The long-term within- and between-laboratory variability for assay of antithrombin and proteins C and S Results derived from the external quality assessment program for thrombophilia screening of the ECAT Foundation
article
A stable laboratory performance is important for comparability and transferability of laboratory data both within and between laboratories. The lack of a reference system within hemostasis hampers laboratories in establishing their laboratory performance over a prolonged period of time. Therefore, based on data from an external quality assessment program, we evaluated the between laboratory variation (CV BETWEEN) and the long-term within-laboratory variation (LCV a) for antithrombin, and proteins C and S. We evaluated the CV BETWEEN for the period 1996-2001, including the results of 64-240 laboratories from 23 different surveys (protein S activity 15 surveys). We observed a quite high CV BETWEEN and a broad range for each analyte. The CV BETWEEN was significantly higher for antithrombin and protein S for samples with low levels similar to heterozygous deficiencies. We also evaluated the LCV a, including the results of 136 laboratories. The lowest LCV a[median and 95% content interval (CI)] was observed for antithrombin (7.6%; 3.6-35.5%), intermediate values for protein C activity and antigen (8.6%; 3.5-25.3% and 10.8%; 4.8-33.1%, respectively) and highest values for the protein S variables (13.4%; 6.4-50.6% for total protein S antigen, 14.1%; 6.5-79.1% for free protein S antigen and 17.2%; 7.2-84.3% for protein S activity). We concluded that the main reason for the high CV BETWEEN is the long-term within-laboratory variability. Application of linear regression on data of an external quality assessment program is a useful model to demonstrate per analyte per laboratory the long-term variability (LCV a). It is concluded that improvement of the long-term within-laboratory test performance is the first priority in hemostasis to yield important improvements in the comparability and transferability of laboratory data. © 2003 International Society on Thrombosis and Haemostasis. Chemicals / CAS antithrombin III, 90170-80-2; protein C, 60202-16-6; Antithrombin III, 9000-94-6; Blood Coagulation Factor Inhibitors; Protein C; Protein S
Topics
Analytical performanceExternal quality assessmentHemostasisblood clotting inhibitorhealth care qualitymass screeningnon profit organizationobserver variationreference valuereproducibilitytimeAntithrombin IIIBlood Coagulation Factor InhibitorsFoundationsHumansMass ScreeningObserver VariationProtein CProtein SQuality Assurance, Health CareReference ValuesReproducibility of ResultsThrombophiliaTime Factors
TNO Identifier
953673
ISSN
15387933
Source
Journal of Thrombosis and Haemostasis, 1(4), pp. 748-753.
Pages
748-753
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