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P107. Usefulness of a rapid test for fecal calprotectin as predictor of relapse in Crohn's disease patients under maintenance treatment with adalimumab

R. Ferreiro, M. Barreiro-de Acosta, A. Lorenzo, J.E. Dominguez-Muñoz, University Hospital Santiago de Compostela, Gastroenterology, Santiago, Spain

Background

Predicting relapse in Crohn's disease (CD) patients by measuring non-invasive biomarkers could allow for early changes of treatment. Data are scarce regarding the usefulness of monitoring with calprotectin to predict relapse. The aim of the study was to evaluate the predictive value of a rapid test of fecal calprotectin to predict for flares in CD patients under maintenance treatment with adalimumab (ADA).

Methods

A prospective, observationalcohort study was designed. Inclusion criteria were CD patients in clinical remission for at least six months under a continuous standard dose of 40 mg/eow ADA therapy. Fresh faecal calprotectin was measured using a rapid test (Quantum blue®) on the day of the first ADA injection. Quantum blue ®is a rapid test for measuring calprotectin in less than half an hour. Clinical examination was performed during the following 4 months. Relapse was defined as a Harvey–Bradshaw score >4. Results are shown as mean±SD and compared by the U-Mann–Whitney test. ROC analysis was performed and the diagnostic accuracy was calculated.

Results

Thirty patients were included (mean age 40 years, 56.7% female). After the four months follow-up, twenty-one (70.0%) patients remained in clinical remission and nine (30.0%) have had a relapse. Fecal calprotectin concentration at inclusion was significantly higher in those patients who relapsed during the follow-up (803±514 µg/g) than in those who maintained in remission (95±104 µg/g) (p < 0.005). The optimal cut-off of fecal calprotectin to predict remission was 204 µg/g according to the ROC analysis. The area under the ROC curve was 0.97 (p < 0.005). Sensitivity, specificity, positive and negative predictive value of fecal calprotectin to predict relapse were 100%, 85.7%, 74.1% and 100%, respectively. Levels of calprotectin were correlated with levels of C-reactive protein (r = 0.51, P < 0.005). After multiple linear regression, we observed that if we made adjustments with other relevant sociodemographic and clinical variables, calprotectin and older age were the most important risk factors for the presence of relapse.

Conclusion

In CD patients under ADA maintenance therapy, fecal calprotectin levels allow predicting relapse over the following months with a high accuracy. Low fecal calprotectin levels exclude relapse within at least the following four months, whereas high levels are associated with relapse in three out of each four patients.