A Double-Blind, Randomized Controlled Trial of the Prevention of Clinically Important Venous Thromboembolism After Isolated Lower Leg Fractures
Bibliographic record
Abstract
BACKGROUND: Among patients with isolated below-knee fractures, previous studies have detected asymptomatic deep vein thrombosis in 10%-40% using contrast venography. However, the clinical relevance of these thrombi is unknown; there is considerable uncertainty about the risk: benefit of routine thromboprophylaxis and clinical practice guidelines differ in their recommendations. METHODS: In this multicenter, double-blind trial, 265 patients with isolated lower leg fractures requiring surgery were randomized to subcutaneous dalteparin 5000 units or matching placebo once daily for 2 weeks with bilateral Doppler ultrasound (DUS) of the proximal leg veins on postoperative day 14±2 and 3-month follow-up. The primary effectiveness outcome was clinically important venous thromboembolism (CIVTE), defined as the composite of symptomatic venous thromboembolism within 3 months after surgery and asymptomatic proximal deep vein thrombosis on DUS. The primary safety outcome was major bleeding. RESULTS: Two hundred fifty-eight patients (97%) were included in the primary outcome analysis for effectiveness (130: dalteparin; 128: placebo). Incidence of CIVTE in the dalteparin and placebo groups was 1.5% and 2.3%, respectively (absolute risk reduction, 0.8%; 95% confidence interval, -2.0 to 3.0). There were no fatal pulmonary emboli or major bleeding. CONCLUSIONS: The overall incidence of CIVTE after surgically repaired, isolated tibia, fibula, and ankle fractures was low (1.9%; 95% confidence interval, 0.7-4.7), with no observed differences between dalteparin and placebo either for CIVTE or safety. Recruitment was stopped at the first interim analysis. This study also demonstrates the substantial discrepancy in venous thromboembolism rates between trials that use venographic outcomes compared with more clinically relevant outcomes. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.
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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 | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.004 | 0.002 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.008 | 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".