Long or Short Antibiotics? Seniors Get Same Results

TOPLINE:

Longer (8-14 days) antibiotic courses were not associated with increased antibiotic-associated adverse effects or benefits than shorter (3-7 days) antibiotic courses in community-dwelling older adults.

METHODOLOGY:

• This retrospective cohort study in Ontario, Canada, used administrative health data from January to December 2018 to assess the effect of physician variability in duration of antibiotic therapy on patient outcomes.
• The analysis included 117,682 outpatients (age range, 66-110 years) who received prescriptions from 3868 prescribers for amoxicillin (n = 68,058), cephalexin (n = 30,658), or ciprofloxacin (n = 18,966) for either a short or long duration.
• Instrumental variable analysis was performed to account for the preference of prescribers to select a long duration of antibiotic course.
• The primary outcome was a composite of antibiotic-associated harms: Adverse events within 21 days, Clostridioides difficile infection within 90 days, and new antibiotic resistance within 90 days.
• The secondary outcomes included all the components of the primary outcome along with a composite of safety measures such as repeat prescriptions of antibiotics within 30 days, all-cause hospital admissions or emergency room visits between 3 and 30 days from antibiotic dispensing, and mortality within 30 days.

TAKEAWAY:

• Longer antibiotic courses were not associated with increased primary harm outcomes for amoxicillin (adjusted odds ratio [aOR], 0.99; 95% CI, 0.84-1.15), cephalexin (aOR, 1.11; 95% CI, 0.90-1.38), or ciprofloxacin (OR, 0.94; 95% CI, 0.74-1.20).
• No significant difference was noted between longer and shorter antibiotic courses in terms of secondary safety outcomes for amoxicillin, cephalexin, or ciprofloxacin.
• Similarly, sensitivity analysis examining antimicrobial resistance in patients with index and follow-up cultures showed no significant differences between those prescribed longer and shorter antibiotic courses.

IN PRACTICE:

“[The study] findings may suggest that in community-dwelling patients who are at lower risk of harms and benefits from antibiotic therapy, the impact of duration may be negligible,” the authors wrote.

SOURCE:

The study was led by Bradley J. Langford, Public Health Ontario, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada. It was published online on December 30, 2024, in Clinical Infectious Diseases.

LIMITATIONS:

Prescriber preference for long duration served as a weak instrumental variable in the study because physicians might have had varying diagnostic skills and used different strategies for testing and follow-up procedures. Additionally, the patients of these prescribers might have had underlying differences, which could have accounted for unmeasured confounding. Information on the known indications of the three prescribed antibiotics was not available.

DISCLOSURES:

This study received support through grants from the Ontario Ministry of Health and Ministry of Long-Term Care to the Institute for Clinical Evaluative Sciences. Additional grant funding was provided by Physician Services Inc. Foundation. The authors declared having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.