The effects of calcium-based versus non-calcium-based phosphate binders on mortality among patients with chronic kidney disease: a meta-analysis

Background. The effects of calcium compared with non-calcium-based phosphate binders on mortality, cardiovascular events and vascular calcification in patients with chronic kidney disease (CKD) are unknown. Methods. To address this question, we conducted a systematic review. We electronically searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and CINAHL. We identified 160 potential studies and included 8 randomized trials. Eligible studies, determined by consensus using predefined criteria, were reviewed, and data were extracted onto a standard from. Results. There was a trend towards a decrease in all-cause mortality among non-calcium-based versus calcium-based phosphate binders [relative risk (RR) 0.68; 95% CI 0.41-1.11] based upon eight randomized controlled trials and 2873 subjects. Two trials reported on cardiovascular events with a RR of 0.85 (95% CI 0.35-2.03) in patients receiving calcium-based versus non-calcium-based binders. Coronary artery calcification was reported in five trials involving 469 patients; the difference in the change in the calcium score from baseline to follow-up among subjects taking non-calcium-based binders versus calcium-based binders was -76.35 (95% CI - 158.25-5.55). Conclusion. Despite the trends observed, we did not find a statistically significant difference in cardiovascular mortality and coronary artery calcification in patients receiving calcium-based phosphate binders compared to non-calcium-based phosphate binders. However, the data are limited by the small number of studies and the confidence intervals do not exclude a potentially important beneficial effect. Therefore, further randomized trials are required.