Background: Routine, initial, empiric vancomycin dosing by clinicians in postoperative coronary artery bypass grafting (CABG) patients was identified as a potential patient safety issue in the Cardiovascular Intensive Care Unit (CVICU) because the rate of postoperative acute renal insufficiency (ARI) and average patient Body Mass Index (BMI) > 35 kg/m2 were significantly higher in our institution than those of the Society of Thoracic Surgeons (STS) database. A vancomycin dosing nomogram was derived from the local patient population in the attempt to improve patient safety by convincing clinicians to use an evidence-based approach to vancomycin prescription.
Methods: We analyzed two different treatment strategies that were applied consecutively to an intensive care unit population. CABG patients dosed empirically with vancomycin (group 1, pre-nomogram) were compared with CABG patients dosed using a vancomycin dosing nomogram (group 2, post-nomogram) derived from the hospital population using an Internet program that facilitated creation of a local nomogram. The two groups were analyzed as to age, sex, body mass index, creatinine clearance, and vancomycin dosage using logistic regression and testing for continuous and categorical variables.
Results: Nomogram use decreased the number of patients receiving the customary dose of one gram every 12 hours in those group 2 patients with diminished CrCl as compared with those in group 1 with diminished CrCl (group 2, 2/21 vs. group 1, 14/21, p < .0001), as well as in those with a normal creatinine clearance, (group 2, 2/15 vs. group 1, 26/34, p < .0001). Therefore, nomogram use affected the customary dose of one g vancomycin every 12 hours between the two groups overall (group 1, 40/55 vs. group 2, 4/36, p < .001), whereby 32/36 (88.9%) of group 2 patients had their dosing altered when compared to what would have been formerly prescribed, p < .0001. Furthermore, nomogram use resulted in fewer doses of antibiotics per year resulting in a cost savings to the hospital with no increase in the rates of infection.
Conclusion: Implementation of the nomogram resulted in a more appropriate antibiotic utilization, regardless of creatinine clearance, that decreased costs without increasing infection rates.