Long-term analytical performance of hemostasis field methods as assessed by evaluation of the results of an external quality assessment program for XXXX .

@entity715 @entity3124 @entity5582 @entity2246
BACKGROUND: It is important for a laboratory to know the stability of performance of laboratory tests over time. The aim of this study was to adapt from the field of clinical chemistry a method to assess the long-term analytical performance of hemostasis field methods. METHODS: The linear regression model was used to compare the laboratory results with the consensus mean value of a survey. This model was applied to plasma @entity5582 activity using the data for 82 laboratories, collected between 1996 and 1999 in the European Concerted Action on @entity715 (ECAT) external quality assessment program. The long-term total, random, and systematic error were calculated. The variables introduced to define the long-term performance in this model were the long-term analytical CV (LCV(a)) and the @entity3124 ( @entity3124 ), which indicates the minimum difference necessary between two samples measured on a long-term time-scale to consider them statistically significantly different. RESULTS: The systematic error (bias) ranged from 4.5 to 103 units/L. The random error ranged from 24.4 to 242 units/L. For the majority of the laboratories, random error was the main component (>75%) of the total error. The LCV(a), after adjustment for the contribution of the bias, ranged from 2.8% to 48%. The @entity3124 ranged from 78 to 1290 units/L with a median value of 190 units/L. No statistically significant differences were observed for either LCV(a) or @entity3124 between the two different measurement principles for @entity5582 activity based on the inhibition of either thrombin or factor Xa. CONCLUSIONS: This linear regression model is useful for assessing the @entity2246 for hemostasis field methods. The LCV(a) and @entity3124 for measurement on a long-term time-scale appear to be useful for assessing the long-term analytical performance.
