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Published on: February 26, 2013
Poor adherence to anticoagulation guidelines in patients with non-valvular atrial fibrillation treated in a tertiary
Guan Sen Kew1, Mabel Tan2, Toon Wei Lim3
1National University Hospital , Singapore , Singapore.
Insights
Adherence to atrial fibrillation (AF) stroke prevention guidelines is poor, with many patients not receiving oral anticoagulants (OAC) despite risk factors. Prescribing OAC, like warfarin, improved survival outcomes in this AF patient cohort.
Area of Science:
- Cardiology
- Stroke Prevention
- Pharmacotherapy
Background:
- Atrial fibrillation (AF) significantly increases stroke risk.
- Oral anticoagulants (OAC) are recommended for stroke prevention in AF patients with risk factors.
- Current adherence to established guidelines for OAC use in AF is suboptimal.
Purpose of the Study:
- To assess adherence to CHADS2 guidelines for OAC prescription in AF patients.
- To identify reasons for non-adherence to OAC therapy.
- To evaluate the impact of OAC use on survival outcomes in AF patients.
Main Methods:
- Retrospective analysis of 163 non-valvular AF patients admitted to a tertiary cardiology unit (Jan-Mar 2010).
- Evaluation of OAC (warfarin) prescription rates and international normalised ratio (INR) control.
- Analysis of reasons for OAC non-prescription and comparison of survival between OAC users and non-users.
Main Results:
- Only 38.7% of eligible AF patients (CHADS2 ≥ 2) were discharged with warfarin.
- Among patients not prescribed warfarin, common reasons included bleeding history (32.9%) and undocumented reasons (23.3%).
- Warfarin use was associated with significantly better survival outcomes (1522 days vs. 1255 days, p=0.001).
Conclusions:
- Guideline adherence for OAC in AF patients is low, even in specialized cardiac units.
- Barriers to effective VKA use for stroke prevention in AF patients are numerous.
- OAC therapy is crucial for improving survival in AF patients at risk of stroke.
Introduction:
Atrial fibrillation (AF) is a well-known cause of strokes and all major society guidelines recommend oral anticoagulants (OAC) such as vitamin K antagonists (VKA) for patients with concomitant risk factors to prevent them. However, compliance with these guidelines is historically poor. This study aims to evaluate the adherence to CHADS2 (congestive heart failure, hypertension,age ≥75 years, diabetes mellitus and prior stroke or transient ischaemic attack) guidelines, explore reasons and evaluate outcomes for non-adherence in a tertiary cardiology unit.
Materials And Methods:
A retrospective study of patients admitted into a tertiary cardiology unit from January to March 2010.
Results:
Of 1826 unique cardiac patients screened, 163 (8.9%) of them had non-valvular AF or atrial flutter. Their mean age was 69.8 years and 58.9% were men. Of the 54 patients on warfarin with documented international normalised ratio (INR), only 22 (40.7%) of them had an INR within the therapeutic range (INR less than two in 22 (40.7%) and greater than three in 10 (18.5%)). Of the 119 patients with CHADS2 greater than or equal to two, only 46 (38.7%) were discharged with warfarin. Among the remaining 73 (61.3%) patients, the most common reasons for not prescribing warfarin include history of bleeding (n=24, 32.9%), no reason documented (n=17, 23.3%) and patient preference (n=12, 19.2%). On follow-up, patients on warfarin were found to have better survival outcomes (mean 1522±41 days) as compared with (mean 1255±63 days) in patients not on OAC (p value=0.001).
Conclusions:
Few patients who require anticoagulation receive it in accordance with the guidelines even in a tertiary cardiology unit. There are many impediments to the effective use of VKA for stroke prevention among patients with AF.
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