Little has been known about patients’ knowledge of atrial fibrillation(af), stroke and warfarin, and frequency distribution of international normalized ratio values (INR) during warfarin taking.
Ninety one patients, with mean follow-up duration of 44 (SD23) months, 330 patient year, 0.9 monitoring test/month, were investigated. Patients were interviewed using open ended and prompted questions on af, stroke and warfarin. 1887 INR, between january 2007 and december 2008, were studied.
Patients’ average age: 73 (SD 8), female: 27 (30%), high school or higher education: 68 (75%). Af was diagnosed, 49 (44%) by subjective symptoms, 23 (25%) incidentally, 20 (22%) by medical checkup and 8 (9%) by onset of stroke. Only 30% knew cardiac performance of af. 64% knew af symptoms or sings > 1. 62% knew stroke is potential complication of af. 30% did not know symptoms of stroke > 1. 52% did not know aim of warfarin monitoring test. Age made signinicant difference in knowledge of monitoring test(P = 0.001). 82% knew adjusted warfarin doses. 69% knew monitored INR. 95% had regular monitoring test 96% took warfarin as prescribed doses. 96% had regular and daily warfarin taking. 90% knew diet (especially natto) influencing on warfarin effect. 90% did not take vitamin K rich food. 78% paid attention to take medicine and dietary supplements. INR were categorized into six groups. Maximum(max) INR and frequencies of INR in each group were as follows: INR < 1.5:max INR: 1.4(SD 0.8), frequency: 108 (5.7%), 1.5≦INR < 2.0: max INR: 1.9 (SD 0.3) frequency: 615 (32.5%), 2.0≦INR < 2.5:2.4 (SD 0.6), 708 (37.5%), 2.5≦INR < 3.0:2.8 (SD 0.2), 327(17.3%), 3.0≦INR < 4.0:4.3 (SD 0.2), 92(4.9%), 4.0≦INR:4.3 (SD 0.3), 9(0.5%). Age made signinificant difference in INR < 1.5 (P = 0.001) and 3.0≦INR (P = 0.01). 43.6% of INR were out of 2.0–3.0. The questionnaire on knowledge of af score revealing 51% of patients diagnosed incidentally and by medical checkup had little knowledge of af,stroke and warfarin.
Af patients need more knowledge on af and warfarin. Elderly patients may need closer INR monitoring.
The results can be useful to further education for closer monitoring to elderly patients.
Nobuyuki Anzai, No Financial Disclosure Information; No Product/Research Disclosure Information