Analysis of vancomycin use and associated risk factors in a university teaching hospital: a prospective cohort study.

Background: Vancomycin use is considered inappropriate in most hospitals. A particular concern is the recent emergence of S. aureus with decreased susceptibility to vancomycin, making it important to reduce overall exposure to vancomycin to minimize the incidence of VRE (vancomycin-resistant enterococci). The aim of this work was to analyze the use of vancomycin and the risk factors associated with inappropriate treatment.

Methods: A prospective survey was conducted on all patients receiving vancomycin between 1st March 2002 and 30th September 2002 in a university-school hospital. Appropriateness of vancomycin use was assessed, according to the criteria established by the Centers for Disease Control and Prevention (CDC), at two time points: first, at the beginning of therapy, and second, continuing after 72 hours.

Results: A total of 557 patients received vancomycin. Three hundred seventy-four (67.1%) were under 60 years old, 374 (67.1%) had prolonged stays (>two weeks) in hospital, and 455 (81.7%) were in the intensive care unit (ICU). Two hundred sixty-three patients (47.2%) had some invasive device. In 324 (58.2%) patients the duration of vancomycin treatment was up to two weeks. Vancomycin was inappropriately used in 65.7% during the first 24 hours and in 67% at the 72 hours point according to CDC criteria 4. The inappropriateness of vancomycin use during the first 24 hours was related to: patients aged less than 60 (OR 1.7; CI 95% 1.1-2.5), non-ICU patients (OR 1.5; CI 95% 1.0-2.4) and patients without neutropenia (OR 7.5; CI 95% 2.4-22.7). At 72 hours, the inappropriateness of vancomycin use was related to: patients aged less than 60 (OR 1.5; CI 95% 1.0-2.3), non-ICU patients (OR 1.7; CI 95% 1.1-2.7) and patients without neutropenia (OR 8.0; CI 95% 2.6-24.3).

Conclusion: Vancomycin was abused. Patients aged less than 60, non-ICU patients and those who did not present neutropenia were the principal groups at risk of inappropriate use.