Mortality and hyperkalaemia-associated hospitalisation in patients with chronic kidney disease: comparison of sodium zirconium cyclosilicate and sodium/calcium polystyrene sulfonate.

Background: Sodium zirconium cyclosilicate (SZC), a novel drug used for treating hyperkalaemia, is effective in reducing serum potassium levels. The effects of potassium adsorbents on the mortality and hyperkalaemia-associated hospitalisation rates remain unclear. We aimed to examine how mortality and hyperkalaemia-associated hospitalisation rates vary with usage of various potassium adsorbents. Methods: This retrospective study used patients' data between April 2008 and August 2021 obtained from a large-scale Japanese medical claims database. Consecutive patients with chronic kidney disease (CKD) prescribed potassium adsorbents were enrolled and divided into three groups according to the adsorbent type [SZC, calcium polystyrene sulfonate (CPS), and sodium polystyrene sulfonate (SPS)] and were observed for 1 year. The primary outcome was a composite of mortality and hyperkalaemia-associated hospitalisation. Results: In total, 234, 54 183, and 18 692 patients were prescribed SZC, CPS, and SPS, respectively. The SZC group showed a higher event-free survival rate than the other two groups. The hazard ratio for the primary outcome in the CPS and SPS groups was similar in the analyses of the subgroups of patients who did not receive renal replacement therapy and those who received haemodialysis. The SZC group had a higher renin-angiotensin-aldosterone system inhibitors (RAASi) continuation rate compared to CPS and SPS groups, the difference being especially significant for SPS. Conclusions: This real-world study demonstrated the therapeutic effect of SZC in reducing mortality and hyperkalaemia-associated hospitalisations. The high RAASi continuation rate in the SZC group might be a contributing factor for improvement of the primary outcome.