Date of publication: June 29, 2018

News & Views

ERA-EDTA 2018: Growing Understanding of the Complexities of Hyperkalaemia

The annual ERA-EDTA conference brings together nephrology experts from around the world, and this, its 55th year, was no different. Here, the COMPACT RENAL team summarise the congress highlights relating to hyperkalaemia (HK), including real-world analysis of the impact of HK and analysis of studies into the potassium binders, patiromer and sodium zirconium cyclosilicate (SZC).

RAASi and hyperkalaemia

The association between renin-angiotensin-aldosterone system inhibition (RAASi) and hyperkalaemia is well recognised. Real-world data presented by Marco Trevisan, Sweden showed the 1-year incidence for HK amongst patients receiving mineralocorticoid receptor antagonists (MRAs). 18% of patients developed HK within the first year, the majority occurring within the first three months. 47% of patients who experienced a moderate/severe HK event had their MRA discontinued and– dose reduction was seen in 10%. [SAO024]

A Japanese study showed that the combination of beta blockers and RASi significantly increases serum potassium levels ([sK+]compared to beta blockers alone in ESRD but non-dialysis patients, with the tendency to be more prominent in patients >75yrs. [SP307]

Rates of moderate and severe HK events among RAASi users in the UK were reported in another poster, with a rate of 11.5 and 12.3 per 100 patient-years in those with CKD Stage 4 and Stage 5, respectively. [SP324]

Hyperkalaemia management and RAASi use

One result of the link between RAASi and HK development can be the suboptimal use of these beneficial therapies. An observational study of data in patients with CKD Stage 3+ in the UK reported that:

  • 67% of patients did not receive the full ESC-recommended dose of any RAASi
  • 5% received<50% of the recommended dose
  • The adjusted odds ratio of a RAASi dose down-titration or discontinuation increased with HK, and HK severity [FP337]

Another study examined the impact of recurrent HK (≥2 episodes of s[K+] ≥5.5 mEq/L in a year) in non-dialysis patients. 83% of patients had two HK episodes and 17% 3 or more episodes, and by the time of the second HK event, RAASi prescription was significantly reduced for all classes of medication, from 60.5% to 51.7% (p<0.001). [FP364]

Identifying the right potassium range – a moving target

The challenges of managing potassium levels include the narrow window within which it needs to be kept and the change in potassium tolerance as CKD progresses. Using data from the Stockholm Creatinine Measurements (SCREAM) project, Dr Alessandro Gasparini, UK and team demonstrated how the mortality risk of CKD patients due to HK differs from those patients with normal kidney function, supporting the evidence that s[K+] is better tolerated with worsening kidney function and challenging the use of a single potassium target range for all patients. [SAO023] A poster presentation using the same data set concluded that the lowest mortality risk was observed in a much narrower potassium range of 4.0-4.4 mmol/L in the overall study population. [FP341]

Another team performed a systematic review to look at the mortality risk associated with s[K+] levels in both dialysis and non-dialysis patients, reporting a 1.77 times increased risk of mortality in a non-dialysis patient with s[K+] of 6.5 mmol/L vs a dialysis patient with the equivalent s[K+]. [SAO068].

The burden of hyperkalaemia

Comparing healthcare costs in the 6 months prior to and after an HK event, a Danish cohort study reported an overall cost of € 9,000 primarily driven by increased use of hospital-based care (74% of overall HK associated costs). [SP299]

Data from the UK found an incidence of s[K+] >5.0mmol/L of 48% in patients with CKD Stage 3+,which was associated with a longer length of stay in hospital. Relative to matched, non-HK controls, in-hospital and post-discharge mortality was 20% greater for patients with s[K+] ≥5.0mmol/L, rising to 60% for those with s[K+] ≥5.5 mmol/L and ≥6.0 mmol/L. [FP371]

Novel potassium binders

Combining data from the AMETHYST-DN, OPAL-HK and TOURMALINE studies, Dr Patrick Rossignol, and colleagues analysed the effect of patiromer on s[K+] in HK (s[K+]> 5.0 mmol/L) patients with and without obesity (obesity defined as ≥30 kg/m2). Over 90% of all patients were receiving RAASi therapy at baseline, with 21% vs 10.9% receiving dual therapy in obese and non-obese groups, respectively. Treatment with patiromer resulted in a similar reduction in s[K+] over time in both patient groups. [FP102]

Retrospective analysis of data from a Phase III study of SZC compared the efficacy and safety in HK patients with and without diabetes, concluding that SZC was similarly effective in both patient groups, reducing s[K+] and maintaining normokalaemia for up to 12 months. [SP421]

Further analysis of the same SZC study compared its efficacy and safety in outpatients with a baseline eGFR<30 vs ≥30 mL/min/1.73 m2. SZC treatment reduced s[K+] and maintained normokalaemia up to 12 months in both groups, although a higher dose was required during the maintenance phase for those with eGFR<30 vs those with eGFR≥30 mL/min/1.73 m2.[FP071]

 

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