Small bowel capsule endoscopy and treat-to-target in Crohn's disease: A systematic review

BACKGROUND Crohn's disease (CD) can affect the entire gastrointestinal tract. Proximal small bowel (SB) lesions are associated with a significant risk of stricturing disease and multiple abdominal surgeries. The assessment of SB in patients with CD is therefore necessary because it may have a significant impact on prognosis with potential therapeutic implications. Because of the weak correlation that exists between symptoms and endoscopic disease activity, the "treat-to-target" paradigm has been developed, and the associated treatment goal is to achieve and maintain deep remission, encompassing both clinical and endoscopic remission. Small bowel capsule endoscopy (SBCE) allows to visualize the mucosal surface of the entire SB. At that time, there is no recommendation regarding the use of SBCE during follow-up. AIM To investigate the impact of SBCE in a treat-to-target strategy in patients with CD. METHODS An electronic literature search was conducted in PubMed and Cochrane library using the following search terms: "capsule endoscopy", in combination with "Crohn's disease" and "treat-to-target" or synonyms. Two authors independently reviewed titles and abstracts identified by the search strategy after duplicates were removed. Following the initial screening of abstracts, all articles containing information about SBCE in the context of treat-to-target strategy in patients with CD were included. Full-text articles were retrieved, reference lists were screened manually to identify additional studies. RESULTS Forty-seven articles were included in this review. Two indexes are currently used to quantify disease activity using SBCE, and there is good correlation between them. SBCE was shown to be useful for disease reclassification in patients who are suspected of having or who are diagnosed with CD, with a significant incremental diagnostic yield compared to other diagnostic modalities. Nine studies also demonstrated that the mucosal healing can be evaluated by SBCE to monitor the effect of medical treatment in patients with CD. This review also demonstrated that SBCE can detect post-operative recurrence to a similar extent as ileocolonoscopy, and proximal SB lesions that are beyond the reach of the colonoscope in over half of the patients. CONCLUSION SBCE could be incorporated in the treat-to-target algorithm for patients with CD. Randomized controlled trials are required to confirm its usefulness and reliability in this indication.