Association of Serum Ferritin Levels with Short-Term Mortality Risk in Sepsis-associated Acute Kidney Injury: A Retrospective Cohort Study

Background: This study aimed to assess the prognostic significance of serum ferritin levels in sepsis-associated acute kidney injury (SA-AKI) and their correlation with short-term mortality. Despite the established predictive value of serum ferritin in various serious diseases, its specific prognostic relevance in SA-AKI remains unexplored. Therefore, this study seeks to fill this research gap by investigating the association between serum ferritin levels and short-term mortality in patients with SA-AKI. Methods: This retrospective cohort study utilized clinical data from the Medical Information Mart for Intensive Care-IV (MIMIC-IV) database, including all patients with SA-AKI admitted to the intensive care unit for the first time. The relationship between serum ferritin levels and 28-day mortality was explored using restricted cubic splines. Kaplan-Meier curves and Cox regression models were employed to evaluate the association between serum ferritin levels and mortality. Subgroup and sensitivity analyses were performed to verify the robustness of the results. Results: In this study, a total of 878 patients (486 males and 392 females) with a median age of 63.7 years were enrolled. The results indicated that increasing serum ferritin levels were linearly associated with a gradual increase in 28-day mortality rates. Specifically, patients in the highest quartile of serum ferritin had significantly higher 28-day mortality compared to those in the reference group (the first quartile of ferritin levels). After adjusting for various factors, the fully adjusted hazard ratio was 1.92 (95% CI: 1.24–2.96, p = 0.003). Conclusion: In patients with SA-AKI, higher serum ferritin levels are associated with an increased 28-day mortality rate.