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.