title: The risk and nature of flares in juvenile idiopathic arthritis: results from the ReACCh-Out cohort.
abstract: To describe probabilities and characteristics of disease flares in children with juvenile idiopathic arthritis (JIA) and to identify clinical features associated with an increased risk of flare.
  
  
  
  We studied children in the Research in Arthritis in Canadian Children emphasizing Outcomes (ReACCh-Out) prospective inception cohort. A flare was defined as a recurrence of disease manifestations after attaining inactive disease and was called significant if it required intensification of treatment. Probability of first flare was calculated with Kaplan-Meier methods, and associated features were identified using Cox regression.
  
  
  
  1146 children were followed up a median of 24 months after attaining inactive disease. We observed 627 first flares (54.7% of patients) with median active joint count of 1, physician global assessment (PGA) of 12 mm and duration of 27 weeks. Within a year after attaining inactive disease, the probability of flare was 42.5% (95% CI 39% to 46%) for any flare and 26.6% (24% to 30%) for a significant flare. Within a year after stopping treatment, it was 31.7% (28% to 36%) and 25.0% (21% to 29%), respectively. A maximum PGA >30 mm, maximum active joint count >4, rheumatoid factor (RF)-positive polyarthritis, antinuclear antibodies (ANA) and receiving disease-modifying antirheumatic drugs (DMARDs) or biological agents before attaining inactive disease were associated with increased risk of flare. Systemic JIA was associated with the lowest risk of flare.
  
  
  
  In this real-practice JIA cohort, flares were frequent, usually involved a few swollen joints for an average of 6 months and 60% led to treatment intensification. Children with a severe disease course had an increased risk of flare.
authors.affiliation: British Columbia Children's Hospital and University of British Columbia, Vancouver, British Columbia, Canada.
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authors.lastname: Guzman
authors.affiliation: Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, Manitoba, Canada.
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authors.affiliation: IWK Health Centre and Dalhousie University, Halifax, Nova Scotia, Canada.
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authors.affiliation: IWK Health Centre and Dalhousie University, Halifax, Nova Scotia, Canada.
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authors.affiliation: McGill University Health Centre and McGill University, Montréal, Québec, Canada.
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authors.affiliation: British Columbia Children's Hospital and University of British Columbia, Vancouver, British Columbia, Canada.
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authors.affiliation: Alberta Children's Hospital and University of Calgary, Calgary, Alberta, Canada.
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authors.lastname: Johnson
authors.affiliation: British Columbia Children's Hospital and University of British Columbia, Vancouver, British Columbia, Canada.
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authors.lastname: Cabral
authors.affiliation: Royal University Hospital and University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
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authors.affiliation: Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
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authors.affiliation: Janeway Children's Health and Rehabilitation Centre and Memorial University, Saint John's, Newfoundland, Canada.
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authors.affiliation: British Columbia Children's Hospital and University of British Columbia, Vancouver, British Columbia, Canada.
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authors.affiliation: Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada.
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authors.affiliation: Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada.
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authors.affiliation: Alberta Children's Hospital and University of Calgary, Calgary, Alberta, Canada.
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authors.affiliation: Centre Hospitalier Universitaire de Laval and Université Laval, Quebec, Québec, Canada.
authors.forename: Anne-Laure
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authors.affiliation: Centre Hospitalier Universitaire Ste. Justine and Université de Montréal, Montréal, Québec, Canada.
authors.forename: Elie
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authors.lastname: Haddad
authors.affiliation: British Columbia Children's Hospital and University of British Columbia, Vancouver, British Columbia, Canada.
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authors.lastname: Houghton
authors.affiliation: Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada.
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authors.lastname: Spiegel
authors.affiliation: British Columbia Children's Hospital and University of British Columbia, Vancouver, British Columbia, Canada.
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authors.lastname: Turvey
authors.affiliation: Alberta Children's Hospital and University of Calgary, Calgary, Alberta, Canada.
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authors.lastname: Schmeling
authors.affiliation: IWK Health Centre and Dalhousie University, Halifax, Nova Scotia, Canada.
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authors.lastname: Lang
authors.affiliation: Stollery Children's Hospital and University of Alberta, Edmonton, Alberta, Canada.
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authors.initials: SE
authors.lastname: Ramsey
authors.affiliation: Centre Hospitalier Universitaire de Sherbrooke and Departments of Medicine and Pediatrics, Université de Sherbrooke, Sherbrooke, Québec, Canada.
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authors.lastname: Bruns
authors.affiliation: Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, Ontario, Canada.
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authors.lastname: Campillo
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authors.lastname: Benseler
authors.affiliation: McGill University Health Centre and McGill University, Montréal, Québec, Canada.
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authors.affiliation: Department of Pediatrics University of British Columbia, Vancouver, British Columbia, Canada.
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authors.affiliation: Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada.
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authors.affiliation: Université de Montréal, Montréal, Québec, Canada.
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authors.lastname: Feldman
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authors.affiliation: Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, Ontario, Canada.
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authors.affiliation: Centre Hospitalier Universitaire de Laval and Université Laval, Quebec, Québec, Canada.
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authors.affiliation: McGill University Health Centre and McGill University, Montréal, Québec, Canada.
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authors.affiliation: Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, Ontario, Canada.
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authors.lastname: Gibbon
authors.affiliation: Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada.
authors.forename: Rae S M
authors.initials: RS
authors.lastname: Yeung
authors.affiliation: Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, Ontario, Canada.
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authors.initials: CM
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authors.affiliation: British Columbia Children's Hospital and University of British Columbia, Vancouver, British Columbia, Canada.
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mesh_terms: D000974:Antibodies, Antinuclear / Q000097:blood; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001171:Arthritis, Juvenile / Q000097:blood / Q000188:drug therapy / Q000473:pathology*; D001685:Biological Factors / Q000627:therapeutic use; D002170:Canada; D002648:Child; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D017063:Outcome Assessment, Health Care; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012008:Recurrence; D012217:Rheumatoid Factor / Q000097:blood; D012307:Risk Factors; D012720:Severity of Illness Index; D013997:Time Factors
chemical_list: D000974:Antibodies, Antinuclear; D018501:Antirheumatic Agents; D001685:Biological Factors; D012217:Rheumatoid Factor
keywords: Disease Activity; Epidemiology; Juvenile Idiopathic Arthritis