Prioritise harm reduction services to prevent hepatitis C re-infection, Scottish study finds

Keith Alcorn
Published:
24 January 2022
Nigel Brunsdon/nigelbrunsdon.com

Limiting re-infection with hepatitis C in people who use drugs is most likely to be achieved by intensifying provision of sterile injecting equipment for people using needle and syringe programmes and increasing the number of people who inject drugs who are treated, rather than withholding treatment for people who inject drugs until they stop injecting, a Scottish study suggests.

The study looked at rates of re-infection according to a person’s pathway to treatment in the Tayside region of Scotland. The region has a high prevalence of hepatitis C and efforts to eliminate hepatitis C have used multiple pathways to reach people with testing and treatment services.

People in Tayside may have been diagnosed and treated through one of six pathways: community pharmacies, drug treatment centres, prisons, injection equipment provision sites, nurse-led outreach services or hospital outpatient clinics.

People diagnosed and treated through these pathways are likely to have different risks of hepatitis C exposure after being cured of hepatitis C. People using injection equipment provision sites are more likely to be injecting drugs than people who had been diagnosed and treated through drug treatment services, for example.

University of Dundee researchers wanted to find out if the risk of re-infection varied according to treatment pathway, in order to provide evidence on where to target resources for prevention of re-infection.

They identified everyone treated for hepatitis C and cured in Tayside between 1998 and 2018, excluding people without follow-up hepatitis C RNA tests after achieving a sustained virologic response. The analysis was confined to people with a history of injecting drug use and excluded people with other risk factors such as exposure to blood products.

The study population comprised 816 people who were not re-infected after treatment and 100 people who acquired hepatitis C after being cured, a re-infection incidence of 5.27 per 100 person-years of follow-up.

People who became re-infected with hepatitis C were younger (40 years vs 47 years). There was no significant difference in the probability of re-infection between people treated with interferon-based regimens (60% of the study population) and people treated with direct-acting antivirals (4.93 vs 7.17 per 100 person-years) in a Kaplan-Meier survival analysis (p=0.84).

Kaplan-Meier survival analysis also showed that the risk of re-infection was greatest in the first 12 months after treatment.

The incidence of re-infection was lowest in people treated through the hospital outpatient clinic (1.81 per 100 PYs). Rates of re-infection ranged from 3.13 per 100 PYs in those treated through drug treatment outreach clinics, 6.39 per 100 PYs in those treated through nurse-led outreach clinics and 8.14 per 100 PYs in those treated in prison, to 12.12 per 100 PYs in those treated through community pharmacies. The highest rate of re-infection was observed in people treated through injection equipment provision sites (19.89 per 100 PYs).

The study investigators say that the high rate of re-infection observed in people treated through the injection equipment provision sites might partly be explained by more frequent hepatitis C RNA testing. Nevertheless, they say their results suggest that resources should be targeted at injection equipment provision sites to prevent re-infections. Opioid substitution therapy and high coverage needle and syringe programmes are likely to prevent a proportion of re-infections but reducing community viral load by increasing the number of people who inject drugs who are treated and cured will also be essential to prevent re-infection.

The study investigators also note that when comparing rates of re-infection between cohorts, it is important to pay attention to definitions of injecting drug use. The risk of re-infection may be much lower in people who are receiving opioid substitution therapy and who have injected infrequently in the preceding six months when compared to people who are injecting drugs on a daily basis.

Reference

Caven M et al. Hepatitis C reinfection by treatment pathway among people who inject drugs in Tayside, Scotland. Journal of Viral Hepatitis, 28: 1744-1750, 2021.