Four hour creatinine clearance is better than plasma creatinine for monitoring renal function in critically ill patients
1 Christchurch Kidney Research Group, Department of Medicine, University of Otago, Riccarton Avenue, Christchurch 8140, New Zealand
2 Department of Medicine and Surgery, University of Otago, Leith Walk, Dunedin 9054, Dunedin, New Zealand
3 Intensive Care, Christchurch Hospital, Riccarton Avenue, Christchurch 8140, New Zealand
4 Department of Nephrology, Prince of Wales Clinical School, University of New South Wales, Barker St, Randwick, Sydney, NSW 2031, Australia
Critical Care 2012, 16:R107 doi:10.1186/cc11391
See related commentary by Molitoris http://ccforum.com/content/16/5/158Published: 19 June 2012
Acute kidney injury (AKI) diagnosis is based on an increase in plasma creatinine, which is a slowly changing surrogate of decreased glomerular filtration rate. We investigated whether serial creatinine clearance, a direct measure of the glomerular filtration rate, provided more timely and accurate information on renal function than serial plasma creatinine in critically ill patients.
Serial plasma creatinine and 4-hour creatinine clearance were measured 12-hourly for 24 hours and then daily in 484 patients. AKI was defined either as > 50% increase in plasma creatinine from baseline, or > 33.3% decrease in creatinine clearance. The diagnostic and predictive performance of the two AKI definitions were compared.
Creatinine clearance decrease diagnosed AKI in 24% of those not diagnosed by plasma creatinine increase on entry. These patients entered the ICU sooner after insult than those diagnosed with AKI by plasma creatinine elevation (P = 0.0041). Mortality and dialysis requirement increased with the change in creatinine clearance-acute kidney injury severity class (P = 0.0021). Amongst patients with plasma creatinine < 1.24 mg/dl on entry, creatinine clearance improved the prediction of AKI considerably (Net Reclassification Improvement 83%, Integrated Discrimination Improvement 0.29). On-entry, creatinine clearance associated with AKI severity and duration (P < 0.0001) predicted dialysis need (area under the curve: 0.75) and death (0.61). A > 33.3% decrease in creatinine clearance over the first 12 hours was associated with a 2.0-fold increased relative risk of dialysis or death.
Repeated 4-hour creatinine clearance measurements in critically ill patients allow earlier detection of AKI, as well as progression and recovery compared to plasma creatinine.
Australian New Zealand Clinical Trials Registry ACTRN012606000032550.