Researchers ignore 'inconvenient' drug trial results

The research, which assessed the published results of more than 100 scientific trials, also found that inconvenient findings were often not disclosed to the public. In several cases, the stated purpose of the trial was altered as it progressed so that acceptable findings, rather than inconvenient results, could be published. The manipulation, which contravenes official guidelines on reporting medical research, was uncovered by academics at Oxford University, led by Dr An-Wen Chan, a researcher on clinical medicine. Dr Chan warned that the findings called into question the National Health Service's evidence-based approach to developing medicine, in which clinical trials are used to determine whether to introduce new treatments.

"The reporting of trial outcomes is not only frequently incomplete but also biased and inconsistent with protocols," said the team. "Published articles, as well as reviews that incorporate them, may therefore be unreliable and overestimate the benefits of an intervention." Suspicion about the reliability of published medical research, which has been increasing for some time, has been prompted by concern over the influence of drugs-company funding.

A recent study at the Yale School of Medicine showed that 80 per cent of clinical trials backed by drug manufacturers reported positive findings - compared to 50 per cent of those carried out by independent academics. Other studies have shown evidence of a bias against unclear trial results being published in academic journals, and of positive results being repeatedly published - giving the impression that a drug is far more effective than it really is.

The Oxford team's findings, which are published in the latest edition of the Journal of the American Medical Association, are based on an assessment of the original paperwork from more than 100 trials of medical techniques ranging from drug to surgical methods. It compared the supposed aims of the trials with what was finally published and found that in half of the studies, results that would have given a more accurate picture of the effectiveness of the treatment being studied were not fully reported.

In almost two-thirds of these cases, the results omitted concerns over potential harmful effects. Independent researchers were just as prone to bias as those funded by industry. Crucial information, from the intensity of pain to survival rates, was either downgraded in importance or omitted from the published report.

In more than half of the trials examined, discrepancies were found between the original aims of the study and those finally reported. Such changes are in direct contravention of official guidelines on trials. Despite this, not one trial report made clear that the original aims of the research had been altered. When contacted by the Oxford team, almost 90 per cent of the research teams denied that they had failed to report everything, despite evidence to the contrary. Dr Doug Altman, a professor of statistics in medicine at the Institute of Health Sciences, Oxford, and a member of the research team, said: "All trials should be published honestly and transparently, and this study shows neither is happening.

The most worrying aspect is that over 50 per cent of the outcomes found by the trials weren't reported - and so can't be included in the reviews used to assess different treatments. This has serious implications for the reliability of the recommendations made to the National Health Service." Dr Altman said that there was no evidence that the cherry-picking of results was because of fraudulent intent, and claimed instead that it was because of pressure from journals to present findings on medical advances.

"There is a lot of pressure from medical journals to publish positive findings and to keep the length of papers down, which can lead to negative results being omitted," he said. Dr Altman added, however, that this did not explain why the original design aims of trials were altered so often. He called for the original design aims and findings of all clinical trials to be made publicly available, to prevent changes going undetected. Other leading authorities on medical research expressed dismay at the findings of the study. Sir Iain Chalmers, the founder of the Cochrane Collaboration, which publishes reviews of clinical evidence for doctors worldwide said: "In the days when no one paid any attention to scientific evidence, this would not have been a worry, but now people are investing huge amounts in research, these skeletons are coming out of the cupboard."

The Association of the British Pharmaceutical Industry said that it agreed that researchers had a duty to reveal any changes made to the original trial design, and supported full disclosure - but only when the trials had been completed.

Richard Ley, a spokesman for the association, said: "There can be commercially confidential information in trial protocols, and with a new drug costing £500 million and 10 years to produce, that is an important issue." A spokesman for the National Institute for Clinical Excellence, which provides the NHS with recommendations on best practice, said that it was already taking steps to avoid the problems of biased reporting of results. "Our appraisal committee considers all of the evidence - including an independent systematic review of the manufacturer's submission - and other literature, which is designed to take into account possible bias in the reporting of trial outcomes."