Review article: the role of rapid virologic response in determining treatment duration for chronic hepatitis C.Poordad FF. Aliment Pharmacol Ther. 2010 Mar 17. [Epub ahead of print] Background: For patients with chronic hepatitis C, attaining rapid virologic response (RVR) is highly predictive of attaining SVR. Aim: To consider the predictive value of RVR in terms of SVR and relapse. Methods: Data were collected from published clinical trials to define the predictive value of RVR for SVR and evaluate the proposed continuum linking RVR to relapse. Results: These data support a 24-week regimen among genotype (G)1 patients who attain RVR with positive predictive values (PPVs) of 77.8% and 85.7% in patients with G1 infection treated for 24 and 48 weeks. Conversely, failure to attain RVR among G1 patients should not be viewed as a criterion for extending treatment duration beyond 48 weeks: negative predictive values (NPVs) were 60.9% and 52.7% in G1 patients without RVR treated for 48 and 72 weeks. Among G2/3 patients, RVR has a high PPV; however, the NPV varied with treatment duration indicating that a 24-week treatment regimen is warranted in G2/3 patients who fail to attain RVR Conclusion: The present analysis confirms RVR as a strong predictor of SVR that can be used to tailor treatment duration, but which also should be appreciated in the context of treatment duration and regimen.