External validation of obese and critically ill vancomycin population pharmacokinetic models in critically ill obese patients.

Obesity combined with critical illness might increase the risk of acquiring infections and hence mortality. In this patient population antimicrobials pharmacokinetics vary significantly making antimicrobial dosing challenging. The objective of this study was to assess the predictive performance of published population pharmacokinetic models of vancomycin in critically ill or obese patients on a cohort of critically ill obese patients. This was a multi-center retrospective study conducted at two hospitals. Adult patients with a BMI ≥ 30 were included. PubMed was searched for published population pharmacokinetic studies in critically ill or obese patients. External validation was performed using Monolix software. Four models were identified in obese patients and 5 models in critically ill patients. In total, 138 critically ill obese patients were included, the most accurate models for patients were the Goti and Roberts models. In our analysis, models in critically ill patients outperformed those in obese patients. When looking at the most accurate models, both (the Goti and Roberts models) had patient characteristics similar to ours in terms of age and creatinine clearance. This indicates that when selecting the proper model to apply in practice, it is important to account for all relevant variables besides obesity. This article is protected by copyright. All rights reserved.