected IDUs was observed after 1997 (interaction P = 0.033).
Conclusions: HCV/HIV coinfection has had a large impact on mortality in IDU. After 1997, mortality increased in HIV negative/HCV positive subjects and decreased in HIV positive/HCV positive.