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Posted on 12.26.01
When Formulary Restrictions Are Not Enough
By Janet Weiner, MPH
Greater oversight of prescriptions may need to be combined with infection-control initiatives to reduce the level of multidrug resistant organisms, said investigator Ebbing Lautenbach, MD, MPH, as he presented the study's results at the Infectious Diseases Society of America's annual meeting, held October 25-28 in San Francisco.
The study tracked the incidence of one resistant strain of bacteria, known as vancomycin-resistant enterococci, or VRE, at the Hospital of the University of Pennsylvania from 1991 to 2000. This strain is associated with greater mortality, longer hospital stays, and higher hospital costs when compared with its nonresistant counterparts.
Previous studies identified prior antibiotic use, particularly the use of vancomycin and cephalosporins, as a risk factor for developing VRE. Thus Dr. Lautenbach and colleagues studied whether limiting the use of these antibiotics, through a hospital's formulary system, reduced the prevalence of this resistant organism. Progressive restrictions on the use of these drugs, including prior approval and mandatory substitutions, began in 1994 and continued through 2000.
Although vancomycin use initially decreased by more than 25%, its use increased to prerestriction levels for the last 3 years of the study. The use of third-generation cephalosporins decreased 85.7% as a result of the interventions. The prevalence of VRE, however, increased from 11% to 42% of organisms during the 10-year study.
Dr. Lautenbach noted that while the interventions were successful in limiting the use of third-generation cephalosporins, they were not effective in changing vancomycin use.
"We need better strategies to reduce vancomycin use," he said.
He added that other tactics to limit antibiotic resistance in hospitals should be explored, including restricting a wider range of drugs and enhancing infection-control efforts.