Systematic Review and Meta-analyses of Effects of Phosphate-lowering Agents in Non-dialysis Chronic Kidney Disease.

Background: Benefits of phosphate-lowering interventions on clinical outcomes in patients with chronic kidney disease (CKD) are unclear; systematic reviews have predominantly involved dialysis patients. This study aimed to summarize evidence from randomized controlled trials (RCTs) concerning benefits and risks of non-calcium-based phosphate-lowering treatment in non-dialysis CKD. Methods: We conducted a systematic review and meta-analyses of RCTs involving noncalcium-based phosphate-lowering therapy compared to placebo, calcium-based binders, or no study medication, in adults with CKD not on dialysis or post-transplant. RCTs had ≥3 months follow up and outcomes included biomarkers of mineral metabolism, cardiovascular parameters, and adverse events. Outcomes were meta-analyzed using the Sidik-Jonkman method for random effects. Unstandardized mean differences were used as effect sizes for continuous outcomes, with common measurement units and Hedge's g standardized mean differences (SMD) otherwise. Odds ratios were used for binary outcomes. Cochrane risk of bias and GRADE assessment determined the certainty of evidence. Results: Twenty trials involving 2,498 participants (median sample size 120, median follow up 9 months) were eligible for inclusion. Overall, risk of bias was low. Compared with placebo, non calcium-based phosphate binders reduced serum phosphate (12 trials, weighted mean difference -0.37, 95% CI -0.58,-0.15 mg/dL, low certainty evidence) and urinary phosphate excretion (8 trials, SMD -0.61, 95% CI -0.90,-0.31, low certainty evidence), but resulted in increased constipation (9 trials, log odds ratio [OR] 0.93, 95% CI 0.02, 1.83, low certainty evidence) and greater vascular calcification score (3 trials, SMD 0.47, 95% CI 0.17, 0.77, very low certainty evidence). Data for effects of phosphate-lowering therapy on cardiovascular events (log OR 0.51 [95% CI -0.51, 1.17]) and death were scant. Conclusions: Non-calcium-based phosphate-lowering therapy reduced serum phosphate and urinary phosphate excretion, but there was an unclear effect on clinical outcomes and intermediate cardiovascular end-points. Adequately powered RCTs are required to evaluate benefits and risks of phosphate-lowering therapy on patient-centered outcomes.