Development and validation of the Flare-OA questionnaire for measuring flare in knee and hip osteoarthritis

Objective: Ability to assess flares in osteoarthritis (OA) of the knee and hip (KHOA) is important in clinical care and research. Using mixed methods, we developed a self-reported instrument measuring flare and assessed its psychometric properties. Methods: We constructed questionnaire items from semi-structured interviews and a focus group (patients, clinicians) by using a dual-language (English-French) approach. A Delphi consensus method was used to select the most relevant items. Patients with OA from Australia, France and the United States completed the preliminary Flare-OA, HOOS, KOOS and Mini-OAKHQOL questionnaires online. We used a factor analysis and content approach to reduce items and determine structural validity. We tested the resulting questionnaire (score 0-100) for internal consistency, convergent and known-groups validity. Results: Initially, 180 statements were generated and reduced to 33 items in five domains (response 0 = not at all, to 10 = absolutely) by Delphi consensus (50 patients, 116 professionals) and an expert meeting. After 398 patients (mean [SD] age 64 [8.5] years, 70.4% female, 86.7% knee OA) completed the questionnaire, it was reduced to 19 items by factor analysis and a content approach (RMSEA = 0.06; CFI = 0.96; TLI = 0.94). The Cronbach's alpha was >0.9 for the five domains and the whole questionnaire. Correlation coefficients between Flare-OA and other instrument scores were as predicted, supporting construct validity. The difference in Flare-OA score between patients with and without flare (31.8) largely exceeded 2 SEM (10.2). Conclusion: Flare-OA is a valid and reliable patient-reported instrument for assessing the occurrence and severity of flare in patients with KHOA in clinical research. Crown Copyright (C) 2022 Published by Elsevier Ltd on behalf of Osteoarthritis Research Society International. All rights reserved.

Automated summary

This study developed a self-reported instrument to assess flares in osteoarthritis (OA) of the knee and hip, and evaluated its psychometric properties. Through a dual-language approach, questionnaire items were generated from interviews and a focus group, and relevant items were selected using a consensus method. The resulting questionnaire showed good validity and reliability, and can be used to assess the occurrence and severity of flares in patients with knee and hip OA.