Among HIV-positive men who have sex with men (MSM), crystal meth use is associated with a much higher risk of contracting hepatitis C virus (HCV) sexually. Researchers conducted a prospective cohort study of MSM in Vancouver, British Columbia, recruiting 774 people 16 years of age and older between 2012 and 2015. Results were presented at the 2016 Conference on Retroviruses and Opportunistic Infections (CROI) in Boston.
The participants visited the study every six months for a computer-assisted self-interview on demographic information and sexual and substance use behaviors. Additionally, a nurse conducted a clinical questionnaire with the men. At each visit, the men received a rapid HIV test and gave a blood sample for hep C testing.
Two percent (15 of 551) of the HIV-negative participants tested positive for hep C upon starting the study, as did 28.3 percent (50 of 223) of the HIV-positive men. Of all these individuals, 86.2 percent (56 of 65) already knew they were HCV positive; and five of the HIV-negative and 17 of the HIV-positive men said they had been treated for hep C, with only a respective two and seven having been cured of that virus.
Among the HIV-negative men and HIV-positive men, those men who did not identify as gay were a respective 6.51 and 3.74 times more likely to have hep C at the study’s outset than those who did identify as gay. And among the HIV-negative and HIV–positive men, those who reported injection drug use were a respective 6.56 times and 9.94 times more likely to have hep C at the outset compared with those who did not report such drug use.
This last finding is unsurprising, since the sharing of injection drug use materials is the primary driver of the hep C epidemic. However, considerable research has suggested that HIV-positive MSM in particular are at risk of contracting hep C sexually and that the risk is increasing steadily as hep C spreads more widely throughout the MSM population.
Out of the 534 participants who provided follow-up data in this new study, five contracted hep C during the trial, for an incidence rate of 0.5 per 100 person-years (or a rate of 0.5 percent per year). Only one of these men reported recently injecting drugs. Contracting hep C during the study was associated with being older and having a greater number of recent anal sex partners. Those who reported recently using crystal meth had a 10.62-fold greater likelihood of contracting hep C (the researchers estimated that the true risk was between 1.77- and 63.64-fold higher).
To read the conference abstract, click here.