Adherence to Potassium Citrate, Changes in 24-Hour Stone Risk Parameters, and Recurrent Kidney Stone Events

Area of Science:

• Nephrology
• Urology
• Pharmacology

Background:

• Patient adherence to preventive pharmacologic therapy (PPT) for urinary stone disease (USD) is suboptimal.
• Effective adherence monitoring is essential for improving PPT outcomes in USD.
• This study investigates potassium citrate adherence measures and their association with urinary parameters and stone recurrence.

Purpose of the Study:

• To assess the association between different potassium citrate adherence measures and changes in 24-hour urine parameters.
• To evaluate the relationship between adherence measures and the risk of recurrent urinary stone events.

Main Methods:

• Retrospective cohort study of Medicare enrollees with USD, hypocitraturia or low urine pH, and potassium citrate prescription.
• Two adherence measures: percentage of days covered (PDC) and change in urinary potassium divided by dose (ΔK/dose).
• Analysis of covariance and Cox models used to assess associations with urine parameters and stone recurrence.

Main Results:

• 63.6% adherence by PDC (≥80%) and 49.1% by ΔK/dose (≥0.5).
• ΔK/dose showed stronger association with increased urinary citrate and pH compared to PDC.
• Lower PDC (<80%) was linked to a higher risk of recurrent stone events (HR 1.431), while ΔK/dose was not significantly associated.

Conclusions:

• Clinically significant differences exist between potassium citrate adherence measures.
• ΔK/dose is a better indicator of medication's effect on urinary citrate and pH.
• Only PDC adherence was a significant predictor of recurrent urinary stone events.