Background: Persistent active endoscopic and histological inflammation is associated with poorer outcomes in ulcerative colitis (UC). Fecal calprotectin is a surrogate marker of endoscopic and histological remission.
Aims: To confirm the correlation between fecal calprotectin and endoscopic or histological disease activity and to define the optimal cutoff value to detect endoscopic and histological remission.
Methods: From a prospectively maintained database, we analyzed 61 UC patients who had fecal calprotectin measurement and endoscopy performed within 1 month. Endoscopic activity was graded using the Mayo endoscopic subscore (MES). Histological remission was defined as normal histology or quiescent histological activity.
Results: Eighteen patients (29.5%) and five patients (8.1%) had endoscopic remission defined as MES ≤ 1 or MES = 0, respectively. We observed a significantly lower median level of fecal calprotectin in patients with endoscopic remission than those with endoscopic activity for both definition of endoscopic remission, i.e., MES ≤ 1 (158 vs 490 µg/g, p = 0.0005) or MES = 0 (94 vs 414 µg/g, p = 0.013). Seven patients (11.5%) were in histological remission. They had a lower median level of fecal calprotectin than those with active histological inflammation (107 vs 416 µg/g, p = 0.016). Using a ROC curve, fecal calprotectin < 250 µg/g predicted endoscopic remission (MES ≤ 1) with a sensitivity of 67% and specificity of 77%, while fecal calprotectin < 200 µg/g predicted histological remission with a sensitivity of 71% and specificity of 76%.
Conclusion: Fecal calprotectin level correlated with both endoscopic activity and histological activity and is a reliable biomarker in assessing mucosal healing in UC.
Keywords: Endoscopic remission; Fecal calprotectin; Histological remission; Mucosal healing; Ulcerative colitis.