Warfarin treatment in patients with atrial fibrillation: Observing outcomes associated with varying levels of INR control

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• 作者：Christopher Ll. Morgan ; Phil McEwan ; Andrzej Tukiendorf ; Paul A. Robinson ; Andreas Clemens ; Jonathan M. Plumb
• 关键词：Atrial fibrillation ; INR ; Stroke ; Treatment failure ; Warfarin
• 刊名：Thrombosis Research
• 出版年：2009
• 出版时间：May 2009
• 年：2009
• 卷：124
• 期：1
• 页码：37-41
• 全文大小：280 K

文摘

Introduction

We aimed to determine the level of INR control associated with reduced stroke and mortality.

Material and methods

The study used a retrospective cohort design using linked inpatient, haematology and mortality data from Cardiff and the Vale of Glamorgan, UK.

Anonymised patients admitted with a diagnosis of non-valvular atrial fibrillation (NVAF) were defined as warfarin or non-warfarin treated by number of repeated International Normalised Ratio (INR) tests. Warfarin treated patients (> 5 INR tests) categorised as at moderate or high risk of stroke (CHADS₂ score ≥ 2) with varying levels of INR control were compared to those who did not receive warfarin treatment using Cox proportional hazards models controlling for age, sex and CHADS₂ score. Outcome measures were time to stroke and mortality.

Results

6,108 patients with NVAF were identified. 2,235 (36.6 % ) of these patients had five or more INR readings and of these 486 (21.7 % ) had CHADS₂ score ≥ 2. There was significant improvement in time to stroke event in those patients with INR control of greater than 70 % of time in therapeutic range (2.0 to 3.0) compared with the non-warfarin treatment group. Overall survival was significantly improved for all warfarin treated groups with INR control of greater than 40 % of time in range.

Conclusions

Patients with INR control of above 70 % of time in range had a significantly reduced risk of stroke. Patient suitability for warfarin treatment should be continuously assessed based on their ability to maintain a consistently therapeutic INR.