Augmented renal clearance--an evolving risk factor to consider during the treatment with vancomycin

Augmented renal clearance (ARC) is a new phenomenon in patients' pathophysiology without universally accepted aetiology and with various incidence rates most often described in critically ill patients in the Intensive Care Unit (ICU). The objective of this retrospective observational comparative study was to estimate the incidence rate of ARC in patients with different medical conditions employing steady state trough vancomycin serum concentrations (VSCss) for analysis.

All patients tested for VCSss during two years (2010-2011) in a tertiary level hospital were analysed and 77 VSCs were eligible for analysis: 38 (50%) and 39 cases were assigned to the ARC (eCrClCG (creatinine clearance, estimated by Cockcroft-Gault) > 130 mL/min) and the control groups (eCrClCG in the range 90-130 mL/min) respectively.

Patients' age, mechanical ventilation and haemodynamically unstable status had significant association with ARC occurrence (P < 0.05). Majority of ARC patients (11 patients (61 %)) were managed in non-ICU settings. ARC event showed statistically significant higher risk for under dosage (RR (relative risk for subtherapeutic VSCss), 1.84; 95% CI, 1.23\x962.74; P = 0.011), and the correlation between different thresholds (eCrClCG >130 mL/min, ≥140 mL/min and ≥150 mL/min) for ARC and VSCss allows to predict decrease of VSCss in case of eCrClCG ≥150 mL/min: every increase of eCrClCG by 40 mL/min predicts clinically relevant decrease of VSCss by 1 mmol/L (1.49 mg/mL).

ARC cases lead to the doubled risk of subtherapeutic VSC, and this phenomenon is a significant event in patients in any hospital department. Investigation of medical patients' status relevant to this phenomenon needs to be continued.