Injection drug-using men who have sex with men had a higher anti-hepatitis C virus prevalence rate compared with men who did not inject drugs, according to study data.
“The Multicenter AIDS Cohort Study (MACS) provided a unique opportunity to compare HCV prevalence and clearance in MSM with and without a history of IDU,” researcher Eric C. Seaberg, PhD, MPH, department of epidemiology, Johns Hopkins Bloomberg School of Public Health, told HCV Next.
Eric C. Seaberg
Seaberg and colleagues recruited 6,972 men who have sex with men (MSM) enrolled in the MACS, an observational study of MSM in Baltimore, Pittsburgh, Chicago, and Los Angeles, and tested serum and plasma samples to determine HCV status. The cohort consisted of injection drug users (IDUs), non-IDUs, HIV-infected men and HIV-uninfected men. The median age of the patients was 33.5 years; 72.7% were white, 42% were HIV-infected and 6,890 were included in final analyses.
Serum sampling showed 532 MSM positive for HCV antibody (anti-HCV). Of those, 42.9% were IDUs compared with 4% of non-IDUs (P<.001). Among non-IDUs, risk factors associated with higher anti-HCV prevalence were black race, recent blood transfusion, cigarette smoking, no prior intercourse with a male and HIV infection. Among IDUs, risk factors for high anti-HCV prevalence were older age, black race, HIV infection and having fewer than 50 male sexual partners. Non-black race and rs12979860-C/C genotype were associated with HCV clearance for both IDUs and non-IDUs, according to univariate and multivariate analyses.
HCV clearance was least likely to occur among IDUs compared with non-IDUs (clearance ratio=0.4; 95% CI, 0.28-0.58).
“Among the important differences between IDUs and non-IDUs that we observed in the MACS, the advantageous IL28B/IFNL4 genotype (rs12979860-C/C) had a significantly greater effect on HCV clearance among the MSM with a history of IDU (clearance ratio = 4.16 vs. 1.71 among non-IDUs, P=0.03),” Seaberg said. “Collectively, the results from our study suggest that different mechanisms drive the immunologic response to an HCV infection that is acquired sexually versus through IDU.” — by Melinda Stevens
Disclosure: One researcher reports being on advisory boards for Roche Molecular Systems and Quidel.