Changing use of antibiotics in community-based outpatient practice, 1991-1999.

BACKGROUND

Judicious use of antibiotics can slow the spread of antimicrobial resistance. However, overall patterns of antibiotic use among ambulatory patients are not well understood.

OBJECTIVE

To study patterns of outpatient antibiotic use in the United States, focusing on broad-spectrum antibiotics.

DESIGN

Cross-sectional survey in three 2-year periods (1991-1992, 1994-1995, and 1998-1999).

SETTING

The National Ambulatory Medical Care Survey, a nationally representative sample of community-based outpatient visits.

PATIENTS

Patients visiting community-based outpatient clinics.

MEASUREMENTS

Rates of overall antibiotic use and use of broad-spectrum antibiotics (azithromycin and clarithromycin, quinolones, amoxicillin-clavulanate, and second- and third-generation cephalosporins). All comparisons were made between the first study period (1991-1992) and the final study period (1998-1999).

RESULTS

Between 1991-1992 and 1998-1999, antibiotics were used less frequently to treat acute respiratory tract infections, such as the common cold and pharyngitis. However, use of broad-spectrum agents increased from 24% to 48% of antibiotic prescriptions in adults (P < 0.001) and from 23% to 40% in children (P < 0.001). Use of broad-spectrum antibiotics increased across many conditions, increasing two- to threefold as a percentage of total antibiotic use for a variety of diagnoses in both adults and children. By 1998-1999, 22% of adult and 14% of pediatric prescriptions for broad-spectrum antibiotics were for the common cold, unspecified upper respiratory tract infections, and acute bronchitis, conditions that are primarily viral.

CONCLUSIONS

Antibiotic use in ambulatory patients is decreasing in the United States. However, physicians are increasingly turning to expensive, broad-spectrum agents, even when there is little clinical rationale for their use.