
Methods: We compared the antibiotic prescribing rates for all ARIs, antibiotic-appropriate diagnoses (e.g., sinusitis or pneumonia), and non-antibiotic-appropriate diagnoses (e.g., acute bronchitis) for the first visit of a half-day clinic session and the last hour of a half-day clinic session (i.e., the 11 am and 4 pm hours) to the remaining visits. We used multivariable generalized estimating equations to identify independent predictors of antibiotic prescribing after adjusting for patient demographics, antibiotic-appropriateness of diagnosis, and clustering by clinician.
Results: There were 678,982 total visits and 31,838 ARI visits scheduled from 8 am to 5 pm, Monday to Friday, by patients aged 18 to 64 years old without chronic lung disease to 561 clinicians in 23 Boston-area primary care practices, between May 2011 and September 2012. The antibiotic prescribing rate for the first visit of the session was significantly lower than later visits for all ARIs (55.2% vs. 58.7%; p<0.001), antibiotic-appropriate diagnoses (74.2% vs. 77.4%; p=0.008), and non-antibiotic-appropriate diagnoses (45.1% vs. 48.8%; p<0.001). The antibiotic prescribing rate was significantly higher during the last hour of each session compared to the remainder of the session for all ARIs (60.3% vs. 57.6%; p<0.001), antibiotic-appropriate diagnoses (78.8% vs. 76.4%; p=0.01), and non-antibiotic-appropriate diagnoses (50.6% vs. 47.6%; p<0.001). In multivariable modeling, clinicians were less likely to prescribe antibiotics at the first visit of the session (odds ratio [OR], 0.88; 95% confidence interval [CI], 0.81 to 0.96) and more likely to prescribe antibiotics in the last hour of a clinic session (OR, 1.12; 95% CI, 1.04 to 1.19).
Conclusion: Primary care clinicians are slightly, but significantly less likely to prescribe antibiotics at the beginning of a clinic session and more likely to prescribe antibiotics at the end of a clinic session.

J. Linder,
None
M. Friedberg, None
H. Reyes Nieva, None
C. Birks, None
J. Falcone, None
Y. Kleyner, None
D. Meeker, None
C. Fox, None