Direct-acting antiviral treatment cured almost everyone treated for
hepatitis C in a large cohort of people receiving opioid substitution therapy,
Swiss researchers report in the Swiss Medical Weekly.
The study also observed a substantial fall in new hepatitis
C diagnoses among people receiving opioid substitution therapy (OST) during a 2-year
period after direct-acting antiviral (DAA) treatment was made available to everyone
with hepatitis C in Switzerland regardless of liver disease stage.
OST reduces drug-related harm by limiting the need for injecting of heroin. It has been shown to reduce the risk of acquiring hepatitis C and keeps people engaged with health services. Switzerland offers two forms of OST:
methadone, or heroin-assisted
treatment through supervised injecting facilities. Uptake of OST is high among people with opioid addiction in
Switzerland; approximately 80% of the estimated 27,000 people with addiction to opioids receive
OST, 15% in the form of heroin-assisted treatment.
- direct-acting antiviral (DAA)
A drug which prevents hepatitis C from reproducing by blocking certain steps in its lifecycle.
A non-invasive test, used instead of a biopsy, to measure the stiffness
or elasticity of the liver using an ultrasound probe.
A high level of engagement in OST,
mainly prescribed by general practitioners, allows regular screening for
hepatitis C and referral for hepatitis C treatment. However, some countries
have proved reluctant to provide DAA treatment to people on OST, citing concerns about adherence to DAA treatment and hepatitis C reinfection among people who
continue to inject drugs while receiving OST.
The Swiss Association for the Medical Management of
Substance Users (SAMMSU) cohort has recruited participants through OST programmes in eight towns and cities since 2014. Cohort researchers carried out
cross-sectional analyses of chronic hepatitis C prevalence, treatment uptake
and cure rates between 2017 and 2019, to assess the impact of expanding access
to DAA treatment from 2017.
The cohort consisted of 623 participants in 2017, 757 in
2018 and 900 in 2019. Demographic characteristics were consistent over time,
87% male, 81% injecting drug users, 13% living with HIV and 66% positive for
hepatitis C virus (HCV) antibodies.
By 2019, 80% of those with HCV antibodies had ever had
chronic hepatitis C (490 persons), and of these, 79% had undergone hepatitis C
treatment (391 persons). Of those treated, 95% had either been cured or had a
negative HCV viral load by 1 May 2019. Correspondingly, the prevalence of HCV
viraemia in the cohort decreased from 36% in 2017 to 19% in 2019 among people
who had tested positive for HCV antibodies.
Some people underwent more than one course of treatment
before they were cured. Thirty-nine per cent had received interferon-based
treatment before 2016, the remainder receiving interferon-free treatment. A
course of interferon-free treatment was 70% more likely to result in a cure. Adherence
to DAA treatment was very good; 98% of participants had
In the period between 2017 and 2019, 35 reinfections were
observed, a rate of 1.6 cases per 100 person-years of follow-up. The investigators
say it is likely that the incidence of reinfection will fall further as the
prevalence of HCV viraemia declines. Similarly, new cases of hepatitis C in
people previously negative for hepatitis antibodies have fallen from
approximately 30 new diagnoses in 2013 to less than ten in 2019 (participants
were tested for hepatitis C on cohort entry and each year thereafter).
The researchers calculate that 98% of people with chronic
infection in the cohort will need to be treated to achieve elimination of
hepatitis C transmission, and they suggest that contact tracing may be
necessary to identify people who inject drugs not yet engaged in care and in
need of hepatitis C testing and treatment.
The researchers conclude that very high rates of treatment
uptake are possible in OST recipients with hepatitis C and that adherence and
treatment success are excellent. “Treating chronic hepatitis C in [OST] patients
requires an extra effort,” they conclude, highlighting several practices which
support treatment uptake:
- Switzerland introduced DAA prescribing by general practitioners in 2019, allowing OST providers to offer
hepatitis C treatment on site, rather than referring patients to liver specialists.
- Dried blood spot sampling for HCV viral load
testing and use of APRI scores instead of Fibroscan to identify patients at
highest risk of fibrosis allow decentralised settings such as general
practitioners or pharmacies to diagnose chronic hepatitis C and assess patients
for treatment without the need for hospital referral.
- Directly observed treatment alongside OST
supports adherence; 45% of people received their treatment as a directly observed