Patients with hepatitis C virus infection who adhere to their drug regimen are more likely to show long-term benefit

Less than optimal adherence by a patient infected with hepatitis C virus (HCV) to a regimen of pegylated interferon and ribavirin decreases the likelihood of finding no detectable viral load 24 weeks after the medication is stopped (a sustained viral response), according to a new study. The standard of care for HCV infection—twice-daily treatment with oral ribavirin and weekly subcutaneous injection of pegylated interferon 2a or 2b—can eradicate the virus, halt or regress liver fibrosis, and reduce the risks for cirrhosis of the liver, hepatic decompensation, and malignant liver cancer. However, the treatment is complex and requires frequent laboratory monitoring of the viral response and possible adverse effects.

The researchers found that patients infected with HCV genotypes 1 or 4 were more likely to have an early virologic response, a 100-fold reduction in viral load, over the initial 12 weeks of treatment with 91–100 percent adherence (63 percent of 2,187 patients). This contrasted with patients with 40 percent adherence or less (37 percent of 68 patients). Patients with HCV genotypes 2 or 3 with adherence of 91–100 percent were also more likely to exhibit EVR (91 percent of 713 patients) than those with adherence of 40 percent or less (67 percent of 18 patients). For patients who showed a virologic response by 24 weeks of treatment, 47 percent of those infected with HCV genotype 1 or 4 and 69 percent of those infected with HCV genotypes 2 or 3 achieved a sustained viral response.

The researchers analyzed electronic medical record data from the National Veterans Affairs (VA) Hepatitis C Clinical Case Registry, together with medication information on these patients from the VA pharmacy database. A total of 5,706 patients treated with pegylated interferon and ribavirin were included in the study. It was funded in part by a grant (HS10399) from the Agency for Healthcare Research and Quality to the University of Pennsylvania Center for Education and Research on Therapeutics (CERT).

For more information on the CERTs program visit http://www.certs.hhs.gov.

More details are in "Relationship between adherence to hepatitis C virus therapy and virologic outcomes," by Vincent Lo Re III, M.D. M.S.C.E., Valerie Teal, M.S., A. Russell Localio, Ph.D., and others in the September 20, 2011, Annals of Internal Medicine 155(6), pp. 353–360.

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