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Update of the Management and Treatment of Hepatitis C Viral Infection, 2012: Definitions of Response

for Health Care Providers

Definitions of Response

HCV RNA decline during therapy is highly associated with the likelihood of achieving an SVR. Attaining rapid virologic response (RVR), extended RVR (eRVR), and early virologic response (EVR) can provide guidance as to the likelihood of achieving an SVR (refer to Figure 1) (11, 12, 13, 14, 15) . A sensitive real-time quantitative HCV RNA PCR assay should be used to assess viral response. The assay should have a lower limit of quantification for HCV RNA of ≤ 25 IU/ml, and a lower limit of detection of 10-15 IU/ml. The lower limit of detection of <10-15 IU/ml should be used for decision-making to determine treatment duration and RGT (34, 35) . Careful virological monitoring and prompt assessment of HCV RNA results are necessary to determine when treatment is futile and should be halted to avoid the emergence of resistance.

Figure 1. Patterns of virologic response related to treatment.

figure 1

Rapid virologic response (RVR): undetectable hepatitis C virus (HCV) RNA at week 4. Extended RVR (eRVR): HCV RNA <10-15 IU/ml at weeks 4 and 12, as defined by clinical trials with telaprevir (TVR)-based therapy (12, 13) . Early virologic response (EVR): ≥ 2 log 10 reduction from baseline HCV RNA, but virus remains detectable (partial EVR) or is undetectable (complete EVR) at week 12. Early responders: HCV RNA <10-15 IU/ml at week 8, as defined by clinical trials with boceprevir (BOC)-based therapy (11, 14) . Partial response: ≥ 2 log 10 reduction from baseline HCV RNA at week 12, but virus remains detectable through week 24 or treatment end. Breakthrough: undetectable HCV RNA during treatment followed by appearance of HCV RNA, despite continued treatment. End-of-treatment response (ETR): undetectable HCV RNA at the end of treatment. Sustained virologic response (SVR): undetectable HCV RNA at 24 weeks after treatment completion. Relapse: undetectable viremia during treatment and/or at the end of treatment, but subsequent viremia following treatment cessation. Non-response: detectable circulating HCV RNA throughout treatment. Null-response: <2 log 10 reduction from baseline HCV RNA during treatment DAA, direct-acting antiviral; PegIFN, peginterferon; RBV, ribavirin.