Use of oral Antithrombotic agents among health maintenance organization members with atherosclerotic cardiovascular disease

Background: Numerous randomized trials document the value of antithrombotic agents for the treatment of cardiovascular disease (CVD). Although antithrombotic agents are often prescribed at hospital discharge after CVD-related events, much less is known about the ongoing use of such agents. Methods: We examined the use of oral antithrombotic agents among a random sample of 2500 persons with atherosclerotic CVD who were enrolled in Kaiser Permanente Northwest Region, a not-for-profit group-model health maintenance organization. Study subjects were identified based on a diagnosis of coronary heart disease, ischemic stroke or transient ischemic attack, or peripheral arterial disease in outpatient problem lists, visit records, and hospital discharge abstracts. Use of prescription antithrombotic agents was identified from pharmacy dispensing records. Regular use of aspirin, recall of aspirin advice and education, and other patient characteristics were ascertained by mail survey. Results: Among the 1844 subjects who returned the survey and answered the question regarding aspirin use, 84% were using either aspirin (72%) or a prescription anti-thrombotic agent (12%), typically warfarin sodium. Antithrombotic therapy was relatively underused in persons with peripheral arterial disease (75% used an antithrombotic agent and 62% used aspirin). Use of antithrombotic agents, including aspirin, did not differ by age but was higher among men (87%, 76%) than women (81%, 67%). Nearly all subjects reported having received aspirin education (94%) or advice (81%); recall of education or advice was associated with a dramatically higher likelihood of using antithrombotic agents. To a lesser extent, so was contact with a cardiologist or vascular surgeon during the prior year. Conclusions: High rates of use of antithrombotic agents can be achieved among persons with CVD in integrated not-for-profit health systems with mechanisms in place to encourage such use, including guidelines, messages to clinicians, nurse care management, alerts and routines embedded in electronic medical records, and direct mailings to patients. Continued efforts should be made in all settings to optimize the use of antithrombotic therapy among persons at an elevated risk of atherothrombotic events.