Adherence to hepatitis C treatment in recovering heroin users maintained on methadone

Injection drug users are often denied hepatitis C (HCV) treatment due to concerns about adherence, despite limited data about the impact of such common issues as psychiatric illness and intercurrent drug use. We sought to define the impact of these and other potential adherence barriers in a real-world sample of recovering drug users.

We conducted a prospective observational study of 71 methadone-maintained patients who received interferon and ribavirin combination therapy in a community-based clinic with expertise in treating addictive disorders. Adherence measures were conducted with monthly interview, medication counts, and urine toxicology testing.

Overall, 48 (68%) were adherent, and adherent patients were significantly more likely to achieve a sustained virologic response (42 vs. 4% in nonadherent patients). Patients with and without a prior psychiatric history were similarly adherent (64 vs. 72%, respectively, P>0.5), and the initiation of new psychiatric medications during HCV treatment was associated with improved adherence overall (P=0.02) and in patients that did not report a preexisting psychiatric diagnosis (P=0.04). Trend towards reduced adherence in patients without a period of abstinence was seen before initiating HCV treatment, 46 vs. 72% of those who had been abstinent for at least 1 month (P=0.10). Although occasional drug users were similarly adherent to those who were completely abstinent, patients who relapsed to regular drug use showed a significantly lower level of adherence (P=0.03).

We conclude that the majority of methadone-maintained drug users can adhere to HCV treatment, even those with psychiatric illness and relatively limited pretreatment drug abstinence. Lack of pre-HCV treatment drug abstinence and regular drug use during HCV treatment may be relative barriers to medication adherence, but the initiation of psychiatric medications during HCV treatment may be a helpful intervention. This report provides further evidence for an individualized approach to HCV treatment that does not categorically exclude patients with potential barriers such as mental illness and limited drug abstinence.