The effectiveness of exercise prehabilitation on aerobic capacity, muscle strength and body composition in patients with cirrhosis awaiting liver transplantation: a systematic review and meta-analysis protocol

Introduction: Cirrhosis is the main cause of morbidity and mortality globally, accounting for approximately 1.2 million deaths annually. Impaired aerobic capacity, muscle wasting and reduced muscle strength are significant complications in patients with cirrhosis. Preoperative exercise intervention "prehabilitation" has been recognised as a potential approach to optimise muscle strength, aerobic capacity and body composition as well as quality of life in patients awaiting abdominal surgery. However, there is little evidence on the effects of preoperative exercise on older adults with cirrhosis and awaiting liver transplant. Thus, the primary objective of this systematic review and meta-analysis will be to assess the effects of exercise interventions in improving aerobic capacity, muscle strength and body composition of older adults with cirrhosis and awaiting liver transplant.

Methods and analysis: This systematic review and metaanalysis protocol was designed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. This systematic review will include all peer-reviewed randomised controlled trials (RCTs), including cluster RCTs, controlled (non-controlled), complex clinical trials (CCTs) or cluster trials, cohort, observational studies published in English from inception until July 2024. The following electronic databases will be searched: MEDLINE (PubMed), Cochrane Central Register of Controlled Trials (CENTRAL), CINAHL (EBSCO) and Scopus (Elsevier) and supplemented by a secondary screening of the reference lists of all included articles. Searches will involve studies with both male and female participants aged $\ge$ 18 years with cirrhosis and awaiting liver transplant. Primary outcomes will include muscle strength, and aerobic capacity. The secondary outcomes include body composition (e.g. body mass index, and thigh circumference). The Cochrane Collaboration Risk of Bias Tool will be used to evaluate quality of the studies and Review Manager (RevMan) V.5.3 (Copenhagen, Denmark: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014). Effect sizes will be expressed as a standardised mean difference, and their 95% confidence intervals will be calculated and presented as a forest plot. The standard χ² and I² tests will be used to test heterogeneity.

Conclusion: This systematic review and meta-analysis is anticipated to provide meaningful and contemporary evidence on the effects of preoperative exercise in older adults living with cirrhosis and awaiting liver transplant. In addition, the findings will help clinicians with developing safe and effective preoperative exercise regimens for these patients.