Evaluating Harms Associated With Prolonged Antibiotic Duration of Therapy in Community-Dwelling Older Adults: A Cohort Study Using Instrumental Variable Analysis
Bibliographic record
Abstract
BACKGROUND: Shorter courses of antibiotic therapy are increasingly recommended to reduce antibiotic exposure. However, quantifying the real-world impact of duration of therapy is hindered by bias common in observational studies. We aimed to evaluate the harms and benefits of longer versus shorter duration of therapy in older adults. METHODS: This was a population-based cohort study using administrative health data from Ontario, Canada. We included outpatients aged 66-110 years who received a prescription for amoxicillin, cephalexin, and/or ciprofloxacin. Prescriptions were categorized as short (3-7 days) or long (8-14 days) duration. The primary outcome was a composite of antibiotic-related harms, including adverse reactions, Clostridioides difficile infection, and antibiotic resistance. The secondary outcome was a composite of safety measures including repeat antibiotic prescriptions, hospital visits, and mortality. To reduce risk of bias, we used an instrumental variable analysis where the instrument was prescriber proportion of antibiotics that were long duration. RESULTS: Among 117 682 eligible patients, there was no difference in the primary harms outcome for patients receiving longer versus shorter courses of antibiotics (adjusted odds ratio and 95% confidence interval [CI]): amoxicillin, 0.99 (.84-1.15); cephalexin, 1.11 (.90-1.38); ciprofloxacin, 0.94 (.74-1.20). Secondary safety outcomes were similar, with longer compared to shorter courses of antibiotic therapy (odds ratio and 95% CI): amoxicillin, 1.01 (.94-1.08); cephalexin, 1.06 (.97-1.17); ciprofloxacin, 0.99 (.85-1.15). CONCLUSIONS: In this instrumental variable analysis of community-dwelling older adults, longer antibiotic courses were not associated with an increased benefit or harm compared to shorter courses.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.018 | 0.036 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.004 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".