title: Comparative persistence of the TNF antagonists in rheumatoid arthritis--a population-based cohort study.
abstract: OBJECTIVE
  To compare persistence with tumor necrosis factor alpha (TNF) antagonists among rheumatoid arthritis patients in British Columbia. Treatment persistence has been suggested as a proxy for real-world therapeutic benefit and harm of treatments for chronic non-curable diseases, including rheumatoid arthritis. We hypothesized that the different pharmacological characteristics of infliximab, adalimumab and etanercept cause statistically and clinically significant differences in persistence.
  
  
  METHODS
  We conducted a population-based cohort study using administrative health data from the Canadian province of British Columbia. The study cohort included rheumatoid arthritis patients who initiated the first course of a TNF antagonist between 2001 and 2008. Persistence was measured as the time between first dispensing to discontinuation. Drug discontinuation was defined as a drug-free interval of 180 days or switching to another TNF antagonist, anakinra, rituximab or abatacept. Persistence was estimated and compared using survival analysis.
  
  
  RESULTS
  The study cohort included 2,923 patients, 63% treated with etanercept. Median persistence in years (95% confidence interval) with infliximab was 3.7 (2.9-4.9), with adalimumab 3.3 (2.6-4.1) and with etanercept 3.8 (3.3-4.3). Similar risk of discontinuation was observed for the three drugs: the hazard ratio (95% confidence interval) was 0.98 (0.85-1.13) comparing infliximab with etanercept, 0.95 (0.78-1.15) comparing infliximab with adalimumab and 1.04 (0.88-1.22) comparing adalimumab with etanercept.
  
  
  CONCLUSIONS
  Similar persistence was observed with infliximab, adalimumab and etanercept in rheumatoid arthritis patients during the first 9 years of use. If treatment persistence is a good proxy for the therapeutic benefit and harm of these drugs, then this finding suggests that the three drugs share an overall similar benefit-harm profile in rheumatoid arthritis patients.
authors.affiliation: Therapeutics Initiative, University of British Columbia, Vancouver, Canada; Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, Canada.
authors.forename: Anat
authors.initials: A
authors.lastname: Fisher
authors.affiliation: Therapeutics Initiative, University of British Columbia, Vancouver, Canada; Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, Canada; Department of Family Practice, University of British Columbia, Vancouver, Canada.
authors.forename: Ken
authors.initials: K
authors.lastname: Bassett
authors.affiliation: Therapeutics Initiative, University of British Columbia, Vancouver, Canada; Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, Canada; Department of Medicine, University of British Columbia, Vancouver, Canada.
authors.forename: James M
authors.initials: JM
authors.lastname: Wright
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America.
authors.forename: M Alan
authors.initials: MA
authors.lastname: Brookhart
authors.affiliation: Department of Medicine, University of British Columbia, Vancouver, Canada.
authors.forename: Hugh
authors.initials: H
authors.lastname: Freeman
authors.affiliation: Therapeutics Initiative, University of British Columbia, Vancouver, Canada; Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, Canada.
authors.forename: Colin R
authors.initials: CR
authors.lastname: Dormuth
mesh_terms: D000068879:Adalimumab / Q000627:therapeutic use; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018501:Antirheumatic Agents / Q000627:therapeutic use*; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000378:metabolism; D001955:British Columbia; D015331:Cohort Studies; D000068800:Etanercept / Q000627:therapeutic use; D005260:Female; D006801:Humans; D000069285:Infliximab / Q000627:therapeutic use; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D000079424:Tumor Necrosis Factor Inhibitors; D055815:Young Adult
chemical_list: D018501:Antirheumatic Agents; D000079424:Tumor Necrosis Factor Inhibitors; D000069285:Infliximab; D000068879:Adalimumab; D000068800:Etanercept