title: Thresholds in disease activity for switching biologics in rheumatoid arthritis patients: experience from a large U.S. cohort.
abstract: OBJECTIVE
  To examine the threshold in disease activity associated with switching biologic treatment regimens in rheumatoid arthritis (RA) patients in real-world clinical practice.
  
  
  METHODS
  Using data from a prospective observational North American cohort of RA patients through December 30, 2009, patients who initiated a new anti-tumor necrosis factor α (anti-TNFα) agent with ≥6 months of followup were identified. Patients were classified as switchers or maintainers depending on whether they continued their anti-TNF treatment or switched (including discontinuation) within 12 months. Level of disease activity measured by the Clinical Disease Activity Index (CDAI) and Disease Activity Score in 28 joints (DAS28) at the time of the switch (corresponding followup visit for maintainers) was examined and random-effect multivariable logistic regression was used to adjust for covariates.
  
  
  RESULTS
  Mean age and RA duration among 1,549 eligible patients were 56.1 and 9.6 years, respectively, 80% were women, 62% were initiating their first biologic, and 30% were initiating their second biologic. At the time of the switch, the median DAS28 and CDAI score were 3.1 and 8.4 among maintainers and 4.0 and 15.2 among switchers, respectively. Maintainers also experienced a greater amount of reduction in disease activity compared with switchers (CDAI: -7.7 versus -2.3, DAS28: -1.1 versus -0.3). The threshold to switch decreased over calendar time, with the greatest amount of reduction observed among patients with moderate disease activity.
  
  
  CONCLUSIONS
  On average, physicians and patients were willing to continue biologic treatment for patients who were at or near low disease activity. The threshold to switch decreased over time, especially among partial responders.
authors.affiliation: University of Alabama at Birmingham, 35294, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Shan
authors.forename: George
authors.initials: G
authors.lastname: Reed
authors.forename: Joel
authors.initials: J
authors.lastname: Kremer
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Greenberg
authors.forename: Scott
authors.initials: S
authors.lastname: Baumgartner
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Curtis
mesh_terms: D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000188:drug therapy* / Q000276:immunology; D001688:Biological Products / Q000627:therapeutic use*; D057915:Drug Substitution; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012042:Registries; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D013997:Time Factors; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*; D014481:United States
chemical_list: D018501:Antirheumatic Agents; D001688:Biological Products; D014409:Tumor Necrosis Factor-alpha