title: Is swollen to tender joint count ratio a new and useful clinical marker for biologic drug response in rheumatoid arthritis? Results from a Swedish cohort.
abstract: OBJECTIVE
  To study the impact of swollen to tender joint count ratio (STR) and other baseline characteristics on treatment response to a first course of anti-tumor necrosis factor (anti-TNF) therapy in rheumatoid arthritis (RA) patients.
  
  
  METHODS
  Patients with RA initiating their first course of anti-TNF treatment were included in a structured clinical followup protocol. Based on pragmatic thresholds and plausibility, patients were categorized as having low (STR <0.5), moderate (0.5 ≤ STR ≤ 1.0), or high (STR >1.0) joint count ratios. The data were collected and followed during the period of March 1999 through December 2010.
  
  
  RESULTS
  A total of 2,507 patients were included in the study (median age 56 years, 78% women). Of these patients, 344 (14%) had a low STR, 1,180 (47%) had a moderate STR, and 983 (39%) had a high STR. According to these STR thresholds, 23% of patients (95% confidence interval [95% CI] 18-29%) with low, 39% (95% CI 35-43%) with moderate, and 40% (95% CI 36-44%) with high STR achieved the American College of Rheumatology criteria for 50% improvement (ACR50) response at 6 months after initiation. Correlation tests showed that STR was associated with ACR50 response independent of both swollen and tender joint counts. Logistic regression analysis consistently showed that moderate STR, high STR, not using prednisolone, high baseline Disease Activity Score in 28 joints, and low baseline Health Assessment Questionnaire scores were significantly associated with favorable ACR50 response with odds ratios of 1.93 (P < 0.01), 2.82 (P < 0.01), 0.65 (P < 0.01), 1.49 (P < 0.01), and 0.47 (P < 0.01), respectively.
  
  
  CONCLUSIONS
  STR is a new and feasible predictor of treatment response in RA. RA patients with a moderate to high STR have a 2- to 3-fold increased likelihood of responding according to ACR50 criteria.
authors: Lund University and Skåne University Hospital, Lund, Sweden; The Parker Institute and Copenhagen University Hospital, Frederiksberg, Denmark.
authors: Lars Erik
authors: LE
authors: Kristensen
authors: Henning
authors: H
authors: Bliddal
authors: Robin
authors: R
authors: Christensen
authors: Johan A
authors: JA
authors: Karlsson
authors: Anders
authors: A
authors: Gülfe
authors: Tore
authors: T
authors: Saxne
authors: Pierre
authors: P
authors: Geborek
mesh_terms: D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology*; D016009:Chi-Square Distribution; D004185:Disability Evaluation; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D007596:Joints / Q000187:drug effects* / Q000276:immunology / Q000473:pathology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011239:Prednisolone / Q000627:therapeutic use; D016016:Proportional Hazards Models; D012372:ROC Curve; D012042:Registries; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D013548:Sweden; D013997:Time Factors; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D018501:Antirheumatic Agents; D005938:Glucocorticoids; D014409:Tumor Necrosis Factor-alpha; D011239:Prednisolone