Antibiotic Prescribing Practice Varies Widely in Canada

Carolyn Crist

May 11, 2022

Even before the COVID-19 pandemic, primary care doctors in Canada often prescribed antibiotics unnecessarily for respiratory tract infections such as the common cold, sinusitis, and acute bronchitis, according to new research.

For some viral conditions, such as the common cold or bronchitis, about half of the doctors never prescribed antibiotics, marking a positive trend. However, a quarter of the providers prescribed antibiotics for nearly all their patients with ear infections or sinusitis and about half of their patients with common colds.

Dr Jerome Leis

"Judicious use of antibiotics is crucial to our fight against the growing public health threat of antimicrobial resistance," senior study author Jerome Leis, MD, medical director of infection prevention and control at Sunnybrook Health Sciences Centre and associate professor of medicine at the University of Toronto, Ontario, told Medscape Medical News.

"We already know that, in general, about 40% of antibiotics prescribed for respiratory tract infection in primary care are unnecessary and could be avoided," he said. "But we cannot improve something without first measuring it accurately…across specific respiratory tract infection conditions."

The findings were published online April 6 in the Canada Communicable Disease Report.

Monitoring Nationwide Trends

Respiratory tract infections represent the leading reason for avoidable antimicrobial use in primary care in Canada, the study authors wrote. However, physician-level data and feedback on antibiotic use is only available in some provinces.

In this study, the investigators looked at the Canadian Primary Care Sentinel Surveillance Network to validate case definitions for respiratory tract infections and determine baseline physician-level variability in antimicrobial prescribing in 2019. They created five case definitions to cover most respiratory tract infections, including the common cold, uncomplicated sinusitis, uncomplicated pharyngitis, acute bronchitis/asthma, and acute otitis media/eustachian tube disorders.

The research team then examined the proportion of patients with one of the five respiratory conditions that received an antibiotic prescription, including medications such as penicillin VK, amoxicillin, amoxicillin-clavulanic acid, cefuroxime, cefaclor, cefadroxil, clarithromycin, azithromycin, moxifloxacin, and levofloxacin.

They found that of the more than 873,000 patients who visited their primary care clinicians in 2019, about 11.3% were diagnosed with a respiratory tract infection. The prevalence was about 4.1% for the common cold, 4% for acute bronchitis/asthma, nearly 2% for sinusitis, 1.2% for pharyngitis, and 1% for otitis media.

Looking at data per encounter, they found that about 3.5% of the 3.7 million medical encounters were linked with a respiratory tract infection diagnosis. Among those, about 1.3% were for acute exacerbation of chronic obstructive pulmonary disease, 1.1% for common cold, 0.5% for sinusitis, 0.3% for otitis media, and 0.3% for pharyngitis.

The research team found significant variability in antibiotic prescribing patterns for the different respiratory tract infections per patient, per episode, and per patient encounter. Acute otitis media carried some of the highest percentages, with a median of 64% prescribed an antibiotic, followed by 54% for sinusitis, 21% for overall respiratory tract infection, 20% for pharyngitis, 8.3% for acute bronchitis/asthma, and 6.7% for the common cold.

The baseline numbers can provide a way to monitor nationwide trends of antimicrobial prescribing practices and provide feedback to primary care clinicians, the study authors wrote.

"We now have a way of measuring antibiotic use at a fairly granular level across a national cohort of primary care providers," Leis said. "Now we need to start the local quality improvement work and track these practices over time to help evaluate the impact of pan-Canadian interventions aimed at improving antibiotic use in primary care."

"Public Health Crisis"

Until now, surveillance of respiratory tract infections and antibiotic prescribing practices has relied on provincial databases, which in turn rely on physician billing claims. The Canadian Primary Care Sentinel Surveillance Network, however, incorporates various demographic factors, diagnostic codes, and terms from electronic medical records that may be more reliable for monitoring multiple respiratory tract infection definitions.

Although the study didn't directly measure the appropriateness of antibiotic prescribing, the study authors wrote, the variability sheds light on areas for improvement, especially for physicians in the upper quartiles. For instance, the highest prescribers gave antibiotics for a median of 94% of otitis media cases, 82% of sinusitis cases, and 57% of pharyngitis cases. On the other hand, the lowest prescribers gave antibiotics for less than 20% of respiratory tract infections overall and nearly zero for the common cold, pharyngitis cases, and bronchitis/asthma cases.

National campaigns such as Using Antibiotics Wisely have developed prescriber-led practice changes and clinical tools to support more appropriate antibiotic use. Specific data on respiratory tract infections could help those campaigns.

"Antimicrobial stewardship is complex and requires a multifaceted approach for improvement," Kevin Schwartz, MD, an infectious disease physician for St. Joseph's Health Centre at Unity Health Toronto, told Medscape Medical News.

Dr Kevin Schwartz

Schwartz, who wasn't involved with this study, has conducted a randomized controlled trial to provide antibiotic-prescribing feedback to high-volume primary care physicians. Individualized letters helped physicians to reduce the amount of antibiotics they prescribed, as well as the treatment duration.

At the same time, overall numbers don't necessarily indicate inappropriate use or provide specific feedback, Schwartz noted. Knowing the details about certain conditions, such as respiratory tract infections, can help primary care clinicians to reduce antibiotic prescriptions for avoidable uses such as viral illnesses.

"It's important to keep stressing that this is a serious public health crisis," Schwartz said. "Even if antimicrobial resistance doesn't directly affect people's health and economics right now, it will in the future. It's a slow-moving tsunami, and we need strategies to improve it now."

Using Antibiotics Wisely, a campaign of Choosing Wisely Canada, is supported by the Public Health Agency of Canada. Leis receives support from Choosing Wisely Canada. Schwartz reported no relevant disclosures.

Canada Communicable Disease Report . Published online April 6, 2022. Full text

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