Patterns and adherence to guidelines of antithrombotic therapy in Thai patients with nonvalvular atrial fibrillation.

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 nonvalvular 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 AFpatients were identified, ofthese, 369 patients had no valvular heart diseases or replacement and were recruited into data analysis. Among non-valvularAF patients, 138 (37.4%), 127 (34.4%), and 1l04 (28.2%) patients were classified as high (CHADS2 score > or =2), intermediate (CHAD S2 = I), 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.