Abstract 16741: The Cost-Effectiveness of Apixaban versus Warfarin in Patients With Atrial Fibrillation: Insights From the ARISTOTLE Study Group
Bibliographic record
Abstract
Background: In Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE), apixaban (vs. warfarin) significantly reduced stroke, death, and major bleeding in 18,201 patients with atrial fibrillation (AF). We assessed the cost-effectiveness of apixaban vs. warfarin from the perspective of the US health care system. Methods: Resource use (service dates, intensive care days, days on drug) was obtained from ARISTOTLE case report forms. Unit costs for components of hospital-based care of AF patients were estimated with generalized linear models using the national Premier database. Daily cost of anticoagulants was based on current acquisition cost (apixaban=$9.49; warfarin=$0.09) for 10 years, after which time apixaban was valued at projected costs of generic substitutes ($1.89). Physician services and anticoagulant monitoring were valued using Medicare fees. Within-trial costs were estimated using inverse probability weighting for differential follow-up. Survival was modeled with patient-level ARISTOTLE data using a two stage approach that combined a time-based Cox model for the within-trial period and an age-based Cox model for extrapolation. Uncertainty surrounding estimates of cost, life expectancy and cost/per life year gained was characterized with bootstraps and sensitivity analyses. Results: After 2 years, costs in the US cohort (n=3417) excluding study drug and monitoring averaged $306 less with apixaban than warfarin ($6257 vs. $6563). This difference was more than offset by higher apixaban anticoagulation costs ($6160 vs. $1181), resulting in an overall increase of $4673/patient. Over a lifetime, gains in life expectancy with apixaban (9.92 vs. 9.69; p<.001) were achieved at an additional cost of $17,564 ($29,447 vs. $11,883; p<.001), yielding a cost-effectiveness ratio (ICER) of $76,365/life year gained (85% likelihood of meeting $110,000 willingness to pay threshold). Cost-effectiveness was most sensitive to cost of apixaban. Conclusions: Reductions in mortality, stroke, and bleeding observed in ARISTOTLE translate to significant increases in life expectancy. At an estimated ICER of $76,365/life year gained, apixaban is a cost-effective alternative to warfarin.
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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 | 0.007 | 0.014 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.003 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".