Accurate disclosure of financial conflicts of interest (COI) among clinical practice guideline (CPG) developers is critical to ensure the quality of CPGs. However, there is limited evidence on the impact of underreporting COIs on the quality of CPGs. This study aimed to examine the proportion of underreported COI disclosures in the development of Japanese CPGs and to estimate the association between underreported COIs and CPG quality using the Appraisal of Guidelines for Research & Evaluation (AGREE) II. Twenty-three Japanese CPGs published in 2019 and their 1114 developers were included in the study. The results show that underreporting of COIs occurred in 52% of the included CPGs and 8% of all CPG developers. Underreporting COI disclosures was negatively associated with low-quality CPG (Odds ratio [OR], 0.57; 95% confidence interval [CI]: 0.11, 3.04). On the other hand, CPGs that had more than 13% of CPG developers with voting rights on recommendation decisions and underreporting of COI disclosures were positively associated with low quality (OR, 1.78; 95% CI: 0.25, 12.45). For individual CPG developers with voting rights for recommendation decisions, the presence of a COI was positively associated with low quality (OR, 1.11; 95% CI: 0.71, 1.75). This study demonstrates that the involvement and underreporting of COIs did not seriously distort the CPG development process. However, the COI-related factors of CPG developers with voting rights for recommendation decisions may be associated with low CPG quality.
Keywords: AGREE II; Japan; clinical guidelines; conflicts of interest; funding; guideline committee; guideline development process.