Comparative efficacy of patiromer and sodium polystyrene sulfonate on potassium levels in chronic haemodialysis patients: a randomized crossover trial

BACKGROUND: Hyperkalaemia is frequent in haemodialysis (HD) patients and associated with increased cardiovascular mortality. Despite routine clinical use, evidence regarding the efficacy of potassium (K(+)) binders in HD is scant. We wished to compare the efficacy of patiromer (PAT) and sodium polystyrene sulfonate (SPS) on K(+) levels in this setting. METHODS: We screened patients in three HD centres with pre-HD K(+) value between 5.0 and 6.4 mmol/L, after an initial 2-week washout period for those previously on K(+) binders. We included patients in an unblinded two-arm crossover trial comparing SPS 15 g before each meal on non-dialysis days with PAT 16.8 g once daily on non-dialysis days with randomized attribution order and a 2-week intermediate washout period. The primary outcome was the mean weekly K(+) value. RESULTS: We included 51 patients and analysed 48 with mean age of 66.4 ± 19.4 years, 72.9% men and 43.4% diabetics. Mean weekly K(+) values were 5.00 ± 0.54 mmol/L, 4.55 ± 0.75 mmol/L and 5.17 ± 0.64 mmol/L under PAT (P = .003), SPS (P < .001) and washout, respectively. In direct comparison, K(+) values and prevalence of hyperkalaemia were lower under SPS as compared with PAT (P < .001). While the incidence of gastrointestinal side effects was similar between treatments, SPS showed lower subjective tolerability score (6.0 ± 2.4 and 6.9 ± 1.9) and compliance (10.8 ± 20.4% and 2.4 ± 7.3% missed doses) as compared with PAT (P < .001 for both). CONCLUSION: Both PAT and SPS are effective in decreasing K(+) levels in chronic HD patients. However, at the tested doses, SPS was significantly more effective in doing so as compared with PAT, despite lower tolerability and compliance. Larger randomized controlled trials should be conducted in order to confirm our findings and determine whether they would impact clinical outcomes.