Choi 2009.

Methods	Generation of allocation sequence: Randomised according to date of endoscopy.Allocation concealment: Not stated.Blinding: Not applicable.Inclusion of all randomised patients: Not stated.
Participants	Number: 228 (108M:1206F) Age: Cap group mean 46.1 +/‐ 11.1 years. Standard group mean 48.5 +/‐ 10.9 years. Source: Yang Hospital, Seoul. Inclusion criteria: All patients undergoing colonoscopy. Exclusion criteria: Prior colonic surgery, colonic obstruction or obstructing tumour.
Interventions	Colonoscope: not stated. Bowel Preparation: 4L polyethylene glycol/ or 50mg sodium phosphate. Intra‐porcedure medication: Midazolam, Propofol, Oxygen. Colonoscopists: Experienced colonoscopists having performed >3000 colonoscopies. Cap: D‐201‐13404 (Olympus, Tokyo, Japan) transparent plastic cap: 13.7mm outer diameter, 11.7mm inner diameter, depth 8mm, protruding 4mm ahead of scope.
Outcomes	Included in review: Caecal intubation rate and time, polyp detection rate, pain during procedure, adverse events.
Notes	Location: Korea. Source of funding: Not stated. Attempts to clarify information: Translation from Korean. Language of Publication: Korean.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Inadequate method ‐ randomised by alternate days.
Allocation concealment (selection bias)	High risk	Not blinded.
Blinding (performance bias and detection bias) All outcomes	High risk	Not blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All data appears complete.
Selective reporting (reporting bias)	Low risk	Appropriate outcomes reported.
Other bias	Unclear risk	Source of funding not stated.