A Pilot Study of OkKidney, a Phosphate Counting Application in Patients on Peritoneal Dialysis

Hyperphosphatemia is associated with adverse outcomes in patients treated with peritoneal dialysis (PD). We have shown that a fixed meal phosphate binder dosing schedule is not appropriate. The purpose of this study was to evaluate the beta version of OkKidney, a phosphate counting app that matches meal phosphate content with binder dose.

A convenience sample of adult patients treated with PD completed a pre-survey that included the technology readiness index (TRI 2.0). After a short information session, patients used OkKidney for 30 days. Pre- and post-intervention serum calcium, serum phosphate, and calcium carbonate binder intake were collected and compared using a paired t-test. A post-intervention survey using a 5-point Likert scale was used to gather patient feedback.

Ten patients (5M, 5F) completed the study protocol. Participants were 55 ± 17 years old, predominately Caucasian, retired (60%), and owned a smartphone (70%). The median TRI score was 3.66 (max 5), indicating a moderate level of readiness. The post-survey results indicated a favorable rating for ease of use (μ = 4.4 ± 0.84) and usefulness (μ = 4.3 ± 0.68) of OkKidney. The average serum phosphate (p = 0.99) and calcium (p = 0.68) were not different pre-/post-intervention, but calcium carbonate intake tended to decrease (p = 0.12).

Patients reported a positive experience with OkKidney. Further patient-specific adjustments of the binder dose to meal phosphate content may be required to demonstrate a statistically significant decrease in phosphate levels. We believe a larger trial is warranted to investigate the clinical implications of this app.