PT-INR測定の新手法―CoaguChek XSの日本人における測定と信頼度

Evaluation of CoaguChek XS for Japanese Patients: A new procedure of PT-INR measurement

要旨　目的：血液検査室でのPT-INRとCoaguChek XSによるPT-INRの簡易測定(COGC-INR)を同時に行い，統計学的な信頼性と内服薬の影響を検討した．

　対象と方法：ワルファリン内服中の入院患者および外来患者109名において合計115回のINRの測定をPT-INRとCOGC-INRの両者を用いて同日に行い，両者で得られた結果を比較した．Bland-Altman法で，平均値±1.96標準偏差から外れるものを有意差のあるデータとした．相関性が低いデータは併用薬の影響を評価した．

　結果：両検査法で得られた値は，相関係数0.97と強い相関関係を示した．正規分布から平均値±1.96標準偏差から外れるものは7例あり，検査値の差は0.3であった．7例と内服薬の関係は認められなかった．

　結語：COGC-INRとPT-INRの測定値は良好な相関があり，今後も病院や在宅診療での使用が期待できる．

　Purpose: A new point-of-care(POC) monitoring system of oral anticoagulation, the CoaguChek XS, has recently been developed to measure the international normalized ratio(INR) and may offer significant advantages. The purpose of our study is to compare values obtained by the CoaguChek XS system(COGC-INR) with the standard venous INR for anticoagulant monitoring, prothrombin time with reference thromboplastin(PT-INR).

　Methods and Results: Paired PT-INR and COGC-INR were measured in consecutive 115 samples from 109 patients. Correlation between COGC-INR and PT-INR was r=0.97. The difference in the value of INR deviating from normal distribution of the Bland-Altman plot was 0.3, and values greater than 0.3 were observed in 7 samples. The chi-square test was performed in these 7 samples to investigate the influence of drugs, but did not show any significant influence of drugs on the differences between COGC-INR and PT-INR.

　Conclusions: The accuracy of the CoaguChek XS POC monitoring system when compared with the standard reference INR was satisfactory. This result will improve clinical decision-making regarding anticoagulation therapy.