Randomized trial to examine the effect of ASA dose or ASA dosing frequency on ASA resistance after coronary artery bypass graft surgery
Bibliographic record
Abstract
Purpose: Low-dose ASA (81 mg daily) is administered after coronary artery bypass graft (CABG) surgery to reduce the risk of graft failure. There is transient ASA resistance after such surgery, which may compromise its effectiveness. Because such resistance may reflect the failure of once-daily, low-dose ASA to acetylate cyclo-oxygenase (COX)-1 and inhibit thomboxane A2 (TXA2) synthesis in the setting of the increased platelet turnover that occurs post-operatively, we performed a randomized trial to determine whether higher-dose once-daily or more frequent ASA dosing overcomes the resistance observed with usual ASA dosing. Methods: Adults undergoing CABG surgery were randomized to one of 3 ASA dosing regimens; 81 mg once-daily, 325 mg once-daily, or 81mg four times daily. ASA was started on the first post-operative day and continued until day 7 or hospital discharge. Using an immunoassay, levels of serum TXB2, the stable metabolite of TXA2, were measured daily before starting ASA. The primary outcome was the median TXB2 level on postoperative day 4. Results: A total of 100 patients undergoing CABG surgery (mean age 65, females 16%) were randomized. On day 4, median TXB2 level in the group receiving ASA 81mg once-daily was 10.7 ng/ml (Q1,Q3; 6.1,30.8 ng/ml). The median TXB2 levels were significantly lower in the groups randomized to ASA 325 mg once-daily and 81 mg four times daily; 3.6 ng/ml (Q1,Q3; 1.9,10.1 ng/ml) and 1.1 ng/ml (Q1,Q3; 0.5,2.4 ng/ml), respectively; P=0.001 and P<0.0001, respectively. Conclusions: ASA resistance after CABG surgery, defined as failure of ASA to suppress TXB2 formation, is attenuated by higher dose once-daily ASA and almost abolished by four times daily low-dose ASA. The efficacy of more frequent ASA dosing supports the concept that resistance reflects, at least in part, increased platelet turnover. Attenuation of TXB2 production by higher dose once-daily ASA raises the possibility that the susceptibility of megakaryocyte COX-1 to acetylation by ASA may be dose-dependent.
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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 | 0.004 | 0.008 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.005 | 0.003 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.004 | 0.004 |
| Insufficient payload (model declined to judge) | 0.011 | 0.001 |
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".