RESUMO
BACKGROUND: The optimization of combination therapy with ribavirin (RBV) and pegylated interferon alpha has substantially improved sustained virologic response (SVR) rates and lowered virologic relapse rates in patients infected with hepatitis C virus (HCV). In this study, we performed an analysis of the relationship between the end-of-treatment plasma RBV concentration and virologic relapse. METHODS: Thirty-four patients with HCV treated with pegylated interferon/RBV and with an end-of-treatment response were assayed for plasma RBV concentration using liquid chromatography assay coupled to tandem mass-spectrometric detection on the last day of the treatment. Clinical data and the concentration of RBV were compared between patients classified as either relapsers or nonrelapsers. RESULTS: Eleven patients (32.4%) relapsed and 23 patients (67.6%) achieved an SVR. The mean plasma RBV concentration on the last day of treatment was 1380 ± 312 ng/mL for relapsers and 2278 ± 569 ng/mL for SVR patients (P < 0.0001). A receiver operating characteristic analysis showed that a threshold of 1960 ng/mL was associated with the greatest sensitivity and specificity (100% and 83%, respectively, with an area under the curve of 0.94; P < 0.0001) for discriminating between patients who relapsed and those who did not. A univariate logistic regression analysis indicated that a plasma RBV concentration of <1960 ng/mL at the end of the treatment was strongly associated with relapse (odds ratio, 55; 95% confidence interval, 7.24-∞; P = 0.0001) independently of age, body weight, RBV dose, baseline viral load, the interleukin-28B genotype, and response to previous courses of treatment. CONCLUSIONS: Our study results highlight the relevance of measuring plasma RBV concentrations during and at the end of HCV treatment, with a view to avoiding virologic relapse.