Study	Reason for exclusion
Atlay 1978	Cross‐over design. No data reported for the first stage of the study.
Briggs 1972	Cross‐over design. No usable data.
Brunclik 1988	High post‐randomisation exclusion rates (20%). Half of the exclusions were for reasons of non‐compliance.
Carne 1964	Cross‐over design. No data reported for the first stage of the study.
Hey 1978	Study focusing on gastric sphincter pressure. No data reported for review outcomes.
Kovacs 1990	No usable data on review outcomes.
Lang 1989	High post‐randomisation attrition rates (38% lost to follow up by 2 weeks).
Larson 1997	Cross‐over design. No data for the first stage of the study.
Ranchet 1990	Not clear whether this was a RCT. No information on how randomisation was achieved and intervention and control group sizes were very different.
Shaw 1978	High attrition rates (24%). Symptoms were only assessed up to 60 minutes after treatment.

RCT: randomised controlled trial