We propose an operational definition of conflicts of interest (COI), a framework for categorizing interests, and an approach to assessing whether an interest qualifies as a COI.

We reviewed the literature and conducted methodological studies to inform the development of a draft framework for classifying interests.

We developed the following operational definition: “a conflict of interest exists when a past, current, or expected interest creates a significant risk of inappropriately influencing an individual's judgment, decision, or action when carrying out a specific duty”. Interest refers to a benefit (e.g., money received from industry) or to an attribute of the individual (e.g., having specific religious beliefs). The proposed framework includes seven types of interests relating to individuals (direct financial benefit, benefit through professional status, intellectual, and personal) or their institution (direct financial benefit to the institution, benefit through increasing services provided by the institution, and nonfinancial). When assessing whether an interest qualifies as a COI, one could consider its relevance, nature (e.g., cash vs. educational support), magnitude, and recency.

The proposed operational definition and categorization framework may help journals, guideline organizations, professional societies, and healthcare institutions enhance transparency in health research.