Rose Adam J, Ozonoff Al, Grant Richard W, Henault Lori E, Hylek Elaine M
Center for Health Quality, Outcomes, and Economic Research, Bedford VA Medical Center, Bedford, MA 01730, USA.
Circ Cardiovasc Qual Outcomes. 2009 Nov;2(6):591-7. doi: 10.1161/CIRCOUTCOMES.109.862763. Epub 2009 Sep 22.
Low international normalized ratio (INR; <or=1.5) increases risk for thromboembolism. However, little is known about the epidemiology of low INR.
We prospectively collected data from 47 community-based clinics located throughout the United States from 2000 to 2002. We examined risk factors for low INR (<or=1.5), reasons given in the medical record for low INR, and proportion of thromboembolic events that occurred during periods of low INR. Of the 4489 patients in our database, 1540 (34%) had at least 1 low INR. Compared with men, women had an increased incidence of low INR (adjusted incidence rate ratio, 1.44; P<0.001). Compared with patients anticoagulated for atrial fibrillation, patients anticoagulated for venous thromboembolism had an increased incidence of low INR (adjusted incidence rate ratio, 1.48; P<0.001). The 5 most common reasons for low INR were nonadherence (17%), interruptions for procedures (16%), recent dose reductions (15%), no reason apparent after questioning (15%), and second or greater consecutive low INR (13%). A total of 21.8% of thromboembolic events (95% CI, 12.2 to 35.4%) occurred during periods of low INR; 58% of these events were related to an interruption of warfarin therapy.
In this cohort of patients receiving warfarin, more than 1 in 5 thromboembolic events occurred during a period of low INR. Women and patients anticoagulated for venous thromboembolism were particularly likely to experience low INR. Improving adherence, minimizing interruptions of therapy, and addressing low INR more promptly could reduce the risk of low INR.
国际标准化比值（INR）低（≤1.5）会增加血栓栓塞风险。然而，关于低INR的流行病学情况却知之甚少。
我们于2000年至2002年期间前瞻性地收集了来自美国各地47家社区诊所的数据。我们研究了低INR（≤1.5）的危险因素、病历中给出的低INR原因以及低INR期间发生的血栓栓塞事件比例。在我们数据库的4489名患者中，1540名（34%）至少有1次INR低的情况。与男性相比，女性低INR的发生率更高（调整后的发病率比值为1.44；P<0.001）。与接受心房颤动抗凝治疗的患者相比，接受静脉血栓栓塞抗凝治疗的患者低INR的发生率更高（调整后的发病率比值为1.48；P<0.001）。INR低的5个最常见原因是不依从（17%）；因手术中断（16%）；近期剂量减少（15%）；询问后无明显原因（15%）；以及连续第二次或更多次INR低（13%）。共有21.8%的血栓栓塞事件（95%可信区间为12.2%至35.4%）发生在INR低的期间；其中58%的事件与华法林治疗中断有关。
在这一接受华法林治疗的患者队列中，超过五分之一的血栓栓塞事件发生在INR低的期间。女性以及接受静脉血栓栓塞抗凝治疗的患者尤其容易出现INR低的情况。提高依从性、尽量减少治疗中断并更及时地处理低INR情况可降低低INR的风险。
