Early Response to Warfarin Initiation and the Risk of Venous Thromboembolism After Total Joint Arthroplasty
Bibliographic record
Abstract
BACKGROUND: Venous thromboembolism chemoprophylaxis with warfarin is common after total joint arthroplasty. Early response to warfarin initiation has been theorized to engender a transient increase in the risk of venous thromboembolism. We hypothesized that a rapid rise in the international normalized ratio is a risk factor for venous thromboembolism after total joint arthroplasty. METHODS: This study was a retrospective analysis of Medicare patients undergoing elective total joint arthroplasty who were given nomogram-dosed warfarin for venous thromboembolism prophylaxis. Logistic regression was used to assess the relationship between the postoperative rate of change in the international normalized ratio and the occurrence of symptomatic venous thromboembolism within 30 days postoperatively. RESULTS: The study included 948 patients (715 total knee arthroplasty, 233 total hip arthroplasty), of whom 4.4% experienced symptomatic venous thromboembolism within 30 days postoperatively. The change in the international normalized ratio from postoperative day 1 to postoperative day 2 was significantly greater in the symptomatic venous thromboembolism group compared with the group that did not have venous thromboembolism (increase of 0.70 versus 0.46; P = 0.008). Regression analysis showed that a higher rate of change in the international normalized ratio was associated with increased risk of symptomatic venous thromboembolism (odds ratio, 2.59 per unit of change in the international normalized ratio; 95% confidence interval, 1.51-4.38; P = 0.001). CONCLUSION: A rapid rise in the international normalized ratio after warfarin initiation in total joint arthroplasty patients is associated with increased risk of symptomatic venous thromboembolism. This novel finding identifies a population at risk for this complication. Further study of the early effects of warfarin therapy is warranted. LEVEL OF EVIDENCE: Level III.
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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 | 0.001 | 0.008 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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) | 0.001 | 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".