The epidemiology of intravenous vancomycin usage in a university hospital. A 10-year study

Abstract

Objectives: To examine the trends of intravenous vancomycin usage during a 10-year period, to classify the indications for which physicians prescribed the antibiotic, and to identify the independent predictors for empirical use of vancomycin.

Design: A descriptive epidemiological study, a cross-sectional study, and a case-control study were performed.

Setting: A 900-bed university-teaching hospital.

Main outcome measures: The annual crude usage (grams) and incidence density (grams/1000 patient-days) of vancomycin were measured for 10 years (July 1981 to July 1991). In 109 randomly selected patient medical records, we evaluated the proportion of usage of vancomycin classified as prophylaxis, empirical therapy, or specifically directed therapy. Univariate and multivariate analyses were performed to identify determinants of empirical administration of vancomycin vs a penicillase-resistant penicillin to 64 case patients and 64 control patients.

Results: The rate of vancomycin usage increased 20-fold from 5.72 g/1000 patient-days in 1981 to 121.25 g/1000 patient-days in 1991. The use of vancomycin was significantly higher (P < .0001) in hematology-oncology areas compared with that in other hospital areas. The rates for each indication for vancomycin were 35.0% for prophylaxis 31.8% for empirical therapy, and 33.2% for therapy specifically directed by culture results. In a multivariate analysis, the presence of "plastic" medical devices was the best independent predictor for patients receiving vancomycin: intravenous lines (odds ratio [OR], 6.23; 95% confidence interval [CI], 2.28 to 17.06; P < .001), Hickman catheters (OR, 76.12; 95% CI, 15.06 to 384.73; P < .001), and other medical devices (OR, 10.50; 95% CI, 2.54 to 43.38; P = .001).

Conclusions: Vancomycin use has increased linearly in the last decade primarily related to the presence of indwelling vascular devices in hematology-oncology patients. Use of vancomycin is equally divided among empirical therapy, prophylaxis, and specific therapy for a documented infection.