SVR is short for Sustained Virological Response. The reason it gets used is as follows:
- Over 99% of patients who treat with the new Direct Acting Antivirals (DAAs) will become undetected for Hepatitis C viral RNA, however when we stop the medication, the virus will grow back in about 5% of patients.
- The term SVR is used only after a patient has stopped taking medication.
- SVR4 means that the patient stopped taking the medication 4 weeks ago and viral RNA can not be detected. It represents a 95% chance of permanent cure.
- SVR12 means that the patient stopped taking the medication 12 weeks ago and viral RNA can not be detected. It represents a 99.5% chance of permanent cure.
- SVR24 means that the patient stopped taking the medication 24 weeks ago and viral RNA can not be detected. It represents a 99.9% chance of permanent cure.
If you have finished taking medication, and the virus can not be detected, there are only 2 possibilities. Either the virus is gone, and it is never coming back, or there has simply not been enough time for enough virus to grow back for us to detect it.
Back in the bad old Interferon/Ribavirin days, SVR24 was used as the definition of cure, and this has proven to be the case with over 20 years of follow-up. In patients who remain undetected 24 weeks after treatment finishes (SVR24) the hepatitis C virus is never coming back.
For all intents and purposes, SVR12 represents a permanent and durable cure, and this is the point we normally use to declare "You are cured".
Glossary of Hepatitis C Language
Doctors are prone to use a lot of jargon when talking to patients. Sorry about that, it's a quick way of communicating to other doctors and sometimes we don't realise we are talking in code.
You will find all the common terms used when talking about Hepatitis C Glossary (Dictionary).