Boyle 1980.

Methods	Randomised cross‐over trial, 2 groups for successive 5‐day treatment periods (2‐day equilibration and 3‐day stool collection).
Participants	8 people with CF, mean age 16 years, age range 12 ‐ 25 years.
Interventions	2 groups: 1. pancreatic enzyme (Viokase®) alone; 2. pancreatic enzyme (Viokase®) plus the H2 receptor antagonist cimetidine .
Outcomes	Faecal bile acids, weight and fat, and postprandial serum bile acids.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomised, but no details of method given.
Allocation concealment (selection bias)	Unclear risk	Not discussed.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Did not report blinding of investigators.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Stool collection from 1 participant was not complete, so stool data based on 7 participants only.