Doctors may prescribe antibiotics inappropriately more in the winter months compared to summer, according to a study at the University of Pennsylvania Perelman School of Medicine. This may affect older adults in long-term care facilities who are commonly exposed to respiratory viruses. The study was published this week in Antimicrobial Stewardship & Healthcare Epidemiology.

The Perelman research team looked at antibiotics that were prescribed for respiratory tract issues at 32 primary care practices in the health system between 2016 and 2017. There were 89,627 visits — 43% in the summer and 57% in the winter. Compared to the summer months, a greater proportion of respiratory visits — 40.2% — had an antibiotic prescribed in the winter. 

The proportion of inappropriate antibiotic prescribing was higher in winter — 72.4% — compared to summer, when it was 62%. The authors say the higher winter prescriptions may have been inappropriate, as in, maybe the person did not need an antibiotic yet received one. They broke down prescriptions into three tiers: tier 1 is always indicated, tier 2 is sometimes indicated and tier 3 is rarely indicated.

A greater proportion of winter visits had an antibiotic that was a tier 2 issue, which is sometimes indicated, and tier 3, which is rarely indicated. Of them, 80.2% prescriptions were tier 2 in the winter compared to 74.2% summer, and 22.9% were tier 3 in the winter compared to 16.2% in the summer.

Decision fatigue could be to blame, the team suspects. That is, clinicians may be so overwhelmed with an increase of visits for respiratory ailments that they mistakenly prescribe the drugs. Their own characteristics — like being more apt to give antibiotics — or those of patients,  like being demanding about getting an antibiotic,  may play a role.

Most antibiotics in the US are prescribed in an outpatient setting, such as a private doctor’s office. Respiratory tract diagnoses are the most common cause for ambulatory antibiotic prescriptions, and up to 50% of are estimated to be inappropriate, or not necessary.