Trends in antibiotic prescribing for adults in the United States--1995 to 2002

Abstract

Context: The impact of national efforts to limit antibiotic prescribing has not been fully evaluated.

Objectives: To analyze trends in outpatient visits associated with antibiotic prescription for U.S. adults.

Design: Cross-sectional study of data (1995 to 2002) from the National Ambulatory Medical Care Survey and the National Hospital Ambulatory Medical Care Survey.

Participants: Adults > or =18 years with an outpatient visit to an office- or hospital-based medical practice or to an emergency department. All visits were classified into 1 of 4 diagnostic categories: (1) acute respiratory infection (ARI)-antibiotics rarely indicated, (2) ARI-antibiotics often indicated, (3) nonrespiratory infection-antibiotics often indicated, and (4) all others.

Measurements: Trends in: (1) Proportion of outpatient visits associated with an antibiotic prescription; (2) proportion of antibiotic prescriptions that were broad spectrum; and (3) number of visits and antibiotic prescriptions per 1,000 U.S. adults > or =18 years of age.

Results: From 1995-1996 to 2001-2002, the proportion of all outpatient visits that generated an antibiotic prescription decreased from 17.9% to 15.3% (adjusted odds ratio [OR] 0.84, 95 % confidence interval [CI] 0.76 to 0.92). The entire reduction was because of a decrease in antibiotic prescriptions associated with visits for ARIs where antibiotics are rarely indicated from 59.9% to 49.1% (adjusted OR 0.64 95% CI 0.51 to 0.80). However, the proportion of prescribed antibiotics for these visits that were classified as broad-spectrum antibiotic prescription increased from 41.0% to 76.8%. Overall outpatient visits increased from 1693 to 1986 per 1,000 adults over the 8 years studied, but associated antibiotic prescriptions changed little, from 302 to 304 per 1,000 adults.

Conclusion: During the study period, outpatient antibiotic prescribing for respiratory infections where antibiotics are rarely indicated has declined, while the proportion of broad-spectrum antibiotics prescribed for these diagnoses has increased significantly. This trend resulted in a 15% decline in the total proportion of outpatient visits in which antibiotics were prescribed. However, because outpatient visits increased 17% over this time period, the population burden of outpatient antibiotic prescriptions changed little.

Figure 1

Antibiotic prescription (as odds ratio) during study periods, by diagnosis. Outpatients aged 18 and older, U.S. 1995 to 2002.(Model adjusted for patient age, sex, race, rural location, practitioner type, region of country, location of care, and patient insurance. The time period 1995 to 1996 is the reference).

Figure 2

Antibiotic prescription (as odds ratio) during the study period by location of care for acute respiratory infection—antibiotics rarely indicated. Outpatients aged 18 and older in the U.S. 1995 to 2002. (Model adjusted for patient age, sex, race, rural location, practitioner type, region of country, and patient insurance. The time period 1995 to 1996 is the reference.)

Figure 3

Trends in Broad-Spectrum antibiotic prescribing in United States for each diagnostic category.