How being in a clinical trial affects the outcome

Reported by Susan Aldridge, PhD, medical journalist

Those who take part in clinical trials of new treatments do no better or no worse on the whole than those who do not.
Without clinical trials, new therapies wouldn't become available to those who need them. Those who take part may do so because they wish to benefit others in the future. But what about the participants themselves?

A review of the evidence, from the Norwegian Health Services Research Centre, shows that getting a treatment within a trial gives results that are little different from getting that same treatment outside the trial. This is important because it suggests that at least patients don't put themselves at risk by being in the trial. It also suggests that treatments that have come through trials can safely be used in the rest of the population. However, there have been a few notable exceptions to this - where drugs have had to be withdrawn because of unexpected risks that only came to light when the treatment was applied to a larger general population.

Source
The Cochrane Database of Systematic Reviews 2005 Issue 1