Creatinine generation is reduced in patients requiring continuous venovenous hemodialysis and independently predicts mortality

• Published in: Nephrology, dialysis, transplantation Vol. 27; no. 11; pp. 4088 - 4094
• Main Authors: WILSON, Francis P, SHEEHAN, Jessica M, MARIANI, Laura H, BERNS, Jeffrey S
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01-11-2012
• Series: Editor's choice
• Subjects: Acute Kidney Injury - blood; Acute Kidney Injury - diagnosis; Acute Kidney Injury - mortality; Aged; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Clinical Science; Cohort Studies; Creatinine - blood; Emergency and intensive care: renal failure. Dialysis management; Female; Glomerulonephritis; Hemofiltration - methods; Hemofiltration - mortality; Hospital Mortality; Humans; Intensive care medicine; Male; Medical sciences; Middle Aged; Nephrology. Urinary tract diseases; Nephropathies. Renovascular diseases. Renal failure; Patient Discharge; Prospective Studies; Renal Dialysis - methods; Renal Dialysis - mortality; Retrospective Studies; Severity of Illness Index; Survival Rate; Treatment Outcome; Kidney disease; Creatinine; Human; Replacement therapy; Urinary system disease; Hemodialysis; continuous renal replacement therapy; Mortality; critical care nephrology; Extrarenal dialysis; creatinine generation; Renal failure; acute kidney injury
• ISSN: 0931-0509; 1460-2385
• DOI: 10.1093/ndt/gfr809

Existing systems for grading severity of acute kidney injury (AKI) rely on a change of serum creatinine concentration over a defined time interval. The rate of change in serum creatinine increases by degree of reduction in glomerular filtration rate, but is mitigated by low creatinine generation rate (CGR). Failure to appreciate variation in CGR may lead to erroneous conclusions regarding severity of AKI and distorted predictions regarding patient outcomes based on AKI severity.
Cohort study of 103 patients who received continuous venovenous hemodialysis (CVVHD) over a 2-year period in a tertiary care hospital setting. Study participants entered the cohort when they were anuric, receiving a stable and uninterrupted dose of CVVHD with serum creatinine in steady state. They were followed until hospital discharge. CGR was measured based on dialyzate effluent volume and effluent creatinine concentration (prospective cohort) and via effluent volume and serum creatinine concentration (retrospective cohort).
CGR (mean 10.5, range 1.7-22.4 mg/kg/day) was substantially lower in this patient population than what would be predicted from existing equations. Correlates of CGR in multivariable analysis included the length of hospitalization prior to measurement and presence of an oncologic diagnosis. Lower CGR was independently associated with in-hospital mortality in unadjusted analysis and after multivariable adjustment for measures of severity of illness.
Grading systems for severity of AKI fail to account for variation in CGR, limiting their ability to predict relevant outcomes. Calculation of CGR is superior to other risk metrics in predicting hospital mortality in this population.