The effect of body mass index and creatinine clearance on serum trough concentration of vancomycin in adult patients

Abstract Background: The aim of this study was to evaluate the influence of patient body mass index (BMI) and estimated creatinine clearance (CrCl) on serum vancomycin concentrations to define a possible optimal dosage regimen in overweight patients based on data obtained during therapeutic drug monitoring. Methods: This retrospective study used data collected from January 2017 to January 2019. Adult patients (n=204) received vancomycin treatment at a dose of 1000 mg every 12 h and underwent serum monitoring. Data collected included patient disease category, sex, age, height, weight, vancomycin concentrations, and serum creatinine. The CrCl values were estimated using the Cockcroft–Gault formula. In this study, statistical comparisons were performed on the results of patients according to serum vancomycin concentration. Results: Serum vancomycin concentration was significantly related to BMI (P < 0.001) and CrCl (P < 0.05) in adult patients. Furthermore, the trough serum vancomycin concentration showed a logarithmic correlation with BMI (R = -0.5108, 95% CI: -0.6082 to -0.3982, P < 0.001) and CrCl (R = -0.5739, 95% CI: -0.6616 to -0.4707, P < 0.001). The multivariate analysis showed that BMI and CrCl are independent contributors to the trough vancomycin concentration. Moreover, some of the patients with higher BMI (≥ 24 kg/m2) met the goal trough concentration after an adjustment from 1000 mg every 12 h to 1000 mg every 8 h. Conclusions: Serum vancomycin concentration decreases progressively with increasing BMI and the augmentation in CrCl in adult patients. The trough concentration of vancomycin should be continuously monitored for patients with a BMI ≥ 24 kg/m2, and the dosage regimen should be adjusted to reach the target trough concentration in these patients to reduce the impact of BMI.