Admission Serum Potassium Level and In-Hospital Mortality

OrlandoWisit Cheungpasitporn and colleagues at the Mayo Clinic in Rochester, Minnesota, recently conducted a single-center retrospective study designed to examine the relationship between serum potassium levels and in-hospital mortality. The study included all hospitalized patients at a tertiary referral hospital. Study results were reported during a poster session at the NKF 2017 Spring Clinical Meetings in a poster titled Admission Serum Potassium Levels and Mortality in Hospitalized Patients.

All patients hospitalized at the center from January 2011 through December 2013 who had admission serum potassium data available were enrolled. Admission serum potassium was stratified into seven groups: <3.0, 3.0 to 3.5, 3.5 to 4.0, 4.0 to 4.5, 5.0 to 5.5, and ≥5.5 mEq/L. Logistic regression analysis was performed to determine the odds ratio (OR) of in-hospital mortality, stratified by various admission serum potassium levels. Admission serum potassium level of 4.0 to 4.5 mEq/L was used as the reference group.

In all, the study included 73,983 patients. The lowest incidence of in-hospital mortality was seen in patients with serum potassium level of 4.0 to 4.5 mEq/L. A U-shaped curve demonstrated the higher in-hospital mortality associated with serum potassium level <4.0 mEq/L and >5.0 mEq/L.

Following adjustment for possible confounders, the ORs for increased risk for in-hospital mortality were 3.26 (95% confidence interval [CI], 2.03-4.98) for potassium level <3.0 mEq/L; 2.40 (95% CI, 1.89-3.04) for potassium level 3.0 to 3.5 mEq/L; 1.38 (95% CI, 1.15-1.60) for potassium level 3.5 to 4.0 mEq/L; 1.89 (95% CI, 1.49-2.38) for potassium level 5.0 to 5.5; and 3.62 (95% CI, 2.73-4.76) for potassium level ≥5.5 mEq/L.

In patients with cardiovascular disease, the highest in-hospital mortality was associated with serum potassium level <3.0 mEq/L (OR, 1.70; 95% CI, 1.31-2.18). In patients with chronic kidney disease, the highest in-hospital mortality was associated with serum potassium level ≥5.5 mEq/L (OR, 2.95; 95% CI, 2.09-4.11).

In summary, the researchers said, “Among all hospitalized inpatients, those with admission serum potassium <4.0 mEq/L and >5.0 mEq/L were associated with an increased risk of in-hospital mortality.”

Source: Cheungpasitporn W, Thongprayoon C, Kittanmongkolchai W, Mao MA, Erickson SB. Admission serum potassium levels and mortality in hospitalized patients. Abstract of a poster presented at the National Kidney Foundation 2017 Spring Clinical Meetings, April 19-22, 2017, Orlando, Florida.