title: Economic impact of combination therapy with infliximab plus azathioprine for drug-refractory Crohn's disease: a cost-effectiveness analysis.
abstract: BACKGROUND
  Combination therapy with infliximab (IFX) and azathioprine (AZA) is significantly more effective for treatment of active Crohn's disease (CD) than IFX monotherapy. However, AZA is associated with an increased risk of lymphoma in patients with inflammatory bowel disease.
  
  
  OBJECTIVE
  To evaluate the cost-effectiveness of combination therapy with IFX plus AZA for drug-refractory CD.
  
  
  METHODS
  A decision analysis model is constructed to compare, over a time horizon of 1year, the cost-effectiveness of combination therapy with IFX plus AZA and that of IFX monotherapy for CD patients refractory to conventional non-anti-TNF-α therapy. The treatment efficacy, adverse effects, quality-of-life scores, and treatment costs are derived from published data. One-way and probabilistic sensitivity analyses are performed to estimate the uncertainty in the results.
  
  
  RESULTS
  The incremental cost-effectiveness ratio (ICER) of combination therapy with IFX plus AZA is 24,917 GBP/QALY when compared with IFX monotherapy. The sensitivity analyses reveal that the utility score of nonresponding active disease has the strongest influence on the cost-effectiveness, with ICERs ranging from 17,147 to 45,564 GBP/QALY. Assuming that policy makers are willing to pay 30,000 GBP/QALY, the probability that combination therapy with IFX plus AZA is cost-effective is 0.750.
  
  
  CONCLUSIONS
  Combination therapy with IFX plus AZA appears to be a cost-effective treatment for drug-refractory CD when compared with IFX monotherapy. Furthermore, the additional lymphoma risk of combination therapy has little significance on its cost-effectiveness.
authors.affiliation: Department of Medical Informatics and Statistics, Niigata University Graduate School of Medicine, Japan. s-saito13@med.niigata-u.ac.jp
authors.forename: Shota
authors.initials: S
authors.lastname: Saito
authors.forename: Utako
authors.initials: U
authors.lastname: Shimizu
authors.forename: Zhang
authors.initials: Z
authors.lastname: Nan
authors.forename: Nozomu
authors.initials: N
authors.lastname: Mandai
authors.forename: Junji
authors.initials: J
authors.lastname: Yokoyama
authors.forename: Kenshi
authors.initials: K
authors.lastname: Terajima
authors.forename: Kouhei
authors.initials: K
authors.lastname: Akazawa
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000191:economics* / Q000627:therapeutic use; D000911:Antibodies, Monoclonal / Q000191:economics* / Q000627:therapeutic use; D001379:Azathioprine / Q000191:economics* / Q000627:therapeutic use; D003362:Cost-Benefit Analysis; D003424:Crohn Disease / Q000188:drug therapy* / Q000191:economics*; D003663:Decision Trees; D004359:Drug Therapy, Combination / Q000191:economics; D006801:Humans; D007166:Immunosuppressive Agents / Q000191:economics* / Q000627:therapeutic use; D000069285:Infliximab; D018803:Models, Economic; D019057:Quality-Adjusted Life Years
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D000911:Antibodies, Monoclonal; D007166:Immunosuppressive Agents; D000069285:Infliximab; D001379:Azathioprine