Background:  Failure to achieve an early virologic response, defined in clinical trials as a 100-fold decrease in HCV RNA by 12 weeks, predicts eventual non-response to hepatitis c virus (HCV) therapy. We evaluated the early virologic response rate of Veterans Affairs HIV/HCV-co-infected patients receiving pegylated interferon (pegIFN) + ribavirin (RBV) in routine medical care.

Methods:  Patients were identified from the Veterans Affairs HIV Clinical Case Registry with a first prescription for pegIFN by March 31, 2005, a RBV prescription within 7 days of the first pegIFN, and a detectable quantitative HCV RNA prior to HCV therapy. Patients were considered on treatment if they received ≥9 weeks of pegIFN within 16 weeks of initiation. Early virologic response was defined as an undetectable HCV RNA or a 100-fold decrease in HCV RNA by 16 weeks. We conducted univariate analyses to compare patient demographics, baseline lab results, and other clinical characteristics. We then performed multiple logistic regression analyses that included those variables differing between groups in univariate analyses. 

Results:  Of 421 HIV/HCV-co-infected patients who began therapy with pegIFN + RBV with a mean baseline HCV RNA >2.4 million IU/mL, 303 patients (72%) remained on treatment. Of these, 224 had at least 1 follow-up HCV RNA test within 16 weeks of starting therapy (IQR 11 to 14 weeks); 119 (28%) had an early virologic response on an intention-to-treat basis, and 53% when limited to those on treatment and tested. Age, sex, baseline use of HIV ART, baseline results for CD4 count, HIV RNA, HCV RNA, hemoglobin, and creatinine did not differ significantly between the 119 early virologic response patients and the 105 patients on treatment and tested with no early virologic response. While race and rates of starting on a recommended or higher RBV dose differed between the 2 groups in univariate analyses, only HCV genotype (p <0.0001, χ² = 21.5) and year of treatment initiation (p = 0.003, χ² = 11.6) were significant in a multivariate logistic regression model. 

Conclusions:  While many HIV/HCV-co-infected patients who started pegIFN + RBV discontinued early, a substantial percentage of those patients who continued on therapy had an early virologic response with the attendant high likelihood of a sustained response. Considering many factors, HCV genotype emerged as the major determinant of whether patients who stay on therapy achieve an early virologic response. The positive effect of later initiation year suggests that some change in clinical practice, not captured in the included variables, has improved over time to increase the early virologic response rate.