WASHINGTON – Medical research that uses animals to test therapies for human brain disorders is often biased, claiming positive results and then failing in human trials, U.S. researchers said Tuesday.
The findings by John Ioannidis at Stanford University could help explain why many treatments that appear to work in animals do not succeed in humans. Bias also wastes money and could harm patients in clinical trials, said the study in PLoS Biology.
Researchers examined 160 previously published meta-analyses of 1,411 animal studies on potential treatments for multiple sclerosis, stroke, Parkinson’s disease, Alzheimer’s disease and spinal cord injury, all done on more than 4,000 animals.
Just eight showed evidence of strong, statistically significant associations using evidence from more than 500 animals. Only two studies seemed to lead to “convincing” data in randomized controlled trials in humans, it said.
The rest showed a range of problems, from poor study design, to small size, to an overarching tendency toward publishing only studies in which positive effects could be reported.
Statistically, just 919 of the studies could be expected to show positive results, but the meta-analysis found almost twice as many — 1,719 — that claimed to be positive.