Discrepancies in International Normalized Ratio Results between Instruments: A Model to Split the Variation into Subcomponents

Abstract

BACKGROUND:Observed differences between results obtained from comparison of instruments used to measure international normalized ratio (INR) have been higher than expected from the imprecision of the instruments. In this study the variation of these differences was divided into subcomponents, and each of the subcomponents was estimated.

Analytical accuracy and precision of two novel Point-of-Care systems for INR determination

“…The CV obtained with the InRhythm may be regarded as desirable imprecision when compared to the average withinsubject variation of the INR in stabilized patients which has been reported previously [14][15][16]. The imprecision of the INRatio for venous blood samples was 7.3% (Table 1), which is in agreement with the values in other reports [5,17]. In previous studies the imprecision of the INR determined with the CoaguChek XS has been assessed.…”

“…For venous blood from patients in the therapeutic range the CV was 2.0 -2.5% [4]. For capillary blood samples the CV with the CoaguChek XS was 3.9 -4.0% [4], and more recently the CV's were 3.2% [17] and 2.24% [18].…”

Weekly and 90-Minute Biological Variations in Cardiac Troponin T and Cardiac Troponin I in Hemodialysis Patients and Healthy Controls

“…When there is a systematic increase or decrease in the results, a constant (i.e., the ␤ value of the systematic change) should be added to the RCV (27,36 ). The present data revealed a significant constant decline (i.e., 90-min variation for hs-cTnT in healthy individuals, hs-cTnT in HD patients, and hs-cTnI in HD patients).…”

Confidence Intervals and Power Calculations for Within-Person Biological Variation: Effect of Analytical Imprecision, Number of Replicates, Number of Samples, and Number of Individuals

“…However, very few papers and databases on SD WP present CIs for the estimated values of the components (4,5,12,13 ), but there are some exceptions (14,15 ). It is therefore difficult to compare the estimates from different publications.…”