New research from the University of California, San Francisco (ICSF) found that in head-to-head trials of two drugs, if the published results favoured the test drug, the trial was 20 times more likely to be sponsored by the maker of the test drug rather than the maker of the comparative drug. The UCSF research team analysed 192 post-marketing trials (Phase IV) conducted between 1999 and 2005, which compared one cholesterol-lowering statin drug to another, or to a non-stating drug, and about half of the trials were funded by industry. The study was published in the peer-reviewed Public Library of Science Medicine online journal today. What is more, the researchers found that if the conclusions or interpretation of the clinical trial - which reflect the impressions of the trial investigators - favoured the test product, the study was 35 times more likely to be funded by the manufacturer of that drug. "Many people are concerned about the growing proportion of drug trials funded by the drugs' manufacturers," said Lisa Bero, UCSF professor of clinical pharmacy and health policy studies. "Results of drug trials affect what drugs are covered by medical plans, and so what drugs physicians will prescribe. If drug trial outcomes are largely determined by who pays for the trial, we don't really know what the best drug is." The researchers also said that the most important weakness found in most of the trials was a lack of clinical measures of outcome, such as heart attacks or mortality - considered better indicators in trial design than less direct measures such as lipid levels. "The lack of true clinical outcome measures in these direct head-to-head comparisons of drugs is disappointing because the studies don't give us the best information we need to choose one statin over another," said Bero. The study pinpointed a number of factors which can explain why results favoured the sponsor's drug. It suggested drug companies may have selectively funded trials likely to produce a statistically significant result or selected lower doses for the comparison drug. In addition, they said, sponsors may have chosen not to report results that didn't favour the drugs they sell. Meanwhile, earlier this year, another study was also published suggesting that industry sponsorship has an influence on drug trial results. Researchers from the University of North Carolina and the Dana Farber Cancer Institute studied the impact of pharma industry funding on the outcome of 140 clinical trials of breast cancer treatments. They found that 84 per cent of industry-sponsored studies showed positive results, compared with 54 per cent of non-industry funded trials. However, the research was not suggesting any misbehaviour from the pharma company, and said that the pattern could just be the result of pharma firms making better or safer choices about which drugs candidates to develop. Amidst this somewhat air of mistrust, several pharmaceutical companies have at least made efforts in the past few years to try and be more transparent by making clinical trial results and in particular post-marketing studies data available on the internet. Most recently pharma giant Pfizer launched a website where information on the status of its US post-marketing (Phase IV) drug studies is accessible to the public. Pfizer is the world's biggest drug maker and its blockbuster Lipitor has the largest share on the cholesterol drug market. Statin medicines generated $35bn ((€26bn) in global sales last year, with Lipitor accounting for nearly $13bn. In addition, the American industry body PhRMA (the Pharmaceutical Research and Manufacturers of America) has created a website where clinical study results are available in a reader-friendly, standardised format.