title: The comparative effectiveness of biologics among older adults and disabled rheumatoid arthritis patients in the Medicare population.
abstract: OBJECTIVE
  Older and disabled rheumatoid arthritis (RA) patients are often not present in large numbers in clinical trials or registries. A novel, claims-based clinical effectiveness algorithm provides the potential to compare the effectiveness of different biologics among this population using large administrative databases.
  
  
  METHODS
  Using Medicare 2006-2010 data for 100% of patients with RA, we identified biologic naïve users of abatacept, adalimumab, etanercept and infliximab, defined as no biologic use during the 12 months before the biologic initiation. The effectiveness was evaluated at 365 days after biologic initiation, determined using a validated claims-based algorithm. We compared the proportion meeting effectiveness criteria for each biologic using robust Poisson regression to compute risk ratios (RRs) adjusted for potential confounders. One year cost per effectively treated patient was calculated by different biologics.
  
  
  RESULTS
  The study included biologic naïve users of abatacept (n = 2129), adalimumab (n = 2944), etanercept (n = 3517) and infliximab (n = 5654). The algorithm classified the medications as 26% effective for abatacept, 24% for adalimumab, 28% for etanercept and 23% for infliximab, indicating comparable effectiveness. However, after adjustment and compared with infliximab, the RRs for effectiveness were 1.17 (95% CI 1.06, 1.30) for abatacept, 1.11 (95% CI 1.02, 1.23) for adalimumab and 1.27 (95% CI 1.17, 1.39) for etanercept. Older patients had a higher effectiveness than patients who were disabled (RR = 1.18, 95% CI 1.08, 1.28). Infliximab had highest cost per effectively treated patient.
  
  
  CONCLUSIONS
  Abatacept, adalimumab and etanercept are more effective than infliximab among RA patients initiating biologics. Effectiveness was significantly higher among older patients compared with disabled RA Medicare patients.
authors.affiliation: Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, AL.|Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Huifeng
authors.initials: H
authors.lastname: Yun
authors.affiliation: Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Fenglong
authors.initials: F
authors.lastname: Xie
authors.affiliation: Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Delzell
authors.affiliation: Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Lang
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Shuo
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, AL.|Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: Saag
authors.affiliation: AMGEN Inc., One thousand Oaks, CA, USA.
authors.forename: George
authors.initials: G
authors.lastname: Joseph
authors.affiliation: AMGEN Inc., One thousand Oaks, CA, USA.
authors.forename: David
authors.initials: D
authors.lastname: Harrison
authors.affiliation: Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, AL.|Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Curtis
mesh_terms: D000368:Aged; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy*; D001688:Biological Products / Q000627:therapeutic use*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D006278:Medicare; D008875:Middle Aged; D012189:Retrospective Studies; D014481:United States
chemical_list: D018501:Antirheumatic Agents; D001688:Biological Products
keywords: biologics; claims-based algorithm; comparative effectiveness; medicare; rheumatoid arthritis