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Published on: February 28, 2012
Anticoagulation therapy in patients with chronic atrial fibrillation: a retrospective claims data analysis
C R Harley1, A A Riedel, O Hauch
1Health Economics and Outcomes, i3 Magnifi, Eden Prairie, MN 55344, USA. carolyn.harley@i3magnifi.com
Insights
Warfarin use in atrial fibrillation patients reduced arterial thromboembolic events but increased bleeding risks. Real-world warfarin performance may lag behind clinical trial expectations.
Area of Science:
- Cardiology
- Pharmacology
- Clinical Research
Background:
- Atrial fibrillation (AF) necessitates anticoagulation to prevent thromboembolic events.
- Warfarin is a commonly prescribed anticoagulant for AF patients.
Purpose of the Study:
- To assess the real-world effectiveness and safety of warfarin in patients with chronic non-valvular atrial fibrillation.
- To compare the risk of thromboembolic events and bleeding complications in warfarin-exposed versus unexposed AF patients.
Main Methods:
- Retrospective cohort study using medical claims data from 1998-2000.
- Included patients with chronic non-valvular atrial fibrillation continuously enrolled for 6 months prior to diagnosis.
- Cox proportional hazards analysis with time-varying covariates was employed.
Main Results:
- Warfarin exposure was associated with a reduced risk of arterial thromboembolic events (HR: 0.710).
- No significant benefit of warfarin was observed for preventing intracranial events (HR: 1.119).
- Warfarin significantly increased the risk of minor bleeding (HR: 3.600) and all bleeding events (HR: 1.502).
Conclusions:
- Warfarin effectively reduces arterial thromboembolic events in AF patients.
- Warfarin use is linked to a higher incidence of bleeding complications.
- A potential discrepancy exists between warfarin's efficacy in clinical trials and its performance in general practice.
Objectives:
This study assessed the risk of thrombo embolic events and bleeding complications among atrial fibrillation patients.
Methods:
A cohort of patients with chronic non-valvular atrial fibrillation were identified from medical claims (diagnosis codes 427.31 and 427.32). Subjects were identified from 1 January 1998-31 December 2000 and were continuously enrolled for 6 months prior to the first occurring atrial fibrillation medical claim. Cox proportional hazards analysis with time varying covariates was used for the event analysis.
Results:
Of 6764 subjects retained for analysis, 3541 (52.4%) were exposed to warfarin. Adjusting for baseline characteristics, warfarin exposure was associated with lower likelihood of an arterial thromboembolic event compared to no exposure (HR: 0.710, CI: 0.540-0.934). No benefit was found in the use of warfarin in the prevention of intracranial events (HR: 1.119, CI: 0.929-1.349). Use of warfarin increased the risk of minor bleeding events (HR: 3.600, CI: 2.537-5.109), and all bleeding events (HR: 1.502, CI: 1.289-1.749).
Conclusions:
The risk of arterial thromboembolic events was associated with warfarin exposure as expected. An increase in the risk of minor and total bleeding events among patients treated with warfarin was observed. The results of this study suggest that there may be a gap between the clinical trial and coagulation clinic performance of warfarin in reducing the risk of thromboembolic events versus what is achievable in general practice.
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