title: Trends in the use of biologic agents among rheumatoid arthritis patients enrolled in the US medicare program.
abstract: OBJECTIVE
  Self-injectable biologic agents have been covered by Medicare Part D since 2006. We hypothesized that this coverage benefit and related financial considerations would lead to increased use of self-injectable biologic agents overtime and would be influential in determining which rheumatoid arthritis (RA) patients received infusion versus self injected biologic agents.
  
  
  METHODS
  We used 100% of US Medicare data (2006–2009) to calculate the prevalence of use of different RA biologic agents and evaluated factors associated with receipt of infliximab versus etanercept or adalimumab among patients starting their first anti–tumor necrosis factor (anti-TNF) agent.
  
  
  RESULTS
  Through 2009, the prevalence of biologic agent use overall (~ 27%) and via infusion (16–17%) or self-injection(10–11%) remained unchanged among Medicare beneficiaries with RA. After adjusting for patient characteristics,stronger physician preference for infused biologic agents was related to physician reimbursement and associated with an increased likelihood of using infliximab as the first anti-TNF agent (odds ratio [OR] comparing the highest to lowest quartile of physician preference 7.3, 95% confidence interval [95% CI] 6.4–8.3). Lower-income patients who received state assistance for Medicare coverage had lower out-of-pocket payments for injectable biologic agents ($4.10/prescription) and were less likely to use infliximab (OR 0.41, 95% CI 0.37–0.45) compared with etanercept or adalimumab.
  
  
  CONCLUSIONS
  The prevalence of injection and infusion biologic agents in RA remained stable in the Medicare program through 2009. The choice between an intravenous infusion versus an injectable anti-TNF agent as first-line treatment appeared to be strongly influenced by financial considerations affecting both patients and physicians.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Fenglong
authors.initials: F
authors.lastname: Xie
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Delzell
authors.forename: Lang
authors.initials: L
authors.lastname: Chen
authors.forename: Meredith L
authors.initials: ML
authors.lastname: Kilgore
authors.forename: Huifeng
authors.initials: H
authors.lastname: Yun
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: Saag
authors.forename: James D
authors.initials: JD
authors.lastname: Lewis
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Curtis
mesh_terms: D000368:Aged; D018501:Antirheumatic Agents / Q000191:economics / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000191:economics; D001685:Biological Factors / Q000191:economics / Q000627:therapeutic use*; D016527:Drug Costs; D018588:Fee-for-Service Plans; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D006278:Medicare / Q000191:economics*; D008875:Middle Aged; D012189:Retrospective Studies; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors; D014481:United States
chemical_list: D018501:Antirheumatic Agents; D001685:Biological Factors; D014409:Tumor Necrosis Factor-alpha