How to improve clinical trials

Subscribe to enjoy similar stories. Last year Roche, a Swiss pharmaceutical firm, published a review of the clinical trials on neurological drugs it had held between 2016 and 2021. It found that black people were under-represented in all but one.

Surprisingly, that news represents progress, because it shows that trial organisers are becoming more aware of a dangerous bias that sets back the safety and efficacy of medical treatments. Many trials exclude certain groups, and do so deliberately—children, for example, or people with physical or learning disabilities, pregnant women and the elderly. For such groups, participation has stalled or even reversed.

There are good explanations for the exclusion, such as the difficulty of getting informed consent or the potential harm to unborn children. Yet the consequences can be absurd. A recent review found that half of trials around the world testing hip-fracture interventions excluded people who lived in nursing homes, were old or had some level of cognitive impairment.

Though these groups make up almost a third of all patients suffering hip fractures, it is unclear if the interventions will work as safely or as effectively on them. Their doctors face an invidious choice: prescribe anyway, with uncertain results; or deny their patients new treatments. A shocking example of such exclusion is of people with Down’s syndrome.

They have long been left out of clinical trials, including recent trials of lecanemab and donanemab, the first drugs against Alzheimer’s that seem to slow the progress of the disease. This is despite the fact that those with Down’s are highly likely to develop it. Yet without data from trials, doctors will not prescribe them the drugs, for fear of unknown