The true picture has emerged only since regulations that control clinical medical trials have been tightened up in the US. Before the stricter rules were introduced in 2000, 57 per cent of large-budget clinical trials for the prevention or treatment of heart disease were returning positive results; since then, just 8 per cent of trials have been positive.
Researchers from Oregon State University explored large trials that were funded by the National Heart, Lung and Blood Institute. In all, of the 55 studies reviewed, 30 were published before the regulations were tightened, and 25 published since. Of the 25 published more recently, just two had positive outcomes, compared with 17 of the 30 studies published under more lax reporting requirements.
Under the tougher rules, all clinical trials involving people must be posted with the clinicaltrials.gov database beforehand. This prevents poor results being forgotten, or massaging the data to achieve a better outcome.
Although their analysis covered drugs and treatments only for heart disease, the researchers are confident they would see a similar picture emerge for treatments for diabetes, cancer and any other disease.
(Source: PLOS ONE, August 2015; doi: 10.1371/journal.pone.0132382)