title: Variability between laboratories performing coagulation tests with identical platforms: a nationwide evaluation study.
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.
authors.affiliation: Division of Hematology and Central Hematology Laboratory, Luzerner Kantonsspital, Lucerne 16 CH-6000, Switzerland. walter.wuillemin@luks.ch.
authors.forename: Michael
authors.initials: M
authors.lastname: Nagler
authors.forename: Lucas M
authors.initials: LM
authors.lastname: Bachmann
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Alberio
authors.forename: Anne
authors.initials: A
authors.lastname: Angelillo-Scherrer
authors.forename: Lars M
authors.initials: LM
authors.lastname: Asmis
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Korte
authors.forename: Adriana
authors.initials: A
authors.lastname: Mendez
authors.forename: Guido
authors.initials: G
authors.lastname: Reber
authors.forename: Hans
authors.initials: H
authors.lastname: Stricker
authors.forename: Dimitrios A
authors.initials: DA
authors.lastname: Tsakiris
authors.forename: Walter A
authors.initials: WA
authors.lastname: Wuillemin