Objectives: This study examined compliance with prescribing guidelines for antithrombotic therapy in patients with atrial fibrillation (AF) in Taiwan, using the 2001 joint guideline from the American College of Cardiology, American Heart Association, and European Society of Cardiology. The study also sought to identify factors associated with the appropriate prescribing of antithrombotic therapy.
Methods: Patients with AF were identified by the presence of > or =2 inpatient or outpatient claims with an International Classification of Diseases, Ninth Revision, Clinical Modification code of 427.31 in the Taiwanese National Health Insurance claims database between July 1, 2003, and June 30, 2004. Patients were stratified according to their stroke risk (highest, high, low, or lowest) and antithrombotic medication (aspirin, warfarin, ticlopidine/clopidogrel, or none). Based on these categories, rates of prescribed treatments that were compliant with the antithrombotic guidelines were calculated. Antithrombotic therapies were considered guideline compliant when warfarin was prescribed for the highest- or high-risk patients, aspirin was prescribed for low-risk patients, and aspirin or no antithrombotic treatment was prescribed for the lowest-risk patients. Because the role of ticlopidine/clopidogrel in AF remains unclear, prescription of these drugs without aspirin or warfarin was considered noncompliant with the guidelines.
Results: Of 39,541 identified patients with AF, 70.3% were at high risk for thromboembolic events and 18.3% were at highest risk; however, only 24.7% of the overall population received appropriate antithrombotic therapy. When patients with risk factors for bleeding were excluded, the rate of compliance increased to 26.2%. Factors that were inversely associated with prescription of warfarin included risk factors for bleeding (cancer, predisposition to falls, previous hemorrhage, history of peptic ulcer, cirrhosis, renal dialysis, and psychiatric disease), hypertension, coronary artery disease, thyrotoxicosis, and age > or =60 years.
Conclusions: Most of these patients with AF in Taiwan did not receive appropriate antithrombotic therapy over the period studied. Bleeding risk factors, hypertension, coronary artery disease, thyrotoxicosis, and older age were associated with low rates of warfarin use.