Abstract:

Objective To evaluate and compare the performance of the Chronic Kidney Disease Epidemiology Collaboration （CKD-EPI） equation， the abbreviated Modification of Diet in Renal Disease （aMDRD） equation， the Cockroft-Gault （C-G） formula， the Mayo Clinic Quadratic （MCQ） equation， and the Berlin Initiative Study 1 （BIS1） equation in determining renal function among critically ill patients， and to identify the most appropriate method for clinical application. Methods Critically ill patients admitted to the Intensive Care Units of the Department of Geriatric Medicine at the First Affiliated Hospital of Nanjing Medical University （Jiangsu Province Hospital） between June 2020 and June 2022 were included. Their renal function was assessed within 48 hours of admission using the 24-hour creatinine clearance rate （CrCl_24h） as the reference standard， and compared with the CKD-EPI equation， aMDRD equation， C-G formula， MCQ equation， and BIS1 equation. The precision and accuracy of each equation in evaluating renal function in critically ill patients were analyzed. Results Total of 534 patients were included in the study. （1） The aMDRD equation exhibited the least bias （-3.91）， yet the accuracy of the five estimated glomerular filtration rate （eGFR） equations was relatively low， ranging from 42.9% to 63.1%. （2） For renal function grading， the weighted κ agreement values between the CKD-EPI equation， aMDRD equation， C-G formula， MCQ equation， BIS1 equation， and CrCl_24h were 0.464， 0.555， 0.403， 0.405， and 0.159， respectively （all P < 0.001）. （3） Among patients with severe kidney function decline ［CrCl_24h ≤ 60 mL/（min·1.73 m²）］， the eGFR value derived from the C-G formula was the lowest， while that from the BIS1 equation was the highest. In patients with normal or moderately reduced renal function ［60 mL/（min·1.73 m²）^{< CrCl_24h ≤ 130 mL/（min·1.73 m2）］， the eGFR value of the C-G formula remained the lowest， whereas the MCQ equation yielded the highest eGFR value. For patients with augmented renal function ［CrCl_24h > 130 mL/（min·1.73 m2）］， the eGFR value of the BIS1 equation was the lowest， and the aMDRD equation produced the highest eGFR value. （4） When renal function was severely decreased or augmented ［CrCl_24h > 130 mL/（min·1.73 m2）］， the accuracy of the CKD-EPI and MCQ equations declined. Conversely， as creatinine clearance increased， the accuracy of the aMDRD equation improved gradually. The C-G formula demonstrated an opposite trend compared to the aMDRD equation， and the BIS1 equation exhibited low accuracy across all groups. （5） The optimal critical values ［mL/（min·m2）］ for diagnosing augmented renal clearance （ARC） using the five eGFR equations were as follows： eGFR_CKD-EPI： 91.1， eGFR_aMDRD： 99.84， eGFR_C-G： 76.27， eGFR_MCQ： 100.87， eGFR_BIS1： 82.36. Conclusions The precision and accuracy of the five eGFR equations are relatively low， making them unsuitable for assessing renal function in critically ill patients. Collecting 24-hour urine to calculate creatinine clearance remains an essential method for evaluating renal function in this population. In the absence of early CrCl_24h data upon ICU admission， the cut-off values of the eGFR equations may serve as a tool for the early identification of ARC. Additionally， the aMDRD equation can provide a rough estimate of creatinine clearance in critically ill patients.}

Key words: critically ill, 24 h creatinine clearances rate, estimated glomerular filtration rate, renal function