Diagnostic value of faecal calprotectin in unselected outpatients referred for colonoscopy: A multicenter prospective study

Objectives: To evaluate the role of faecal calprotectin in consecutive outpatients referred for colonoscopy. Methods: Outpatients undergoing colonoscopy at five participating institutions were eligible. Demographic and clinical data were collected. Faecal samples were tested at a single laboratory by means of a commercially available kit. Results: We consecutively enrolled 870 patients. Mean levels of calprotectin were significantly higher in patients with neoplastic and inflammatory disorders when compared with subjects with a normal colonoscopy or trivial endoscopic findings. Elevated calprotectin levels (>50 mg/dl) were detected in 85% of patients with colorectal cancer, and 81% of those with inflammatory conditions but also in 37% of patients with normal or trivial endoscopic findings. In patients referred for chronic diarrhoea, sensitivity and negative predictive value were 100% in detecting either any organic colonic disease. In patients referred for symptoms of "suspected functional origin" sensitivity and negative predictive value for colorectal cancer were also 100%. Conclusions: In unselected outpatients referred for colonoscopy, a single measurement of faecal calprotectin is not sufficiently accurate to identify those with significant colorectal disease. However, a normal result can help rule out organic disease among patients with diarrhoea and those with abdominal pain and/or constipation.