Duration of Preoperative β-Blockade and Outcomes After Major Elective Noncardiac Surgery
Bibliographic record
Abstract
BACKGROUND: Although practice guidelines recommend that perioperative β-blockade be initiated at least several days to weeks before noncardiac surgery is performed, the minimum required period of preoperative therapy is unclear. METHODS: Population-based administrative databases were used to conduct a cohort study of 48,103 patients aged ≥ 66 years who underwent major elective noncardiac surgery in Ontario, Canada and received preoperative β-blocker therapy. We used multivariable logistic regression to determine the association of duration of preoperative β-blocker treatment (classified as 1-7 days, 8-30 days, and ≥ 31 days) with 30-day mortality, 30-day myocardial infarction (MI), 30-day ischemic stroke, and 1-year mortality. RESULTS: The duration of preoperative β-blocker treatment was 1-7 days in 1105 patients (2.3%), 8-30 days in 2639 patients (5.5%), and ≥ 31 days in 44,269 patients (92.0%). Compared with ≥ 31 days of preoperative therapy, 1-7 days of therapy was associated with increased 30-day mortality (odds ratio [OR], 1.49; 95% confidence interval [CI], 1.03-2.16; P = 0.03], whereas 8-30 days of therapy was not (OR, 0.95; 95% CI, 0.69-1.31; P = 0.77). One to 7 days of preoperative therapy was not significantly associated with 1-year mortality (OR, 1.06; 95% CI, 0.84-1.35; P = 0.62), 30-day MI (OR, 1.26; 95% CI, 0.92-1.71; P = 0.15), or 30-day ischemic stroke (OR, 1.37; 95% CI, 0.64-2.94; P = 0.41). CONCLUSIONS: Initiation of β-blocker therapy 1-7 days before noncardiac surgery is associated with increased 30-day mortality. The findings merit further evaluation by randomized trials.
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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 | 0.000 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".