title: Serum IgA rheumatoid factor and pyridinoline in very early arthritis as predictors of erosion(s) at two years: a simple model of prediction from a conservatively treated community-based inception cohort.
abstract: OBJECTIVE
  To identify, in conservatively treated, very early arthritis patients, predictors of ≥1 erosion(s) at 2 years, and to construct a prediction model.
  
  
  METHODS
  Community-based adults (n=310) who had never taken disease-modifying antirheumatic drugs (DMARDs) or steroids with swelling of ≥2 joints persisting for >4 weeks and lasting <6 months were recruited. Erosion status was assessed at 0, 6, 12, and 24 months; evaluations were comprised of clinical criteria (Disease Activity Score, Health Assessment Questionnaire), C-reactive protein level, erythrocyte sedimentation rate, autoantibodies, bone and cartilage markers, hand densitometry, and HLA class II shared epitopes. Patients meeting American College of Rheumatology rheumatoid arthritis (RA) criteria or with undifferentiated arthritis (UA) were followed and treated conservatively: one-third of RA patients and three-fourths of UA patients received no DMARDs during 2 years; a biologic agent was given to 1.8% of the patients during the first year. The main judgment criterion was ≥1 erosion(s) at 2 years.
  
  
  RESULTS
  At 2 years, 219 patients were assessed; 31.3% with RA and 10.6% with UA had ≥1 erosion(s). Logistic regression analysis at that time showed erosion(s) strongly associated with serum IgA rheumatoid factor (IgA-RF) and pyridinoline levels for the 190 patients with no baseline erosions, with the corresponding receiver operating characteristic curve having an area under the curve of 0.77 (95% confidence interval 0.64-0.86). A prediction model was constructed with IgA-RF thresholds of 5 and 25 IU/ml and a pyridinoline threshold of 10 nM/liter; odds ratios ranged from 1 for IgA-RF<5 IU/ml and pyridinoline <10 nM/liter to 50.75 for the association of IgA-RF≥5 IU/ml and pyridinoline≥10 nM/liter.
  
  
  CONCLUSIONS
  This model, using serum IgA-RF and pyridinoline concentrations, was able to predict≥1 erosion(s) at 2 years in very early arthritis patients.
authors.affiliation: INSERM Unit 905 and Rouen University Hospital, Rouen, France. xavier.le-loet@chu-rouen.fr
authors.forename: Xavier
authors.initials: X
authors.lastname: Le Loët
authors.forename: Michel
authors.initials: M
authors.lastname: Brazier
authors.forename: Othmane
authors.initials: O
authors.lastname: Mejjad
authors.forename: Patrick
authors.initials: P
authors.lastname: Boumier
authors.forename: Alain
authors.initials: A
authors.lastname: Daragon
authors.forename: Alain
authors.initials: A
authors.lastname: Gayet
authors.forename: Sophie
authors.initials: S
authors.lastname: Pouplin
authors.forename: François
authors.initials: F
authors.lastname: Tron
authors.forename: Charles
authors.initials: C
authors.lastname: Zarnitsky
authors.forename: Olivier
authors.initials: O
authors.lastname: Vittecoq
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Menard
authors.forename: Patrice
authors.initials: P
authors.lastname: Fardellone
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000097:blood*; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000188:drug therapy / Q000453:epidemiology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012217:Rheumatoid Factor / Q000097:blood*; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D013997:Time Factors; D055815:Young Adult
chemical_list: D000596:Amino Acids; D018501:Antirheumatic Agents; D007070:Immunoglobulin A; C015484:pyridinoline; D012217:Rheumatoid Factor