State legislatures have increased the prescribing capabilities of nurse practitioners and physician assistants and broadened the scope of their practice roles. To determine the impact of these changes, we compared outpatient antibiotic prescribing by practicing physicians, nonphysician clinicians, and resident physicians.

Using the National Ambulatory Medical Care Survey (NAMCS) and the National Hospital Ambulatory Medical Care Survey (NHAMCS), we conducted a cross-sectional study of patients ≥18 years of age receiving care in 3 outpatient settings: office practices, hospital practices, and emergency departments, 1995–2000. We measured the proportion of all visits and visits for respiratory diagnoses where antibiotics are rarely indicated in which an antibiotic was prescribed by practitioner type.

For all patient visits, nonphysician clinicians were more likely to prescribe antibiotics than practicing physicians for visits in office practices (26.3% vs 16.2%), emergency departments (23.8% vs 18.2%), and hospital clinics (25.2% vs 14.6%). Similarly, for the subset of visits for respiratory conditions where antibiotics are rarely indicated, nonphysician clinicians prescribed antibiotics more often than practicing physicians in office practices (odds ratio [OR] 1.86, 95% confidence intervals [CI]: 1.05 to 3.29), and in hospital practices (OR 1.55, 95% CI: 1.12 to 2.15). In hospital practices, resident physicians had lower prescribing rates than practicing physicians for all visits as well as visits for respiratory conditions where antibiotics are rarely indicated (OR 0.56, 95% CI: 0.36 to 0.86).

Nonphysician clinicians were more likely to prescribe antibiotics than practicing physicians in outpatient settings, and resident physicians were less likely to prescribe antibiotics. These differences suggest that general educational campaigns to reduce antibiotic prescribing have not reached all providers.