Surrogate markers and clinical indices, alone or combined, as indicators for endoscopic remission in anti-TNF-treated luminal Crohn's disease

Objective. Endoscopically confirmed mucosal healing has become an important therapeutic goal in the treatment of Crohn's disease (CD). The role of clinical indices, such as the Crohn's disease activity index (CDAI) and the Harvey-Bradshaw index (HBI), and surrogate markers, such as C-reactive protein (CRP) and fecal calprotectin, to indicate remission determined by endoscopy needs to be clarified. We analyzed the role of surrogate markers and clinical indices, separately and in combination, by comparing them with endoscopically scored disease activity in biologically treated CD patients. Material and methods. Prospectively collected data of all patients with inflammatory bowel disease treated with tumor necrosis factor alpha antibodies in a tertiary center between 2007 and 2010. Altogether 210 endoscopies in 64 CD patients were analyzed. The simple endoscopic score for Crohn's disease (SES-CD) was used for scoring disease activity and compared with available data on concurrent CDAI, HBI, CRP, and calprotectin. Results. Endoscopic activity demonstrated a stronger correlation with calprotectin and CRP than with the clinical indices. Neither the clinical indices nor CRP was reliable at identifying endoscopic remission. However, calprotectin alone identified endoscopic remission with a sensitivity of 84% and specificity of 74%, but was beaten, although not statistically significantly, by a combined index, based on calprotectin and the HBI. Conclusions. Clinical scores commonly used in the assessment of disease activity are unreliable at differentiating endoscopic remission from active CD. Despite this, a score based on a combination of fecal calprotectin and the HBI is a new promising tool for identifying endoscopic remission.