Prevalence and Risk Factors for Augmented Renal Clearance in a Population of Critically Ill Patients.

Background: Critically ill patients show a high, albeit variable, prevalence of augmented renal clearance (ARC). This condition has relevant consequences on the elimination of hydrophilic drugs. Knowledge of risk factors for ARC helps in the early identification of ARC. The aims of this study were evaluation of (1) risk factors for ARC and (2) the prevalence of ARC in critically ill patients over a period of 1 year.

Methods: A retrospective cohort study was performed for all consecutive patients admitted to our intensive care unit (ICU). Augmented renal clearance was defined by a creatinine clearance ≥130 mL/min/1.73 m. "Patient with ARC" was defined as a patient with a median of creatinine clearance ≥130 mL/min/1.73 m over the period of admission. Four variables were tested, Simplified Acute Physiology Score II (SAPS II), male gender, age, and trauma as cause for ICU admission. An analysis (patient based and clearance based) was performed with logistic regression.

Results: Of 475 patients, 446 were included in this study, contributing to 454 ICU admissions and 5586 8-hour creatinine clearance (8h-CL). Overall, the prevalence of patients with ARC was 24.9% (n = 113). In a subset of patients with normal serum creatinine levels, the prevalence was 43.0% (n = 104). Of the set of all 8h-CL measurements, 25.4% (1418) showed ARC. In the patient-based analysis, the adjusted odds ratio was: 2.0 (confidence interval [CI]:1.1-3.7; < .05), 0.93 (CI: 0.91-0.94; < .01), 2.7 (CI: 1.4-5.3; < .01), and 0.98 (CI: 0.96 -1.01; = .15), respectively, for trauma, age, male sex, and SAPS II. In the clearance-based analysis, the adjusted odds ratio were 1.7 (CI: 1.4-1.9; < .01), 0.94 (CI: 0.932-0.942; < .01), and 2.9 (CI: 2.4-3.4; < .01), respectively, for trauma, age, and male sex.

Conclusions: Trauma, young age, and male sex were independent risk factors for ARC. This condition occurs in a considerable proportion of critical care patients, which was particularly prevalent in patients without evidence of renal dysfunction.