Abstract : Background - The individual performances and the complementarity of Crohn's disease (CD) activity index (CDAI), C-reactive protein (CRP) and faecal calprotectin (Fcal) to monitor patients with CD remain poorly investigated in the era of "tight control" and "treat to target" strategies. Aim - To assess CDAI, CRP and Fcal variation, alone or combined, after 12 wk (W12) of anti-tumor necrosis factor (TNF) therapy to predict corticosteroids-free remission (CFREM = CDAI < 150, CRP < 2.9 mg/L and Fcal < 250 μg/g with no therapeutic intensification and no surgery) at W52. Methods - CD adult patients needing anti-TNF therapy with CDAI > 150 and either CRP > 2.9 mg/L or Fcal > 250 μg/g were prospectively enrolled. Results - Among the 40 included patients, 13 patients (32.5%) achieved CFREM at W52. In univariable analysis, CDAI < 150 at W12 ( = 0.012), CRP level < 2.9 mg/L at W12 ( = 0.001) and Fcal improvement at W12 (Fcal < 300 μg/g; or, for patients with initial Fcal < 300 μg/g, at least 50% decrease of Fcal or normalization of Fcal (< 100 μg/g) ( = 0.001) were predictive of CFREM at W52. Combined endpoint (CDAI < 150 and CRP ≤ 2.9 mg/L and FCal improvement) at W12 was the best predictor of CFREM at W52 with positive predictive value = 100.0% (100.0-100.0) and negative predictive value = 87.1% (75.3-98.9). In multivariable analysis, Fcal improvement at W12 [odd ratio (OR) = 45.1 (2.96-687.9); = 0.03] was a better predictor of CFREM at W52 than CDAI < 150 [OR = 9.3 (0.36-237.1); = 0.145] and CRP < 2.9 mg/L (0.77-278.0; = 0.073). Conclusion - The combined monitoring of CDAI, CRP and Fcal after anti-TNF induction therapy is able to predict favorable outcome within one year in patients with CD.
