Controlling Antimicrobial Costs and Antimicrobial Resistance

Abstract & Commentary

Synopsis: A recent study examined the results of a survey on hospital antimicrobial management practices and expenditures and found that costs actually increased in some cases.

Source: Rifenburg R P, et al. Benchmark analysis of strategies hospitals use to control antimicrobial expenditures. Am J Health-Syst Pharm 1996;53:2054-2062.

This paper by rifenburg et al summarizes the results of a survey sent to 122 hospitals, of which 88 (72%) responded. The survey requested information on hospital antimicrobial management practices and expenditures on antimicrobial drugs during the period of 1993-94. The results indicated that although 61-74% of the respondents used an antimicrobial formulary to restrict drug choices and control costs, costs actually increased. Further, replacement of one formulary item with another resulted in a shift to the use of antimicrobials other than the replacement drug. This led to more cost shifting rather than overall savings.

In another more general study looking at outpatient prescription drug formularies,1 the authors found similar results. They conclude that while restrictive formularies reduced drug costs in some situations, the predominant effect of formulary restrictions was to shift costs by increasing the use of non-restricted drugs or other health care services. These conclusions were challenged by Curtiss, who challenged the methodology employed, the variations in the practice sites that responded to the questionnaires, and the lack of specific information as to patient selection and data gathering.2 A response commentary from Horn defended their Managed Care Outcomes Project and analysis methodology and stated that "In fact, at least 30 other studies support our study findings about formularies and their relationship to increase health care costs."3


Hospital administrators and pharmacy directors have always been facing the problem of escalating drug costs. In the mid 1980s, the solution appeared to be "drug formularies"—controlling costs by controlling the number of drugs available and using lower-cost pharmaceuticals. Not only has the effectiveness of this strategy been placed in question by the above studies, but there is now concern that drug formularies may also contribute to the spread of antimicrobial resistance.

Antimicrobial resistance was the topic of a presentation at the annual meeting of the American Society for Microbiology (September 1996) by Schentag. In his presentation, he outlined a number of ways to prevent or reverse antimicrobial resistance. The methods presented included formulary cycling strategies, temporarily removing antimicrobials exhibiting resistance, and changing from intravenous to oral therapies as soon as possible.

Antimicrobial resistance was also the topic of a symposium at the annual meeting of the American Society of Health-Systems Pharmacists (December 1996). Ebert outlined some of the mechanisms of resistance and antimicrobial use practices that contribute to resistance. He stated that while it is obvious that over-treatment, under treatment, and unnecessary use of antimicrobials lead to resistance, there is not always a clear correlation between drug use and resistance. The message here is that the removal of antimicrobials exhibiting resistance, as suggested by Schentag, may not always reverse resistance because other antimicrobials being used may be perpetuating resistance. This highlights the need to closely monitor laboratory resistance patterns and antimicrobial usage.

Probably the most sophisticated and integrated system for controlling drug costs is that in place at LDS Hospital in Salt Lake City, Utah. Their system was described in a recent article in the Annals of Internal Medicine.5 In this article, Pestotnik outlined how their computer-assisted approach has achieved lower costs, decreased adverse drug reactions, decreased mortality, and maintained low antimicrobial resistance patterns—all without a restrictive formulary. They use an advanced computer hardware and software system that assists the physician in choosing the optimum antimicrobial regimen. The system has access to all available patient, laboratory, and epidemiological data and can recommend the most cost-effective and appropriate antimicrobial therapy. Dosages of medications are also automatically adjusted based on patient parameters such as renal or hepatic function. Some of the problems associated with this system are its high cost and the concern that clinicians may become somewhat dependent on the computer suggested regimens and dosages. This approach is exemplary, however, in demonstrating how a multi-departmental approach to patient management can both improve care and reduce costs.

Does this mean that antimicrobial formularies are inappropriate? Absolutely not! Restrictive formularies for the sake of cost-containment should be questioned, but properly implemented formularies have been shown to be effective in controlling bacterial resistance and improving the quality of care as well.6,7 What is required in an effective antimicrobial formulary is to closely integrate it with laboratory resistance patterns, infection control policies, and patient clinical outcomes. Drug use patterns must also be monitored to prevent the shifting of antimicrobials from one category to another. Formularies should be one of many components of a multi-disciplinary approach to patient therapy.


1. Horn SD, et al. Managed Care Outcomes Project: study design, baseline patient characteristics and outcomes measures. Am J Manage Care 1996;2: 237-247.

2. Curtiss, FR. Drug formularies provide a path to best care. Am J Health-Syst Pharm 1996;53:2201-2203.

3. Horn SD. Unintended consequences of drug formularies. Am J Health-Syst Pharm 1996;53:2204-2206.

4. Levy RA, Cocks D. Component management fails to save health care system costs. The case of restrictive formularies. Reston, VA: National Pharmaceutical Council; 1996.

5. Pestotnik SL, et al. Implementing antibiotic practice guidelines through computer-assisted decision support: clinical and financial outcomes. Ann Intern Med 1996;124:884-890.

6. Pear SM, et al. Decrease in nosocomial Clostridium difficile-associated diarrhea by restricting clindamycin use. Ann Intern Med 1994;120:272-277.

7. Gerding DN, et al. Aminoglycoside resistance and aminoglycoside usage: ten years of experience in one hospital. Antimicrob Agents Chemother 1991;35:1284-1290.