What Is a Sustained Virologic Response?

Understanding This Hepatitis C "Cure"

Man taking a pill for hepatitis C
What is the meaning of a sustained virologic response with treatment for hepatitis C?. Photo Credit: Paul Bradbury/Getty Images

sustained virologic response (SVR) for people with a hepatitis C infection simply means that there is no evidence of the hepatitis C virus (HCV​) in their blood after they have received hepatitis C treatment. SVR is the ultimate goal of HCV therapy and, in most cases, can be clinically defined as a "cure" if the HCV viral load remains undetectable 24 weeks after the completion of treatment.

In almost all cases, people with an SVR of 24 weeks are unlikely to experience viral rebound (i.e., a return of virus).

Most research suggests that rebound rates are as a low as 1 percent to 2 percent in such cases.

Defining SVR and Other Virologic Responses

Following the initiation of hepatitis C therapy, the blood is tested to measure viral activity. The ultimate goal is to achieve an undetectable viral load. "Undetectable," in this case, doesn't necessarily mean zero or the complete absence of viral activity in the body; rather, it is defined as having no detectable virus in the blood using current testing technologies.

Each stage of response is given a classification, with some stages correlating to greater or lesser likelihood of treatment success. Take a look at this chart, below.

TermMeaningDefinitionPrognosis
RVRRapid viral responseAn undetectable viral load after four weeks of treatmentGenerally more likely to achieve SVR
eRVRExtended rapid viral responseAn undetectable viral load at week 12, following the initial RVRGenerally more likely to achieve SVR
EVREarly viral responseAn undetectable viral load or a 99 percent reduction in viral load by week 12Failure to achieve EVR correlates to less than a 4 percent chance of achieving SVR
ETREnd of treatment responseAn undetectable viral load achieved by the end of week 12Not helpful in predicting treatment outcomes
Partial responder Able to achieve EVR but unable to sustain an undetectable viral load 24 weeks after therapy completionConsidered treatment failure
Null responder Unable to achieve EVR by week 12Treatment is typically terminated if EVR is not achieved by week 12
SVRSustained viral responseAble to sustain an undetectable viral load for 12 weeks (SVR-12) and 24 weeks (SVR-24) following completion of therapySVR-24 is considered a “cure,” and patients with SVR-12 are usually able to achieve SVR-24

Increasing Your Chances of Achieving SVR

One of the main determinants of SVR success is timing, with earlier therapy benefiting patients more than delayed therapy. By treating your infection before there is marked liver damage (or, ideally, any damage), you generally have a better chance of achieving a clinical cure for HCV.

Additionally, newer-class direct-acting antivirals (DAAs) have had a profound effect on cure rates in people with chronic HCV infection. Even in people with compensated cirrhosis, who had previously had a 50/50 chance of treatment success, SVR rates have gradually climbed to 95 percent and above in many of these cases.

Phase III human trials have estimated the following cure rates for newly treated (naïve) and previously treated (experienced) patients with HCV:

What Failing to Achieve SVR Means

While the goal of HCV therapy is to effectively eradicate the virus and to allow a person to live a healthy, hepatitis-free life, a patient shouldn't despair if he or she is unable to achieve these goals.

Even if you have only a partial response, studies have shown that the benefits to the liver can be profound—not only slowing the course of the disease but in some cases reversing fibrosis, even in those with marked liver damage.

If you fail your first- or second-line of therapy, take time to monitor your blood results with your doctor. If you feel that you are ready to try again, your doctor can perform a number of tests to determine which drugs may provide you with the best chance of achieving SVR success.

Coping with Hepatitis C

Don't let a hepatitis C infection make you feel isolated. There is help available.

Beyond asking your friends and family members to help you during your journey, you may find comfort joining the active hepatitis C community online or a chronic hepatitis support group. Also, learning more about chronic hepatitis nutrition can both make you feel better and potentially improve your treatment response. 

Sources:

Chopra, S., and D. Muir. Treatment Regimens for Chronic Hepatitis C Virus Genotype 1. UpToDate. Updated 09/14/16.

Kattakuzhy, S., Wilson, E., Sidharthan, S. et al. Moderate Sustained Virologic Response Rates With 6-Week Combination Directly Acting Anti-Hepatitis C Virus Therapy in Patients With Advanced Liver Disease. Clinical Infectious Disease. 2016. 62(4):440-7.

Kattakuzhy, S., Wilson, E., Sidarthan, S. et al. Evolution of Resistance Associated Variants During Initial Treatment, Viral Failure, and Re-Treatment with Directly Acting Antiviral Therapy (NIH SYNERGY Trial). AASLD Liver Meeting; 2015; abstract 220.

Smith-Palmer, J., Cerri, K., and W. Valentine. Achieving Sustained Virologic Response in Hepatitis C: A Systematic Review of the Clinical, Economic and Quality of Life Benefits. BMC Infectious Disease. 2015. 15:19.

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