Cost Benefit Analysis of Monitoring Serum Vancomycin Concentrations in a Teaching Hospital

Objective: To evaluate the economic benefits of routine monitoring of serum vancomycin concentrations and recommend monitoring guidelines. Design: An IRB approved 5-months retrospective chart review. Setting: The study was conducted using patients' medical records in a Teaching hospital. Patients: All patients on intravenous vancomycin, who have stable serum creatinine at the time of initiating vancomycin. Main Outcome Measures: Benefit-to-cost ratio and Return-on-investment were calculated. Benefits were determined using costs avoided that would have occurred in managing SVC-related toxicity, while the cost was the hospital charge for determining SVC. Interventions: Using a computer-generated list of patients on vancomycin from August to December 1995, thirty-one patients' charts were randomly retrieved from the medical records department and reviewed. We extracted and recorded pertinent data on a data collection sheet. The data extracted included SVCs, frequency of SVC determination, dose and duration of vancomycin treatment, and vancomycin untoward effects. Other data recorded were age, weight, height, sex, status of renal function, and other concurrent nephrotoxic or ototoxic drugs. Result: The Benefit-to-cost ratio was 0.696, and the Return-on-investment was -30.4%. A mean of 2.83 ± 3.1 SVCs was obtained per patient during a mean therapy duration of 10.2 ± 6.8 days. The mean daily dose (27.8 ± 7.0 mg/kg), peak (21.7 ± 6.54 mcg/mL), and trough (7.4 ± 5.98 mcg/mL) were within recommended standards. Also, two (8.3%) patients experienced increased serum creatinine. Conclusion: Our results show that the routine monitoring of SVCs is not cost beneficial. We recommend only one trough SVC for patients with normal or stable renal functions for a course of treatment. Patients with unstable renal function may require more than one trough SVC determination and should be evaluated on a case-by-case basis. Peak and trough SVCs should be reserved for patients with other risk factors for ototoxicity.