Reviewed by Dr. Adrian Peña
Silverman et al, Ann Int Med. 2017 June 6;166 (11):765-774

This study was a one-year, retrospective analysis examining the prevalence and predictors of antibiotic prescribing for non-bacterial acute upper respiratory infections (AURIs) among older (≥66 years) Canadian patients in primary care settings. Data was obtained from population-based administrative databases from the Institute for Clinical Evaluation Sciences and included all primary care physician visits for nonbacterial AURIs in Ontario, Canada. The primary outcome was the prescription of antibiotics within 30 days of patient presentation with a nonbacterial AURI.

Data from 185,014 distinct patient episodes were included in the study. The most common infections were the common cold (53.4%), acute bronchitis (31.3%), acute sinusitis (13.6%), and acute laryngitis (1.6%). Overall, antibiotics were prescribed to 46.2% of patients. Regression analysis showed that patients were more likely to receive antibiotic prescriptions from male physicians (43.0% vs 41.8% female physicians, p=.016); late-career physicians (43.0%) as compared to early-career physicians (38.4%, p<.001); physicians without hospital affiliation (43.3% vs 40.8%, p<.001); physicians whose daily patient load exceeded 45 patients per day (44.4%) as compared to physicians who saw <25 patients per day (40.3%, p<.001); and physicians who trained outside of the US and Canada (45.2%) as compared to physicians who were US/Canadian graduates (41.6%, p<.001). Finally, US/Canada-trained physicians were more likely to prescribe broad-spectrum antibiotics for nonbacterial AURIs (66.0%) than physicians who trained outside of the US and Canada (71.6%, p<.001).

Antibiotic resistance is recognized as a major public health concern and one of the greatest threats to human health worldwide (CDC). While antibiotic resistance has historically been a clinical problem in hospital settings, recent data show resistant organisms have been detected in primary care settings as well (IDSA). This phenomenon is largely driven by unnecessary antibiotic use. Despite guidelines discouraging this practice, antibiotics continue to be prescribed at high rates for non-bacterial AURIs (CDC). Prior studies have found that rates of inappropriate antibiotic prescribing may be explained in part by facility and regional characteristics (Zhang, Steinman and Kaplan). In this retrospective cohort study, Silverman et al sought to explore physician factors associated with inappropriate antibiotic prescribing.

This study found that physician career stage, daily patient volume, and location of training were predictive of inappropriate antibiotic prescribing. Limitations of the study include an older cohort (in large part due to the eligibility of the Ontario Drug Benefit Program), and a widespread catchment area including both rural and urban settings (patient and practice location were not accounted for), which may limit generalization of results. Also, the study did not capture a physician’s motivation to prescribe antibiotics, which could reveal medical justification and/or identify additional modifiable factors.

Identifying physician factors contributing to inappropriate antibiotic prescribing may help guide the development of stewardship interventions. For late career physicians, one reasonable approach might include accountable justification for prescription, financial incentives for reducing antibiotic prescription, and peer-comparison approaches along with electronic medical record-based decision support where available. Another high-impact cohort would be trainees in undergraduate and graduate medical education. Possible interventions in this target group include emphasizing adverse drug events associated with macrolide and quinolone use (i.e. cardiac arrhythmias, drug interactions, neuropathic toxicity), education on morbidity and mortality associated with antibiotic overuse (especially with regards to multi-drug resistant organisms), reinforcement of knowledge on clinical indications for antibiotic usage in the outpatient setting, and promotion of antibiotic stewardship at an earlier stage of clinical training.

Given that clinical practice guidelines alone have had limited effects on antibiotic prescribing practices, alternative strategies are needed. These study findings may aid the development of future educational initiatives if confirmed in other practice settings.

1. CDC. “Centers for Disease Control and Prevention. Antibiotic Resistance Threats in the United States, 2013.” Url: Https://Www.Cdc.Gov/Drugresistance/Pdf/Ar-Threats-2013-508.pdf.

2. IDSA. “Infectious Diseases Society of America. Combating Antimicrobial Resistance: Policy Recommendations to Save Lives.” Clin Infect Dis 52 Suppl 5 (2011): S397-428.

3. Zhang, Y., M. A. Steinman, and C. M. Kaplan. “Geographic Variation in Outpatient Antibiotic Prescribing among Older Adults.” Arch Intern Med 172.19 (2012): 1465-71.