The cure rate of Hepatitis C (HCV) treatment with newer direct-acting antiviral (DAA) agents is very high (>95%). These treatments are also well-tolerated, bringing significant optimism to expanding treatment options to include more people at risk, particularly people who inject drugs (PWID). Barriers to accessing treatment by PWID have been widely reported, which has fueled both ethical and public health concerns.
People remain at risk of reinfection even after clearing an HCV infection spontaneously or following a successful course of HCV therapy. The concern of HCV reinfection is paramount, worsened by the fact that no effective vaccine against HCV exists, and the DAAs are prohibitively expensive (treatment cost ranges between $45,000-$110,000 CAD per person).
As HCV treatment in British Columbia is publicly covered through the BC Medical Services Plan, public health policy faces an unpleasant dilemma. While more PWID should be offered HCV treatment (from both an ethical and treatment-as-prevention point of view), these are the people who are at most risk of HCV reinfection.
To get the most out of publicly-funded HCV therapy, more evidence is needed on how to minimize HCV reinfection among PWID. There is a dearth of data around HCV reinfection, particularly from larger cohort studies with longer follow-up times.
The BC Centre for Disease Control recently published the largest study to-date, describing potential predictors of HCV reinfection and the role of harm reduction interventions (e.g., opioid substitution therapy and mental health counseling) in preventing HCV reinfection.
This 19-year follow-up study, based on the data from the BC Hepatitis Testers Cohort, identified 5,915 cases of HCV that cleared their first infection either spontaneously or after successful HCV therapy.
Cases were followed up for a median of 5.4 years (interquartile range: 2.9-8.7). The study also collected data on age, sex, birth cohort, year of HCV diagnosis, HIV coinfection, risk behaviours (injection drug use and alcohol dependence), harm-reduction interventions (opioid substitution therapy and mental health counselling), and socioeconomic deprivation.
- Of 5,915 cases, 3,690 (62%) cleared their first infection spontaneously and 2,225 (38%) achieved treatment-induced clearance (i.e., sustained virological response (SVR)).
- Overall, 452 (8%) cases developed reinfection. The rate was significantly higher among the spontaneous clearance group (11%; n= 402) compared to the SVR group (2%; n=52).
- After adjusting for other confounders, risk of HCV reinfection was higher in the spontaneous clearance group, those coinfected with HIV, and PWID.
- Among those with a history of current injection drug use, opioid substitution therapy was significantly associated with a 27% lower risk of reinfection, while engagement with mental health counselling services was associated with a 29% reduction in reinfection risk.
The findings from this study indicate that HCV treatment, complemented with opioid substitution therapy and mental health counselling, could reduce HCV reinfection risk among PWID. These findings also support policies of post-clearance follow-up of PWID, and provision of harm-reduction services to minimise HCV reinfection and transmission. A significant reduction in HCV reinfection may have substantial economic savings in the era of expensive DAA.
For more information
This study was recently published in the Lancet Gastroenterology and Hepatology: http://www.thelancet.com/journals/langas/article/PIIS2468-1253(16)30182-0/fulltext
The study was funded by the British Columbia Centre for Disease Control, Canadian Institutes of Health Research, and Vanier Canada Graduate Scholarship.
Co-authors: Mel Krajden, Jean Shoveller, Paul Gustafson, Mark Gilbert, Jane A Buxton, Jason Wong, Mark W Tyndall, and Naveed Z Janjua