A new statistical method for evaluating long-term analytical performance of laboratories applied to an external quality assessment scheme for flow cytometry.
Coucke, Wim; Van Blerk, Marjan; Libeer, Jean*-Claudeet al.
2010 • In Clinical Chemistry and Laboratory Medicine, 48 (5), p. 645-50
Clinical Laboratory Techniques/standards; Flow Cytometry/methods/standards; Models, Statistical; Quality Assurance, Health Care
Abstract :
[en] BACKGROUND: The Belgian External Quality Assessment Scheme for Flow Cytometry evaluates the long-term analytical performance of participating laboratories by calculating a regression line between the target and reported values of each parameter for each laboratory during the past 3 years. This study aims to develop a method to find laboratories with aberrant variability or bias using robust techniques and to obtain robust estimates of the variability. METHODS: A method is proposed to find outliers with respect to the individual regression line, followed by a step to find regression lines with excessive variability and finally a step to find regression lines with high bias. RESULTS: The model was applied to the results obtained by 52 laboratories for CD4%. From the 1340 data points, 35 were determined to be regression outliers. The second step revealed one regression line with excessive variability; the third step detected three regression lines with exceeding bias. CONCLUSIONS: The methodology allows assessment of the long-term performance of laboratories, taking into account samples with different target values. Outliers in the first step indicate accidental mistakes, outliers in the second and third step point to high analytical variability or bias.
Disciplines :
General & internal medicine
Author, co-author :
Coucke, Wim
Van Blerk, Marjan
Libeer, Jean*-Claude
Van Campenhout, Christel
Albert, Adelin ; Université de Liège - ULiège > Département des sciences de la santé publique > Informatique médicale et biostatistique
Language :
English
Title :
A new statistical method for evaluating long-term analytical performance of laboratories applied to an external quality assessment scheme for flow cytometry.
Van Blerk M, Bernier M, Bossuyt X, Chatelain B, D'Hautcourt JL, Demanet C, et al. National external quality assessment scheme for lymphocyte immunophenotyping in Belgium. Clin Chem Lab Med 2003;41:323-30.
Healy MJ. Outliers in clinical chemistry quality-control schemes. Clin Chem 1979;25:675-7.
Rocke DM. Robust statistical analysis of interlaboratory studies. Biometrika 1983;70:421-31.
Rousseeuw PJ, Leroy AM. Robust regression and outlier detection. New York: John Wiley & Sons, 1987:164-74.
Rousseeuw PJ, van Zomeren B. Unmasking multivariate outliers and leverage points. J Am Stat Assoc 1990;85:633-9.