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Clinical Chemistry and Laboratory Medicine (CCLM)

Published in Association with the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM)

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Ed. by Gillery, Philippe / Greaves, Ronda / Lackner, Karl J. / Lippi, Giuseppe / Melichar, Bohuslav / Payne, Deborah A. / Schlattmann, Peter

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Volume 55, Issue 3


Looking beyond linear regression and Bland-Altman plots: a comparison of the clinical performance of 25-hydroxyvitamin D tests

Gellert Karvaly
  • Corresponding author
  • Department of Laboratory Medicine, Semmelweis University, Budapest, Hungary
  • Bionics Innovation Center, Budapest, Hungary
  • Email
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Katalin Mészáros
  • Department of Laboratory Medicine, Semmelweis University, Budapest, Hungary
  • HAS-SE “Momentum” Hereditary Endocrine Tumours Research Group, Budapest, Hungary
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Krisztián Kovács
  • Department of Laboratory Medicine, Semmelweis University, Budapest, Hungary
  • Bionics Innovation Center, Budapest, Hungary
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Attila Patócs
  • Department of Laboratory Medicine, Semmelweis University, Budapest, Hungary
  • Bionics Innovation Center, Budapest, Hungary
  • HAS-SE “Momentum” Hereditary Endocrine Tumours Research Group, Budapest, Hungary
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Zoltán Sipák / Barna Vásárhelyi
  • Department of Laboratory Medicine, Semmelweis University, Budapest, Hungary
  • Bionics Innovation Center, Budapest, Hungary
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2016-08-15 | DOI: https://doi.org/10.1515/cclm-2016-0536



The systematic evaluation of the clinical concordance of various 25-hydroxyvitamin D (25OHD) testing methods is presented. The need for this approach is raised by the discrepancies in the analytical performance of the available assays.


The analytical and clinical performance of six automated 25OHD assays and an in-house liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was investigated. Leftover serum samples (n=162, SA: n=114) were analyzed and all 21 assay combinations were evaluated. The utility of Cohen’s κ values was assessed by transforming them into minimum percentage agreement (MPA). McNemar’s hypothesis test was employed for testing the symmetry of the disagreeing classification outcomes within each method pair.


Depending on the assay method, the ratio of results classified as positive (<20 ng/mL) was 13.5%–40.0%. The percentage agreement (PA) was 74.1%–92.6%. Compared to other methods, significantly more hypovitaminosis cases were delivered by DiaSorin Liaison® 25 OH vitamin D Total (DL) and significantly fewer by IDS-iSYS 25-Hydroxy Vitamin DS (II). The strongest clinical concordance was exerted by II vs. LC-MS/MS. The κ-derived MPA showed close similarity to the PA scores. McNemar’s tests confirmed the asymmetry of the disagreement in the classification in 14 method combinations.


The presented approach allows the prediction of the clinical consequences of a 25OHD method transfer. Differences in the clinical classification of assay results are likely encountered when transferring to a new method, even between assays standardized according to the Vitamin D Standardization Program (VDSP) Reference Method Procedure (RMP).

This article offers supplementary material which is provided at the end of the article.

Keywords: 25-hydroxyvitamin D; hypovitaminosis D; immunoassay; liquid chromatography-tandem mass spectrometry; method comparison; multicriteria evaluation


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About the article

Corresponding author: Gellert Karvaly, DPharm, PhD, Department of Laboratory Medicine, Semmelweis University, 4 Nagyvárad tér, H-1089 Budapest, Hungary, Phone: +361.2351600/extension 55545, Fax: +361.4591500/extension 55545

Received: 2016-06-19

Accepted: 2016-07-05

Published Online: 2016-08-15

Published in Print: 2017-03-01

Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

Research funding: The study was supported by grant ED_14-1-2014-0002.

Employment or leadership: None declared.

Honorarium: None declared.

Competing interests: The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.

Citation Information: Clinical Chemistry and Laboratory Medicine (CCLM), Volume 55, Issue 3, Pages 385–393, ISSN (Online) 1437-4331, ISSN (Print) 1434-6621, DOI: https://doi.org/10.1515/cclm-2016-0536.

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