Initiation of warfarin in patients with atrial fibrillation: early effects on ischaemic strokes
Bibliographic record
Abstract
AIMS: An increased risk of stroke was observed in two atrial fibrillation (AF) trials of oral factor Xa inhibitors, when patients were transitioned to open label warfarin at the end of the study. The objective of this study is to determine whether initiation of warfarin is associated with an increased risk of stroke in patients with AF. METHODS AND RESULTS: Using the UK Clinical Practice Research Datalink, a nested case-control analysis was conducted within a cohort of 70 766 patients with AF between 1993 and 2008. Stroke cases were randomly matched with up to 10 controls on age, sex, date of AF diagnosis, and time since AF diagnosis. Conditional logistic regression was used to estimate adjusted rate ratios (RRs) with 95% confidence intervals (CIs) of stroke associated with current warfarin use classified according to time since initiation of treatment (<30 days, 31-90 days, and >90 days), when compared with non-use. A total of 5519 patients experienced a stroke during follow-up. Warfarin was associated with a 71% increased risk of stroke in the first 30 days of use (RR: 1.71, 95% CI: 1.39-2.12), while decreased risks were observed with initiation >30 days before the event (31-90 days: RR: 0.50, 95% CI: 0.34-0.75 and >90 days: RR: 0.55, 95% CI: 0.50-0.61, respectively). CONCLUSION: Patients initiating warfarin may be at an increased risk of stroke during the first 30 days of treatment, supporting the biological plausibility of a transient hypercoagulable state at the start of the treatment, although additional studies are needed to confirm these findings.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".