Predictive accuracy of fecal calprotectin for histologic remission in ulcerative colitis.

Background/aims: Accurate assessment of disease activity is crucial for effective management and treatment of ulcerative colitis (UC). This study evaluated the correlation between clinical, endoscopic, and histologic measures of disease activity in UC.

Methods: Clinical, biochemical, endoscopic, and histologic disease activity was studied in 347 patients with UC. Agreements among various histologic classification systems, namely the Geboes Score (GS), Continuous GS, Nancy Index (NI), and Robarts Histopathology Index (RHI), were analyzed. The predictive accuracy of fecal calprotectin (FC) for endoscopic and histologic remission was assessed.

Results: We demonstrate a fair to moderate correlation between clinical, endoscopic, and histologic measures of disease activity in UC. There was a robust concordance among GS, Continuous GS, NI, and RHI in distinguishing between patients in histologic remission or activity. The NI detected 75% of patients who met the remission criteria according to the RHI, whereas the RHI identified all patients in remission as defined by the NI. FC levels below 150 μg/g had >70% accuracy in predicting endoscopic remission. FC levels below 150 μg/g showed ≥80% accuracy, and FC levels below 100 μg/g demonstrated ≥ 85% accuracy in predicting histologic remission, regardless of the scoring index applied. Elevated FC levels were associated with both acute and chronic inflammatory infiltrates in biopsy samples.

Conclusions: FC is a reliable predictor of histologic remission, with higher accuracy at lower thresholds. The GS, Continuous GS, NI, and RHI demonstrate comparable performance. FC could help stratify patients' need for colonoscopy for the assessment of endoscopic and histologic remission.