Objectives: We evaluated the performance of blood and faecal biomarkers for differentiating between endoscopic inflammation and mucosal healing, and clinically active disease and sustained clinical remission, and determined the predictive value for a flare in patients with ulcerative colitis [UC]. Methods: Clinical Activity Index [CAI], faecal lactoferrin [FLA], calprotectin [CAL], PMN-elastase [PMN-e], C-reactive protein [CRP], white blood cells [WBC], Endoscopic Index [EI], and UC-Disease Activity Index [DAI] were determined repeatedly during 12 months and at acute flares. Results: Of 91 patients [45 female; mean age 48.1 +/- 13.4 years] entering in remission, 42 [46%] patients developed a clinical flare. A total of 529 CAI and 179 EI assessments were performed. Median levels for active disease confirmed by EI [n = 35] vs clinical remission with endoscopic inflammation [n = 37] vs mucosal healing [n = 107] for FLA were 44/37/4 mu g/g, CAL 25/20/10 mu g/g [both p < 0.0001], PMN-e 0.06/0.03/0.02 mu g/g, CRP 0.7/0.2/0.2 mg/dl [both p < 0.001], and WBC 7.0/6.5/6.4/nl [p = 0.1]. There was no difference for any of the markers for defining mucosal healing by EI = 0 vs EI = 1 with the exception of PMN-e [p = 0.03], where the difference was very small and with questionable clinical relevance. Using manufacturers' cut-offs, only FLA at baseline was associated with a significant higher relative risk [RR] of flaring [RR 1.69; p = 0.018]. Using optimised cut-offs, CAL, PMN-e, and CRP were also predictive of a flare. Conclusions: Faecal biomarkers FLA, CAL, and PMN-e were able to distinguish between UC patients with mucosal healing from clinical remission and mild disease, showed significant correlations with endoscopy, and were predictive of a flare.
