Sodium zirconium cyclosilicate treatment and rates of emergency interventions for hyperkalaemia: a propensity-score weighted case-control study.

Background: Sodium zirconium cyclosilicate (SZC) reduces serum potassium in patients with chronic hyperkalaemia in clinical trials, but its role in the emergency treatment of hyperkalaemia is unproven. We hypothesized that SZC use for emergent hyperkalaemia would be associated with a reduction in rates of emergency interventions for hyperkalaemia. Methods: This was a single-centre, propensity score-weighted case-control study of patients admitted with hyperkalaemia to a specialist renal centre. We randomly selected 250 patients admitted between April 2021 and September 2022 (post-SZC era) with a potassium level ≥5.5 mmol/l treated with at least one ≥10 g dose of SZC (treatment group). We randomly selected a comparator group of 250 patients admitted between January 2018 and December 2019 (pre-SZC era) with a potassium level ≥5.5 mmol/l (control group). Baseline demographic and clinical characteristics were recorded and used as covariates for propensity scoring and inverse probability treatment weighting (IPTW). Our primary outcome measure, rates of emergency haemodialysis (HD), was tested using unadjusted models and multivariable logistic regression models on unweighted data in addition to unadjusted models on weighted data. We also reviewed rates of emergency temporary central venous access as a secondary outcome. Results: A total of 59% were male, the mean age was 67 years (standard deviation 14) and 149 (30%) were receiving maintenance dialysis. IPTW achieved satisfactory balance of covariates between the treatment and control groups. In the treatment group, patients were 77% less likely to need emergency HD {odds ratio [OR] 0.23 [confidence interval (CI) 0.17-0.31]}. This result was consistent following analysis of weighted and unweighted data. Similarly, patients treated with SZC were 73% less likely to require emergency temporary central venous access [OR 0.27 (CI 0.20-0.36)]. Conclusion: SZC was associated with a significant reduction in the rates of emergency HD and emergency temporary central venous access in patients admitted to a specialized renal centre with emergent hyperkalaemia.