title: A Real-World Study of Switching From Allopurinol to Febuxostat in a Health Plan Database.
abstract: OBJECTIVE
  The objective of this study was to assess the real-world comparative effectiveness of continuing on allopurinol versus switching to febuxostat.
  
  
  METHODS
  In a retrospective claims data study of enrollees in health plans affiliated with Optum, we evaluated patients from February 1, 2009, to May 31, 2012, with a gout diagnosis, a pharmacy claim for allopurinol or febuxostat, and at least 1 serum uric acid (SUA) result available during the follow-up period. Univariate and multivariable-adjusted analyses (controlling for patient demographics and clinical factors) assessed the likelihood of SUA lowering and achievement of target SUA of less than 6.0 mg/dL or less than 5.0 mg/dL in allopurinol continuers versus febuxostat switchers.
  
  
  RESULTS
  The final study population included 748 subjects who switched to febuxostat from allopurinol and 4795 continuing users of allopurinol. The most common doses of allopurinol were 300 mg/d or less in 95% of allopurinol continuers and 93% of febuxostat switchers (prior to switching); the most common dose of febuxostat was 40 mg/d, in 77% of febuxostat switchers (after switching). Compared with allopurinol continuers, febuxostat switchers had greater (1) mean preindex SUA, 8.0 mg/dL versus 6.6 mg/dL (P < 0.001); (2) likelihood of postindex SUA of less than 6.0 mg/dL, 62.2% versus 58.7% (P = 0.072); (3) likelihood of postindex SUA of less than 5.0 mg/dL, 38.9% versus 29.6% (P < 0.001); and (4) decrease in SUA, 1.8 (SD, 2.2) mg/dL versus 0.4 (SD, 1.7) mg/dL (P < 0.001). In multivariable-adjusted analyses, compared with allopurinol continuers, febuxostat switchers had significantly higher likelihood of achieving SUA of less than 6.0 mg/dL (40% higher) and SUA of less than 5.0 mg/dL (83% higher).
  
  
  CONCLUSIONS
  In this "real-world" setting, many patients with gout not surprisingly were not treated with maximum permitted doses of allopurinol. Patients switched to febuxostat were more likely to achieve target SUA levels than those who continued on generally stable doses of allopurinol.
authors.affiliation: From the *Optum, Eden Prairie, MN; †Takeda Pharmaceuticals International, Inc, Deerfield, IL; and ‡Birmingham VA Medical Center; and Department of Medicine, School of Medicine, and Division of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, AL; and Department of Orthopedic Surgery, Mayo Clinic College of Medicine, Rochester, MN.
authors.forename: Aylin
authors.initials: A
authors.lastname: Altan
authors.forename: Aki
authors.initials: A
authors.lastname: Shiozawa
authors.forename: Tim
authors.initials: T
authors.lastname: Bancroft
authors.forename: Jasvinder A
authors.initials: JA
authors.lastname: Singh
mesh_terms: D000328:Adult; D000368:Aged; D000493:Allopurinol / Q000008:administration & dosage*; D057186:Comparative Effectiveness Research; D016903:Drug Monitoring / Q000379:methods; D057915:Drug Substitution / Q000379:methods / Q000706:statistics & numerical data; D000069465:Febuxostat / Q000008:administration & dosage*; D005260:Female; D006073:Gout / Q000097:blood / Q000188:drug therapy; D006074:Gout Suppressants / Q000008:administration & dosage; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome; D014481:United States; D014527:Uric Acid / Q000097:blood*; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors
chemical_list: D006074:Gout Suppressants; D000069465:Febuxostat; D014527:Uric Acid; D000493:Allopurinol; D014969:Xanthine Oxidase