The effects of amino acid/protein supplementation in hemodialysis patients: study protocol for a systematic review and meta-analysis

Background Multiple factors including older age, comorbidities, inflammation, metabolic acidosis, dialysis-related hypercatabolism and anabolic resistance of skeletal muscle, extraction of circulating amino acids through hemodialysis and inadequate dietary protein intake due to anorexia, and strictly limited dietary phosphorus intake are likely to contribute to the high prevalence of malnutrition and metabolic abnormalities, more aptly called protein-energy wasting, in patients on hemodialysis. The consensus from the International Society of Renal Nutritional and Metabolism states that nutritional supplementation is effective for replenishing protein and energy stores. Although we hypothesize that amino acid/protein supplementation can overcome the anabolic resistance of skeletal muscle tissue and attenuate or even prevent the accelerated loss of skeletal muscle mass and strength through nutritional status improvement in patients on hemodialysis, whether amino acid and/or protein administration is associated with improvements in these outcomes is unknown. The main objective of this study is to systematically review the impact of amino acid/protein supplementation on skeletal muscle mass, muscle strength, physical function, and quality of life in end-stage renal disease patients requiring hemodialysis. Methods Published randomized controlled trials (RCTs) assessing the effectiveness of amino acid/protein supplementation in hemodialysis patients with respect to body composition, muscle mass, muscle strength, physical function, and quality of life will be included. The bibliographic databases include MEDLINE, the Web of Science, the Cochrane Central Register of Controlled Trials, and Embase. The risk of bias of the included RCTs will be assessed using the Cochrane Collaboration’s tool by two independent reviewers. The primary outcome will be skeletal muscle mass, muscle strength, and physical function, and the secondary outcome will be quality of life. This review protocol is reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocol (PRISMA-P) 2015 checklist. Ethics and dissemination Ethical approval is not required because this study does not include confidential personal data or involve patient interventions. This review is expected to inform readers on the effect of amino acid/protein supplementation in patients undergoing hemodialysis. The findings will be presented at conferences and submitted to a peer-reviewed journal for publication. Trial registration The trial registration number is ( CRD42020181087 ), and the trial was registered on 5 July 2020.