The pharmaceutical industry has become adept at manipulating results and selectively withholding unfavourable data that could expose patients to harm. Now it is accused of skewing the debate over one drug, Avandia, prescribed to millions of people around the world with Type 2 diabetes. Avandia, made by the British multinational GlaxoSmithKline (GSK), which helps diabetics control their blood sugar levels, was linked with an increased risk of heart attacks in research published in 2007.

...The latest study helps illuminate why the scientific opinions on Avandia are conflicting. Researchers from the Mayo Clinic in Minnesota - one of the few US research organisations that does not rely on commercial sponsorship - analysed more than 200 articles published in scientific journals, including original papers, editorials and letters, which commented on the heart attack risk associated with Avandia after 2007.

They found almost half (47 per cent) of the study authors had financial conflicts of interest but almost a quarter (23 per cent) did not disclose it. They were discovered by searching other publications by the same author or on the internet. Three authors declared no conflict of interest but did in fact have one.

More than nine out of 10 (94 per cent) of the authors who had positive views about Avandia had financial links with pharmaceutical companies involved in diabetes and 87 per cent had financial links with the drug's manufacturer, GSK. In contrast, less than 30 per cent of those with financial links with the industry "expressed unfavourable views" of Avandia. Those authors who were critical of Avandia safety were "largely free of identifiable conflicts of interest", the study says.