Abstract: The search identified 16 eligible studies, in which only adults with cirrhosis were included. In one study, people with portal thrombosis were also included. We classified most of the studies at high risk of bias for the 'Participants selection' and the 'Flow and timing' domains. One study assessed the accuracy of capsule endoscopy for the diagnosis of large (high-risk) oesophageal varices. In the remaining15 studies that assessed the accuracy of capsule endoscopy for the diagnosis of oesophageal varices of any size in people with cirrhosis, 936 participants were included; the pooled estimate of sensitivity was 84.8% (95% confidence interval (CI) 77.3% to 90.2%) and of specificity 84.3% (95% CI 73.1% to 91.4%). Eight of these studies included people with suspected varices or people with already diagnosed or even treated varices, or both, introducing a selection bias. Seven studies including only people with suspected but unknown varices were at low risk of bias; the pooled estimate of sensitivity was 79.7% (95% CI 73.1% to 85.0%) and of specificity 86.1% (95% CI 64.5% to 95.5%). Six studies assessed the diagnostic accuracy of capsule endoscopy for the diagnosis of large oesophageal varices, associated with a higher risk of bleeding; the pooled sensitivity was 73.7% (95% CI 52.4% to 87.7%) and of specificity 90.5% (95% CI 84.1% to 94.4%). Two studies also evaluated the presence of red marks, which are another marker of high risk of bleeding; the estimates of sensitivity and specificity varied widely. Two studies obtained similar results with the use of a modified device as index test (string capsule). Due to the absence of data, we could not perform all planned subgroup analyses. Interobserver agreement in the interpretation of capsule endoscopy results and any adverse event attributable to capsule endoscopy were poorly assessed and reported. Only four studies evaluated the interobserver agreement in the interpretation of capsule endoscopy results: the concordance was moderate. The participants' preferences for capsule endoscopy or oesophago-gastro-duodenoscopy were reported differently but seemed in favour of capsule endoscopy in nine of 10 studies. In 10 studies, participants reported some minor discomfort on swallowing the capsule. Only one study identified other significant adverse events, including impaction of the capsule due to previously unidentified oesophageal strictures in two participants. No adverse events were reported as a consequence of the reference standard. We cannot support the use of capsule endoscopy as a triage test in adults with cirrhosis, administered before oesophago-gastro-duodenoscopy, despite the low incidence of adverse events and participant reports of being better tolerated. Thus, we cannot conclude that oesophago-gastro-duodenoscopy can be replaced by capsule endoscopy for the detection of oesophageal varices in adults with cirrhosis. We found no data assessing capsule endoscopy in children and in people with portal thrombosis.

Plain-language summary: We searched scientific databases for clinical studies comparing OGD to capsule endoscopy and reporting the size and appearance of varices in children or adults with chronic liver disease or portal vein thrombosis (narrowing of the portal vein). The evidence is current to October 2013. We found 16 studies assessing the ability of capsule endoscopy to diagnose the presence of varices and grade the risk of bleeding and comparing it with OGD in adults with cirrhosis. Capsule endoscopy, even if more acceptable to participants, cannot replace OGD for the detection of oesophageal varices as about 15% are left undetected and 15% are not confirmed by endoscopy. Even the accuracy in detecting large varices or red marks on varices was very lower than endoscopy. Hence, in conclusion, capsule endoscopy is not sufficiently accurate to replace OGD for the detection of oesophageal varices in cirrhotic participants. In nine of the sixteen studies there were problems concerning participant selection and incompleteness of reported data which impair accuracy estimates and the transferability of the results.