Phosphate binder in dialysis: a cross-sectional study of patients' adherence and pill burden.

Introduction: Phosphate (P) binders are among the most common medications prescribed to control P levels in patients with chronic kidney disease on dialysis. There is still a paucity of data on adherence to P binders with no comparison between dialysis modalities.

Methods: We accessed factors associated with P binder adherence among patients on dialysis in an academic hospital. Adherence was calculated as the ratio between the number of pills taken per day as reported and the prescribed number of pills. Patients were considered non-adherent if adherence was at least 20% less or 30% more than prescribed.

Results: Patients (N = 137) were young, mostly women, and on dialysis for a median time of 53 months. Sevelamer and calcium carbonate were prescribed as P binders to 70.8% and 10.2% of patients, respectively, with no difference across dialysis modalities (p = 0.839). P correlated with the number of pills prescribed (r = 0.368, p = 0.001) and the number of pills taken per day (r = 0.275, p = 0.001). Hyperphosphatemia was found in 52 patients (36.4%). Adherence to Ca carbonate and sevelamer was 100% and 68.4%, respectively. Non-adherent patients were women, younger, with higher serum albumin and urea, and lower serum calcium. Logistic regression showed that female sex (HR 3.30, 95% CI: 1.39-7.84, p = 0.007) and hemodialysis vs. peritoneal dialysis (HR 4.55, 95%, CI: 1.26-16.39, p = 0.021) remained independently associated with a non-adherence behavior.

Conclusions: The current study suggests that strategies to increase adherence should be implemented. Whether phosphate binder adherence is associated with better outcomes deserves further investigation.