Swiss opioid substitution therapy programme reports strong progress towards hepatitis C elimination

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.

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 excellent adherence.

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 regimen.