Hyperkalemia Management in Older Adults With Diabetic Kidney Disease Receiving Renin-Angiotensin-Aldosterone System Inhibitors: A Post Hoc Analysis of the AMETHYST-DN Clinical Trial.

Rationale & Objective: Older people are more likely to have reduced kidney function and multiple comorbid conditions predisposing them to hyperkalemia. This post hoc subgroup analysis aimed to evaluate the effectiveness of patiromer, a sodium-free nonabsorbed polymer, in lowering serum potassium levels in older patients receiving a renin-angiotensin-aldosterone system inhibitor with chronic kidney disease (CKD), type 2 diabetes mellitus (T2DM), and hypertension.

Study Design: Post hoc subgroup analysis of the randomized open-label AMETHYST-DN clinical trial.

Setting & Participants: Multicenter clinical trial. Individuals 75 years and older with CKD, T2DM, hypertension, and hyperkalemia at baseline (N = 60; mean age, 77 years; 30 men [50%]; mean estimated glomerular filtration rate, 41.6 ± 14.3 mL/min/1.73 m).

Intervention: Patients with hyperkalemia were randomly assigned to receive patiromer at doses ranging from 4.2 to 16.8 g twice daily.

Outcomes: We evaluated changesin serum potassium levels from baseline to week 4 and time points through 52 weeks. Long-term safety and tolerability were assessed through the end of 52 weeks and included frequency of adverse events, clinical laboratory measurements, and vital signs.

Results: Of 306 AMETHYST-DN participants, 60 were 75 years or older. All 60 patients had CKD and T2DM; 37% had heart failure. At screening, patients had an estimated glomerular filtration rate of 42 mL/min/1.73 m, median urinary albumin-creatinine ratio of 127 mg/g, and baseline mean serum potassium level of 5.19 mEq/L. Mean serum potassium level was reduced at each time point from the first postbaseline visit (day 3) through week 52.

Limitations: This small subgroup analysis was not prespecified and therefore randomization was lost; thus, it should be considered hypothesis generating.

Conclusions: Among older patients with hyperkalemia and diabetic kidney disease, treatment with patiromer resulted in significant reductions in serum potassium levels after 4 weeks and lasted through 52 weeks. Patiromer was effective in lowering serum potassium levels and was well tolerated in older patients.

Funding: Vifor Pharma, Inc.

Trial Registration: NCT01371747.