External validation of serum biomarkers predicting short-term and mid/long-term relapse in patients with Crohn’s disease stopping infliximab by Pierre, N, Huynh-Thu, VA, Baiwir, D, Mazzucchelli, G, Fléron, M, Trzpiot, L, Eppe, G, De Pauw, E, Laharie, D, Satsangi, J, Bossuyt, P, Vuitton, L, Vieujean, S, Colombel, J, Meuwis, M, Louis, E, GETAID and the SPARE-Biocycle research group