Context: To date, research regarding the influence of conflicts of interest on the presentation of findings by researchers has been limited.
Objective: To evaluate the sources of funding for published manuscripts, and association between reported findings and conflicts of interest.
Methods: Data from both print and electronic issues of The New England Journal of Medicine (NEJM) and The Journal of the American Medical Association (JAMA) were analyzed for sources of funding, areas of investigation, conflict of interest (COI), and presentation of results. We reviewed all original manuscripts published during the year 2001 within NEJM (N = 193) and JAMA (N = 205). We use 3 definitions for COI in this paper: a broadly defined criterion, the criterion used by The International Council of Medical Journal Editors (ICMJE), and a criterion defined by the authors.
Results: Depending on the COI criteria used, 16.6% to 32.6% of manuscripts had 1 or more author with COI. Based on ICMJE criterion, 38.7% of studies investigating drug treatments had authors with COI. We observed a strong association between those studies whose authors had COI and reported positive findings (P <.001). When controlling for sample size, study design, and country of primary authors, we observed a strong association between positive results and COI (ICMJE definition) among all treatment studies (adjusted odds ratio [OR], 2.35; 95% confidence interval [CI], 1.08 to 5.09) and drug studies alone (OR, 2.64; 95% CI, 1.09 to 6.39).
Conclusion: COI is widespread among the authors of published manuscripts and these authors are more likely to present positive findings.