Impact of admission serum potassium on mortality in patients with chronic kidney disease and cardiovascular disease.

BACKGROUND

Little is known about the effect of admission potassium (K) on risk of in-hospital mortality in chronic kidney disease (CKD) and cardiovascular disease (CVD) patients.

AIM

The aim of this study was to assess the relationship between admission serum K and in-hospital mortality in all hospitalized patients stratified by CKD and/or CVD status.

DESIGN AND METHODS

All adult hospitalized patients who had admission serum K between years 2011 and 2013 were enrolled. Admission serum K was categorized into seven groups (<3.0, 3.0-3.5, 3.5-4.0, 4.0-4.5, 4.5-5.0, 5.0-5.5 and ≥5.5 mEq/L). The odds ratio (OR) of in-hospital mortality by admission serum K, using K 4.0-4.5 mEq/L as the reference group, was obtained by logistic regression analysis.

RESULTS

73,983 patients were studied. The lowest incidence of in-hospital mortality was associated with serum K within 4.0-4.5 mEq/L. A U-shaped curve emerged demonstrating higher in-hospital mortality associated with both serum K < 4.0 and >4.5 mEq/L. After adjusting for potential confounders, both serum K < 4.0 mEq/L and >5.0 mEq/L were associated with increased in-hospital mortality with ORs of 3.26 (95% CI 2.03-4.98), 2.40 (95% CI 1.89-3.04), 1.38 (95%CI 1.15-1.66), 1.89 (95% CI 1.49-2.38) and 3.62 (95%CI 2.73-4.76) when serum K were within <3.0, 3.0-3.5, 3.5-4.0, 5.0-5.5, and ≥5.5 mEq/L, respectively. In CVD patients, the highest in-hospital mortality was associated with serum K < 3.0 mEq/L (OR 1.70, 95%CI 1.31-2.18). In CKD patients, the highest in-hospital mortality was associated with serum K ≥ 5.5 mEq/L (OR 3.26, 95%CI 2.14-4.90).

CONCLUSION

Admission serum K < 4.0 mEq/L and >5.0 mEq/L were associated with increased in-hospital mortality. The mortality risk among patients with various admission potassium levels was affected by CKD and/or CVD status.