Red Cell Distribution Width Can Differentiate Inflammatory Bowel Disease Sub-Types: 705

Introduction: Anemia is common in patients with Inflammatory Bowel Disease (IBD) which includes Crohn's disease (CD) and Ulcerative Colitis (UC).Anemia may result from malabsorption, chronic blood loss or from treatment. Red Cell Distribution Width (RDW) is a simple and inexpensive test which is widely available. It is also a reliable index of anisocytosis. We postulate RDW could be used as an additional inexpensive marker in differentiating patients with IBD. Methods: A retrospective analysis using an IBD natural history registry from a single tertiary care referral center. The database consists of various demographic variables, nutritional and inflammatory markers, medication use, anatomic demarcation and endoscopic disease severity information. High (abnormal) RDW was defined as any value >14.2. Categorical variables were compared using chi-square test and continuous variables using t-test. Univariate logistic regression analysis was used to evaluate the potential relationship(s) of high RDW, IBD subtype, disease location and disease severity. All statistical analyses were performed using SAS University edition v9.4. Results: Three hundred twenty-five IBD patients (105 UC, 209 CD, and 11 indeterminate colitis) were included in this study. 170 (52.3%) were female.There were no significant differences in mean RDW based on gender or race.Patients with CD on average had higher RDW compared to UC patients; {100 (48%) vs 35 (35%), P=0.008}. No significant differences were noted in RDW for endoscopic severity or disease location for either CD or UC. Using univariate regression analysis, CD patients were more likely to have an abnormally elevated RDW (1.8: 1.1-2.9, P ≤ 0.05). IBD patients on biologic treatment were more likely to exhibit an abnormal RDW [76 (56%) vs 80 (44%), P ≤ 0.05]. There were no differences in RDW based on ethnicity, mesalamine, immunomodulator or steroid use. Conclusion: Patients with CD have higher odds of having abnormal RDW compared to UC patients. With implementation of a more rigorous study design and analysis of further data, RDW may prove to be an additional simple and inexpensive marker in differentiating aspects of CD from UC. It may be a useful tool for general physicians to further characterize IBD patients in their care.705_A Figure 1. Patients' Characterization Based on RDW Value.705_B Figure 2. Odds of abnormal RDW based on endoscopic disease severity in CD and UC patients when compared to CD and UC patients with normal endoscopic findings.705_C Figure 3. Odd of abnormal RDW based on anatomic involvement of CD and UC.