Andreas Lundh , postdoc 1 , Lisa Bero , professor 2 1Center for Evidence-based Medicine, Odense University Hospital and University of Southern Denmark, 5000 Odense C, Denmark 2Charles Perkins Centre and Faculty of Pharmacy, University of Sydney, Sydney, Australia Correspondence to: A Lundh andreas.hover.lundh{at}rsyd.dk

Authors’ financial ties may be a source of bias in trials and must be disclosed in full

Substantial evidence shows that sponsorship or funding of trials of drugs and devices by companies producing the drug or device results in publications that tend to favour the sponsor’s product.1 Personal financial ties—including travel expenses, honorariums, payment for advisory work, or stock ownership—between commercial companies and authors of reviews, meta-analyses, editorials, and letters are also associated with conclusions favourable to the sponsor.23

However, studies of the relation between trial authors’ financial ties and trial results have been conflicting.4 One reason for the inconsistent results is that trials by authors with financial ties are also often funded by industry, which may confound the association of financial ties with favourable outcomes.

Ahn and colleagues (doi:10.1136/bmj.i6770) investigated the association between financial ties of principal investigators and outcomes in a random sample of 195 drug trials published in 2013.4 They found that trials authored by principal investigators with financial ties to drug manufacturers were more likely than other trials to …