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

Abstract

Abstract Background: Acute kidney injury (AKI) is a serious illness with high mortality rates, particularly in older adult patients in intensive care units (ICUs). Early detection of AKI is crucial to prevent complications, but creatinine-based eGFR could result in systematic bias in older patients. Methods: This study aimed to analyze estimated glomerular filtration rate (eGFR) using the Berlin Initiative Study (BIS)-creatinine and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations in older adult who developed AKI after admission in ICU and assess its association with mortality. Results: A total of 36 patients who developed AKI during their ICU stay were included. The majority were women (66.7%), average age of 71.67 years. All patients required mechanical ventilation support and 91.7% required the administration of vasopressors during hospitalization, only 25% of the patients were notified to nephrologists. 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). Regarding KDIGO classification, 69% of the patients were classified as stage 1. Mortality was 88.9% and in the multivariate analysis, the factors associated 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 BIS-creatinine value < 60 mL/min/1.73 m² (OR 1.19, 95% CI: 1.07-4.79, p = 0.048). Serum creatinine alone was unsatisfactory screening test for evaluating renal function in older adult patients, leading to under-recognition of AKI. Conclusion: In conclusion, monitoring renal function through eGFR calculation, particularly BIS-creatinine, is crucial for detection and management of AKI in older adult ICU patients. Lower eGFR values were associated with increased mortality. These findings emphasize the need for proper investigation and referral of older adults with renal injury to improve outcomes and reduce morbidity and mortality.