Effects of dietary interventions focused on adding base in the management of metabolic acidosis in adults with chronic kidney disease: A protocol for systematic review and meta-analysis of randomized clinical trials

BackgroundMetabolic acidosis is a common complication of chronic kidney disease (CKD) which can impair the function of multiple organs and accelerate CKD progression to kidney failure. The condition is usually treated with sodium bicarbonate (NaHCO3), which is an alkali salt. Although effective, alkali therapy has numerous side effects including gastric discomfort and bloating, with many people having difficulty tolerating higher doses. Research has shown that base producing fruit and vegetables may have the ability to increase serum bicarbonate concentrations similar to what is achieved with alkali therapy, but also provides added benefits. This systematic review aims to identify, critically-appraise and meta-analyze findings from randomized clinical trials (RCTs) comparing the effects of dietary interventions, including base producing fruit and vegetables, on serum bicarbonate concentrations as well as other factors related to kidney function in adult patients with CKD. MethodsRCTs (in adult participants (18 years of age or older), with CKD will be included in the study. Studies will be excluded if participants are undergoing dialysis or have chronic obstructive pulmonary disease (COPD) requiring oxygen therapy. The interventions of interest are any dietary intervention aimed at manipulating dietary acid load, compared with usual care, no treatment or placebo. Our primary outcome measure will be changes in serum bicarbonate concentration, while other parameters related to kidney function will be considered as secondary outcomes. A knowledge synthesis librarian developed a literature search strategy for MEDLINE (Ovid). The search strategy was then adjusted for use in Cochrane Central (Ovid), Embase (Ovid), Web of Science Core Collection (Clarivate) and CINAHL (EBSCO). Two independent reviewers will select studies for eligibility in Covidence and data extraction will be conducted using a custom MS Excel worksheet. We are planning to perform meta-analysis wherever possible using random effects model. Standardized mean difference (95% confidence interval) and risk ratio will be used to present continuous and dichotomous data, respectively. The assessment of publication bias will be performed using funnel plots and Eggers regression test while I2 statistics will be used to assess heterogeneity. We are planning to perform subgroup analysis to deal with potential heterogeneity. DiscussionThe results of this systematic review and meta-analysis will be useful in designing effective dietary strategies for the management of CKD-related metabolic acidosis. Systematic review registrationThe present systematic review is registered in International Prospective Register of Systematic Reviews (PROSPERO) (https://www.crd.york.ac.uk/, registration ID: CRD42022342612).