Clinical trials research happens in many places. This includes hospitals, medical institutes, universities, and research centres. They may be funded by private organisations, universities, government agencies or pharmaceutical companies.
Clinical trials start after a treatment has promising findings in the ‘preclinical’ research phase. Preclinical research usually involves laboratory (in vitro) or animal (in vivo) experiments. These show if the new treatment might be safe and effective. Usually, the new treatment is tested in a lab first, before it is tested in animals.
The results from preclinical studies should show whether the treatment is likely to be safe for testing in humans. While these findings are helpful, they are not a substitute for testing in the human body.
Clinical trials measure how a treatment will work by testing it on a large number of people. This is to make sure that any effects observed are actually related to the treatment and occur for many people, rather than just random effects in one person.
In most (but not all) clinical trials, the new treatment is compared to something else, called a ‘control’. The people in the control group might be given a placebo (a substance, test or procedure that looks the same as the new treatment but has no effect), or a treatment that is already being used for the same condition.
The aim of a clinical trial is to compare what happens to all the people in the different trial groups. The results need to be different enough between the groups to prove that the difference didn’t happen by chance.
The most reliable way to show any differences is to include similar types of people in each clinical trial group. For example, if people in one group start the trial already much sicker than those in another, the effect of the new medicine may seem better or worse than it really is.
The best way to make all the trial groups similar is to randomly put people into the groups. Studies set up in this way are called randomised clinical trials. They are generally considered to produce stronger evidence than non-randomised trials.