title: Time and predictors of response to tumour necrosis factor-alpha blockers in psoriatic arthritis: an analysis of a longitudinal observational cohort.
abstract: OBJECTIVE
  To determine predictors and time to response to treatment with TNF-alpha blockers in patients with PsA in a longitudinal observational cohort.
  
  
  METHODS
  We performed a cohort analysis of patients who were followed prospectively in a large PsA clinic. Response to treatment was defined as an improvement of at least 40% in active (tender and/or swollen) and swollen joint count (SJC) and 50% improvement in the Psoriasis Area and Severity Index (PASI) score.
  
  
  RESULTS
  Ninety-five patients were included in the analysis. Of the total patients, 72.6 and 77.9% demonstrated 40% improvement in active joint counts at 3 and 12 months, respectively. Also, 80.5 and 87.4% of the patients showed 40% improvement in SJC at 3 and 12 months, respectively. A PASI50 was achieved by 54 and 60.4% after 3 and 12 months of treatment, respectively. Of 17 patients who did not achieve 40% improvement in total SJC at 3 months, 11 (64.7%) responded at 12 months. In multivariate analysis, the number of swollen joints at baseline predicted response of total active joints at 12 months [odds ratio (OR) 1.34; P = 0.02], whereas past use of TNF-alpha blocker decreased odds of response (OR 0.05; P = 0.01).
  
  
  CONCLUSIONS
  TNF-alpha blockers are effective in most PsA patients with the majority responding within 3 months of treatment. A significant proportion of the early non-responders will have a delayed response to treatment. Higher SJC at baseline and no prior use of TNF-alpha blockers predict response.
authors.affiliation: Centre for Prognosis Studies in the Rheumatic Diseases, Toronto Western Hospital, Toronto, ON, Canada.
authors.forename: Lihi
authors.initials: L
authors.lastname: Eder
authors.forename: Vinod
authors.initials: V
authors.lastname: Chandran
authors.forename: Catherine T
authors.initials: CT
authors.lastname: Schentag
authors.forename: Hua
authors.initials: H
authors.lastname: Shen
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Cook
authors.forename: Dafna D
authors.initials: DD
authors.lastname: Gladman
mesh_terms: D000328:Adult; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D015535:Arthritis, Psoriatic / Q000188:drug therapy*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
chemical_list: D018501:Antirheumatic Agents; D014409:Tumor Necrosis Factor-alpha