Evaluation of the Roche CoaguChek XS handheld coagulation analyzer in a cardiac outpatient clinic

This study evaluated the performance of a handheld coagulation analyzer for measurements of capillary blood specimens of 93 outpatient cardiology patients with atrial fibrillation who were receiving oral anti-coagulant therapy. The international normalized ratio (INR) results of the CoaguChek XS system (Roche Diagnostics) were compared with those obtained in the central laboratory with citrated venous blood specimens using the ACL9000 coagulation analyzer (Instrumentation Laboratory). The INR results for prothrombin time by the CoaguChek XS analyzer were closely correlated with the central laboratory's results in the INR range of 0.96-8.53 (r = 0.964). A statistically significant difference was noted between 2 lots of test strips, but the difference was miniscule (mean ± 95% confidence interval: 0.04±0.02). The CV of 8 replicate assays with the CoaguChek XS for a blood specimen with high INR value (INR=3.9) was 1.4%; for a blood specimen with medium INR value (INR=1.3), the CV of 8 replicate assays was <0.1%. This study shows that the CoaguChek XS analyzer is precise and reliable for assessment of INR results at clinically significant ranges in cardiac outpatients.