Acute Kidney Injury in Critically Ill Older Adults: Baseline Estimated Glomerular Filtration Rate and Its Association With In-Hospital Mortality

Abstract

Abstract Background: The diagnosis and treatment of Acute Kidney Injury (AKI) rely on recognizing elevated serum creatinine levels as the indicator for suspicion. However, in older adults, lower baseline creatinine levels can hinder the diagnosis, as it may falsely appear normal even in the presence of established AKI. To mitigate this issue, the use of age-validated estimated glomerular filtration rate (eGFR) can enhance the timeliness of interventions. Methods: This study aimed to analyze the baseline eGFR, before the confirmation of AKI, using the Berlin Initiative Study (BIS)-creatinine and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations in older adults who developed AKI after admission to the ICU and its association with mortality. Results: A total of 36 patients, who developed AKI after ICU admission were included. Women were 66.7% and average age of 71.67 years. All patients required mechanical ventilation support, and 91.7% required vasopressors. Initial serum creatinine levels appeared normal (0.87 ± 0.22 mg/dL), but eGFR values indicated reduced renal function, particularly using BIS-creatinine (33% vs 18.2%, CKD-EPI). Mortality was 88.9%, and in the multivariate analysis, the associated factors were age (odds ratio [OR] 1.2, 95% confidence interval [CI]: 1.07-1.5, p = 0.049), persistent AKI (OR 16.20, 95% CI: 2.38-48.88, p = 0.026) and baseline BIS-creatinine value < 60 mL/min/1.73 m² (OR 1.19, 95% CI: 1.07-4.79, p = 0.048). Conclusion: monitoring renal function through eGFR calculation, particularly BIS-creatinine, is important for detecting patients at risk of AKI and contributes to the timely management of AKI in older adult ICU patients.