Background: Conflict of interest (COI) is an important potential source of bias in the development of clinical practice guidelines (CPGs) and high rates of COI among guideline authors have been reported in the past. Our objective was to report current rates of disclosure and specific author COI across a broad range of CPGs and to examine whether CPG characteristics were associated with the presence of disclosures and of conflicts.
Methods and findings: We selected a random sample of 250 CPGs listed in the National Guideline Clearinghouse on November 22, 2010, representing approximately a 10% sample of guidelines listed in the NGC on that date. We abstracted information on author COI from each CPG and examined predictors of the disclosures and COI using a logistic generalized estimating equation regression model. 87% of organizations developing guidelines had a CPG-specific policy, however, 40% of CPGs did not indicate that they had collected disclosures from guideline authors. In addition, 42% of organizations that did collect author disclosures did not have those disclosures available in the public domain. Of CPGs where we had disclosures for all authors, 60% had one or more authors with a conflict. On average, 28% of the authors of CPGs with available disclosures had a COI. Guidelines that were published in journals with an impact factor greater than 5.0 were more likely to have one or more authors with a COI than guidelines not published in journals.
Conclusions: Rates of disclosure of author COI and the public availability of that information are unacceptably low, however rates of COI among guideline authors may have decreased in recent years. Continued efforts are needed to establish and enforce optimal COI policies in clinical practice guideline development in order to minimize the risk of bias associated with those conflicts.