The association of elevated trough serum vancomycin concentrations with obesity.

BACKGROUND: Obese patients display differences in vancomycin drug disposition, which may complicate attainment of appropriate serum vancomycin concentrations (SVCs). This study was conducted to determine if obesity leads to trough SVCs above the therapeutic range.

METHODS: This retrospective cohort study sought to determine the rate and predictors of high (i.e. >20 mg/L) serum trough levels according to level of obesity.

RESULTS: Increasing BMI predicted SVCs > 20 mg/L after controlling for dose, age, and serum creatinine. Obese patients had significantly higher mean trough SVCs compared to non-obese patients (16.5 mg/L vs 12.1 mg/L, p = 0.004) and a significantly higher proportion of obese patients had trough SVCs > 20 mg/L (18.9% vs 4.2%, p = 0.03).

CONCLUSION: Increasing obesity predicted higher probabilities of SVCs > 20 mg/L. Development of alternative dosing and management strategies for vancomycin may be necessary to account for pharmacokinetic changes associated with obesity.