Data documenting the performance of the PT/INR line correction method for reconciling INR discrepancies between central laboratory coagulation analyzers using different thromboplastins during the evaluation of a portable Coagulometer.

The data presented here was produced as part of an evaluation of the performance of the CoaguChek XS point-of-care coagulation analyzer, which is discussed in the research article "POCT PT INR - Is it adequate for Patient Care? A Comparison of the Roche Coaguchek XS vs. Stago Star vs. Siemens BCS in Patients Routinely Seen in an Anticoagulation Clinic" (Baker et al., in press) [1]. An effort to reconcile discrepancies in the patient INR result distributions from different central lab instruments (Stago Star and Siemens BCS) with the PT/INR line method is described (Poller et al., 2010, 2011; Ibrahim et al., 2011) [2], [3], [4]. While regression analysis of the ECAA Poller calibrant data provided a linear PT/INR line for all methods, Pearson's chi-squared and one-way repeated measures ANOVA analyses showed that central lab INR measurements continued to exhibit measurement site dependence after the PT/INR line correction was applied. According to paired t-test analysis, only the human thromboplastin dependent methods (CoaguChek XS and Siemens BCS both before and after PT/INR line correction) showed statistically significant agreement (p-value >0.05).

POCT PT INR - Is it adequate for patient care? A comparison of the Roche Coaguchek XS vs. Stago Star vs. Siemens BCS in patients routinely seen in an anticoagulation clinic.

BACKGROUND: In this study we examined the difference in patient INR values as measured by the POCT CoaguChek XS device and central laboratory Stago Evolution and Siemens BCS XP analyzers. METHODS: This study composed of 100 warfarin therapy patients and 20 coagulation normal subjects, showed that the difference between the POCT and clinical laboratory values increased with increasing INR and was exacerbated by the use of different thromboplastin reagents by the POCT and central lab. RESULTS: The CoaguChek XS and on-site Stago analyzers which used human recombinant (ISI=1.01) and rabbit brain thromboplastin (ISI=1.25), respectively, showed reasonable agreement for INR<3.0 (k=0.62) but significant difference for INR≥3.0 (k=0.10). In contrast, the CoaguChek XS and Siemens BCS XP, which both employed human recombinant thromboplastin (BCS ISI=1.02), showed greater agreement for the complete range INR values (INR<3.0 k=0.84; INR≥3.0 k=0.70). ECAA Poller calibrant data showed the automated instruments were performing as expected, indicating that ISI calibrations were correct but insufficient to standardize the INR values for the different thromboplastin methods across the full range of measured INRs. Central lab verification of POCT INR>5.0 with the Stago Evolution prevented adverse treatment events for the warfarin therapy patients in the six months preceding and following this investigation.

Effect of freezing plasma at -20°C for 2 weeks on prothrombin time, activated partial thromboplastin time, dilute Russell viper venom time, activated protein C resistance, and D-dimer levels.

To assess the impact of preanalytical variables of time and temperature on prothrombin time (PT), activated partial thromboplastin time (aPTT), dilute Russell viper venom time (DRVVT), activated protein C resistance (APCR), and d-dimer, samples from 23 healthy individuals and 18 patients having coagulopathy with known abnormal PT and aPTT were collected. Plasma from each individual was separately pooled and aliquoted; the first 2 aliquots were stored at room temperature then analyzed at 2 hours (baseline) and 4 hours postcollection. The remaining aliquots were stored at -20°C and thawed for analysis at 48 hours, 1, and 2 weeks. In both healthy participants and participants with coagulopathy, PT, aPTT, APCR, DRVVT, and D-dimer had no significant changes at 4 and 48 hours, and 1 and 2 weeks postcollection compared to baseline, or the changes were less than 10%. The results indicate PT, aPTT, DRVVT, APCR, and d-dimer can be stored for 2 weeks at -20°C without compromising clinical interpretation in both healthy individuals and individuals with coagulopathy. Increasing storage time will facilitate sample processing from off-site clinics.