[en] External Quality Assessment (EQA) schemes are national or transnational programmes designed to control the analytical performance of clinical laboratories and to maintain inter-laboratory variability within acceptable limits. In such EQA programmes, participants are usually grouped by the type of assay technique/equipment they use. The coefficient of variation (CV) is a simple tool for comparing the inter-laboratory reproducibility of such techniques: the lower the CV, the better the analytical performance. Serum protein electrophoresis, a laboratory test profile consisting of five fractions (albumin, α1, α2, β and γ globulins) summing up to 100% of total proteins, can also be assayed in different ways depending on the media or the analytical principle. We propose a multivariate coefficient of variation for comparing the performance of electrophoretic techniques in EQA, thus extending the univariate CV concept. First, the compositional nature of electrophoretic data requires a one-to-one transformation from the 5-dimensional to the 4-dimensional space. Next, robust estimations of the mean and the covariance matrix are needed to avoid the effect of outliers. The new approach is illustrated on electrophoretic datasets from the French and Belgian national EQA programmes.
Disciplines :
Public health, health care sciences & services Laboratory medicine & medical technology
Author, co-author :
Zhang, Lixin ; Université de Liège - ULiège > Département des sciences de la santé publique > Informatique médicale et biostatistique
Albarède, Stéphanie; Direction de l'Évaluation des DIspositifs Médicaux (DEDIM) > Agence Française de Sécurité Sanitaire des Produits de Santé (AFSSaPS)
Dumont, Gilles; Direction de l'Évaluation des DIspositifs Médicaux (DEDIM) > Agence Française de Sécurité Sanitaire des Produits de Santé (AFSSaPS)
Van Campenhout, Christel; Department of Clinical Biology > Belgian Scientific Institute of Public Health
Libeer, Jean-Claude; Department of Clinical Biology > Belgian Scientific Institute of Public Health
Albert, Adelin ; Université de Liège - ULiège > Département des sciences de la santé publique > Informatique médicale et biostatistique - Département de mathématique
Language :
English
Title :
The multivariate coefficient of variation for comparing serum protein electrophoresis techniques in External Quality Assessment schemes
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