Defining Fecal Calprotectin Cutoffs That Predict Endoscopic and Histologic Remission in Patients With Ulcerative Colitis.

Background: Fecal calprotectin is a reliable surrogate marker for disease activity in ulcerative colitis. However, there are no consensus cutoff values for histoendoscopic remission. This study aimed to correlate fecal calprotectin with Mayo endoscopic score and histological disease activity (Geboes score) for ulcerative colitis patients in clinical remission.

Methods: Prospective study including adult ulcerative colitis patients in clinical remission or disease relapse, undergoing endoscopy for disease activity or dysplasia surveillance at an inflammatory bowel disease center between 2013 and 2020. Fecal calprotectin was collected before bowel preparation and Mayo endoscopic score was documented during colonoscopy. Biopsies were taken throughout the colon and histological activity was assessed using Geboes score by a blinded expert gastrointestinal pathologist.

Results: Two hundred fifty-three patients were included, 117 (46%) were male (mean age of 38.2 years-standard deviation ± 24.8). A fecal calprotectin ≥ 123 μg/g predicts Mayo endoscopic score > 0 (58% sensitivity and 70% specificity), also aiding to differentiate Mayo endoscopic score 0 from 1 (61% sensitivity and 70% specificity). A fecal calprotectin ≥ 80 μg/g identified histological disease activity using Geboes score > 3.1 in patients with clinical remission (64.7% sensitivity, 58.7% specificity). Using Geboes score > 2, a fecal calprotectin ≥ 50 μg/g, is the most clinically relevant to identify patients in clinical remission with active histologic inflammation (49.6% sensitivity, 41.6% specificity).

Conclusions: Fecal calprotectin correlates with endoscopic and histologic disease activity and can be used as a surrogate marker for disease activity. Our study prospectively demonstrated optimal cutoff values to discriminate histoendoscopic remission.