Mucosal healing is the goal for ulcerative colitis (UC) therapy, but it needs to be confirmed via colonoscopy. Colon capsule endoscopy (CCE) is a noninvasive technique for colon investigation. Our study investigated the accuracy of second-generation CCE (CCE-2) in assessing mucosal lesions and disease activity in UC.

In this prospective study, CCE-2 and conventional colonoscopy were performed on the same day. CCE-2 reviewers and colonoscopists used the Mayo endoscopic subscore (MES) and the Ulcerative Colitis Endoscopic Index of Severity (UCEIS) to assess disease activity, and they were blinded to each other’s findings. Diagnostic parameters of CCE-2 for identifying mucosal lesions were evaluated by using colonoscopy as the reference.

A total of 150 patients were enrolled. Of the 150 patients, 108 were included for per-patient analysis. CCE-2 and colonoscopy showed substantial agreement in measuring MES (intraclass correlation coefficient [ICC] 0.69; 95% confidence interval [CI], 0.46-0.81; P < .001) and UCEIS (ICC 0.64; 95% CI, 0.38-0.78; P < .001). CCE-2 had a sensitivity of 97% and 94% to detect mucosal inflammation (MES >0) and moderate to severe inflammation (MES >1), respectively. In per-segment analysis, the negative predictive values of CCE-2 to detect mucosal inflammation, including vascular pattern loss, bleeding, and erosions reached 94% to 95%. Interobserver agreement between 2 independent CCE-2 readers for both scoring systems was good (ICC > .80). The sensitivity and specificity of CCE-2 in detecting postinflammatory polyps were 100% and 91%, respectively. CCE-2 was better tolerated and preferred by patients than was colonoscopy.

CCE-2 yields high accuracy in detecting mucosal lesions and determining disease severity in UC. It represents a well-tolerated and reliable tool for disease monitoring in UC. (Clinical trial registration number: NCT02469103.)