The clinical utility of kinetic glomerular filtration rate

Background: In acutely unwell patients with rapidly changing renal function, estimating glomerular filtration rate (GFR) and predicting adverse renal outcomes are challenging and often inaccurate. Kinetic GFR (kGFR) is an estimate of immediate biomarker clearance derived from two discreet measurements that may better represent acute function. Our objective is to assess the clinical utility of kGFR as a predictive tool and examine the association of kGFR to adverse renal outcomes compared with measurements to traditional estimates. Methods: We compared the association of kGFR and Modification of Diet in Renal Disease (MDRD) with acute kidney injury (AKI), renal replacement therapy (RRT), cardiovascular morbidity, 30-day mortality and new chronic kidney disease development. A total of 107 acute admissions to a medical high dependency and intensive care unit were assessed retrospectively. Creatinine measurements and outcomes were recorded and kGFR was calculated at the earliest possible time point. This was then compared with simultaneous MDRD estimated GFR. Results: Mean age was 60 years old, AKI occurred in 25% of patients, acute cardiovascular events occurred in 13%, RRT was initiated in 15% and 30-day mortality was 30%. kGFR predicted the AKI more accurately than MDRD [area under the receiver operating characteristic curve (AUC) = 0.86 versus AUC = 0.64]. kGFR predicted the need for RRT more accurately than MDRD (AUC = 0.901 versus AUC = 0.79). Neither kGFR nor admission MDRD was associated with 30-day mortality or cardiovascular morbidity. Conclusions: Measuring kGFR in the acute setting could help clinicians better predict adverse renal outcomes.