Association between sodium-to-potassium ratio in spot urine and hospitalization due to heart failure in high-risk Japanese patients

Abstract

Background: In Japanese cardiovascular (CV) high-risk patients, the ESPRIT (Evaluation of Sodium Intake for the Prediction of Cardiovascular Events in Japanese High-risk Patients) study showed that high sodium excretion (≥4.0 g/day) was associated with a composite CV events of heart failure (HF) hospitalization, acute coronary syndrome, cerebrovascular events, and CV deaths. In this context, the sodium-to-creatinine (Na/Cr) ratio in spot urine was found to be significantly associated with HF hospitalizations. Since a stable potassium balance plays a particularly relevant role for CV patients, this post-hoc study was designed to investigate the extent to which consideration of the sodium-to-potassium (Na/K) ratio represents a better predictor of HF hospitalizations in the ESPRIT study population. Methods: This is a post-hoc analysis of a previously reported ESPRIT study (n = 520, 60 HF hospitalizations). Results: Receiver operating curve analysis yielded optimal Na/K ratio cut-off value of 2.9 for detecting HF hospitalization. Kaplan–Meier curve showed that high Na/K ratio in spot urine was associated with increased HF hospitalization (p < 0.001). Cox proportional hazards model analysis revealed that high Na/K ratio was associated with HF hospitalization with a hazard ratio of 2.97 (confidence interval: 1.67–5.61). An association between high Na/K ratio and HF hospitalization remained after adjustments for Na/Cr ratio in spot urine or the use of diuretics. Conclusion: The Na/K ratio in spot urine is associated with HF hospitalization in high-risk Japanese patients.

Keywords

• ESPRIT study
• Post-hoc analysis
• Heart failure hospitalization
• Sodium
• Potassium
• Spot urine