Anti-Factor Xa Levels in Low-weight Surgical Patients Receiving Enoxaparin for Venous Thromboembolism Prophylaxis: A Prospective Cohort Study
Bibliographic record
Abstract
Enoxaparin is indicated for thromboprophylaxis in non-orthopedic surgical patients at a fixed dose of 40 mg daily. According to the US Food and Drug Administration’s enoxaparin prescribing information, this dose exposes low-weight patients (males < 57 kg, females < 45 kg) to a higher risk of bleeding. This study aimed to determine the rate of achieving a prophylactic peak anti-factor Xa (AFXa) level in low-weight surgical patients using enoxaparin 30 mg daily. Low-weight patients admitted for abdominopelvic or noncardiac thoracic surgery from May 2018 to May 2019 were prospectively studied. After receiving daily enoxaparin 30 mg, peak AFXa levels were assessed for achieving a prophylactic level (0.2-0.5 IU/mL). In 121 patients, the proportion of achieving a prophylactic peak AFXa level was 66.1%. More females (84.8%) achieved a prophylactic level compared to males (54.7%, P = .001). All out-of-range peak AFXa levels (33.9%) were sub-prophylactic. The median peak AFXa level was lower in males (0.24 [0.1-0.47] IU/mL) than females (0.31 [0.1-0.5] IU/mL; P < .001). On univariate analysis, female sex and weight were associated with achieving a prophylactic peak AFXa level. On multivariate analysis, only female sex was independently associated with an adequate prophylactic AFXa level (odds ratio 3.17, 95% CI: 1.32-11.94; P = .014). Four venous thromboembolism events (3.3%) were observed in patients with sub-prophylactic peak AFXa levels (9.7%). Two-thirds of low-weight surgical patients achieved a prophylactic peak AFXa level using daily enoxaparin 30 mg. This dose is likely to provide adequate thromboprophylaxis in low-weight females.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".