| Summary: | Introduction: Over 300,000 Canadians have chronic Hepatitis C virus (HCV) infection, over half being current or former Injection drug users (IDUs). The possibility of re-infection is often cited as a reason for not initiating treatment in this group of patients, although recent observational data suggest that the rate of re-infection may be reduced following spontaneous or treatment-induced virologic clearance, such data are often retrospective and incomplete.
Methods: In a prospective study to evaluate the incidence of HCV viremia, we indentified a cohort of IDUs at risk of new infection, who were receiving care at the Pender Community Health Centre on Vancouver’s Downtown East Side. Potential subjects were identified as either: never been infected with HCV (non-infected arm), spontaneously cleared the virus (spontaneous arm), or achieved a sustained virologic response after treatment (SVR arm). A questionnaire to identify demographics, health status, risk behavior and drug use was administered at baseline and every 6 months, along with blood tests to identify their HCV status.
Results: 518 subjects were screened, 245 (47%) were excluded because of being viremic and 69 (13 %) met the criteria for inclusion in the study: 18 in the non-infected, 29 in the spontaneous and 22 in the SVR arm respectively. There were no significant differences among the 3 groups with respect to age, ethnicity, source of income, unstable housing, and being on opioid maintenance program. Over follow-up, 20% of the non-infected group became viremic, as compared to 0% of the other two groups (p=0.04). Injecting drugs in the past 30 days (p=0.004), sharing non-injection equipments (p=0.015), heroin, amphetamines, and combined drugs use was significantly higher in the non-infected compared to SVR arm (p=0.02, 0.04 and 0.02 respectively). There were no significant differences in drug use and risk behavior between non-infected and spontaneous arms.
Conclusion: We have demonstrated in a prospective cohort with systematic follow-up that HCV infection is more likely to occur in those who have never been previously infected, and that this susceptibility to infection cannot be completely explained by an increase in risk behavior, at least as compared to individuals who have cleared their viremia spontaneously.
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