Background and Importance Suboptimal treatment adherence to phosphate-binding drugs frequently occurs in hemodialysis patients, mostly because of a high pill burden and a complex treatment schedule. Several pharmacist interventions have been developed to improve adherence to phosphate-binding drugs, often with minor effects on adherence and phosphate concentrations.

Aim and Objectives We designed a complex, adherence-improving pharmacist intervention in which barriers to adherence are discussed, combined with a dose reduction of phosphate-binding drugs with the aim to increase adherence and thereby reduce phosphate concentrations.

Material and Methods We performed a prospective, single-centre intervention study in 69 hemodialysis patients with hyperphosphatemia and a high pill burden of phosphate-binding drugs. The complex, adherence-improving intervention consisted of three pharmacist-patient consultations at baseline, at 1–2 weeks, and at 3 months. At baseline the Quick Barrier Scan (QBS), to investigate barriers to adherence, and MARS-5 (Medication Adherence Report Scale 5, patient-reported adherence), were administered. At 1–2 weeks, the pharmacist provided patient recommendations based on the QBS, plus a dose reduction for phosphate-binding drugs. After three months, patient experiences were discussed, and MARS-5 was repeated. The primary outcome parameter was the mean phosphate concentration in the three months after start of the intervention versus the three months before. Secondary outcome parameters were pill burden for phosphate-binding drugs and patient-reported adherence (MARS-5) at baseline and after three months. Data were analysed with SPSS version 28.0, a paired T-test was used to compare phosphate concentrations and pill burden, the Wilcoxon signed rank test was used to compare MARS-5.

Results The mean (±SD) phosphate concentration did not change (1.99±0.38 mmol/L before versus 2.04±0.35 mmol/L after, p=0.193). Mean daily phosphate-binder pill burden decreased from 8.6±3.1 to 5.7±2.7 units (p<0.001). Patient-reported adherence increased, although the median adherence did not change (24 IQR 22–25, before, versus 24 IQR 23.25–25 after, p=0.008).

Conclusion and Relevance Although the intervention did not reduce phosphate concentrations, a major reduction in phosphate-binder pill burden was achieved, which implies a more effective use of the phosphate-binding drugs. This complex, adherence-improving intervention seems promising in decreasing pill burden and improving adherence, but our results need to be confirmed in larger, controlled studies.

Conflict of Interest Conflict of interest.

Corporate sponsored research or other substantive relationships:

The study was partially finananced with the PIONIER+ fund from the Dutch Kidney foundation