Understanding effectiveness

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 known as a randomised controlled trial. In these, volunteers are randomly split up into two or more groups but in such a way that 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 this group is given a placebo, 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, meaning that neither the doctors nor the patients know who is taking what. This rules out any psychological effect. In hepatitis C trials, this is often impracticable because of obvious differences in the medicine for example, alpha interferon is taken 3 times a week, whereas pegylated interferon is taken only once a week.

The measure of effectiveness is how many people achieved a Sustained Virological Response, meaning that the hepatitis C virus remained undetectable in their blood 6 months after they finished taking the treatment. Figures are always expressed as a percentage, so the overall figure of 55% for pegylated interferon and ribavirin means that for over half the people in trials treatment was successful. It should be noted that the figures refer to people who are doing treatment for the first time, known as nave patients, and who are chronically infected.

These figures, however, can never be more than a guide because the trials are made up of volunteers each with their own individual characteristics, some of which may have a very significant bearing on whether treatment worked for them. The 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 the figures can do is to give you a rough idea.

Having said that, there is one factor that makes a major difference to the outcome of treatment. That is genotype. So, although overall effectiveness figures are given, 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 and these can make up for the negative ones you cant do anything to change.

To see the pages on adherence (click here), preparing for treatment (click here) and managing treatment (click here)