Abstract 12444: Outcomes After Starting Beta-Blockade Within a Clinically Sensible Period Before Major Elective Noncardiac Surgery
Bibliographic record
Abstract
INTRODUCTION: Guidelines recommend that perioperative beta-blockade be started days to weeks before surgery. Nonetheless, all randomized trials except for the controversial DECREASE trials started treatment ≤1 day before surgery, while most observational studies did not distinguish between long-term beta-blockade versus beta-blockers started for perioperative reasons. We thus conducted a population-based cohort study of the effectiveness of beta-blockade started within a clinically sensible period (8-60 days) before surgery. METHODS: Following research ethics approval, we conducted a cohort study of patients (≥66 years) who underwent major elective noncardiac surgery from 2003 and 2012 in Ontario, Canada. Propensity-score methods were used to form a matched cohort that reduced important differences between patients who started beta-blockers 8-60 days before surgery versus controls (no beta-blockers within 1 year before surgery). We measured the association of beta-blockade with 30-day (death, MI, stroke) and 1-year (death) outcomes post-surgery. Subgroup analyses were performed based on Revised Cardiac Risk Index class and history of prior CAD. RESULTS: The cohort included 4268 beta-blocked patients and 154,357 controls. Metoprolol (median daily dose 50 mg) was prescribed to 36% of beta-blocked patients, atenolol (median 25 mg) to 26%, and bisoprolol (median 5 mg) to 37%. In the matched cohort (n=8492), beta-blockade was not associated with death (RR 0.96; CI 0.70-1.32), MI (RR 0.92; CI 0.72-1.17), and stroke (RR 1.31; CI 0.68-2.52) at 30-days, or death at 1-year (Figure). Associations with outcomes did not differ significantly across subgroups. CONCLUSIONS: Outcomes were not altered in patients who start perioperative beta-blockade within a clinically sensible period before surgery. A large randomized trial is needed to determine if the continued use of perioperative beta-blockade in clinical practice is justified.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".