Potassium-guided sodium zirconium cyclosilicate kept more haemodialysis patients in range, in a post hoc analysis

Design

Post hoc analysis of a single-centre, open-label randomised trial

Population

116 maintenance haemodialysis patients with chronic hyperkalaemia (58 per group)

Primary outcome

Sustained potassium response during months 3 to 6

Effect

43.1% vs 13.8% (adjusted RR 3.02, 95% CI 1.49 to 6.14)

This exploratory post hoc analysis used data from a single-centre, open-label randomised trial of 116 haemodialysis patients with chronic hyperkalaemia (58 per group). The treated group had individualised potassium-guided sodium zirconium cyclosilicate on non-dialysis days. The primary outcome was sustained response during months 3 to 6: at least three of four predialysis potassium values after the long interdialytic gap within 4.0 to 5.0 mmol/L, with no unplanned dialysis for potassium of 6.5 or more. Missing values counted as non-response.

The primary outcome was met in 43.1% of treated and 13.8% of control patients (adjusted risk ratio 3.02, 95% CI 1.49 to 6.14). Sustained response in the wider 4.0 to 5.5 range was 65.5% vs 37.9% (aRR 1.74). Two or more values of 5.5 or above occurred in 19.0% vs 62.1% (aRR 0.31, 95% CI 0.18 to 0.55).

The authors state that clinical outcomes were not evaluated and the biochemical improvement should not be taken as proof of clinical benefit. The trial was retrospectively registered and open-label.

• Sustained potassium control (4.0 to 5.0 mmol/L) occurred in 43.1% vs 13.8% (aRR 3.02).
• Two or more potassium values of 5.5 or above occurred in 19.0% vs 62.1%.
• The analysis was post hoc, from a single-centre open-label trial with retrospective registration.
• No clinical outcomes were evaluated.
• Check predialysis potassium after the long interdialytic gap when judging control.

Why it matters

A single predialysis potassium misses patients who repeatedly cross the threshold across months.

Don't overread it

This is an exploratory post hoc analysis of biochemical results, and it cannot show fewer arrhythmias or deaths.

The statistics, in plain English

Counting missing potassium measurements as failures makes the analysis conservative but also means part of the difference could reflect who attended. The wide confidence interval around 3.02 (1.49 to 6.14) shows how uncertain the size of the effect is in 116 patients.

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