P0284Fecal Calprotectin as a Non-Invasive Biomarker of Pouch Inflammation

Abstract Background Ileal pouch–anal anastomosis is the standard restorative surgery for ulcerative colitis (UC) following total proctocolectomy. Pouchitis is its most common long-term complication, typically confirmed through pouchoscopy. Fecal calprotectin (FC) is a non-invasive biomarker of intestinal inflammation, but its diagnostic thresholds for pouch inflammation vary and are inconsistent. This study aimed to evaluate the diagnostic performance of FC across pouch phenotypes. Methods A single-center, retrospective analysis was conducted on a prospectively maintained IPAA registry at the Mount Sinai Hospital. Patients with UC who had paired FC, clinical, endoscopic, and histologic data within 90 days were included. Pouch phenotypes were classified as normal pouch (NP), acute pouchitis (AP), chronic pouchitis (CP), or Crohn’s disease–like pouch inflammation (CDLPI). Group comparisons used Kruskal–Wallis and Mann–Whitney tests; correlations were measured with Spearman’s ρ; and diagnostic accuracy was assessed using ROC analysis. Results A total of 163 patients were included: NP (n = 32), AP (n = 23), CP (n = 42), CDLPI (n = 66). Median FC levels differed significantly across phenotypes (NP 50.5 µg/g; AP 244; CP 370.5; CDLPI 231.5; p 0.001). FC correlated positively with endoscopic disease activity (ρ = 0.27, p 0.001); each one-point increase in the endoscopic Pouchitis Disease Activity Index (PDAI) was associated with a 53% increase in FC. ROC analysis demonstrated an AUC of 0.82 for distinguishing inflammatory pouch phenotypes from NP (optimal cutoff 170 µg/g; specificity 0.94) and an AUC of 0.87 for predicting endoscopic activity defined by an endoscopic PDAI 3 (optimal cutoff 373 µg/g). FC levels were significantly higher in symptomatic compared with asymptomatic patients (p 0.001). Among patients with NP, FC did not differ between those with active versus normal histology (p = 0.85). Conclusion FC is a reliable, non-invasive biomarker of pouch inflammation, with levels correlating with endoscopic activity. Thresholds near 170 µg/g and 373 µg/g effectively identify inflamed pouches and active endoscopic disease, respectively, supporting the integration of FC into routine pouch disease activity assessment and monitoring. Conflict of interest: Dr. Tubal Bronze, Sérgio Manuel: No conflict of interest Jimenez, Darwin: No conflict of interest Reyes Mercedes, Pamela: No conflict of interest Kayal, Maia: Grant: NIH, Crohn’s and Colitis Foundation, Rainin Personal Fees: Abbvie, Pfizer, BMS, Johnson&Johnson, GoodRx