Department of Gastroenterology and Hepatology, University Medical Center Utrecht, Utrecht, the Netherlands.
Introduction. Poor adherence to treatment for various chronic diseases is a frequent phenomenon. Current guidelines for the treatment of chronic hepatitis B (HBV) and hepatitis C (HCV) recommend optimal adherence, since it has been suggested that poor adherence is associated with an increased risk of virological failure. We aimed to give an overview of studies exploring adherence to combination treatment (PEG-interferon plus ribavirin) for HCV and nucleos(t)ide analogues for HBV. Material and methods. A systematic review was conducted using the databases PubMed, Embase, Cochrane Library and Web of Knowledge. Search terms included "adherence" or "compliance" combined with "hepatitis B", "hepatitis C" or "viral hepatitis". Results. The final selection included 19 studies (13 HCV, 6 HBV). Large differences in patient numbers and adherence assessment methods were found between the various studies. For HCV mean adherence varied from 27 to 97%, whereas the proportion of patients with ≥ 80% adherence varied from 27 to 96%. Mean adherence reported in HBV studies ranged from 81 to 99%, with 66 to 92% of patients being 100% adherent. For both HCV and HBV studies, the highest adherence rates were reported in studies using self-report whereas lower adherence rates were reported in studies using pharmacy claims. Poor adherence to treatment was associated with an increased risk of virological failure. Conclusion. Non-adherence to treatment in chronic viral hepatitis is not a frequent phenomenon. However, given the increased risk of virological failure in poorly adherent patients, clinicians should routinely address adherence issues in all patients treated for chronic viral hepatitis.