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P175. Thiopurine metabolism in inflammatory bowel diseases: A worldwide survey of experts

X. Roblin1, A. Oussalah2, J. Chevaux2, M. Sparrow3, L. Peyrin-Biroulet2

1University Hospital of Saint-Etienne, Saint-Etienne, France; 2University Hospital of Nancy, Vandoeuvre-lès-Nancy, France; 3The Alfred Hospital, Melbourne, Australia

Aim: We performed a worldwide survey to evaluate the extent to which gastroenterologists who are experts in the field of inflammatory bowel diseases (IBD) are utilizing thiopurine metabolism to optimize and monitor thiopurine treatment.

Materials and Methods: This was a Web-based cross-sectional survey of IBD experts consisting of 30 multiple-choice and open-ended questions.

Results: Between December 20, 2009 and April 9, 2010, 175 questionnaires were received. The total number of IBD patients followed by all responders was 82,379. The proportion of practitioners with access and reimbursement for thiopurine S-methyltransferase (TPMT) genotype, TPMT phenotype, 6-thioguanine nucleotides (6-TGN) levels, and 6-methylmercaptopurine ribonucleotides (6-MMP) levels, was 48%, 54%, 44%, and 35%, respectively. Before AZA initiation, TPMT genotype and phenotype were performed by only 30% and 43% of responders, respectively. In patients on thiopurine therapy, 6-TGN and 6-MMP levels were determined by 54% and 44% of responders, respectively. Only 27% of physicians always wait for TMPT activity/genotype results before initiating AZA and 81% do not routinely re-check metabolite levels after dose escalation or reduction. In cases of very high or low TPMT activity, 75% and 74% of practitioners take into account TMPT activity result, respectively. If access to all AZA metabolite measurements was available and if all these tests were reimbursed by public health insurance, 47% of responders would use these tests more often in their practice. In multivariate analysis, the availability and reimbursement of TPMT status and AZA metabolites strongly influences the management of IBD patients treated with thiopurines.

Conclusion: In this worldwide survey, the proportion of practitioners who have access to thiopurine metabolism monitoring tests ranges from 35% to 54%. Less than half of physicians determine TPMT status before AZA initiation. Approximately half of practitioners check thiopurine metabolites after AZA initiation. Only one fourth of physicians wait for TPMT results before initiating AZA. Almost half of physicians optimize AZA treatment without measuring thiopurine metabolites. Three-quarters of physicians adapt thiopurine dose according to TPMT activity. Full access to and reimbursement of thiopurine metabolism monitoring tests should result in their increased use in clinical practice in the future.