Comparison between the Portable Prothrombin Time Self Monitor CoaguChek XS and a Standard Laboratory Method, Sysmex CA-1500 for Monitoring Anticoagulant Therapy of Outpatients

ABSTRACT

BACKGROUND AND OBJECTIVES: Patients on oral anticoagulation therapy (OAT) require regular monitoring of the prothrombin time (PT) and dosage adjustment to prevent thromboembolic diseases without the risk of hemorrhage. Portable self PT monitors have been recently developed because the standard PT measurements are complicated and take considerable time. This study compared the International normalized ratio (INR) results that were obtained with using the CoaguChek XS device (Roche Diagnostic, Mannheim, Germany) with those obtained using a standard laboratory method Sysmex CA-1500 (Sysmex Corporation, Kobe, Japan) in the patients on OAT and also a healthy control group. SUBJECTS AND METHODS: 100 outpatients on OAT and 20 healthy controls were enrolled on a volunteer basis after providing informed consent at the Dong-A University Hospital. The outpatients and the healthy control group provided us the INR measurements with using both the CoaguChek XS and the Sysmex CA-1500. RESULTS: The coefficients of variation for CoaguChek XS and Sysmex CA-1500 were less than 10%. The PT (INR) results of CoaguChek XS and Sysmex CA-1500 were 2.0+/-0.7 and 2.2+/-0.7, respectively (p<0.001). There was a good correlation between CoaguChek XS and Sysmex CA-1500 (r=0.974, p<0.001). On the regression analysis, the slope of the regression line was 0.9197 and the y-intercept was 0.0058. On the Bland-Altman analysis, the INR mean difference (bias) between the two methods (CoaguChek XS INR-Sysmex CA-1500 INR) was -0.2 and the limit of agreement was +0.168~-0.568. CONCLUSION: The measurement with using CoaguChek XS has high repeatability, rapid availability and good accuracy that are comparable to the standard laboratory method. Therefore, CoaguChek XS can be a valuable tool for the self-monitoring of patients on OAT.