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The results of medical trials are used to judge the effectiveness of conventional treatment. The most reliable type of trial for hepatitis C treatment is a randomised controlled trial (or RCT). In these, volunteers are randomly split into two or more groups. Each group has roughly the same number of people with roughly similar key characteristics (in hepatitis C trials this might be age, viral load, etc. see below).

One of these groups is the control group against which the other groups are measured. Sometimes the control group is given a placebo, which is a substance that appears to be the medicine on trial but actually has no active ingredients. The best trials are those that are double-blind. This means that neither the doctors nor the patients know who is taking what. This cancels out any psychological effect. In hepatitis C trials, this is often impractical because of obvious differences in the medicine.

For example, alpha interferon is taken three times a week, whereas pegylated interferon is taken only once a week.

In relation to hepatitis C treatment the measure of effectiveness is gauged by how many people achieve a sustained virological response (or SVR). This is when the hepatitis C virus remains undetectable in the blood 6 months after finishing the treatment. .

Figures like these can never be more than a guide because trials are made up of volunteers each with their own individual characteristics. Some of these characteristics may have a very significant bearing on whether treatment worked for them. Trials also often use slightly different dosages and, on top of that, there is always a margin of error of a few percentage points. So the best that figures can do is to give you a rough idea.

There is one factor that makes a major difference to the outcome of treatment. That is genotype. So, although overall effectiveness figures are given, in hepatitis C trials they are also split into genotype.

Aside from genotype, some other factors appear to influence outcome. If you are thinking about treatment for yourself and trying to assess how the percentages apply to you, it is worth knowing that the following points may have some impact on outcome, either positively or negatively. Some of them you can do nothing about but some are in your control.

Factors outside your control

Positive impact

Negative impact



Under 40 years old

Over 40 years old

Acute infection
Low viral load
(less than 2 million copies per mil)

High viral load

HIV co-infection

Factors within your control

Positive impact

Adherence to treatment, meaning taking every dose and completing the course

Being prepared mentally, physically and practically

Managing treatment successfully, including minimising the impact of side effects

Being the right weight for your height

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