Abstract: We included 38 RCTs with a total of 1828 participants. Eight RCTs had a low risk of bias in the assessment of mortality. All trials had a high risk of bias in the assessment of the remaining outcomes. Random-effects meta-analysis showed a beneficial effect of non-absorbable disaccharides versus placebo/no intervention on mortality when including all RCTs with extractable data (RR 0.59, 95% CI 0.40 to 0.87; 1487 participants; 24 RCTs; I2 = 0%; moderate quality evidence) and in the eight RCTs with a low risk of bias (RR 0.63, 95% CI 0.41 to 0.97; 705 participants). The Trial Sequential Analysis with the relative risk reduction (RRR) reduced to 30% confirmed the findings when including all RCTs, but not when including only RCTs with a low risk of bias or when we reduced the RRR to 22%. Compared with placebo/no intervention, the non-absorbable disaccharides were associated with beneficial effects on hepatic encephalopathy (RR 0.58, 95% CI 0.50 to 0.69; 1415 participants; 22 RCTs; I2 = 32%; moderate quality evidence). Additional analyses showed that non-absorbable disaccharides can help to reduce serious adverse events associated with the underlying liver disease including liver failure, hepatorenal syndrome, and variceal bleeding (RR 0.47, 95% CI 0.36 to 0.60; 1487 participants; 24 RCTs; I2 = 0%; moderate quality evidence). We confirmed the results in Trial Sequential Analysis. Tests for subgroup differences showed no statistical differences between RCTs evaluating prevention, overt, or minimal hepatic encephalopathy. The evaluation of secondary outcomes showed a potential beneficial effect of the non-absorbable disaccharides on quality of life, but we were not able to include the data in an overall meta-analysis (very low quality evidence). Non-absorbable disaccharides were associated with non-serious (mainly gastrointestinal) adverse events (very low quality evidence). None of the RCTs comparing lactulose versus lactitol evaluated quality of life. The review found no differences between lactulose and lactitol for the remaining outcomes (very low quality evidence). This review includes a large number of RCTs evaluating the prevention or treatment of hepatic encephalopathy. The analyses found evidence that non-absorbable disaccharides may be associated with a beneficial effect on clinically relevant outcomes compared with placebo/no intervention.

Plain-language summary: We included 29 RCTs comparing non-absorbable disaccharides with inactive placebo or no intervention and nine RCTs comparing lactulose with lactitol. Seven of the included RCTs evaluated the prevention of hepatic encephalopathy and 31 evaluated the treatment of hepatic encephalopathy. Sixteen of the treatment RCTs included people with overt hepatic encephalopathy while 15 included people with minimal hepatic encephalopathy. The duration of treatment varied depending on the type of hepatic encephalopathy from five days to one year. People who received non-absorbable disaccharides were less likely to die than people given a placebo or no treatment. They were also less likely to develop serious complications of their liver disease such as liver failure, bleeding, and infections. The non-absorbable disaccharides were also effective in preventing the development of hepatic encephalopathy and increased the number of participants who recovered from hepatic encephalopathy. There was some evidence from a small number of trials that lactulose has a beneficial effect on the quality of life, but we were unable to include the data in an overall analysis. The non-absorbable disaccharides were associated with adverse events including diarrhoea, nausea, bloating, and flatulence. None of the RCTs comparing lactulose versus lactitol reported quality of life. The analyses showed no differences between the two interventions for the remaining outcomes. In the comparison of non-absorbable disaccharides versus placebo/no intervention, we found moderate quality evidence of benefit for the outcomes of death, hepatic encephalopathy, and serious complications. The evidence for the remaining outcomes was of very low quality.