Development of a core domain set for ankle osteoarthritis: An international consensus study of patients and health professionals.

Objectives: To develop an internationally agreed-upon core domain set for ankle osteoarthritis (OA).

Methods: In a three-part Delphi process, a group of multidisciplinary health professionals with expertise in ankle OA and people with ankle OA responded to online questionnaires. The questionnaires proposed a list of 29 candidate domains derived from a systematic review of ankle OA research, and interviews with people with ankle OA and health professionals. Consensus was defined a priori as ≥70% agreement in people with ankle OA and health professionals whether a domain should or should not be included in a core domain set. An online consensus meeting was held to discuss and resolve undecided candidate domains.

Results: A total of 100 people (75 health professionals and 25 people with ankle OA) from 18 countries (4 continents) participated in this study. Five domains reached consensus for inclusion in a core domain set for ankle OA - pain severity, health-related quality of life, function, disability and ankle range of motion. Twenty-one candidate domains reached agreement not to be included in the core domain set, and three domains remained undecided (ankle instability, physical capacity, and mental health).

Conclusion: This international consensus study, which included people with ankle OA and health professionals, has established a core domain set for ankle OA with five domains that should be measured and reported in all ankle OA trials - pain severity, health-related quality of life, function, disability and ankle range of motion. This core domain set will guide the reporting of outcomes in clinical trials on ankle OA. Future research should determine which outcome measurement instruments should be used to measure each of the core domains.