title: External quality control program for inter-laboratory quality control.
abstract: BACKGROUND
  The accuracy and precision of tumor marker testing is of high clinical importance requiring the implementation of effective quality control procedures in the diagnostic laboratory. An external quality control program including an inter-laboratory comparison could be of help in improving the quality of test results.
  
  
  METHODS
  Laboratories using BIOREF reference material sent their routine internal quality control results of each monthly control period to the evaluation center for statistical analysis and inter-laboratory comparison.
  
  
  RESULTS
  The inter-laboratory comparison showed that the mean values of test results obtained by different laboratories can vary considerably especially when different test kits are used. A comparison of test results of laboratories using the same test kit showed much better correlation but discrepancies of coefficients of variation between these laboratories were still observed.
  
  
  CONCLUSIONS
  An external quality control program revealed problems in the accuracy and precision of tumor marker test results in the individual laboratory, which could serve as a basis for the improvement of test performance.
authors.affiliation: BIOREF GmbH, Dammweg 1, D-63776, Mömbris, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Bewarder
authors.forename: P
authors.initials: P
authors.lastname: Müller
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D019411:Clinical Laboratory Techniques / Q000592:standards*; D006801:Humans; D011786:Quality Control; D011933:Reagent Kits, Diagnostic / Q000592:standards
chemical_list: D014408:Biomarkers, Tumor; D011933:Reagent Kits, Diagnostic