Reinfection risk after hepatitis C treatment higher in recent drug users

7 Sep 2018 Keith Alcorn
Originally published on www.infohep.org

Reinfection with hepatitis C after successful treatment is more common in younger people who inject drugs and recent and former drug users are at greatest risk of reinfection, a cohort study in the Canadian province of British Columbia has found. Providing harm reduction and support services after hepatitis C treatment is needed to prevent reinfections, the researchers say.

The study also found that daily use of opioid agonist therapy to minimise heroin use was associated with a lower risk of reinfection. The study is published in the Journal of Hepatology.

Direct-acting antiviral therapy cures at least nine out of ten people with hepatitis C after a course of once-daily treatment lasting 8 to 12 weeks. Reinfection after treatment can occur if people continue to share needles or injecting equipment. Men who have sex with men are also at risk of reinfection if they have unprotected sex.

The risk of reinfection in these groups of people has led some clinicians to question whether active drug users should be treated for hepatitis C while they continue to use drugs, or to argue that men who have sex with men who become reinfected with hepatitis C should not be prioritised for re-treatment.

Beliefs about reinfection risk are based largely on data from the interferon treatment era or from small studies, and estimated that the rate of reinfection was between 0.19 and 2.2 cases per 100 person-years of follow-up. Evidence from large population-based studies after direct-acting antiviral treatment has been lacking, leading researchers from the University of British Columbia to investigate the incidence of reinfection in the British Columbia Hepatitis C Testers cohort. The cohort tracks health and treatment outcomes in everyone diagnosed with hepatitis C in the province.

Researchers identified 5292 people who achieved a sustained virologic response (SVR) after direct-acting antiviral treatment, and of these, 4114 had at least one sustained HCV RNA measurement after SVR (defined as a negative HCV RNA result at least ten weeks after completing treatment).

Two-thirds were male with a median age of 60 years, and two-thirds were people who inject drugs. Of those who had injected drugs, just under one third had a history of recent injecting drug use (less than three years prior to hepatitis C cure). Ten per cent of the entire sample had co-infection with HIV.

Participants were followed for a median of 123 days after SVR and the first post-SVR measurement of HCV RNA took place a median of 86 days after SVR.

During 2766 person-years of follow-up, 40 reinfections were identified and 33 persisted. The overall rate of reinfection was 1.44 cases per 100 person-years and the persistent infection rate was 1.19 per 100 person-years.

Persistent reinfection rates were highest among recent drug users (2.67 per 100 PY), recent drug users born after 1975 (10.2 per 100 PY), people with HIV co-infection (5.67 per 100 PY) and problematic alcohol users (4.55 per 100 PY). Multivariable analysis showed that only a history of recent (incidence rate ratio 6.7) or former drug use (IRR 3.7) was associated with reinfection.

Daily use of opioid agonist therapy in the 12 weeks prior to SVR was associated with a low risk of reinfection: 513 of 2668 people with a history of drug use used opioid agonist therapy, but only one became reinfected. However, the reduction in risk associated with use of opioid agonist therapy was non-significant in multivariable analysis (IRR 0.7, 95% CI 0.1-5.6).

The authors point out that, as treatment eligibility expands and the number of younger people with less advanced liver fibrosis are identified for treatment, the proportion of recent and current injectors receiving direct-acting antiviral treatment is likely to rise. Education about reinfection risk, engagement in harm reduction services and provision of opioid agonist therapy need to be provided alongside direct-acting antiviral therapy, the authors recommend.

“Our results highlight the need to engage people with ongoing injection risk in harm reduction and support services following successful treatment,” they conclude.