Clinical and Economic Implications of Apixaban Versus Aspirin in the Low-Risk Nonvalvular Atrial Fibrillation Patients
Bibliographic record
Abstract
BACKGROUND AND PURPOSE: Although recommended by guidelines, the benefits of treating patients with atrial fibrillation with a low-stroke risk score, with aspirin or anticoagulants, have not been clearly established. With advent of safer non-vitamin K antagonist oral anticoagulant, we assessed the clinical and economic implications of 5 mg BID of apixaban versus aspirin among patients with a relative low risk of stroke as assessed using the CHADS2 (congestive heart failure, hypertension, age>75, diabetes mellitus, stroke/transient ischemic attack) and CHA2DS2-VASc (congestive heart failure, hypertension, age, diabetes mellitus, stroke/transient ischemic attack, vascular disease) stroke risk classification. METHODS: A previously developed and validated Markov model was adapted. A secondary analysis of the Apixaban Versus Acetylsalicylic Acid to Prevent Stroke in Atrial Fibrillation Patients Who Have Failed or Are Unsuitable for Vitamin K Antagonist Treatment (AVERROES) study was conducted to estimate event rates in different low-risk cohorts by treatment. Three cohorts (n=1000) with a CHADS2 score of 1, CHA2DS2-VASc score of 1, and CHA2DS2-VASc of score 2 to 4 were simulated to assess the number of clinical events avoided in terms of strokes and major bleeds, as well as life years gained, quality-adjusted life years gained, costs, and incremental costs per quality-adjusted life year gained. RESULTS: Apixaban was associated with fewer strokes and systemic embolism versus aspirin across all subgroups; however, it caused more major bleeding events. The reduction in systemic embolism offset the increase in major bleeding events leading to increased life expectancy and quality-adjusted life year gains, achieved at an increased cost that was lower than the UK threshold of $44,400 (ie, £30,000) per quality-adjusted life year gained across the 3 cohorts examined. CONCLUSIONS: Anticoagulant treatment with apixaban versus aspirin in low-risk patients, as identified using CHADS2 or CHA2DS2-VASc, is projected to increase life expectancy and provide clinical benefits that are cost effective.
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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 | 0.005 | 0.012 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".