BETWEEN-COUNTRY COMPARABILITY OF CLINICAL-CHEMISTRY RESULTS - AN INTERNATIONAL QUALITY ASSESSMENT SURVEY OF 17 ANALYTES IN 6 EUROPEAN COUNTRIES THROUGH EXISTING NATIONAL SCHEMES

Two lyophilized control sera were distributed through seven national e xternal quality assessment schemes in six European countries-Belgium, Switzerland, France, The Netherlands, Sweden and the United Kingdom-pa rticipated in the study. The results for 17 routine analytes were obta ined from almost 5000 laboratories for the two sera. The organizers of the schemes were asked to process the results according to a common o utlier removal procedure, and submit method-related data if available. The two sera were also distributed through the external/internal sche me of The Netherlands, and the within-laboratory standard deviations c alculated in this scheme have been used in a scaling procedure for the external mean values and between-laboratory standard deviations of th e participating countries. The results show remarkable agreement in th e national mean values for practically all analytes, but considerable differences in the between-laboratory variation. Data from comparable method groups was obtained for 12 analytes from Belgium, France, The N etherlands and the UK. Though revealing some specific differences betw een methods and countries, the method-related data are generally in ag reement with the all-method data. In this study reference method value s were only available for cholesterol. The high degree of agreement fo und suggests, however, that mutual recognition of all-method mean valu es in national schemes could be acceptable, especially for analytes fo r which reliable reference methods are not available. The major elemen t of variation is between-laboratory rather than between-country.