Declining incidence of hepatitis C virus infection among people who inject drugs in a Canadian setting, 1996-2012

• Published in: PloS one 2014-06, Vol.9 (6), p.e97726
• Main Authors: Grebely, Jason, Lima, Viviane Dias, Marshall, Brandon D L, Milloy, M-J, DeBeck, Kora, Montaner, Julio, Simo, Annick, Krajden, Mel, Dore, Gregory J, Kerr, Thomas, Wood, Evan
• Format: Article
• Language: English
• Subjects: Acquired immune deficiency syndrome; Adult; AIDS; Biology and Life Sciences; Canada - epidemiology; Cocaine; Confidence intervals; Density; Drug abuse; Drug use; Drugs; Female; Hazard assessment; Health aspects; Health risk assessment; Hepatitis; Hepatitis C; Hepatitis C - epidemiology; Hepatitis C - etiology; Hepatitis C virus; Heroin; HIV; Housing; Human immunodeficiency virus; Humans; Incidence; Infection; Infections; Male; Medicine and health sciences; Methamphetamine; Morbidity; Needle exchange programs; Public health; Risk analysis; Risk Factors; Seroconversion; Statistical analysis; Substance Abuse, Intravenous - complications; Surveys and Questionnaires; Trends; Viruses
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0097726

People who inject drugs (PWID) are at high risk of hepatitis C virus (HCV) infection. Trends in HCV incidence and associated risk factors among PWID recruited between 1996 and 2012 in Vancouver, Canada were evaluated. Data were derived from a long-term cohort of PWID in Vancouver. Trends in HCV incidence were evaluated. Factors associated with time to HCV infection were assessed using Cox proportional hazards regression. Among 2,589, 82% (n = 2,121) were HCV antibody-positive at enrollment. Among 364 HCV antibody-negative participants with recent (last 30 days) injecting at enrollment, 126 HCV seroconversions were observed [Overall HCV incidence density: 8.6 cases/100 person-years (py); 95% confidence interval (95% CI): 7.2, 10.1; HCV incidence density among those with injecting during follow-up: 11.5 cases/100 py; 95% CI 9.7, 13.6]. The overall HCV incidence density declined significantly from 25.0/100 py (95% CI: 20.2, 30.3) in 1996-99, as compared to 6.0/100 py (95% CI: 4.1, 8.5) in 2000-2005, and 3.1/100 py (95% CI: 2.0, 4.8) in 2006-2012. Among those with injecting during follow-up, the overall HCV incidence density declined significantly from 27.9/100 py (95% CI: 22.6, 33.6) in 1996-99, as compared to 7.5/100 py (95% CI: 5.1, 10.6) in 2000-2005, and 4.9/100 py (95% CI: 3.1, 7.4) in 2006-2012. Unstable housing, HIV infection, and injecting of cocaine, heroin and methamphetamine were independently associated with HCV seroconversion. HCV incidence has dramatically declined among PWID in this setting. However, improved public health strategies to prevent and treat HCV are urgently required to reduce HCV-associated morbidity and mortality.