Abstract
The clinical significance of elevated baseline serum potassium (K+) levels in hospitalised patients is rarely described. Hence, we performed a retrospective study assessing the significance of elevated K+ levels in a one-year admission cohort. Adult patients without hypokalaemia or end-stage renal disease were included. Adverse outcomes were all-cause mortality, hospital-acquired acute kidney injury, and events of arrhythmia. In total, 17,777 patients were included in the study cohort, and a significant difference (P < 0.001) was observed in mortality according to baseline serum K+ levels. The adjusted hazard ratios (HRs) and associated 95% confidence intervals (CIs) of all-cause mortality for K+ levels above the reference range of 3.6–4.0 mmol/L were as follows: 4.1–4.5 mmol/L, adjusted HR 1.075 (95% CI 0.981–1.180); 4.6–5.0 mmol/L, adjusted HR 1.261 (1.105–1.439); 5.1–5.5 mmol/L, adjusted HR 1.310 (1.009–1.700); >5.5 mmol/L, adjusted HR 2.119 (1.532–2.930). Moreover, the risks of in-hospital acute kidney injury and arrhythmia were higher in patients with serum K+ levels above 4.0 mmol/L and 5.5 mmol/L, respectively. In conclusion, increased serum K+ levels, including mild elevations may be related to worse prognosis. Close monitoring and prompt correction of underlying causes or hyperkalaemia itself is warranted for admitted patients.
Highlights
Risks of all-cause mortality, hospital-acquired acute kidney injury (AKI), and arrhythmia increased in admitted patients with elevated baseline serum K+ levels
Our study is the first on to demonstrate a significant association between mild elevations in baseline serum K+ levels, which were previously considered normal or without clinical significance[18], and risk of short-term mortality and AKI in patients admitted to general wards
Few previous studies have considered the impact of elevated serum K+ level, with most of them focussing on the relationship between serum K+ levels and adverse prognosis in patients with cardiovascular or chronic kidney diseases[8, 11, 12, 21,22,23]
Summary
Hyperkalaemia is one of the major electrolyte disturbances in medicine[1, 2] This electrolyte imbalance is prevalent in patients with cardiovascular disease or impaired kidney function[3, 4], and the recent use of several medications related to serum potassium (K+) levels has further increased its incidence[5,6,7]. We evaluated the clinical significance of baseline serum K+ levels on prognosis in a one-year cohort of patients who were admitted to general wards. We assessed the risks of mortality, acute kidney injury (AKI), as well as arrhythmia, and demonstrated that elevation of serum K+ levels was an independent risk factor for worse prognosis regardless of the presence of cardiovascular disease or impaired renal function
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