Endorsement of the domains of knee and hip osteoarthritis (OA) flare: A report from the OMERACT 2020 inaugural virtual consensus vote from the flares in OA working group

Objective: Towards developing an instrument to measure knee and hip osteoarthritis (KHOA) flare, the Outcome Measures in Rheumatology (OMERACT) Flares in OA Working Group first sought to identify and define relevant domains of flare in KHOA. Methods: Guided by OMERACT Filter 2.1, candidate domains were identified from data generated in interviews, in English or French, with persons with KHOA and health professionals (HPs) who treat OA. The first and second rounds of an online Delphi process with patients and HPs, including researchers, selected relevant domains. The third round provided agreement on the selected domains and their definitions. At the virtual OMERACT 2020 workshop, the proposed domains and their definitions were discussed in facilitated breakout groups with patients and HPs. Participants then voted, with consensus set at ≥70%. Results: Qualitative interviews characterizing OA flare were completed with 29 persons with KHOA and 16 HPs. Content was analyzed and grouped into nine clusters. These candidate domains were included in two Delphi rounds, completed by 91 patients and 165 HPs then 50 patients and 116 HPs, per round, respectively. This resulted in selecting five relevant domains. A final Delphi round, completed by 38 patients and 89 HPs, provided agreement on these domains and their definitions. The OMERACT virtual vote included 27 patients and 106 HPs. The domains and their definitions were endorsed with ≥98% agreement. Domains include: Pain, Swelling, Stiffness, Psychological aspects, and Impact of symptoms, all defined “during flare”. Conclusion: Using OMERACT methodology, we have developed five domains of KHOA flare that were highly endorsed by patients and HPs.