Correlation of Mucosal Healing with Surrogate Markers in Crohn's Disease

Aims: Mucosal healing (MH) is widely recognized as a major therapeutic goal in Crohn's disease (CD). However, the precise definition of MH has not been set yet, but is expected to reflect complete absence of inflammation and ulcerative lesions at endoscopy. The goal of this study was to investigate the relationship between endoscopic index and known surrogate markers including CD activity index (CDAI), C-reactive protein (CRP), faecal calprotectin (f-Calpro) and a novel CT enterography (CTE) score in CD.Methods: In 40 patients, CDAI, CRP, f-Calpro, endoscopic index (SES-CD), and CTE score (based on bowel wall thickness, mural hyper-enhancement, stratification and engorged versa recta) were factored into analyses. MH was defined as absence of ulceration at peranal balloon enteroscopy, which is defined as a score of 0 in SES-CD. The correlation between SES-CD and other markers was assessed by univariate and multivariate analyses.Results: SES-CD showed significant correlation with CDAI, CRP, f-Calpro and CTE score in univariate analyses. Likewise, the CTE score was correlated with CDAI, CRP and faecal calprotectin. However, in multivariate analyses, SES-CD showed correlation only with f-Calpro (P<0.05). Ten patients had an SES-CD score of 0 and all maintained clinical remission during the observation (average 35.3 weeks), even though f-Calpro level was >100 µg/g faeces in 4 patients.Conclusion: In this study, f-Calpro appeared to be a clinically relevant surrogate marker ofMH in CD.