Association of vancomycin trough concentration with response to treatment for acute pulmonary exacerbation of cystic fibrosis

Background. Our goal was to determine the relationship between serum vancomycin trough concentrations (VTCs) and changes in pulmonary function among individuals with an acute pulmonary exacerbation (APE) of cystic fibrosis (CF). Methods. We included subjects who were ≥6 years of age, were hospitalized for an APE of CF between May 1, 2012, and April 30, 2014, were administered vancomycin for ≥48 hours, and had a history of airway infection with methicillin-resistant Staphylococcus aureus. Pearson correlations were performed to characterize the relationship between VTC and pulmonary function. Results. The mean final VTC (± standard deviation) was 12.6 ± 3.3 μg/mL; 40 (81.6%) of 49 final VTCs were in the range of 10 to < 15 μg/mL. The mean change in forced expiratory volume in 1 second (FEV₁) between admission and discharge was 24.5% ± 24.4% (P < . 001) of predicted values. Forty-two (85.7%) patients returned to their baseline FEV₁. No correlation between the change in FEV₁ and VTC (Pearson r = -0.10; P = .49) was identified. Similarly, VTC, daily weight-adjusted vancomycin dose, and vancomycin area under the concentration-time curve normalized to the minimum inhibitory concentration (AUC/MIC) were not significant predictors of change in FEV₁ or return to baseline FEV₁ on multivariate analysis. One (2%) subject experienced acute kidney injury. Conclusions. The majority of patients experienced improvement in pulmonary function and a return to their baseline FEV₁ while achieving a VTC in the range of 10 to < 15 μg/mL. We were unable to identify a correlation between markers of vancomycin exposure and change in pulmonary function test results. Additional studies are needed to reinforce the efficacy of VTCs of 10 to 15 μg/mL for treating APEs of CF.