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Open Access Original clinical investigation

Variability between laboratories performing coagulation tests with identical platforms: a nationwide evaluation study

Michael Nagler1, Lucas M Bachmann2, Lorenzo Alberio3, Anne Angelillo-Scherrer4, Lars M Asmis125, Wolfgang Korte6, Adriana Mendez7, Guido Reber8, Hans Stricker9, Dimitrios A Tsakiris10 and Walter A Wuillemin111*

Author Affiliations

1 Division of Hematology and Central Hematology Laboratory, Luzerner Kantonsspital, Lucerne 16 CH-6000, Switzerland

2 Medignition Inc, Zug CH-6300, Switzerland

3 Department of Hematology and Central Hematology Laboratory, Inselspital University Hospital and University of Berne, Berne CH-3010, Switzerland

4 Service and Central Laboratory of Hematology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne CH-1011, Switzerland

5 Unilabs Zurich, Zurich CH-8034, Switzerland

6 Institute for Clinical Chemistry and Hematology, Cantonal Hospital St Gallen, St Gallen CH-9007, Switzerland

7 Center for Laboratory Medicine, Cantonal Hospital Aarau, Aarau CH-5001, Switzerland

8 Laboratory for Special Hemostasis, University Hospital of Geneva, Geneva CH-1211, Switzerland

9 Division of Surgery, Regional Hospital La Carita, Locarno CH-6600, Switzerland

10 Diagnostic Hematology, University Hospital of Basel, Basel CH-4031, Switzerland

11 University of Berne, Berne CH-3000, Switzerland

12 Division of Hematology, University Hospital and University of Zurich, Zurich CH-8091, Switzerland

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Thrombosis Journal 2013, 11:6  doi:10.1186/1477-9560-11-6

Published: 7 March 2013

Abstract

Background

While the assessment of analytical precision within medical laboratories has received much attention in scientific enquiry, the degree of as well as the sources causing variation between them remains incompletely understood. In this study, we quantified the variance components when performing coagulation tests with identical analytical platforms in different laboratories and computed intraclass correlations coefficients (ICC) for each coagulation test.

Methods

Data from eight laboratories measuring fibrinogen twice in twenty healthy subjects with one out of 3 different platforms and single measurements of prothrombin time (PT), and coagulation factors II, V, VII, VIII, IX, X, XI and XIII were analysed. By platform, the variance components of (i) the subjects, (ii) the laboratory and the technician and (iii) the total variance were obtained for fibrinogen as well as (i) and (iii) for the remaining factors using ANOVA.

Results

The variability for fibrinogen measurements within a laboratory ranged from 0.02 to 0.04, the variability between laboratories ranged from 0.006 to 0.097. The ICC for fibrinogen ranged from 0.37 to 0.66 and from 0.19 to 0.80 for PT between the platforms. For the remaining factors the ICC’s ranged from 0.04 (FII) to 0.93 (FVIII).

Conclusions

Variance components that could be attributed to technicians or laboratory procedures were substantial, led to disappointingly low intraclass correlation coefficients for several factors and were pronounced for some of the platforms. Our findings call for sustained efforts to raise the level of standardization of structures and procedures involved in the quantification of coagulation factors.

Keywords:
Inter-rater variability; Intraclass correlation coefficient; Reproducibility of testing; Test validity