CoaguChek XSにおけるPT-INR測定の有効性と可能性についての検討

Evaluation of the CoaguChek XS for Measuring PT-INR and Self-monitoring of Oral Anticoagulant Therapy

要旨　経口抗凝固薬であるワルファリンは弁置換術後や心房細動などの血栓塞栓症のリスクがある患者においては重要な薬剤であるが，その管理には定期的な採血によるプロトロンビン時間国際標準化比(prothrombin time-international normalized ratio；PT-INR)を治療域にコントロールする必要がある．また，測定値が不安定な場合は，出血や血栓塞栓症のリスクを伴ってくる．簡易PT-INR測定器であるCoaguChek XSは指尖穿刺での測定が可能であり，簡便かつ迅速に測定でき，安定した治療域の維持が可能となる．今回，従来法とCoaguChek XSにおけるPT-INR値の相関について検討した．弁置換術後でワルファリンを服用している患者を対象にPT-INRを従来法とCoaguChek XSを用いて測定した．PT-INR値は従来法では1.97±0.44，CoaguChek XSでは1.95±0.45と有意差を認めず，統計学的に非常に高い相関があった(r＝0.962，r²＝0.93，p＜0.01)．CoaguChek XSにおける測定法は簡便かつ迅速であり，患者のquality of life向上と安定したPT-INRの治療域の維持に有効と考えられた．

　There has been a significant increase during recent years in the number of patients receiving oral anticoagulant therapy with warfarin. The standard test for evaluating the effect of warfarin is the prothrombin time(PT), which is expressed in terms of the international normalized ratio(INR). Regular monitoring of the INR during treatment is required since an inappropriate dose of warfarin increases the risk of complications and its therapeutic range for correct anticoagulation is narrow. A new point-of-care testing(POCT) system, the CoaguChek XS, has recently been developed to measure the prothrombin time international normalized ratio(PT-INR), and it has several advantages. The International Sensitivity Index(ISI) is approximately 1.0, the measuring time is one minute, and the measurable range of PT-INR is between 0.8 and 8.0. We compared conventional measurement of the PT-INR with collection of capillary blood samples obtained via a finger prick for measurement with the CoaguChek XS. This apparatus was used to measure the PT-INR a total of 377 times in 95 patients after heart valve replacement. Their mean age was 60.2±9.6 years and the indication for oral anticoagulant therapy was a mechanical valve(89.5%) or a bioprosthetic valve(10.5%). There was a good correlation between the laboratory PT-INR and the value obtained with the CoaguChek XS. Optimization of the dose of warfarin can reduce the rate of complications. The CoaguChek XS was easy to use, data were obtained rapidly, and the results were reliable. This device will not only be useful for outpatients, but also for self-monitoring.