Non-linear Association between Serum Sodium-To-Potassium Ratio and 14-day Mortality in AKI Patients with COPD: A Retrospective Cohort Study

Abstract BACKGROUND There is a lack of evidence about association between serum sodium-to-potassium ratio on admission and 14-day mortality in AKI patients with chronic obstructive pulmonary disease. Herein, we aimed to identify the association between serum Na/K ratio and short term mortality in AKI patients with COPD. METHODS A retrospective analysis of data from the Dyrad database was performed on AKI patients identified by electronic recordings. A multivariate Cox proportional hazard regression model and Kaplan-Meier survival curve analysis were used to analyse the correlation of serum sodium-to-potassium ratio between the serum sodium-potassium ratio and 14-day mortality in AKI patients with COPD. Furthermore, interaction and subgroup analyses were evaluated for the consistency of these correlations. RESULTS A total of 1867 AKI patients with COPD were included in this study. The 14-day mortality was 7.6% (142/1867). Multivariate analysis after adjusting for potential confounders indicated that high serum Na/K ratio(≥33) were associated with decreased risk of 14-day mortality as compared to low serum Na/K ratio (>33), (hazard ratio (HR): 0.67 [95% CI: 0.47–0.97]). Similarly, the Kaplan–Meier (K–M) survival curve also showed that patients with high serum Na/K ratio had a great survival rate. Stratified analyses further showed that depending on the variable tests, an association between higher serum Na/K ratio and 14-day mortality in different subgroups was observed. CONCLUSIONS Among AKI patients with COPD, high serum Na/K ratio was associated with decreased short-term mortality.