Serum total protein-to-albumin ratio predicts risk of death in septic acute kidney injury patients: A cohort study

Objective: Sepsis is the leading cause of acute kidney injury (AKI). Increasing evidence shows that serum total protein-to-albumin ratio (TAR) could serve as an inflammation- and nutrition-based prognostic marker in various diseases. The purpose of this study was to assess the prognostic value of TAR in predicting the clinical outcomes of septic AKI patients.Methods: We retrospectively enrolled septic AKI patients between August 2015 and August 2022 at West China Hospital of Sichuan University. Patients admitted between August 2015 and August 2021 were defined as the original cohort. The primary outcomes were 30-day and 90-day all-cause mortality of septic AKI patients. The secondary outcomes were septic shock, transfer to the intensive care unit, mechanical ventilation, requirement for renal replacement therapy, and stage 3 AKI. The utility of TAR was further verified in a validation cohort of septic AKI patients admitted between September 2021 and August 2022.Results: In the original cohort, a total of 309 eligible patients with a median age of 58 years were enrolled, of which 70.2 % were males. In multivariate Cox analysis, after adjustments for age, sex, and other confounding factors, higher TAR at admission was associated with an increased risk of 30-day and 90-day all-cause mortality in septic AKI patients (HR 1.91, 95 % CI 1.18-3.09, P = 0.008; HR 1.54, 95 % CI 1.01-2.34, P = 0.043, respectively). Subgroup analysis revealed no significant interactions in most strata. TAR at AKI diagnosis or discharge was not significantly related to 30-day (P = 0.120 and 0.153, respectively) or 90-day mortality (P = 0.147 and 0.124, respectively). We found no relationship between baseline TAR and septic shock, transfer to the intensive care unit, mechanical ventilation, requirement for renal replacement therapy, or stage 3 AKI (all P > 0.05). In the validation cohort of 81 septic AKI patients, TAR at admission remained a significant prognosticator for 30-day and 90-day mortality (HR 4.367, 95 % CI 1.20-15.87, P = 0.025; HR 4.237, 95 % CI 1.59-11.27, P = 0.004).Conclusions: TAR at admission is an independent risk factor for 30-day and 90-day mortality in septic AKI patients and could be used as a convenient and economic septic AKI prognostic indicator.