Guest Essay

Celebrate 15 years of evidence-based quality goals! The 8th update of the biologic variation database, with updated specifications and new analytes for 2014.
[Please note: in August or October of 2018, the EFLM and SEQC have requested that Westgard.com no longer display this data.]

Biological variation database, and quality specifications for imprecision, bias and total error (desirable and minimum). The 2014 update

Joana Minchinela[1,2], Carmen Ricós[1], Carmen Perich* [1,3], Pilar Fernández-Calle[1,4], Virtudes Alvarez[1,5], Mariví Domenech[1,6], Margarita Simón[1,7], Carmen Biosca[1,8], Beatriz Boned[1,9], Fernando Cava[1,10], José-Vicente García-Lario[1,11], Mª Pilar Fernández-Fernández[1]

1. Analytical Quality Commission, Spanish Society of Clinical Biochemistry and Molecular Pathology (SEQC)
2. Laboratori Clínic del Barcelonès Nord i Vallès Oriental Badalona)
3. Laboratori Clínic Bon Pastor (Barcelona)
4. Servicio Análisis Clínicos Hospital La Paz (Madrid)
5. Laboratori Clínic de l’Hospitalet (Barcelona)
6. Laboratori Clínic Manso (Barcelona)
7. Consorci del Laboratori Intercomarcal de l’Alt Penedès, l’Anoia i el Garraf (Barcelona)
8. Servei de Bioquímica Hospital GermansTrias i Pujol (Badalona)
9. Hospital Royo Villanova (Zaragoza)
10. Laboratorio Central BR Salud-Hospital Universitario Infanta Sofía (Madrid)
11. Laboratorio de Análisis Clínicos, Hospital Universitario Virgen de las Nieves (Granada).

* President of the Analytical Quality Committee, Spanish Society of Clinical Chemistry and Molecular Pathology (SEQC).

This is the 8th edition of data regarding the components of biological variation (intra and inter-individual -CV_I and CV_G , respectively) which compiles the published papers studying this item in healthy population, up to December 2013. The aim of this work is to provide quality specifications for imprecision, bias and total error to be used in laboratory medicine. The number of analytes with BV data available in this edition is: 357.

IMPORTANT UPDATE: "[T]he BV data on your website is provided by the Analytical Quality Commission of the SEQC....
"The Analytical Quality Commission and ourselves have discussed this and agree that the EFLM database probably will provide estimates of Total allowable error. Furthermore, once the EFLM database is available, the BV database provided by the SEQC should be removed from both your website and the SEQC website. We would therefore not agree to new data being added to the 2014 BV database update. The aim is for the EFLM website to be available within 4-6 months and we will contact you once it has been published. Thank you for your understanding.
Kind regards,
Aasne Krine Aarsand, Sverre Sandberg,  Pilar Fernandez Calle, Carmen Perich & Carmin Ricos
On behalf of the Working Group on Biological Variation, EFLM and the Analytical Quality Commission, SEQC, April 26, 2018"

Here are the links to the updated tables:

• Desirable specifications for allowable total error
• List of all references used in the database
• Analytes listed with related references
• Optimal specifications for allowable total error
• Minimum specifications for allowable total error

In this edition 19 new analytes have been added (table 1); however the total number of analytes included here is shortly lower than the presented in previous edition, because components not directly measured but calculated from other analytes (i.e urine albumin/creatinine ratio, or serum LDL cholesterol calculated).

Some changes with respect to the 7th edition have been made; they are:

• Serum and plasma Troponin-I: CV_I values obtained in studies made within a 24 hours period are lower than those found in a longer time span. Because this analyte is mainly used in monitoring AMI at initial stage, with short-term monitoring, the specifications proposed have been derived from the 24-hour studies.
• Urinary analytes have different CV_I values, depending on the type of urine specimen. Quality specifications proposed are derived from the lowest specimen variability.
• Some calculation errors, not detected in the previous edition have been amended here.
• For analytes shown in table 2 new papers have been found, so quality specifications may have changed compared with those of the 7th edition.
• Annex I, showing quality specifications, has a new column with the number of articlescompiled for each analyte. This information also appears in Annex II; however, the number of consultations received dealing with this item seemed us to indicate that many readers did not realize about annex II.
  This column highlights the robustness of CV_I and CV_G described (median of values compiled for each analyte). For example, there are 58 cholesterol CV_I values coming from 46 papers, which results to a median of CV_I=5.9% and a confidence interval (p<0.05) of 0.43, with values ranging from 2.4% to 9.7%. AST has 21 data coming from 13 papers, with a median of CV_I = 12.3%, a confidence interval of 2.02% and values ranging between 4.7 and 24.2%. There are many analytes with a reduced number of papers published, thus the CV_I and CV_G estimated are quite poor and further studies should be made.

A brief summary: first edition was presented at the Stockholm international consensus conference on Strategies to Set Global Analytical Quality Specifications in Laboratory Medicine, was published in the Scan J Clin Lab Invest 1999;59:475-586 and also published on this website in June 2000. Successively, database has been updated every two years, up to the present 8th edition. Number of analytes included evolved from 316 up to the present 357. This information is also published at the SEQC website (http://www.seqc.es) in Spanish language.

-          Annex I, showing quality specifications, has a new column with the number of articles compiled for each analyte. This information also appears in Annex II; however, the number of consultations received dealing with this item seemed us to indicate that many readers did not realize about annex II.

This column highlights the robustness of CV_I and CV_G described (median of values compiled for each analyte). For example, there are 58 cholesterol CV_I values coming from 46 papers, which results to a median of CV_I=5.9% and a confidence interval (p<0.05) of 0.43, with values ranging from 2.4% to 9.7%.  AST has 21 data coming from de 13 papers, with a median of  CV_I = 12.3%,   a confidence interval of 2.02% and values ranging between 4.7 and 24.2%. There are many analytes with a reduced number of papers published, thus the CV_I and CV_G estimated are quite poor and further studies should be made.