Vancomycin Dosing in Obese and Morbidly Obese Patients with Methicillin-Resistant Staphylococcus aureus (MRSA) Pneumonia
Methods: This national retrospective cohort study included obese patients (pts; BMI ≥ 30) admitted to VA hospitals with MRSA-positive cultures from respiratory sites between 2002 - 2012. Pts initiating vancomycin (VAN) in the hospital were selected for inclusion. Exclusion criteria included death or discharge within 2 days of treatment initiation and exposure > 2 consecutive days of MRSA antibiotic therapy in the 3 days prior to treatment initiation or during treatment with VAN. Pts were included if they had appropriately collected VAN troughs and no evidence of acute kidney injury prior to VAN initiation per VAN guidelines. Logistic regression models were used to measure the effect of various VAN dosing regimens on trough levels in obese and MO (BMI ≥ 40) pts.
Results: We identified 263 obese and 73 MO pts treated with VAN with appropriately collected VAN trough levels. Total body weight ranged from 69 to 244 kg. The mean total daily dose of VAN was lower in obese vs. MO pts (2005 ± 736 vs. 2298 ± 923 mg, p <0.05) however the mean mg/kg/day dose was higher in obese vs. MO pts (20 ± 7 vs. 17 ± 7 mg/kg/day, p<0.05). About 20% of pts in each group had a vancomycin trough level of >15-20 mg/L. The mean mg/kg/day VAN dose was also higher in obese vs. MO pts with a trough of >15-20 mg/L (20 ± 7 vs. 15 ± 7 mg/kg/day, p<0.05). In obese pts, the standard dose of ~30mg/kg/day was appropriate for reaching a VAN trough of >15-20 mg/L (odds ratio [OR] 3.348, 95% confidence interval [CI] 1.2 - 9.2). In MO pts, as the mg/kg/day VAN dose increased, the odds of achieving a VAN trough of 15-20 mg/L decreased (OR 0.870, 95% CI 0.78 - 0.98).
Conclusion: We offer additional consideration on the dosing of VAN in obese and MO pts. MO patients may require a lower mg/kg/day VAN dose than obese patients to reach a trough of >15-20 mg/L. However, further research is warranted to determine which VAN trough levels are associated with the best outcomes in obese and MO patients.
Pfizer: Research Funding, Research grant
E. Noh, Pfizer: Research funding, Research support
K. Laplante, Astellas, Cubist, Forest, the National Institutes of Health, Pfizer, Theravance, Marvao, Davol, Durata, Cepheid : Research funding, advisor, and/or consultancy and Scientific Advisor, Research grant