OBJECTIVE: To determine the strength of oral anticoagulation therapy in atrial fibrillation that provides the best balance between the prevention of thromboembolism and the occurrence of bleeding complications. METHODS: We studied 435 patients with atrial fibrillation who were hospitalized from 2000 to 2002 and given warfarin for prevention of thromboembolism. INR-specified rates for both ischemic and major hemorrhagic events were analyzed and the optimal levels of anticoagulation in atrial fibrillation patients determined. RESULTS: The average dose of warfarin was (2.77 +/- 0.83) mg and the median duration of anticoagulation is 7 months (from 1 month to 3 years). In total, there were 31 confirmed bleeding events, with major hemorrhage occurring in 5 patients. Age of the patients in the hemorrhage group is not significantly higher than that in control group (65.09 +/- 9.99 vs 62.01 +/- 12.19, P = 0.259). Chronic heart failure or hypertension increased the risk of bleeding during warfarin therapy. Multivariate analysis showed that INR >or= 3.0 is an independent risk factor for hemorrhage (OR = 3.7435, 95% CI 1.2819 - 8.9838). The risk of stroke or thromboembolism rose steeply with INR below 1.5. CONCLUSIONS: To achieve optimal levels of anticoagulation with the lowest risk in patients with atrial fibrillation, values of INR below 1.5 and above 3.0 should be avoided.
OBJECTIVE: To determine the strength of oral anticoagulation therapy in atrial fibrillation that provides the best balance between the prevention of thromboembolism and the occurrence of bleeding complications. METHODS: We studied 435 patients with atrial fibrillation who were hospitalized from 2000 to 2002 and given warfarin for prevention of thromboembolism. INR-specified rates for both ischemic and major hemorrhagic events were analyzed and the optimal levels of anticoagulation in atrial fibrillationpatients determined. RESULTS: The average dose of warfarin was (2.77 +/- 0.83) mg and the median duration of anticoagulation is 7 months (from 1 month to 3 years). In total, there were 31 confirmed bleeding events, with major hemorrhage occurring in 5 patients. Age of the patients in the hemorrhage group is not significantly higher than that in control group (65.09 +/- 9.99 vs 62.01 +/- 12.19, P = 0.259). Chronic heart failure or hypertension increased the risk of bleeding during warfarin therapy. Multivariate analysis showed that INR >or= 3.0 is an independent risk factor for hemorrhage (OR = 3.7435, 95% CI 1.2819 - 8.9838). The risk of stroke or thromboembolism rose steeply with INR below 1.5. CONCLUSIONS: To achieve optimal levels of anticoagulation with the lowest risk in patients with atrial fibrillation, values of INR below 1.5 and above 3.0 should be avoided.