Eligible for inclusion in the review were randomised controlled clinical trials (RCTs) that compared rifaximin with non-absorbable disaccharides, in patients with signs and symptoms of acute, chronic or minimal hepatic encephalopathy (according to Conn's modification of Parsons Smith Classification). Eligible trials had to include patient populations aged 18 years and over, with serum ammonia levels greater than 75 μmol/L. The following were excluded from the review: non-controlled clinical trials; studies with patients with certain concomitant conditions; pregnant or lactating women; patients who did not fulfil protocol requirements; and results published in abstract form and where raw data was not completed.
The primary outcome was clinical efficacy, which was defined as an improvement in hepatic encephalopathy clinical syndrome, or a significant decrease in the portosystemic encephalopathy index. Secondary outcomes were blood ammonia concentration and adverse reports of diarrhoea and abdominal pain.
Included trials were performed in Spain, Italy and Korea. Type of hepatic encephalopathy in the included trials varied in terms of grade and chronic or acute status. A range of evaluation criteria for hepatic encephalopathy were used.
Two reviewers independently selected the studies for inclusion in the review. It was not reported how disagreements were resolved.