Patterns and Adherence to Guidelines of Antithrombotic
Therapy in Thai Patients with Nonvalvular Atrial Fibrillation
Arom Jedsadayanmata Pharm D, PhD*
Affiliation :
* Center of Pharmaceutical Outcomes Research, and Department of Pharmacy Practice, Faculty of Pharmaceutical
Sciences, Naresuan University, Phitsanulok, Thailand
Background : Antithrombotic therapy is essential in patients with atrial fibrillation (AF) to prevent systemic thromboembolism,
particularly ischemic stroke. Several studies conducted in North America and European countries revealed that AF patients
at high risk for thromboembolism did not adequately receive antithrombotic therapy as recommended by relevant guidelines.
However, such a few studies were reported from Asian countries.
Objective : To describe patterns and adherence to the guideline of antithrombotic therapy in ambulatory patients with non-
valvular AF in Thailand.
Material and Method: From an electronic medical database, data of all patients that were diagnosed with AF and presented
to the ambulatory care clinic between June 1 and September 30, 2008 were retrieved for analysis. The most recently
prescribed antithrombotics and associated risk factors for thromboembolism were reviewed for patterns and adherence to
guidelines of antithrombotic therapy according to the CHADS2 (congestive heart failure, hypertension, age ≥75, diabetes
and stroke/transient ischemic attack) score.
Results : Five hundred thirteen AF patients were identified, of these, 369 patients had no valvular heart diseases or replacement
and were recruited into data analysis. Among non-valvular AF patients, 138 (37.4%), 127 (34.4%), and 104 (28.2%) patients
were classified as high (CHADS2 score ≥2), intermediate (CHADS2 = 1), and low (CHADS2 = 0) risk for ischemic stroke,
respectively. Patients who were classified as low and intermediate risk were prescribed warfarin as antithrombotic therapy
in 51.0% and 52.8%, respectively. Among high-risk patients, 70.3% were prescribed warfarin while 19.6% received only
antiplatelets and 10.1% received no antithrombotic therapy.
Conclusion : The present study has demonstrated that a proportion of non-valvular AF patients at high-risk for ischemic
stroke had not received anticoagulation therapy as recommended by relevant guidelines. Further, low-risk patients were
over-treated with anticoagulants. The finding should prompt health care policy makers to take action to improve quality of
care for these patients.
Keywords : Atrial fibrillation, Anticoagulation, Antithrombotics, Thromboembolism, Warfarin
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