Utility of Phosphate Binder Equivalent Dose Concept

We read with interest the AMPLIFY trial.1 The authors must be commended for selection of study participants that reflected real-world difficulties in managing elevated phosphorus levels. The study participants were treated with different phosphate binders such as Sevelamer, Lanthanum Carbonate, Sucroferric Oxyhydroxide, and calcium-based phosphate binders. The phosphate binders received by the patients were not balanced in both arms of the trial. Stratification was done on the basis of sevelamer and nonsevelamer phosphate binders. However, not all nonsevelamer-based binders are equal in their phosphate binding capacity. For example, in Supplemental Table 2, 14.3% in the placebo plus binder group were on sucroferric oxyhydroxide (SFOH) as compared with 4.3% in the Tenapanor plus binder group. SFOH is a potent phosphate binder, and it cannot be compared with other binders. Each gram of SFOH binds to approximately 260 mg of phosphorous in the gut compared with 1 g of sevelamer that binds to 21 mg of phosphorous.2 Using the concept of phosphate binder equivalent dose (PBED) would have simplified comparison of phosphate binders.3 This would give a clear picture of how much phosphate binder each trial arm received. Although it may not be possible to quantify exact amounts of phosphate bound by phosphate binders, the relative phosphate-binding capacity of various binders can be a useful tool for comparing therapy when doses of multiple phosphate binders are given to patients.