Interferon alpha therapy for hepatitis C: Treatment completion and response rates among patients with substance use disorders

Background: Individuals with substance use disorders (SUDs) are at increased risk for hepatitis C viral infection (HCV), and few studies have explored their treatment responses empirically. The objective of this study was to assess interferon alpha therapy (IFN) completion and response rates among patients with HCV who had a history of comorbid SUDs. More data is needed to inform treatment strategies and guidelines for these patients. Using a medical record database, information was retrospectively collected on 307,437 veterans seen in the Veterans Integrated Service Network 20 (VISN 20) of the Veterans Healthcare Administration (VHA) between 1998 and 2003. For patients treated with any type of IFN (including regular or pegylated IFN) or combination therapy (IFN and ribavirin) who had a known HCV genotype, IFN completion and response rates were compared among patients with a history of SUD (SUD+ Group) and patients without a history of SUD (SUD- Group). Results: Odds ratio analyses revealed that compared with the SUD- Group, the SUD+ Group was equally likely to complete IFN therapy if they had genotypes 2 and 3 (73.1% vs. 68.0%), and if they had genotypes 1 and 4 (39.5% vs. 39.9%). Within the sample of all patients who began IFN therapy, the SUD- and SUD+ groups were similarly likely to achieve an end of treatment response (genotypes 2 and 3, 52.8% vs. 54.3%; genotypes 1 and 4, 24.5% vs. 24.8%) and a sustained viral response (genotypes 2 and 3, 42.6% vs. 41.1%; genotypes 1 and 4: 16.0% vs. 22.3%). Conclusion: Individuals with and without a history of SUD responded to antiviral therapy for HCV at similar rates. Collectively, these findings suggest that patients who have co-morbid SUD and HCV diagnoses can successfully complete a course of antiviral therapy.