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Identifying flares in rheumatoid arthritis: reliability and construct validation of the OMERACT RA Flare Core Domain Set
  1. Vivian P Bykerk1,2,
  2. Clifton O Bingham3,
  3. Ernest H Choy4,
  4. Daming Lin2,
  5. Rieke Alten5,
  6. Robin Christensen6,
  7. Daniel E Furst7,8,
  8. Sarah Hewlett9,
  9. Amye Leong10,
  10. Lyn March11,
  11. Thasia Woodworth12,
  12. Gilles Boire13,
  13. Boulos Haraoui14,
  14. Carol Hitchon15,
  15. Shahin Jamal16,
  16. Edward C Keystone2,
  17. Janet Pope17,
  18. Diane Tin18,
  19. J Carter Thorne18 and
  20. Susan J Bartlett3,19
  21. on behalf of the OMERACT RA Flare Group and CATCH Investigators
    1. 1Department of Rheumatology, Hospital for Special Surgery, Weill Cornell Medical College, New York, New York, USA
    2. 2Rebecca McDonald Center for Arthritis & Autoimmune Disease, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
    3. 3Division of Rheumatology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA
    4. 4Section of Rheumatology, Arthritis Research UK & Health and Care Research Wales CREATE Centre, Cardiff University, Cardiff, UK
    5. 5Schlosspark Klinik, Charité University Medicine, Berlin, Germany
    6. 6Musculoskeletal Statistics Unit, Department of Rheumatology, The Parker Institute, Copenhagen University Hospital, Bispebjerg and Frederiksberg, Denmark
    7. 7Division of Rheumatology, University of California, Los Angeles, Los Angeles, California, USA (Emeritus)
    8. 8University of Washington, Seattle Wash; University of Florence, Florence, Italy
    9. 9University of the West of England, Bristol, UK
    10. 10Bone and Joint Decade, Healthy Motivation, Santa Barbara, California, USA
    11. 11Department of Rheumatology, University of Sydney, Institute of Bone and Joint Research, Royal North Shore Hospital, St Leonards, New South Wales, Australia
    12. 12Division of Rheumatology, University of California, Los Angeles, Los Angeles, California, USA
    13. 13Division of Rheumatology, Université de Sherbrooke, Sherbrooke, Québec, Canada
    14. 14Rheumatic Disease Unit, Institut de Rheumatologie, Montreal, Québec, Canada
    15. 15Arthritis Center, University of Manitoba, Winnipeg, Manitoba, Canada
    16. 16Vancouver Coastal Health Institute, Vancouver, British Columbia, Canada
    17. 17Division of Rheumatology, St. Joseph's Health Care London, University of Western Ontario, London, Ontario, Canada
    18. 18Southlake Regional Health Centre, Newmarket, Ontario, Canada
    19. 19Divisions of Clinical Epidemiology, Rheumatology, and Respiratory Clinical Trials Unit, McGill University, Montreal, Québec, Canada
    1. Correspondence to Dr Vivian P Bykerk; bykerkv{at}


    Objective To evaluate the reliability of concurrent flare identification using 3 methods (patient, rheumatologist and Disease Activity Score (DAS)28 criteria), and construct validity of candidate items representing the Outcome Measures in Rheumatology Clinical Trials (OMERACT) RA Flare Core Domain Set.

    Methods Candidate flare questions and legacy measures were administered at consecutive visits to Canadian Early Arthritis Cohort (CATCH) patients between November 2011 and November 2014. The American College of Rheumatology (ACR) core set indicators were recorded. Concordance to identify flares was assessed using the agreement coefficient. Construct validity of flare questions was examined: convergent (Spearman's r); discriminant (mean differences between flaring/non-flaring patients); and consequential (proportions with prior treatment reductions and intended therapeutic change postflare).

    Results The 849 patients were 75% female, 81% white, 42% were in remission/low disease activity (R/LDA), and 16–32% were flaring at the second visit. Agreement of flare status was low–strong (κ's 0.17–0.88) and inversely related to RA disease activity level. Flare domains correlated highly (r's≥0.70) with each other, patient global (r's≥0.66) and corresponding measures (r's 0.49–0.92); and moderately highly with MD and patient-reported joint counts (r's 0.29–0.62). When MD/patients agreed the patient was flaring, mean flare domain between-group differences were 2.1–3.0; 36% had treatment reductions prior to flare, with escalation planned in 61%.

    Conclusions Flares are common in rheumatoid arthritis (RA) and are often preceded by treatment reductions. Patient/MD/DAS agreement of flare status is highest in patients worsening from R/LDA. OMERACT RA flare questions can discriminate between patients with/without flare and have strong evidence of construct and consequential validity. Ongoing work will identify optimal scoring and cut points to identify RA flares.

    • Rheumatoid Arthritis
    • Outcomes research
    • Disease Activity
    • Patient perspective

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