The Lewis score or the capsule endoscopy Crohn's disease activity index: which one is better for the assessment of small bowel inflammation in established Crohn's disease?

Background: Small-bowel capsule endoscopy (CE) is a prime modality for evaluation of the small bowel. The Lewis score (LS) and the Capsule Endoscopy Crohn's Disease Activity Index (CECDAI) are validated endoscopic indices for quantification of small-bowel inflammation on CE. It is unclear whether these indexes are interchangeable for the evaluation of mucosal inflammation in established Crohn's disease (CD). The aim of this study was to compare the quantitative evaluation of small-bowel inflammation by LS and CECDAI. Methods: Patients with known quiescent small-bowel CD for at least 3 months (Crohn's disease activity index < 150) were prospectively recruited and underwent CE. The LS was calculated using RAPID 8 capsule-reading software and the CECDAI was calculated manually. Cumulative LS (C-LS) was calculated by summation of individual tertile LS. Fecal calprotectin (FCP) and C-reactive protein (CRP) levels were measured and correlated with the scores. Results: A total of 50 patients were included in the study. There was a moderate correlation between the worst segment LS and CECDAI (Pearson's r = 0.66, p = 0.001), and a strong correlation between C-LS and CECDAI (r = 0.81, p = 0.0001). CECDAI < 5.4 corresponded to mucosal healing (LS < 135), while CECDAI > 9.2 corresponded to moderate-to-severe inflammation (LS. 790). There was a moderate correlation between capsule scores and FCP levels (r = 0.39, p = 0.002 for LS, r = 0.48, p = 0.001 for C-LS, and r = 0.53, p = 0.001 for CECDAI, respectively). CRP levels were not significantly correlated with either score. Conclusions: CECDAI and C-LS are strongly correlated and perform similarly for quantitative assessment of mucosal inflammation in established CD.