Cost-effectiveness of thiopurine methyltransferase genotype screening in patients about to commence azathioprine therapy for treatment of inflammatory bowel disease

Aliment Pharmacol Ther. 2004 Sep 15;20(6):593-9. doi: 10.1111/j.1365-2036.2004.02124.x.


Background: Azathioprine is a useful agent in the management of inflammatory bowel disease. Its use is limited by its side-effect profile. Marrow toxicity occurs in approximately 3.2% of patients and is known to be associated with diminished thiopurine methyltransferase enzyme activity resulting from genetic polymorphisms.

Aim: To evaluate the cost-effectiveness of screening for thiopurine methyltransferase gene polymorphisms prior to initiation of azathioprine therapy.

Methods: Analysis of the literature was undertaken to calculate the expected frequency of leucopenia and its relationship with thiopurine methyltransferase polymorphisms in a model of theoretical inflammatory bowel disease patients. Decision analysis was then applied to assess the cost of a pre-treatment genotyping strategy, taking account of direct costs and cost per life-year saved.

Results: In 1000 inflammatory bowel disease patients treated with azathioprine, 32 will develop myelosuppression and one will die because of this. Of those who develop myelosuppression during azathioprine therapy, 32% are attributable to lower thiopurine methyltransferase activity. Pre-treatment genotyping costs pound 347 per life-year saved for a 30 year old and pound 817 per life-year saved for a 60 year old. This compares favourably with other health care technologies.

Conclusion: The use of pre-treatment screening for thiopurine methyltransferase polymorphisms in inflammatory bowel disease patients commencing azathioprine therapy represents good value for money.

Publication types

  • Validation Study

MeSH terms

  • Adult
  • Azathioprine / economics
  • Azathioprine / therapeutic use*
  • Cost Savings
  • Cost of Illness
  • Cost-Benefit Analysis
  • Genetic Testing / economics*
  • Genetic Testing / methods
  • Genotype
  • Heterozygote
  • Homozygote
  • Humans
  • Immunosuppressive Agents / economics
  • Immunosuppressive Agents / therapeutic use*
  • Inflammatory Bowel Diseases / drug therapy
  • Inflammatory Bowel Diseases / economics
  • Inflammatory Bowel Diseases / genetics*
  • Methyltransferases / genetics*
  • Middle Aged
  • Polymorphism, Genetic / genetics*


  • Immunosuppressive Agents
  • Methyltransferases
  • thiopurine methyltransferase
  • Azathioprine