Benchmarks for antibiotic use and cost in long-term care.

OBJECTIVES: To evaluate previously described antibiotic use and cost indicators in community nursing homes to determine whether they may be useful as benchmarks and to evaluate the association between functional status, infection occurrence, and antibiotic use.
DESIGN: Retrospective observational study.
SETTING: Eleven proprietary long-term care facilities owned by one company. PARTICIPANTS: Only facility-specific cumulative data were used. MEASUREMENTS: Antibiotic use and cost indicators (incidence of antibiotic use, antibiotic utilization ratio, cost of antibiotics per resident care day (RCD), and cost per antibiotic day), infection rates, and functional status as measured using the case-mix index (CMI) of the Resource Utilization Groups II system. Mean yearly values for each measure were calculated for each facility.
RESULTS: There was significant variation in all of the antibiotic indicators between the 11 nursing homes, but there was no correlation between mean facility CMI and infection rate. However, there was a trend toward a significant correlation between mean facility CMI and mean facility incidence of antibiotic use, antibiotic utilization rate, and cost per RCD. Variation in mean facility infection rate explained 66% of the variation in mean facility incidence of antibiotic use (P<.001). In a multivariate analysis, mean facility infection rate (P=.003) and mean facility CMI (P=.046) were predictors of mean incidence of antibiotic use and explained 83% of the variation in dependent variable.
CONCLUSION: The significant variation in mean antibiotic use and cost indicators between the 11 study facilities suggests that these indicators may be useful as benchmarks for quality-improvement efforts. For the first time, objective evidence is provided demonstrating the influence of functional status on antibiotic use in the nursing home setting.