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Determination of 21-hydroxylase autoantibodies: inter-laboratory concordance in the Euradrenal International Serum Exchange Program

Falorni, Alberto; Bini, Vittorio; Betterle, Corrado; Brozzetti, Annalisa; Castano, Luis; Fichna, Marta; Kampe, Olle; Mellgren, Gunnar; Peterson, Part and Chen, Shu, et al. (2015) In Clinical Chemistry and Laboratory Medicine 53(11). p.1761-1770
Abstract
Background: 21-Hydroxylase autoantibodies (21OHAb) are markers of an adrenal autoimmune process that identifies individuals with autoimmune Addison's disease (AAD). Quality and inter-laboratory agreement of various 21OHAb tests are incompletely known. The objective of the study was to determine inter-laboratory concordance for 21OHAb determinations. Methods: Sixty-nine sera from 51 patients with AAD and 51 sera from 51 healthy subjects were blindly coded by a randomization center and distributed to 14 laboratories that determined 21OHAb, either by an "in-house" assay (n=9) using in vitro-translated S-35-21OH or luciferase-labeled 21OH or a commercial kit with I-125-21OH (n=5). Main outcome measures were diagnostic accuracy of each... (More)
Background: 21-Hydroxylase autoantibodies (21OHAb) are markers of an adrenal autoimmune process that identifies individuals with autoimmune Addison's disease (AAD). Quality and inter-laboratory agreement of various 21OHAb tests are incompletely known. The objective of the study was to determine inter-laboratory concordance for 21OHAb determinations. Methods: Sixty-nine sera from 51 patients with AAD and 51 sera from 51 healthy subjects were blindly coded by a randomization center and distributed to 14 laboratories that determined 21OHAb, either by an "in-house" assay (n=9) using in vitro-translated S-35-21OH or luciferase-labeled 21OH or a commercial kit with I-125-21OH (n=5). Main outcome measures were diagnostic accuracy of each participating laboratory and inter-laboratory agreement of 21OHAb assays. Results: Intra-assay coefficient of variation ranged from 2.6% to 5.3% for laboratories using the commercial kit and from 5.1% to 23% for laboratories using "in-house" assays. Diagnostic accuracy, expressed as area under ROC curve (AUC), varied from 0.625 to 0.947 with the commercial kit and from 0.562 to 0.978 with "in-house" methods. Cohen's. of inter-rater agreement was 0.603 among all 14 laboratories, 0.691 among "in-house" laboratories, and 0.502 among commercial kit users. Optimized cutoff levels, calculated on the basis of AUCs, increased the diagnostic accuracy of every laboratory (AUC >0.9 for 11/14 laboratories) and increased the Cohen's. of inter-rater agreement. Discrepancies in quantitation of 21OHAb levels among different laboratories increased with increasing autoantibody levels. Conclusions: The quality of 21OHAb analytical procedures is mainly influenced by selection of cutoff value and correct handling of assay materials. A standardization program is needed to identify common standard sera and common measuring units. (Less)
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published
subject
keywords
Addison's disease, adrenal antibodies, autoimmunity, diagnosis, RIA, standardization
in
Clinical Chemistry and Laboratory Medicine
volume
53
issue
11
pages
1761 - 1770
publisher
De Gruyter
external identifiers
  • wos:000362510000023
  • scopus:84944066379
ISSN
1434-6621
DOI
10.1515/cclm-2014-1106
language
English
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yes
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176a1163-ed24-430e-9a76-39f622e64595 (old id 8212317)
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2015-12-01 07:06:10
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2017-07-02 03:22:01
@article{176a1163-ed24-430e-9a76-39f622e64595,
  abstract     = {Background: 21-Hydroxylase autoantibodies (21OHAb) are markers of an adrenal autoimmune process that identifies individuals with autoimmune Addison's disease (AAD). Quality and inter-laboratory agreement of various 21OHAb tests are incompletely known. The objective of the study was to determine inter-laboratory concordance for 21OHAb determinations. Methods: Sixty-nine sera from 51 patients with AAD and 51 sera from 51 healthy subjects were blindly coded by a randomization center and distributed to 14 laboratories that determined 21OHAb, either by an "in-house" assay (n=9) using in vitro-translated S-35-21OH or luciferase-labeled 21OH or a commercial kit with I-125-21OH (n=5). Main outcome measures were diagnostic accuracy of each participating laboratory and inter-laboratory agreement of 21OHAb assays. Results: Intra-assay coefficient of variation ranged from 2.6% to 5.3% for laboratories using the commercial kit and from 5.1% to 23% for laboratories using "in-house" assays. Diagnostic accuracy, expressed as area under ROC curve (AUC), varied from 0.625 to 0.947 with the commercial kit and from 0.562 to 0.978 with "in-house" methods. Cohen's. of inter-rater agreement was 0.603 among all 14 laboratories, 0.691 among "in-house" laboratories, and 0.502 among commercial kit users. Optimized cutoff levels, calculated on the basis of AUCs, increased the diagnostic accuracy of every laboratory (AUC >0.9 for 11/14 laboratories) and increased the Cohen's. of inter-rater agreement. Discrepancies in quantitation of 21OHAb levels among different laboratories increased with increasing autoantibody levels. Conclusions: The quality of 21OHAb analytical procedures is mainly influenced by selection of cutoff value and correct handling of assay materials. A standardization program is needed to identify common standard sera and common measuring units.},
  author       = {Falorni, Alberto and Bini, Vittorio and Betterle, Corrado and Brozzetti, Annalisa and Castano, Luis and Fichna, Marta and Kampe, Olle and Mellgren, Gunnar and Peterson, Part and Chen, Shu and Ronnelid, Johan and Seissler, Jochen and Tiberti, Claudio and Uibo, Raivo and Yu, Liping and Lernmark, Åke and Husebye, Eystein},
  issn         = {1434-6621},
  keyword      = {Addison's disease,adrenal antibodies,autoimmunity,diagnosis,RIA,standardization},
  language     = {eng},
  number       = {11},
  pages        = {1761--1770},
  publisher    = {De Gruyter},
  series       = {Clinical Chemistry and Laboratory Medicine},
  title        = {Determination of 21-hydroxylase autoantibodies: inter-laboratory concordance in the Euradrenal International Serum Exchange Program},
  url          = {http://dx.doi.org/10.1515/cclm-2014-1106},
  volume       = {53},
  year         = {2015},
}