Crohn's disease activity assessed by fecal calprotectin and lactoferrin: Correlation with Crohn's disease activity index and endoscopic findings

Background: Correlation of endoscopic Crohn's disease activity with fecal calprotectin and lactoferrin is insufficiently studied. We evaluated the clinical significance of these neutrofil-derived proteins in assessment of Crohn's disease activity by comparing them with endoscopic disease activity and with Crohn's disease activity index (CDAI) and serum CRP. Methods: A total of 77 CD patients underwent one or more ileocolonoscopies (n = 106) with scoring of Crohn's disease index of severity (CDEIS). Patients provided stool samples for calprotectin and lactoferrin measurements and blood samples for CRP. Clinical activity was based on the CDAI. Results: Both fecal calprotectin and lactoferrin correlated significantly with CDEIS (Spearman's r 0.729 and 0.773, P < 0.001). With a cutoff level of 200 mu g/g for a raised fecal calprotectin concentration, sensitivity was 70%, specificity 92%, positive predictive value (PPV) 94%, and negative predictive value (NPV) 61% in predicting endoscopically active disease (CDEIS >= 3). A fecal lactoferrin concentration of 10 mu g/g as the cutoff value gave a sensitivity, specificity, PPV, and NPV of 66%, 92%, 94%, and 59%. Sensitivity of CDAI >= 150 to detect endoscopically active disease was only 27%, specificity 94%, PPV 91%, and NPV 40%. A raised serum CRP (> 5 mg/l) gave a sensitivity, specificity, PPV, and NPV of 48%, 91%, 91 %, and 48%. Conclusions: For evaluation of Crohn's disease activity, based on endoscopic findings, more sensitive surrogate markers than is CDAI or CRP are fecal calprotectin and lactoferrin. These prove to be useful tools for estimation of disease activity in Crohn's disease.