Renal biomarkers and electrolytes as predictors of 6-month emergency readmission in heart failure: analysis stratified by sex

Introduction: heart failure leads to hospital readmissions, with potential differences in renal biomarkers and serum electrolytes measured during the prior hospitalization. Objective: to evaluate which renal biomarkers and serum electrolytes predict six-month emergency readmission in patients with heart failure, stratified by sex. Materials and Methods: retrospective cohort study using a secondary database that included 1904 hospitalized heart-failure patients with complete information on renal biomarkers, serum electrolytes, age, sex, and six-month emergency readmission. The variables analyzed were creatinine, urea, uric acid, calcium, potassium, chloride, cystatin C, and GFR. The outcome was emergency readmission within six months. Descriptive analyses and sex-stratified Cox regression models were applied. Results: in men, each 1 mL/min decrease in GFR was associated with an increased risk of emergency readmission (HR = 1.007; p = 0.01), whereas this association was not significant in women. Calcium was associated with higher risk only in women (HR = 2.212; p = 0.002), as was age ≥70 years (HR = 1.308; p = 0.034). No significant associations were observed for creatinine, uric acid, urea, potassium, chloride, or cystatin C. When including sex interactions, the interactions sex × creatinine (p = 0.045) and sex × chloride (p = 0.007) were significant. Conclusions: renal biomarkers and serum electrolytes showed sex-specific prognostic associations. In particular, calcium in women and GFR in men, along with older age, demonstrated utility in identifying patients at higher risk of emergency readmission within six months following hospitalization for heart failure.