Propensity Matching AMETHYST-DN and Real-World Population

According to Rajkumar Chinnadurai, MBBS, MD, and colleagues, guideline-directed therapy with renin-angiotensin-aldosterone system inhibitors is rarely achieved in clinical settings, due in part to the risk of hyperkalemia. The AMETHYST-DN trial was designed to assess the effect of patiromer, a potassium binder, on continuation of RAAAS inhibitor therapy in a population of patients with chronic kidney disease, type 2 diabetes mellitus, and hyperkalemia. Study participants were propensity-score matched to a real-word cohort not receiving patiromer.

A total of 304 adults with CKD, type 2 diabetes, and hyperkalemia who were being treated with  RAASA inhibitors were enrolled in the phase 2, open-label AMETHYST-DN trial and randomized to receive patiromer at doses of 8.4 to 33.6 g/day for 12 months.

Propensity-score matching adjusted for systolic blood pressure, heart failure status, and estimated glomerular filtration rate (eGFR) matched the 304 participants with 321 participants in the prospective Salford Kidney Study with CKD, type 2 diabetes, hyperkalemia, and treatment with RAAS inhibitors. Mann-Whitney U or chi-squared tests were used to assess changes in RAAS inhibitor utilization, serum potassium level, blood pressure, proteinuria, and eGFR during 12 months of follow-up.

After matching, the cohort included 135 patients who were matched in a 1:1 ratio to 135 patients who were similar in age, sex, systolic blood pressure, serum potassium level, eGFR, and heart failure status. There were differences between the two groups in diastolic blood pressure (P<.01).

At the 12-month follow-up, 100% of patients in the patiromer group remained on RAAS inhibitor therapy, compared with 38.5% of the Salford Kidney Study group who discontinued RAAS inhibitor therapay (P<.001). Forty-two percent of the RAAS inhibitor discontinuations were associated with hyperkalemia.

Patients in the patiromer group experienced greater reductions in serum potassium level and blood pressure, but no reductions in proteinuria or eGFR, compared with those in the Salford Kidney Study group (P<.05)

In conclusion, the authors said, “These results demonstrate the benefit of patiromer for serum potassium management to enable RAAS inhibitor use, while revealing beneficial effects on blood pressure.”

Source: American Journal of Nephrology