When researchers receive money from pharmaceutical companies, their trials are more likely to produce favorable results, a review of almost 200 published studies has found. Although the influence of money on trials has long been suspected, quantitative evidence has been scarce. The review also has a lesson for cynics who think corporate involvement means all drug trials are suspect, as many studies were also apparently conducted without bias.
To see how much difference funding makes, Oregon Health and Science University student Rosa Ahn picked a random sample of 195 drug trials whose results were published in 2013, and investigated the independence of the researchers involved. Attempts to examine industry influence have been done before, but most have not differentiated between direct funding for a study and other financial connections to researchers. Ahn looked at each independently.
Two-thirds of trials had one or more principal investigators who had received money from the pharmaceutical industry, although this could be as small as getting travel expenses paid or as large as owning stock in the company whose drug was being tested. Five percent held a patent over the drug they were investigating.
More than three-quarters of trials with positive results had a principal investigator with financial connections to the industry, while just 49 percent of those that produced negative results had such conflicts of interest.
Ahn's findings have been published in the British Medical Journal. The paper notes that there are other possible explanations for the raw data besides researcher bias. For example, it's possible that financial connections are more common at a particular study phase, which might in turn be one where positive outcomes are more common.