Clinical experience with nonstandard doses ofinterferon alfa-2b and ribavirin in the treatment of chronic hepatitis C infection: A retrospective analysis.

Background: Hepatitis C virus (HCV) infection is the most common blood-borne virus in the United States. Several mono- and combination therapies have been approved by the US Food and Drug Administration for the treatment of HCV, but their routes of administration, dosing approaches, eras of introduction, and actual use in clinical practice and resulting effectiveness have not yet been reported.

Objectives: The aim of this article was to characterize clinical use and virologic response (VR) of the HCV treatments interferon alfa-2b plus ribavirin (IFN + RBV) and peginterferon alfa-2b plus ribavirin (peg-IFN + RBV).

Methods: This retrospective chart review of office-based practices in theUnited States was conducted at 200 physicians' offices across the United States. We collected data concerning dosing patterns, VR (HCV RNA load, ≤1000 IU/mL or "negative" on polymerase chain reaction qualitative analysis), and adverse events (AEs) from the medical records of a geographically diverse sample of patients receiving treatment for chronic HCV infection in the United States from July 2001 to June 2002. For efficacy assessment, factors that were statistically different at baseline were adjusted using logistic regression. Providers also reviewed the medical records for symptoms or signs consistent with HCV treatment-related AEs.

Results: Data from the records of 675 patients (423 men, 252 women; mean [SD] age of 45.5 [8.2] years; mean [SD] body weight, 80.8 [19.4] kg) were analyzed. At baseline, the IFN + RBV treatment group (330 patients) had significantly higher percentages of black patients (22.1% vs 15.7%; P = 0.032) and patients with hepatic disease based on clinician-reported cirrhosis and liver dysfunction (18.8% vs 9.9%; P < 0.001), and a significantly lower percentage of white patients (60.3% vs 69.6%; P = 0.012) compared with the peg-IFN + RBV treatment group (345 patients). The difference in log-transformed baseline HCV RNA loads between the 2 treatment groups in this study was <1 log unit. A significantly higher percentage of IFN + RBV-treated patients compared with peg-IFN + RBV-treated patients were prescribed HCV therapy on diagnosis (37.3% vs 29.9%; P = 0.041), and the mean (SD) duration of treatment was significantly different between the 2 treatment groups (52.5 [37.0] vs 27.5 [15.0] weeks; P < 0.001). Peg-IFN + RBV was associated with a higher rate of VR compared with IFN + RBV on univariate analysis (28.5% vs 17.5%; P = 0.018). Recommended doses of peg-IFN and higher-than-recommended doses of RBV were associated with an increased likelihood of VR. Higher-than-recommended doses of peg-IFN without a concomitant increase in RBV was not associated with an increased likelihood of VR. The incidences of the 3 most commonly reported AEs in the IFN + RSV group were significantly higher compared with those in the peg-IFN + RSV group: fatigue, 217 (65.8%) versus 185 (53.6%) patients (P = 0.001); depression, 147 (44.5%) versus 120 (34.8%) (P = 0.009); and anxiety, 87 (26.4%) versus 64 (18.6%) (P = 0.014). Nausea, however, was reported in a significantly higher number of patients in the peg-IFN group compared with the IFN + RBV group (74 [21.4%] vs 51 [15.5%]; P = 0.045). The frequencies of dose modification and treatment discontinuation due to AEs were similar between the 2 treatments and were similar to or less than those reported in other studies.

Conclusions: In this retrospective data analysis of US office-based practicesconcerning HCV treatment, clinicians were observed to prescribe IFN + RBV at doses that differ from recommendations in the product information (PI), as well as prescribe the RBV component of peg-IFN + RBV at doses that differed from PI recommendations. Although patients treated with peg-IFN + RBV appeared to achieve higher VR compared with those treated with IFN + RBV in our analysis of data from clinical practice, peg-IFN + RBV was associated with lower VR rates compared with those reported in clinical studies.