(continued)

Industry sponsored studies were less likely to be published than research funded by other sources. However, drug company backed studies were four times more likely to show favourable results than studies funded by other sponsors.

But of the 13 studies that looked at the scientific methods used, none reported that the industry-backed trials were of lower quality. Lexchin says this is because standard scales used to examine scientific quality do not cover all issues, such as what drug was used in a trial as a comparison.

Industry-backed studies often compare a new drug to placebo or a second line agent, he says, which makes it easier to get a positive result for a new drug. "My preference would be to compare with what's recommended as the current best therapy," he says.

Lexchin notes that in Canada and the US, the pharmaceutical industry is the largest funder of medical research. "It does have implications in terms of whether or not we can believe the results of research they are funding" he says. "I certainly hope we can, but our study raises questions."