Apixaban versus Enoxaparin for Thromboprophylaxis after Hip Replacement
Bibliographic record
Abstract
BACKGROUND: There are various regimens for thromboprophylaxis after hip replacement. Low-molecular-weight heparins such as enoxaparin predominantly inhibit factor Xa but also inhibit thrombin to some degree. Orally active, specific factor Xa inhibitors such as apixaban may provide effective thromboprophylaxis with a lower risk of bleeding and improved ease of use. METHODS: In this double-blind, double-dummy study, we randomly assigned 5407 patients undergoing total hip replacement to receive apixaban at a dose of 2.5 mg orally twice daily or enoxaparin at a dose of 40 mg subcutaneously every 24 hours. Apixaban therapy was initiated 12 to 24 hours after closure of the surgical wound; enoxaparin therapy was initiated 12 hours before surgery. Prophylaxis was continued for 35 days after surgery, followed by bilateral venographic studies. The primary efficacy outcome was the composite of asymptomatic or symptomatic deep-vein thrombosis, nonfatal pulmonary embolism, or death from any cause during the treatment period. Patients were followed for an additional 60 days after the last intended dose of study medication. RESULTS: A total of 1949 patients in the apixaban group (72.0%) and 1917 patients in the enoxaparin group (71.0%) could be evaluated for the primary efficacy analysis. The primary efficacy outcome occurred in 27 patients in the apixaban group (1.4%) and in 74 patients in the enoxaparin group (3.9%) (relative risk with apixaban, 0.36; 95% confidence interval [CI], 0.22 to 0.54; P<0.001 for both noninferiority and superiority; absolute risk reduction, 2.5 percentage points; 95% CI, 1.5 to 3.5). The composite outcome of major and clinically relevant nonmajor bleeding occurred in 129 of 2673 patients assigned to apixaban (4.8%) and 134 of 2659 assigned to enoxaparin (5.0%) (absolute difference in risk, -0.2 percentage points; 95% CI, -1.4 to 1.0). CONCLUSIONS: Among patients undergoing hip replacement, thromboprophylaxis with apixaban, as compared with enoxaparin, was associated with lower rates of venous thromboembolism, without increased bleeding. (Funded by Bristol-Myers Squibb and Pfizer; ClinicalTrials.gov number, NCT00423319.).
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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 | 0.003 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".