Influence of iron metabolism on all-cause death in patients with sepsis-associated acute kidney injury: a retrospective cohort study

Objective To investigate the relationship between iron metabolism and all-cause mortality in patients with sepsis-associated acute kidney injury (SA-AKI). Methods The clinical data of SA-AKI patients from the First Affiliated Hospital of Guangxi Medical University were analyzed retrospectively. All patients were followed up for 90 days, after which they were divided into survival and death groups Cox regression analysis was used to explore the risk factors for all-cause death in patients with SA-AKI. Receiver operating characteristic (ROC) and Kaplan–Meier curves were used to analyze the relationship between different iron metabolism indexes and prognosis in patients with SA-AKI. Results A total of 3,049 SA-AKI patients were included, with a male-to-female ratio of 1.22:1 and an average age of 64.32 ± 16.46 years. Of these patients, 40.0% underwent renal replacement therapy (RRT), 21.4% received invasive mechanical ventilation, 14.5% received transfusions, and 44.8% were treated with vasoactive drugs. The 90-day all-cause mortality was 20.5%. The area under the curve (AUC) for the combined indexes of iron metabolism (serum iron, serum ferritin (SF) , and transferrin (TRF)) for predicting all-cause mortality in SA-AKI patients was 0.757. Kaplan–Meier survival curves revealed that the 90-day cumulative survival rate of the increased serum iron, increased SF and decreased TRF groups were significantly lower than that of the normal group. Multivariate Cox regression analysis revealed that the increased serum iron concentration, and SF concentration; decreased TRF concentration were independent risk factors for 90-day all-cause death in SA-AKI patients. Conclusion Elevated serum iron and SF concentrations and decreased TRF concentration are important factors affecting the mortality of patients with SA-AKI. Abnormal iron metabolism indexes in patients with SA-AKI may be associated with a high risk of all-cause death.