Abstract 6048: An Indirect Comparison of the Efficacy and Safety of Factor Xa Inhibitors with Thrombin Inhibitors nn Preventing Venous Thromboembolism after Hip or Knee Surgery
Bibliographic record
Abstract
Introduction Selective factor Xa inhibitors and thrombin inhibitors are effective in the prevention of venous thromboembolism (VTE) after hip or knee surgery, but they have not been compared directly against each other. We performed an indirect comparison of the relative efficacy and safety of these two classes of inhibitors, from meta-analyses of randomized controlled trials (RCTs) of these agents, in which a low molecular heparin (LMWH) was used as a common comparator. Methods Relevant RCTs were identified by searching MEDLINE (Ovid MEDLINE® 1950 to March week 1, 2008), EMBASE (1980 to 2008, week 10) and the Cochrane Central Register of Controlled Trials (1 st quarter 2008), supplemented by hand searching and screening meeting websites. We restricted our search to the five agents (ximelagatran, dabigatran, fondaparinux, idraparinux and rivaroxaban) that have been evaluated in phase III trials. Trials were included if the study drug was compared against a LMWH and was administered in the pre- and/or postoperative (12–24hrs from surgery) period, to patients undergoing elective, hip or knee replacement surgery. The outcomes assessed were total VTE, symptomatic VTE, major bleeding and the need for blood transfusions. We obtained summary estimates (RR and 95% CI) for each outcome for the Xa and thrombin inhibitor studies, using a random-effects model. We then performed indirect comparisons between these estimates using standard statistical methods. Results We included 12 trials (18110 patients) of factor Xa inhibitors (fondaparinux, rivaroxaban) and 10 trials (17777 patients) of thrombin inhibitors (ximelagatran, dabigatran). These agents were compared with enoxaparin, except in two studies where dalteparin was the control agent. On indirect comparison, factor Xa inhibitors were significantly better than thrombin inhibitors in preventing total VTE (RR 0.54, 95% CI 0.40 – 0.75) and symptomatic VTE (RR 0.49, 95% CI 0.25– 0.97). There was no difference in the risk of major bleeding (RR 1.17, 95% CI 0.71–1.93) or the number of transfusions (RR 1.02, 95% CI 0.94–1.11). Conclusion Based on this indirect comparison, selective factor Xa inhibitors appear to be more effective than thrombin inhibitors, for the prevention of VTE after elective hip or knee surgery.
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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 | 0.047 | 0.122 |
| Meta-epidemiology (narrow) | 0.004 | 0.002 |
| Meta-epidemiology (broad) | 0.014 | 0.034 |
| Bibliometrics | 0.008 | 0.007 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.002 | 0.003 |
| Research integrity | 0.003 | 0.004 |
| Insufficient payload (model declined to judge) | 0.014 | 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".