Colon Capsule Endoscopy: Looking Beyond the Colon in Crohn's Disease
We write to communicate the results from our work with the PillCam Colon 2 as a means of assessing mucosal activity in Crohn's disease.
Mucosal healing is increasingly becoming a goal in Crohn's disease management, given its association with better long-term outcomes.1 Conventional optical colonoscopy is currently the mainstay of follow-up, but a less invasive method such as capsule endoscopy would be preferred, in part to reduce pressure on endoscopy waiting lists. Colon capsule endoscopy is a relatively new technology which, unlike its predecessor, the small bowel capsule, has two cameras and can assess both the small and large bowel. This allows it to visualize beyond the reach of the colonoscope.
Several reports have previously aimed to correlate the results from colon capsule endoscopy with conventional colonoscopy to validate its use in clinical practice. Our experience with 34 subjects represents the second largest study using the technology.2 Subjects were participants with previously confirmed Crohn's disease without previous radiological or clinical features of obstruction who underwent both procedures in a 24-hour period (Fig. 1). The mucosal activity was assessed using the Simple Endoscopic Activity Score in Crohn's Disease (SES-CD) and correlated using Spearman's coefficient.
We found moderate correlation in SES-CD overall (0.598, P = 0.004), much better in proximal than distal segments (0.818 [P < 0.001], 0.522 [P = 0.003], 0.480 [P = 0.010], 0.322 [P = 0.109], and 0.166 [P = 0.617] in terminal ileum, right colon, transverse colon, left colon, and rectum, respectively). Unlike previous studies, we also aimed to determine the potential role of colon capsule endoscopy (CCE) in clinical decision-making. Impressively, agreement between colon CCE-informed recommendation for clinical management and actual treatment decision (upgrade, downgrade/no change) was 91.2%.
The major limitation was a low rate of completion of 61.8% within the life of the battery. This was likely related to our use of a polyethylene glycol-based bowel preparation and booster, rather than of sodium phosphate as described in other studies,3 but which is avoided in Australia because of concerns about phosphate nephrotoxicity. There were no cases of capsule retention requiring emergent retrieval, although one capsule was visualized during same day colonoscopy to be above a stricture and opportunistically retrieved by Roth basket. This highlights the ongoing challenge of selecting participants unlikely to retain capsules because of stricturing disease.4
Overall, our data suggest that CCE is promising as an alternative for the assessment of endoscopic disease severity; however, the methodology still needs further optimization.