Data monitoring committees 

Some longer clinical trials that produce a lot of information over several years have early warning systems.

These help identify whether the benefits of a treatment or intervention are so good, or the potential risks so high, that the trial should be stopped early.

In a large trial that lasts several years, a data monitoring committee, which is independent of the running of the trial, will look at the information being produced by the trial earlier than the researchers.

The committee members look at results at fixed intervals, or when a reason for investigation emerges in between these intervals.

Trials should be stopped if it becomes obvious that one of the treatments being compared is clearly better or worse than the other.

However, if things are going as expected with no completely clear signals that one treatment is better, the committees will recommend the researchers carry on as intended.

Whether it's always a good idea to stop a clinical trial early is a controversial issue. Read more about Are drugs trials stopped too early?

Page last reviewed: 05/01/2015

Next review due: 05/01/2017