Background: This study examined whether fecal calprotectin can be used in daily practice as a marker to monitor patients with ulcerative colitis (UC) receiving infliximab maintenance therapy.
Methods: This prospective multicenter study enrolled adult patients with UC in clinical remission under infliximab maintenance therapy. Fecal calprotectin levels were measured every 4 weeks. Sigmoidoscopies were performed at inclusion and at study end. Relapse was defined as a clinical need for change in treatment or an endoscopic Mayo subscore of ≥2 at week 52. Sustained deep remission was defined as a partial Mayo score <3 at all points and an endoscopic Mayo score 0 at week 52.
Results: Full analysis was possible for 87 of 113 included patients with UC (77%). Of these patients, 30 (34.4%) were considered to be in sustained deep remission and 13 (14.9%) to have relapsed. Calprotectin levels in patients with sustained deep remission remained very low (median < 40 mg/kg at all time points). Patients who flared had significantly higher calprotectin levels (median > 300 mg/kg) already 3 months before the flare. Further receiver operator curve analysis suggested that a calprotectin level >300 mg/kg had a reasonable sensitivity (58.3%) and specificity (93.3%) to model flare. Two consecutive calprotectin measurements of >300 mg/kg with 1-month interval were identified as the best predictor of flare (61.5% sensitivity and 100% specificity).
Conclusions: Fecal calprotectin can be used in daily practice to monitor patients with UC receiving infliximab maintenance therapy. Two consecutive measurements >300 mg/kg is more specific than a single measurement for predicting relapse.