Results of drugs tests that are sponsored by the industry portray a tendency to publish favourable results, a study has revealed.
When published results are systematically tracked for drug trials registered with ClinicalTrials.gov, those from industry-funded trials are the likeliest to be favourable to the drug in question, according to researchers at Children's Hospital Boston.
The researchers said there should be more public disclosure about clinical drug trials at their outset to reduce the possibility of bias in the findings.
The research team, led by Florence Bourgeois, of Children's Division of Emergency Medicine, and Kenneth Mandl, Laboratory Director in the Children's Hospital Informatics Program, reviewed 546 drug trials conducted between 2000 and 2006 and listed with ClinicalTrials.gov, a comprehensive, web-based federal registry of clinical trials.
The analysis focused on five classes of drugs: cholesterol-lowering drugs, antidepressants, antipsychotics, proton-pump inhibitors and vasodilators. The researchers scanned the medical literature for publications associated with each trial, checking four separate databases and contacting trial investigators directly if necessary.
Overall, allowing for a three-year lag time from the completion of the trial, two-thirds of the trials had published results.
The industry-funded trials reported positive outcomes 85 percent of the time, as compared with 50 percent for government-funded trials and 72 percent for trials funded by nonprofits or non-federal organizations.
In addition, among the nonprofit/nonfederal trials, those that had industry contributions (nearly half) were more likely than those without to report positive outcomes (85 vs. 61 percent).
These differences were all statistically significant.
The researchers acknowledge that the pharmaceutical industry was probably more selective in which trials it funded, helping to account for their greater proportion of favorable outcomes.
"Industry is very good at knowing what they want to study, and industry-sponsored studies are more efficient and well funded. But despite these potential biases, this is a stunning result," said Bourgeois, the study's first author.
The study was published in the Annals of Internal Medicine.