Better medication adherence leads to better outcomes in hepatitis C

Patients with hepatitis C virus (HCV) who were more adherent to their pegylated interferon and ribavirin treatment were more likely to achieve both an early (EVR, decrease of ≥2 log₁₀ HCV RNA at 12 weeks) and sustained virologic response (SVR, undetectable HCV RNA 24 weeks after end of treatment), according to a study published in the September 20, 2011 edition of the Annals of Internal Medicine.

Using the "Veteran Affairs Hepatitis C Clinical Case Registry," researchers retrospectively identified a cohort of 5,706 adult HCV (genotypes 1, 2, 3, and 4) patients receiving ≥1 prescription for pegylated interferon and ribavirin between January 2003 and December 2006, and whom had pre- and post-treatment viral loads measured. Adherence was assessed at 12-week intervals using pharmacy refill records.

In total, researchers found 1,787 of 3,014 (59%) patients with HCV genotype 1 or 4 and 867 of 978 (89%) patients with genotype 2 or 3 achieved EVR, and 901 of 1,929 (47%) patients with genotype 1 or 4 and 620 of 905 (69%) patients with genotype 2 or 3 achieved SVR. In both genotype subgroups, there was a statistically significant association between increasing adherence to interferon and ribavirin and achievement of EVR (P<.001 for all). Moreover, in patients with HCV genotype 1 or 4, increasing drug adherence was associated with a statistically significant increased achievement of SVR; however, a similar association for genotype 2 or 3 was not seen. Of note, adherence declined for both drugs over time, but adherence to interferon therapy always remained higher than ribavirin. Co-administration of growth factors or thyroid medication; however, positively influenced adherence to antiviral therapy.

SOURCE

Lo Re V III, Teal V, Localio AR, Amorosa VK, Kaplan DE, Gross R. Relationship between adherence to hepatitis C virus therapy and virologic outcomes. Ann Intern Med 2011;155:353–360.