Antimicrobial prescribing in long-term care facilities: prospective evaluation of potential antimicrobial use and cost indicators.

BACKGROUND: Few studies exist regarding methods of monitoring antimicrobial prescribing in the long-term care setting.
METHODS: Data were collected monthly in 4 long-term care facilities (LTCFs) for 20 to 26 months. The data included incidence (No. of antimicrobial courses started per 1000 resident care days) of antimicrobial use, antimicrobial utilization ratio (ratio of the number of antimicrobial-days to the number of resident care days), cost of antimicrobial-day, and cost of therapy per resident care day. In one facility, physician-specific data were also collected.
RESULTS: Seasonal variation in the incidence of antimicrobial use was identified, with the highest rates occurring in the winter months. Significant differences in the mean incidence of antimicrobial use, mean antimicrobial utilization ratio, mean cost per antimicrobial-day, and mean cost per resident care day were identified among the 4 LTCFs during the study period. A significant correlation existed between incidence of antimicrobial use or antimicrobial utilization ratio and the overall infection rate or site-specific rates when the data from all 4 LTCFs were aggregated for analysis. Monthly variation in cost per antimicrobial-day was best explained by the monthly variation in prescribing of high-cost (>$15 per day) agents. With these same parameters for use and cost, considerable variation in prescribing and cost of therapy was noted among 7 physicians in the same facility.
CONCLUSIONS: The parameters evaluated detected significant differences in prescribing and cost of antimicrobials among 4 LTCFs. If these findings are verified in larger studies, these parameters may be useful for monitoring trends in prescribing and for interfacility comparisons after adjustment for case-mix differences.