Azathioprine use in patients with Inflammatory Bowel Disease. Adherence to treatment and adverse events. A single center experience

Background: Azathioprine is frequently used in achieving and maintaining remission in patients with inflammatory bowel disease. Aim: We performed a prospective study on patients with inflammatory bowel disease receiving azathioprine who were followed up at our hospital, in order to record their adherence to treatment and the frequency of adverse events. Methods: Fifty seven patients (23 males, 34 females, mean age 40.3 years) were included in our analysis. Thirty patients had Crohn's disease and 27 patients were diagnosed with ulcerative colitis. All patients were followed up at our outpatient's clinic with complete blood counts, liver enzymes and pancreatic enzyme levels monitored at weeks 1, 2, 4, 8 and 12 after initiation of azathioprine administration, with subsequent testing every 12 weeks for the duration of azathioprine treatment. Meanwhile, all patients, after 1 year of azathioprine administration, fulfilled a specialized questionnaire in order to determine their adherence to treatment. Results: The most common adverse event was a rise in amylase levels occurring in 3 of our patients (5.3%). Leukopenia requiring dose reduction (leukocyte count < 3.5 x 10(9)) was seen in 2 patients (3.5%), while severe leukopenia (leukocyte count < 2.5 x 10(9)) was seen in only 1 patient (1.7%). In this patient leukocyte count returned to normal after azathioprine discontinuation. Hepatotoxicity was less common occurring in 1.7% of our study population (1 patient only). Nonadherence rate was 24.5% of the patients included. The only factor associated with a better adherence was a more complicated course of the disease(p=.02). Conclusions: Azathioprine use in patients with inflammatory bowel disease appears to be safe, with adverse events being reversible and occurring in a minority of those treated. An important proportion of patients with IBD admit to forgetting some doses of the prescribed medication in the setting of a specialized unit of a referral centre.