Key result
PT-INR 2.0-2.99 links to a ~0.9% annual major event rate in older Japanese NVAF patients.
Why the study?
What is the optimal PT-INR range to minimize thromboembolic and major bleeding events in Japanese NVAF patients aged ≥65 years with low CHADS2 scores taking warfarin?
Cohort (n=382)
No
What is the optimal PT-INR range to minimize thromboembolic and major bleeding events in Japanese NVAF patients aged ≥65 years with low CHADS2 scores taking warfarin?
In Japanese NVAF patients aged ≥65 years with low CHADS2 scores, maintaining a PT-INR of 2.00-2.99 optimizes the balance between preventing thromboembolism and avoiding major bleeding.
May inform INR targets in low-risk elderly Japanese NVAF; hypothesis-generating pending randomized confirmation.
Background: Japanese physicians tend to empirically maintain lower-intensity prothrombin time-international normalized ratios (PT-INR) of 1.6-2.6 for most non-valvular atrial fibrillation (NVAF) patients taking warfarin. However, the optimal anticoagulant intensity in Japanese patients with low CHADS2 (Congestive heart failure, Hypertension, Age ≥75, Diabetes, Stroke [doubled]) scores is not clear. This study aimed to evaluate the clinical outcome and anticoagulant intensity in Japanese NVAF patients aged ≥65 years with CHADS2 scores of 0-1 and taking warfarin.Methods: We included 382 consecutive NVAF patients aged ≥65 years with CHADS2 scores of 0-1, who took warfarin between 2001 and 2006 (median age, 68 years; 29.8% women). This study included a median follow-up period of 54 months (1-154 months). The occurrence of thromboembolic events including ischemic stroke, transient ischemic attack and other systemic embolism, as well as major bleeding events were validated through a medical record review.Results: The incidence of thromboembolic and major bleeding events was both 0.9 per 100 patient-year. All thromboembolic events occurred in patients with a PT-INR <2.00. The incidence of major bleeding events increased markedly in patients with a PT-INR ≥3.00. A HAS-BLED (Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile INR, Elderly and concomitant Drugs/alcohol) score ≥3 was a risk for major bleeding (hazard ratio 4.8, 95% confidence interval 1.6-14.4). A PT-INR of 2.00-2.99 predicted a low incidence of thromboembolic and major bleeding events.Conclusions: Our results showed that a PT-INR of 2.00-2.99 was associated with a low incidence of both thromboembolism and major bleeding in Japanese NVAF patients aged ≥65 years with CHADS2 score of 0-1 and taking warfarin.
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Naganuma et al. (2015) conducted a cohort in Nonvalvular Atrial Fibrillation (n=382). Warfarin was evaluated on Incidence of thromboembolic and major bleeding events (per 100 patient-years). A PT-INR of 2.00-2.99 was associated with a low incidence of both thromboembolism and major bleeding in Japanese nonvalvular atrial fibrillation patients aged ≥65 years with a CHADS2 score of 0-1 taking warfarin.
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