Investigating Fecal Calprotectin: Unmasking the Sneaky Subtypes of Non-IBD Colitis

Document Type

Conference Proceeding

Publication Date

10-1-2024

Publication Title

Am J Gastroenterol

Abstract

Introduction: The current gold standard for diagnosing non-inflammatory bowel disease (IBD) colitis is colonoscopy with biopsy. Imaging and stool-based tests are also often utilized during initial evaluation to screen for intestinal inflammation. Fecal calprotectin (FC) is a sensitive marker in assessing IBD disease activity, but its utility in non-IBD colitis has not been extensively evaluated. In this study, we aim to assess the utility of fecal calprotectin as a screening test for various subtypes of non-IBD colitis. Methods: This was a retrospective study of clinic patients at a tertiary care medical system who presented with subacute or chronic diarrhea between 2013-2023. Patients who had an abnormal FC during their clinic visit and underwent a colonoscopy within 3 months of this test result were included. Patients with a new or prior diagnosis of IBD or infectious colitis were excluded. Baseline patient characteristics, FC levels, histologic, and endoscopic findings on colonoscopy were collected from medical records. FC levels in patients with non-IBD colitis were compared to those without colitis. Results: 282 patients met our inclusion criteria, of which 36 had specific types of non-IBD colitis diagnosed based on histology. These clinical subtypes included microscopic colitis (66%), immune checkpoint inhibitor (ICI) colitis (14%), nonsteroidal anti-inflammatory drug induced colitis (6%), ischemic colitis (8%), radiation colitis (3%), and segmental colitis associated with diverticulosis (SCAD) (3%) (Figure 1). 233 patients had no gross or histologic features of colitis. The mean FC level of patients with a specific clinical subtype of non-IBD colitis was 246 (SD 265) compared to 90 (SD 284) in patients without colitis. Figure 1 shows the mean FC levels of patients diagnosed with each clinical sub-type of non-IBD colitis. A Mann-Whitney test was performed demonstrating a significant difference in these 2 groups (P < 0.001). Conclusion: Our study demonstrates a significant quantitative difference in FC level between patients with non-IBD colitis and those without colitis. However, this difference was primarily seen in patients with microscopic colitis and ICI colitis whereas patients with NSAID induced, ischemic, radiation colitis, and SCAD had FC levels similar to patients without colitis. These preliminary findings suggest that although FC shows promise as a screening marker for non-IBD colitis, clinicians should not rely too heavily on this test, especially when a patient has risk factors for a specific type of colitis. (Table Presented).

Volume

119

Issue

10

First Page

S178

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