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* = Presenting author

P385 Azathioprine and 6-Mercaptopurine use in the Swiss IBD cohort: adverse effects, causes of discontinuation and risk of "flares" according to 6-TG levels

D. Lavrek*1, N. Fournier1, V. Pittet1, D. Müller2, C. Mottet1, 3, 4

1Lausanne University Hospital, Institute of Social & Preventive Medicine (IUMSP), Lausanne, Switzerland, 2Zürich University Hospital, Institute of Clinical Chemistry, Zürich, Switzerland, 3Lausanne University Hospital, Division of Gastroenterology & Hepatology, Lausanne, Switzerland, 4Hôpital Neuchâtelois, Division of Gastroenterology, Neuchâtel, Switzerland

Background

To characterize and analyze in the Swiss IBD Cohort : a) reported Azathioprine (AZA) and 6-Mercaptopurine (6-MP) adverse effects (AE), b) causes of discontinuation and c) response to therapy according to gastroenterologists' clinical judgment, d) whether level of 6-TGN < 235pmol/8 x108 red blood cells (RBC) is associated with a higher risk of "flare" occurrence.

Methods

Retrospective statistical description, Cox model and Kaplan-Meier survival estimation.

Results

1499 patients with Crohn's Disease (CD) and 1066 with Ulcerative colitis (UC).

a) Of 1670 patients ever treated with AZA/6-MP, there were 611 reported AE: 149 intolerances are observed (24.4%), 81 pancreatitis (13.2%), 61 hepatitis (10.0%), 33 hematologic side effects (5.4%), 20 hypersensitivities (3.2%), 17 infections (2.8%), 13 cases of fatigue (2.1%), 7 malignancies (1.2%) and 207 not further specified AE (33.9%).

b) Of 566 reported causes of discontinuation according to gastroenterologists' clinical judgment, 209 "treatment no long needed" (36.9%), 196 "breakthrough/loss of response (34.6%), 92 "patient wish" (16.3%), 45 "primary non-response" (7.9%) and 21 "Conception/Pregnancy or wish of it" (3.7%) were described.

c) Of 1187 gastroenterologists' clinical judgment of AZA/6-MP responses, 417 (35%) were judged as "successful", 639 (54%) as "failure", 131 (11%) "unknown".

d) Of 364 CD patients under AZA/6-MP, 199 (54.7%) developed a "flare" during the observation period (median 13.3 mo, IQR 11.9-23.4, range 5.8-59.0). Of 204 patients with UC under AZA/6-MP, 106 (52.0%) developed a "flare" during the observation period (median 14.0 mo, IQR 12.2-24.9, range 7.3-48.2). 6-TGN levels ≥ 235 pmol/8 x 108 RBC showed a not statistically significant tendency to improve "flare"-free survival time in CD and UC (HR=1.157, 95CI: 0.680-1.971, p=0.590).

Conclusion

In the SIBDC, AZA/6-MP are frequently used, AE and failure are frequently reported, 6-TGN levels ≥ 235 showed a tendency to improve "flare"-free survival.