Background: Although acute and chronic microscopic inflammation has been associated with risk of relapse in patients with ulcerative colitis (UC), histological remission is still not recommended as a therapeutic endpoint. Sparse data exist about prediction of histological activity by Fecal Calprotectin (FCP). The aim of this study was explore the association of FCP with acute and chronic histological activity.
Methods: 82 patients with UC from a single tertiary IBD Centre were enrolled in this prospective observational study. Endoscopic activity was evaluated by Mayo endoscopic sub-scores. For the assessment of histological activity, Geboes score was used to evaluate active (structural changes, the presence of polymorphonuclear leucocytes with cryptitis and crypt absessus, and erosions or mucosal ulcers) and chronic inflammation. Basal plasmocytosis, as a predictor of relapse, was described as well. Buhlmann rapid test was used to determine FCP using cut off level of 100 μg/g3. Statistical analysis was carried out using SPSS 20.0 (Chicago, IL).
Results: 38% (31/82) of patients were in endoscopic remission while 33% (27/82) achieved histological remission. Strong correlation was found between level of FCP and Geboes score (p<0.001 and ρ=0.521 – Spearman correlation). Statistically significant association was observed between FCP and histological indicators of active inflammation: a. structural changes p=0.001, CI ±8.58; b. presence of the presence of polymorphonuclear leucocytes with cryptitis and crypt absessus p<0.001, CI ±10.61; c. presence of erosion and mucosal ulcers p<0.001, CI ±6.72, as well as with basal plasmocytosis (p<0.001, CI ±6.42). The relation with chronic inflammation was not observed (p=0.002, CI ±9.37)
Conclusions: Elevated value of FCP beyond 100 μg/g among patient with clinical and endoscopic remission of UC should always be carefully interpreted. It may indicate a histological activity and predict a forthcoming relapse.