All-cause mortality associated with hyperkalaemia in hospitalised adult patients: a scoping review

Hyperkalaemia (HK) is a common and potentially fatal electrolyte disturbance encountered in hospitalised adult patients. An acute increase in potassium concentration reduces the resting membrane potential of muscle and the cardiac conduction system, causing muscle weakness and cardiac arrhythmias such as ventricular tachycardia and ventricular fibrillation (4). HK is generally defined as a serum potassium concentration (K+) exceeding 5.5 mmol/L. The prevalence of HK varies depending on the threshold set for the K+. A 2022 systematic review reported an overall global prevalence of 8.6% with an incidence of 5.1 cases per 100 person-years. A total of 144 studies examined the prevalence of hyperkalaemia (HK) in hospitalised patients, reporting it to be 8.7% regardless of the definition used. When HK was specifically defined as a K+ of ≥5.5 mmol/L, the prevalence was similar at 8.6%. Only 14 of 542 included studies were performed in Africa. Another large study performed in Cape Town, South Africa that included 1921 adult patients reported a period prevalence of 3.7% over one year. HK is frequently encountered in patients with acute and chronic kidney disease, heart failure, diabetes mellitus and with use of certain drugs that interfere with renal elimination such as potassium-sparing diuretics, renin-angiotensin-aldosterone system inhibitors, non-steroidal anti-inflammatory drugs and trimethoprim, or cause a shift of potassium out of cells such as beta-blockers. The association between HK and all-cause hospital mortality has been well established and ranges from 12.9–42.5%. A recent study from sub-Saharan Africa reported an all-cause mortality rate of nearly 30% in hospitalised patients with HK which was similar to another study. Predictors of all-cause mortality included the severity of HK, age, acute kidney injury and received emergency therapy for HK. We could not identify any systematic or scoping reviews that reported on the all-cause mortality of hospitalised adult patients with HK. Therefore, by performing this scoping review, we aim to fill this knowledge gap.