Barriers to patient self-testing of prothrombin time: national survey of anticoagulation practitioners

Oral anticoagulation with warfarin requires routine monitoring of prothrombin time, expressed as the international normalized ratio (INR). Patient self-testing for INR is common in Europe but not in the United States. In order to determine the frequency of INR self-testing among patients whose anticoagulant therapy is managed in U.S. anticoagulation clinics, to describe the processes that support this self-testing, and to identify the barriers as experienced by anticoagulation clinic providers, a three-part survey was mailed to 538 anticoagulation specialists in the United States. The response rate was 43.7%. Policies and procedures of almost 60% of anticoagulation clinics prohibited INR self-testing for enrolled patients. In addition, less than 1% of patients being managed by U.S. anticoagulation clinics use self-testing to obtain INR results. Primary barriers were the cost of self-testing instruments (78.7% of respondents), cost of reagent cartridges (60.4%), and fear that self-testing might lead to unintended self-management (35.7%). Over 75% of respondents believed that some reimbursement for the cost of self-testing devices and supplies would increase the likelihood that anticoagulation clinics would recommend INR self-testing.