Singer Daniel E, Chang Yuchiao, Fang Margaret C, Borowsky Leila H, Pomernacki Niela K, Udaltsova Natalia, Go Alan S
Clinical Epidemiology Unit, General Medicine Division, Massachusetts General Hospital, Boston, MA 02114, USA.
Circ Cardiovasc Qual Outcomes. 2009 Jul;2(4):297-304. doi: 10.1161/CIRCOUTCOMES.108.830232. Epub 2009 Jun 9.
Randomized trials and observational studies support using an international normalized ratio (INR) target of 2.0 to 3.0 for preventing ischemic stroke in atrial fibrillation. We assessed whether the INR target should be adjusted based on selected patient characteristics.
We conducted a case-control study nested within the ATRIA cohort's 9217 atrial fibrillation patients taking warfarin to define the relationship between INR level and the odds of thromboembolism (TE; mainly stroke) and of intracranial hemorrhage (ICH) relative to INR 2.0 to 2.5. We identified 396 TE cases and 164 ICH cases during follow-up. Each case was compared with 4 randomly selected controls matched on calendar date and stroke risk factors using matched univariable analyses and conditional logistic regression. We explored modification of the INR-outcome relationships by the following stroke risk factors: prior stroke, age, and CHADS(2) risk score. Overall, the odds of TE were low and stable above INR 1.8. Compared with INR 2.0 to 2.5, the relative odds of TE increased strikingly at INR <1.8 (eg, odds ratio, 3.72; 95% CI, 2.67 to 5.19, at INR 1.4 to 1.7). The odds of ICH increased markedly at INR values >3.5 (eg, odds ratio, 3.56; 95% CI: 1.70 to 7.46, at INR 3.6 to 4.5). The relative odds of ICH were consistently low at INR <3.6. There was no evidence of lower ICH risk at INR levels <2.0. These patterns of risk did not differ substantially by history of stroke, age, or CHADS(2) risk score.
Our results confirm that the current standard of INR 2.0 to 3.0 for atrial fibrillation falls in the optimal INR range. Our findings do not support adjustment of INR targets according to previously defined stroke risk factors.
随机试验和观察性研究支持将国际标准化比值（INR）目标设定为2.0至3.0以预防心房颤动患者发生缺血性卒中。我们评估了是否应根据选定的患者特征调整INR目标。
我们在ATRIA队列中纳入9217名服用华法林的心房颤动患者进行了一项病例对照研究，以确定INR水平与相对于INR 2.0至2.5的血栓栓塞（TE；主要为卒中）及颅内出血（ICH）几率之间的关系。在随访期间，我们确定了396例TE病例和164例ICH病例。使用匹配的单变量分析和条件逻辑回归，将每个病例与4名在日历日期和卒中风险因素方面匹配的随机选择的对照进行比较。我们通过以下卒中风险因素探讨了INR与结局关系的修正：既往卒中、年龄和CHADS(2)风险评分。总体而言，INR高于1.8时TE的几率较低且稳定。与INR 2.0至2.5相比，INR<1.8时TE的相对几率显著增加（例如，比值比为3.72；95%CI为2.67至5.19，INR为1.4至1.7时）。INR值>3.5时ICH的几率显著增加（例如，比值比为3.56；95%CI：1.70至7.46，INR为3.6至4.5时）。INR<3.6时ICH的相对几率一直较低。没有证据表明INR水平<2.0时ICH风险较低。这些风险模式在卒中病史、年龄或CHADS(2)风险评分方面没有显著差异。
我们的结果证实，目前心房颤动的INR标准2.0至3.0处于最佳INR范围内。我们的研究结果不支持根据先前定义的卒中风险因素调整INR目标。
