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BackgroundCALM was a randomized phase 3 trial in patients with Crohn's disease (CD) that demonstrated improved endoscopic outcomes when treatment was escalated based on cutoffs for inflammatory biomarkers, fecal calprotectin (FC), C-reactive protein (CRP), and CD Activity Index (CDAI) remission vs CDAI response alone. The purpose of this post hoc analysis of CALM was to identify drivers of treatment escalation and evaluate the association between biomarker cutoff concentrations and endoscopic end points.MethodsThe proportion of patients achieving CD Endoscopic Index of Severity (CDEIS) <4 and no deep ulcers 48 weeks after randomization was evaluated according to CRP <5 mg/L or ≥5 mg/L and FC <250 μg/g or ≥250 μg/g. Subgroup analyses were performed according to disease location, and sensitivity analyses were conducted in patients with elevated CRP and/or FC at baseline. The association between endoscopic end points and biomarker cutoffs was performed using χ 2 test.ResultsThe proportion of patients who achieved the primary end point CDEIS <4 and no deep ulcers was significantly greater for those with FC <250 µg/g (74%; P < 0.001), with an additive effect for CRP <5 mg/L. The association of FC <250 µg/g with improved endoscopic outcomes was independent of disease location, although the greatest association was observed for ileocolonic disease. Fecal calprotectin <250 µg/g, CRP <5 mg/L, and CDAI <150 gave a sensitivity/specificity of 72%/63% and positive/negative predictive values of 86%/42% for CDEIS <4 and no deep ulcers 48 weeks after randomization.ConclusionThis post hoc analysis of CALM demonstrated that a cutoff of FC <250 µg/g is a useful surrogate marker for mucosal healing in CD.

Original publication

DOI

10.1093/ibd/izaa025

Type

Journal article

Journal

Inflammatory bowel diseases

Publication Date

09/2020

Volume

26

Pages

1562 - 1571

Addresses

Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria.

Keywords

Colon, Feces, Humans, Crohn Disease, C-Reactive Protein, Leukocyte L1 Antigen Complex, Colonoscopy, Treatment Outcome, Remission Induction, Severity of Illness Index, Sensitivity and Specificity, Predictive Value of Tests, Reference Values, Adult, Middle Aged, Female, Male, Biomarkers, Clinical Decision Rules