Barrioz 1994.

Methods	Generation of the allocation sequence: method unclear. Allocation concealment: method unclear. Blinding: Not blinded. Intention‐to‐treat: not stated. Exclusions from analysis: not stated. Follow up period: unclear. Jadad‐score: 2.
Participants	Twenty patients with malignant biliary stricture and endoscopically inserted biliary polyethylene stent.
Interventions	Ursodeoxycholic acid (13‐15 mg/kg/d) and norfloxacin (400 mg/d) versus no treatment.
Outcomes	Duration of stent patency. Mortality. Duration of hospitalisation.
Notes	Cholangiocarcinoma was more common in the drug treated group.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Unclear risk	B ‐ Unclear