Factors Associated With Use of Azathioprine in Patients With Ulcerative Colitis

Abstract

Background: Ulcerative colitis (UC) is a chronic inflammatory bowel disease of unknown etiology characterized by diffuse mucosal inflammation limited to the colon. Azathioprine (AZA) is widely used to treat corticosteroid-dependent IBD patients but there are few studies that examine factors that could predict its use in UC patients. The aim was to investigate factors associated with azathioprine use in Mexican patients with UC. Methods: Retrospective case control study that included 180 patients with UC diagnosed between 1998 and 2008 and currently managed in the inflammatory bowel disease clinic. Patients were divided in two groups: (1) UC patients who currently or previously received AZA (N = 90) and (2) UC patients receiving 5-Aminosalicylic acid (5-ASA) alone (N = 90). Medical records were reviewed and clinical, biochemical and demographic data were assessed such as age at diagnosis, tobacco use, gender, UC extent, steroid use, clinical behavior, blood count, antinuclear antibodies (ANA) and anti-neutrophil cytoplasmic antibodies (ANCA). All variables were analyzed using parametric statistics. Odds ratio (OR) and 95% confidence intervals (CI) assessing the risk of AZA use were estimated by univariate and logistic analyses. A P-value d0.05 was considered statistically significant. Results: A total of 180 UC patients were studied, 85 female and 95 male, with a mean age at diagnosis of 34.57±12.2 years. In univariate analyses eight factors correlated with AZA use: previous tobacco use (p < 0.006 OR = 2.55 95% CI 1.33 4.89); requirement of hospitalization at diagnosis (p < 0.008 OR = 2.53 95% CI 1.29 4.96); use of systemic steroids within the first 6 months of diagnosis (p < 0.001, OR = 8.93 95% CI 3.28 24.3); distal/extensive colitis (p < 0.007 OR = 4.63 95% CI 1.26 14.57); positive ANA (p < 0.03 OR = 5.86 95% CI 1.15 19.8); positive ANCA (p < 0.003 OR = 2.66 95% CI 1.42 4.99); anemia (p < 0.014 OR = 2.37 95% CI 1.22 4.60) and thrombocytosis at diagnosis (p < 0.004 OR = 3.09 95% CI 1.45 6.55). Logistic analyses showed that previous tobacco use (p < 0.002 OR = 3.84 95% CI 1.63 9.01); hospitalization on diagnosis (p < 0.030 OR = 2.44 95% CI 1.09 5.46); use of steroids within 6 months of diagnosis (p < 0.001 OR = 13.52 95% CI 3.95 46.2) and positive ANCA (p < 0.001 OR = 4.67 95% CI 1.93 11.28) were the most significant. Conclusions: Previous tobacco use, requirement of hospitalization at diagnosis of UC, use of steroids within the first 6 months of diagnosis and positive ANCA were associated with azathioprine use in UC patients.