McMurdo 2005.

Methods	Study design: parallel group Power calculation: yes Intention‐to‐treat analysis: yes
Participants	Inclusion criteria Setting: single centre Country: UK (Scotland) 60 years or over admitted to either acute medicine for the elderly assessment or rehabilitation units for elderly people Number: 376 randomised and analysed Exclusion criteria Mental State Questionnaire (MSQ) score < 5/10; dysphagia; symptoms of a UTI; antibiotic treatment; anticipated length of stay < 1 week; regular drinkers of cranberry juice; presence of an in‐dwelling catheter; terminal illness In light of a UK Committee on Safety of Medicines alert about a potential interaction between cranberry juice and warfarin which emerged during the final 8 weeks of recruitment, warfarin was added as an exclusion for that period only.
Interventions	Treatment group Cranberry juice: 300 mL Control group Matching placebo beverage Duration of treatment: 6 months
Outcomes	Time to onset of first symptomatic UTI: defined as a culture positive urine growing a single organism of > 104 cfu/mL urine specimen Adherence to beverage drinking, courses of antibiotics prescribed, and organisms responsible for UTIs
Notes	Exclusions post randomisation: none Method of obtaining urine sample: clean catch Definition of bacteriuria Only pure growths of ≥ 104 cfu/mL were reported with an antibiotic sensitivity
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Stratified by gender and computer generated
Allocation concealment (selection bias)	Low risk	Held by pharmacy, sealed numbered enveloped
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinding stated
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinding stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	All patients analysed and reported; Losses to follow‐up/withdrawals: 115
Selective reporting (reporting bias)	Low risk	Appropriate clinical outcomes
Other bias	Low risk	No other bias apparent, well reported study Source of funding: Chief Scientist Office at the Scottish Executive Department of Health. The cranberry juice and matching placebo were supplied by Ocean Spray Cranberries, Inc.