title: Identifying flares in rheumatoid arthritis: reliability and construct validation of the OMERACT RA Flare Core Domain Set.
abstract: 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.
authors.affiliation: Department of Rheumatology, Hospital for Special Surgery, Weill Cornell Medical College, New York, New York, USA; Rebecca McDonald Center for Arthritis & Autoimmune Disease, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Vivian P
authors.initials: VP
authors.lastname: Bykerk
authors.affiliation: Division of Rheumatology , Johns Hopkins School of Medicine , Baltimore, Maryland , USA.
authors.forename: Clifton O
authors.initials: CO
authors.lastname: Bingham
authors.affiliation: Section of Rheumatology , Arthritis Research UK & Health and Care Research Wales CREATE Centre, Cardiff University , Cardiff , UK.
authors.forename: Ernest H
authors.initials: EH
authors.lastname: Choy
authors.affiliation: Rebecca McDonald Center for Arthritis & Autoimmune Disease, Mount Sinai Hospital, University of Toronto , Toronto, Ontario , Canada.
authors.forename: Daming
authors.initials: D
authors.lastname: Lin
authors.affiliation: Schlosspark Klinik, Charité University Medicine , Berlin , Germany.
authors.forename: Rieke
authors.initials: R
authors.lastname: Alten
authors.affiliation: Musculoskeletal Statistics Unit, Department of Rheumatology , The Parker Institute , Copenhagen University Hospital, Bispebjerg and Frederiksberg , Denmark.
authors.forename: Robin
authors.initials: R
authors.lastname: Christensen
authors.affiliation: Division of Rheumatology, University of California, Los Angeles, Los Angeles, California, USA (Emeritus); University of Washington, Seattle Wash; University of Florence, Florence, Italy.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Furst
authors.affiliation: University of the West of England , Bristol , UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Hewlett
authors.affiliation: Bone and Joint Decade, Healthy Motivation , Santa Barbara, California , USA.
authors.forename: Amye
authors.initials: A
authors.lastname: Leong
authors.affiliation: Department of Rheumatology , University of Sydney, Institute of Bone and Joint Research, Royal North Shore Hospital , St Leonards, New South Wales , Australia.
authors.forename: Lyn
authors.initials: L
authors.lastname: March
authors.affiliation: Division of Rheumatology , University of California, Los Angeles , Los Angeles, California , USA.
authors.forename: Thasia
authors.initials: T
authors.lastname: Woodworth
authors.affiliation: Division of Rheumatology , Université de Sherbrooke , Sherbrooke, Québec , Canada.
authors.forename: Gilles
authors.initials: G
authors.lastname: Boire
authors.affiliation: Rheumatic Disease Unit , Institut de Rheumatologie , Montreal, Québec , Canada.
authors.forename: Boulos
authors.initials: B
authors.lastname: Haraoui
authors.affiliation: Arthritis Center, University of Manitoba , Winnipeg, Manitoba , Canada.
authors.forename: Carol
authors.initials: C
authors.lastname: Hitchon
authors.affiliation: Vancouver Coastal Health Institute , Vancouver, British Columbia , Canada.
authors.forename: Shahin
authors.initials: S
authors.lastname: Jamal
authors.affiliation: Rebecca McDonald Center for Arthritis & Autoimmune Disease, Mount Sinai Hospital, University of Toronto , Toronto, Ontario , Canada.
authors.forename: Edward C
authors.initials: EC
authors.lastname: Keystone
authors.affiliation: Division of Rheumatology , St. Joseph's Health Care London, University of Western Ontario , London, Ontario , Canada.
authors.forename: Janet
authors.initials: J
authors.lastname: Pope
authors.affiliation: Southlake Regional Health Centre , Newmarket, Ontario , Canada.
authors.forename: Diane
authors.initials: D
authors.lastname: Tin
authors.affiliation: Southlake Regional Health Centre , Newmarket, Ontario , Canada.
authors.forename: J Carter
authors.initials: JC
authors.lastname: Thorne
authors.affiliation: Division of Rheumatology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA; Divisions of Clinical Epidemiology, Rheumatology, and Respiratory Clinical Trials Unit, McGill University, Montreal, Québec, Canada.
authors.forename: Susan J
authors.identifier: 0000-0001-9755-2490
authors.initials: SJ
authors.lastname: Bartlett
keywords: Disease Activity; Outcomes research; Patient perspective; Rheumatoid Arthritis