Hammarstrom 1995.

Methods	Randomised clinical trial comparing ERCP/ES and stone removal versus open surgery alone for pts found to have CBDS proven on ERCP, intravenous cholangiogram, or USS, with an intact gallbladder. Drop‐outs: 3 (all in surgery arm); 2 refused operation, 1 missing set of notes. Follow‐up: Median 92 (63 to 113) months Group 1, 82 (60 to 113) months Group 2. Sample size calculations: no.
Participants	Trial from Sweden. Commenced Sept 1984, completed Jan 1989, but with 5‐year follow‐up data. 83 pts randomised. Inclusion criteria: CBDS found either on ERC, USS or IVC, intact gallbladder, age < 85 yrs (arbitrary), informed consent. Exclusion criteria: Previous B2 anastomosis, malignancy, perforated cholecystitis, unfit for surgery.
Interventions	Group 1 (ERCP/ES): Proceeded to ES and stone extraction by a variety of means (basket, balloon, mechanical lithotriptor). Subsequent surgery only if ongoing biliary symptoms. Group 2 (Surgery): Open cholecystectomy and ECBD on next available list. T‐tube always used. Choledochoscopy optional.
Outcomes	Successful stone clearance, additional endoscopic procedures, median hospital stay, complications ‐ bile leak, gastric retention, duodenal injury after surgery, biliary colic (no surgery), pancreatitis (no surgery), re‐operation for bleeding, bile duct injuries, late complications: incisional hernia, retained stone.
Notes	Surgery arm all had ERCP to diagnose CBD stones. Unclear if surgery for late symptoms was included in complication assessment.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random numbers.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not possible.
Selective reporting (reporting bias)	Low risk	All outcomes were clearly defined and reported.
Incomplete outcome data	Unclear risk	No missing data.
For‐profit bias	Low risk	Appears free of for‐profit support.
Other bias	Low risk	None.