Abstract 11689: The Association Between Serum Potassium and Mortality in a Cohort of Patients With Diminished Kidney Function
Introduction: Serum potassium (K) is tightly regulated by the kidney between 3.5 and 5.0 mEq/L, which is essential for cardiac action potential and normal function. However, due to impaired excretory capacity, patients with chronic kidney disease (CKD) often have elevated serum K that potentially increases morbidity and mortality.
Hypothesis: To better understand the burden of hyperkalemia and how this may vary by severity of renal disease, we studied the association of serum K with rates of mortality within narrow strata of estimated glomerular filtration rate (eGFR).
Methods: We identified a retrospective cohort of patients with eGFR <60 mL/min/1.73m2 between Jan-2009 and Jun-2013 (N=55,266). Patients were followed until 30-Jun-2013 or censoring (death, end-stage renal disease, transfer of care). Serum K, eGFR, and 13 covariates including demographics, comorbidities and medication use (beta blockers, centrally acting calcium channel blockers, loop and thiazide diuretics) were considered on a time-varying basis, updated at each K measurement. Death was considered as event per time at-risk.
Results: At baseline, 15%, 4%, and 1% of patients had serum K 5.0-5.4, 5.5-5.9, and ≥6.0 mEq/L, respectively; prevalence was greater in lower eGFR strata. In each eGFR stratum, a U-shaped association between serum K and mortality was observed (figure shown for eGFR <30 mL/min/1.73m2). Compared to K 4.5-4.9 mEq/L, adjusted incidence rate ratios (IRRs) for K ≥6.0 mEq/L were 3.08 [95%CI, 2.17-4.37], 2.74 [1.13-6.74], 1.72 [0.76-3.86], and 3.90 [1.23-12.32] in eGFR <30, 30-39, 40-49, and 50-59 mL/min/1.73m2 strata, respectively.
Conclusions: Serum K ≥6.0 mEq/L is potently and independently associated with increased mortality among CKD patients. This association is independent of degree of kidney failure. Future population studies should examine cause-specific mortality according to hyperkalemia strata to identify possible mechanisms of cardiac death.
Author Disclosures: A. Yang: Employment; Modest; ZS Pharma. J. Luo: None. D.E. Jensen: None. S.M. Brunelli: Consultant/Advisory Board; Modest; Keryx, Otsuka.
- © 2014 by American Heart Association, Inc.