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Abstract

Introduction: Critically ill patients are at high risk for adverse drug events because of the complexity of their disease states and their vulnerability to rapid changes in pharmacotherapy, with optimization of drug therapy remaining as a constant challenge and concern. In the critical care paradigm, septic shock is the most common reason for admission and is associated with high mortality and morbidity. The purpose of this study is to evaluate the incidence of inappropriate antibiotic dosing in critically ill patients. Hypothesis: We hypothesized there were increasing incidences of inappropriate antibiotic dosing in the obese patients and patients with acute kidney injury in the critical care setting. Methods: This was a nested retrospective cohort of adult patients admitted to six ICUs at three tertiary hospitals of the Montefiore Medical Center, Bronx, New York. The inclusion criterion was patients administrated with gentamicin, an antibiotic which required adjusted body weight dosing in obese patients. We intended to evaluate the first dosing because it was likely given in an urgent situation without the assistance from a pharmacist clinician and/or infectious disease specialist. Statistical analyses were performed using Stata version 11.2. Results: Between January 1, 2011 and December 31, 2011, there were 2,270 patients admitted to six ICUs, of which 106 (4.7%) received gentamicin. Among the patients who had received gentamicin, 26 patients (24.5%) were subjected to inappropriate gentamicin dosing. The mean±SD ages of patients with and without inappropriate dosing were 62.25 ± 18.3 and 63.73 ± 14.64 year respectively (p=0.90). 31% of patients with inappropriate dosing and 29% of patients with adequate dosing were obese (BMI?30) (p=0.20). 38% of patients with inappropriate dosing and 50% with optimized dosing had serum creatinine? 2.5 mg/dl (p=0.17). Multivariate analysis showed patients with BMI? 35 (OR=7.45; 95% CI 1.7-33.5) and serum creatinine less than 2.5 mg/dl (OR=2.32; 95% CI 0.99-5.48) were associated with inappropriate gentamicin dosing. Conclusions: The incidence of gentamicin dosing errors was high in the critically ill patients, and it was associated with obesity and moderate renal insufficiency.