Supplementary Material for: Association between serum albumin to creatinine ratio and readmission in elderly heart failure patients: A Retrospective Cohort Study

Introduction: This study aimed to investigate the relationship between the serum albumin to serum creatinine ratio (sACR) and readmission in elderly heart failure patients.
Methods: We conducted a retrospective cohort study using data from the PhysioNet Restricted Health Data database. The exposure variable was sACR and the outcome variable readmission. Multivariate logistic regression and subgroup analyses were performed to assess the independent association between sACR and readmission. Smooth curve fits were applied to examine the non-linear relationship. We employed multiple imputation and E-value sensitivity analyses to assess the robustness of our results.
Results: Our study included 1,725 participants, of whom 40.6% were male, 59.2% were aged 60-79 years, and 40.8% were aged 80 years and older. After adjusting for potential confounders, we found that for each unit increase in sACR, the 28-day readmission rate decreased by 48% (OR = 0.52, 95% CI: 0.29-0.95, P = 0.003). The 28-day readmission rate was significantly higher in the low sACR group (sACR<0.32) than in the high sACR group (sACR>0.51) (OR = 0.47, 95% CI: 0.3-0.76, P=0.002). Similar results were observed for 3-month and 9-month readmission. Subgroup analysis showed no significant interactions. A nonlinear relationship was observed between the sACR and readmission. Sensitivity analyses have confirmed the robustness of our results.
Conclusion: There is a negative association between sACR and readmission in Chinese heart failure patients. Our study may offer novel insights into the management of heart failure readmissions.