Are clinical trials good for your health?

Q: Do people who volunteer for clinical trials have better outcomes than people who do not enrol?

A: There are risks for patients who participate in clinical trials, but they may get access to the latest treatments.

The Cochrane Collaboration has therefore carried out a systematic review to see if the benefit of being in a trial outweighs the harm.

This review included studies in which patients had the same interventions within or outside of a clinical trial. It included five randomised controlled trials and 80 non-randomised cohort studies.

Most of the randomised trials only studied small numbers of people. Participating in a trial did not significantly affect the outcome for patients.

In the non-randomised studies, there were 86,362 people who were treated within a trial and 57,071 who were treated outside a trial.

These studies contained 98 comparisons, but there was no significant difference in 85.

Among the 13 comparisons which showed a significant difference, five found that patients had a better outcome if they were not enrolled in a trial.

Some of these differences were due to greater patient satisfaction.

There were 37 comparisons which included mortality as an outcome. Only three showed that patients in trials had a statistically lower risk of dying.

Although the review found little evidence that patients in trials have different outcomes, the finding is not conclusive, because of significant heterogeneity in the studies.

Other reviews have also been unable to tell whether or not volunteering for a trial is beneficial or harmful.