title: Healthcare costs for Crohn's disease patients treated with infliximab: a propensity weighted comparison of the effects of treatment adherence.
abstract: OBJECTIVE
  The objective for the research was to evaluate the direct healthcare costs for Crohn's disease (CD) patients categorized by adherence status.
  
  
  METHODS
  Adult patients with ≥1 claim for infliximab and ≥2 claims for CD who were continuously insured for 12 months before and after their first infliximab infusion (index date) were identified in a 2006-2009 US managed care database. Patients were excluded if they had rheumatoid arthritis claims, received infliximab billed as a pharmacy benefit, or received another biologic drug. Patients were categorized as being either adherent or intermittently adherent to infliximab using a pre-defined algorithm. Total and component direct costs, CD-related costs, rates of surgery, and days of hospitalization were estimated for the 360-day post-index period. Propensity weighted generalized linear models were used to adjust the cost estimates for potential confounding variables.
  
  
  RESULTS
  The total propensity weighted cost for infliximab adherent patients was $40,425 (95% CI = [$38,686, $42,242]), compared to $41,082 (95% CI = [$38,163, $44,223]) for the intermittently adherent (p = 0.71). However, adherent patients had lower total direct medical costs, exclusive of infliximab, that were $13,097 (95% CI = [$12,141, $14,127]) compared with $20,068 (95% CI = [$17,676, $22,784]) for intermittently adherent patients as a result of substantially lower hospital and outpatient costs (p < 0.0001).
  
  
  CONCLUSIONS
  Greater drug-related costs for infliximab adherent patients were offset by lower costs from hospitalization and outpatient visits. These findings indicate that adherent patients have improved clinical outcomes, at a similar aggregate cost, than patients who are only intermittently adherent to therapy.
authors.affiliation: Robarts Research Institute, University of Western Ontario , Canada.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Feagan
authors.forename: Chris M
authors.initials: CM
authors.lastname: Kozma
authors.forename: Terra L
authors.initials: TL
authors.lastname: Slaton
authors.forename: William H
authors.initials: WH
authors.lastname: Olson
authors.forename: George J
authors.initials: GJ
authors.lastname: Wan
mesh_terms: D000328:Adult; D000911:Antibodies, Monoclonal / Q000191:economics* / Q000627:therapeutic use; D003424:Crohn Disease / Q000188:drug therapy* / Q000191:economics; D016527:Drug Costs; D005260:Female; D005765:Gastrointestinal Agents / Q000191:economics* / Q000627:therapeutic use; D017048:Health Care Costs; D006801:Humans; D000069285:Infliximab; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D018803:Models, Economic; D057216:Propensity Score; D012189:Retrospective Studies
chemical_list: D000911:Antibodies, Monoclonal; D005765:Gastrointestinal Agents; D000069285:Infliximab
keywords: Adherence; Cost; Crohn’s disease; Inflammatory bowel disease; Infliximab