Rheumatology Division, 117265University of São Paulo, São Paulo, Brazil.
Rheumatology Division, 424848Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, Brazil.
Lupus. 2022 Apr;31(5):565-574. doi: 10.1177/09612033221086134. Epub 2022 Mar 10.
The standard of care for thrombotic antiphospholipid syndrome (APS) is anticoagulation with vitamin K antagonists (VKAs). Prothrombin time, and its corresponding international normalized ratio (INR), is the laboratory test routinely performed to assess anticoagulation. Self-management of VKA therapy using point-of-care (POC) devices seems to be an attractive option.
PURPOSE/OBJECTIVE: To evaluate the accuracy of a POC device (CoaguChek XS) in APS patients by comparing it with venous laboratory INR. Furthermore, we analyzed whether other clinical and laboratory features could interfere with the CoaguChek XS results.
This is a single-center cross-sectional study with 94 APS patients from a tertiary rheumatology clinic performed from August 2014 to March 2015. The comparison between CoaguChek XS and venous laboratory INR results was evaluated using the coefficient of determination (r) followed by the Bland-Altman test. A paired t-test was also applied. A difference of up to ±0.5 INR unit between the two systems was considered clinically acceptable.
The mean CoaguChek-INR was 2.94 ± 1.41 and venous laboratory INR was 2.43±0.86, with a correlation coefficient (r) of 0.95. Categorizing INR values in ranges (INR <2, INR 2-3, INR 3-4, and INR >4), we found that the INR >4 group presented a lower correlation (r = 0.64) compared to the other ranges ( < 0.05). Although both methods were highly correlated, CoaguChek XS showed higher values than the venous laboratory INR, with an increased average of 0.42 ± 0.54. Therefore, we proposed a simple linear regression model to predict the venous laboratory INR values, using results obtained from CoaguChek XS. A difference ≤0.5 INR unit between the two systems was observed in 57.4% of patients, and the aPL profile did not influence the results.
Although CoaguChek XS and venous laboratory INR demonstrated a good linear correlation in the group of INR ≤4, extra caution should be taken in APS patients, since a reasonable proportion of patients can present differences in INR results that are not acceptable. We do not recommend routine POC in APS patients.
血栓性抗磷脂综合征（APS）的标准治疗方法是使用维生素 K 拮抗剂（VKA）进行抗凝治疗。凝血酶原时间及其对应的国际标准化比值（INR）是常规用于评估抗凝效果的实验室检测。使用即时检测（POC）设备进行 VKA 治疗的自我管理似乎是一种有吸引力的选择。
目的/目标：通过比较即时检测设备（CoaguChek XS）与静脉实验室 INR，评估该即时检测设备在 APS 患者中的准确性。此外，我们还分析了其他临床和实验室特征是否会干扰 CoaguChek XS 的结果。
这是一项单中心的横断面研究，纳入了 2014 年 8 月至 2015 年 3 月期间来自一家三级风湿病诊所的 94 例 APS 患者。通过决定系数（r）评估 CoaguChek XS 与静脉实验室 INR 结果之间的相关性，随后进行 Bland-Altman 检验。还应用了配对 t 检验。两种系统之间 INR 差值在 ±0.5 以内被认为具有临床可接受性。
平均 CoaguChek-INR 为 2.94±1.41，静脉实验室 INR 为 2.43±0.86，相关系数（r）为 0.95。将 INR 值分为不同范围（INR <2、INR 2-3、INR 3-4 和 INR >4），我们发现 INR >4 组的相关性较低（r=0.64），与其他范围（<0.05）相比。尽管两种方法高度相关，但 CoaguChek XS 显示的 INR 值更高，平均增加 0.42±0.54。因此，我们提出了一个简单的线性回归模型，使用 CoaguChek XS 结果来预测静脉实验室 INR 值。两种系统之间 INR 差值在 ≤0.5 的患者占 57.4%，抗磷脂抗体谱并未影响结果。
尽管 CoaguChek XS 和静脉实验室 INR 在 INR ≤4 的患者中表现出良好的线性相关性，但在 APS 患者中应格外小心，因为相当一部分患者的 INR 结果存在不可接受的差异。我们不建议常规在 APS 患者中使用 POC。
