Incidence and characteristics of antibiotic use in aged nursing home patients.

OBJECTIVE: To measure the prevalence, incidence, types, and certain characteristics of antibiotics prescribed in nursing homes.

DESIGN AND SETTING: Periodic survey over 1 year of patient charts in 53 stratified, randomly selected nursing homes in the state of Maryland.

PATIENTS: All patients 65 years of age or more residing in these nursing homes on the first day of study.

RESULTS: Of 4,165 patients in 53 nursing homes, records over the year were satisfactory in 3,899 patients in 52 nursing homes. The prevalence of antibiotic use on the first day of the study was 8%. Over the next 12 months, observations of more than one million patient-days revealed an incidence of 0.46 antibiotic courses/100 patient-days; 54% of the 3,899 patients received at least one antibiotic course. For presumed active infections, beta lactam antibiotics were the most commonly used, 54% of antibiotic orders. For all antibiotics, urinary tract infection was the most common indication, eliciting 36% of orders including 9% for asymptomatic bacteriuria. Skin, lower respiratory, and upper respiratory infections comprised 14%-17% each. Physicians prescribed 94% of courses but documented examinations of only 44% of patients at the outset of these courses. Consensus criteria for minimal diagnostic evaluation of four selected infections were met in only 11% of episodes of infection. Although the most serious infections tended to be better evaluated than others, 31% of the former were not noted to have been examined by a physician. Three percent of orders were for prophylaxis and two-thirds of these antibiotics were administered for more than 2 days.

CONCLUSIONS: Antibiotics are frequently prescribed for aged nursing home patients, often in the absence of a physician's examination and other features commonly performed in evaluation of specific infectious diseases. More than one-fifth of antibiotics prescribed by presumed active infections were for two infections usually thought not to require antibiotic therapy, "viral" upper respiratory infection (13%) and asymptomatic bacteriuria (9%). To optimize antibiotic use in nursing homes, greater attention should be directed to appropriate durations of prophylaxis for urologic, dental, and minor surgical procedures; to standards for diagnostic evaluations of common infections; and to the roles of antibiotics in upper respiratory infections and in asymptomatic bacteriuria.