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* = Presenting author

P302. A prospective evaluation of the predictive value of faecal calprotectin in quiescent Crohn's disease

L.A. Smith1, G. Naismith1, S. Barry2, K. Rankin3, J. Munro1, S. Laird1, J. Winter1, A.J. Morris1, D. Gaya1, 1Glasgow Royal Infirmary, Gastroenterology, Glasgow, United Kingdom, 2University of Glasgow, Robertson Centre for Biostatistics, Glasgow, United Kingdom, 3Glasgow Royal Infirmary, Biochemistry, Glasgow, United Kingdom

Background

Faecal calprotectin (FC) concentration has been shown to be useful in the diagnosis of IBD and has been demonstrated to correlate with mucosal healing in IBD; thus has a role in monitoring and assessing disease activity. The purpose of this study was to evaluate the role of FC in predicting relapse in adult patients with quiescent Crohn's disease followed up for a minimum of 12 months.

Methods

Patients with Crohn's disease in clinical remission were recruited and followed up prospectively for a minimum of 1 year. All patients provided stool for FC concentration analysis and the study was terminated once the last recruited patient reached a follow up period of 365 days post stool sample donation.

Remission was defined clinically as a Crohn's disease activity index (CDAI) of <150. Relapse was defined as either a need for escalation of medical therapy, surgery for active Crohn's disease or progression of disease phenotype using the Montreal classification.

Results

98 patients were recruited. One patient was lost to follow up and the care of 4 patients was transferred to another centre before 12 months of follow up data was available. Of the 93 remaining patients 11 (12%) relapsed within 12 months. The median FC was lower for non-relapsers, 79 µg/g (IQR 39–226) than for relapsers, 322 µg/g (IQR 136–557) (p = 0.002). The area under the ROC curve to predict relapse using FC was 74.8%. (Figure 1).

Utilising a cut-off FC value of 240 µg/g to predict relapse of quiescent Crohn's disease over the course of one year was associated with a sensitivity of 72.7% and specificity of 74.3%, negative predictive value was high at 95.3% and a positive predictive value of 27.6%. On Kaplan–Meier plots, there is a significant difference in time to relapse for those with the first FC value below or above 240 µg/g (p = 0.01) (Figure 2).

Figure 1. Kaplan–Meier plot for FC value above and below 240 mcg/g.

Figure 2. Receiver operating characteristic curve for FC in predicting relapse.

Conclusion

In this prospective dataset, FC appears to be a useful, non-invasive tool to help identify quiescent Crohn's disease patients at a higher risk of relapse over the ensuing 12 months.