Natural history of azathioprine-associated lymphopenia in inflammatory bowel disease patients: a prospective observational study.

Introduction: Azathioprine (AZA) is commonly used in inflammatory bowel disease (IBD) patients. Lymphopenia is a recognized effect of this treatment, but lymphopenia-related complications in IBD patients have not been widely reported. The incidence and progression of AZA-induced lymphopenia in IBD patients is not well described. There is no consensus on its optimal management in this group.

Aims And Methods: We assessed the incidence and progression of lymphopenia and its related complications in a cohort of IBD patients over a 14-month period in two large tertiary gastroenterology units. Analysis of prospectively collected data was performed.

Results: Fifty-two patients were studied prospectively with a median age of 34 years. Eighteen patients (34.6%) developed lymphopenia (<1.0×10(9)/l) during the course of treatment and 10 of them had severe lymphopenia (<0.6×10(9)/l). Lymphopenia lasted on average 85.4 days and spontaneously resolved in 13 patients. No lymphopenia related-complications were documented. Patients treated with steroids had a significantly higher rate of lymphopenia (83.3 vs. 44.1%, P=0.0083).

Conclusion: Lymphopenia is common among IBD patients treated with AZA. However, it did not seem to be associated with a higher risk of opportunistic infections and spontaneously resolved in the majority of cases.