Comparison of test performance of two commonly used multiplex assays to measure micronutrient and inflammatory markers in serum: Results from a survey among pregnant women in South Africa

Tsitsi Chimhashu*, Hans Verhoef, Elizabeth A. Symington, Lizelle Zandberg, Jeannine Baumgartner, Linda Malan, Cornelius M. Smuts, Edith Feskens, Alida Melse-Boonstra

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The combined sandwich-ELISA (s-ELISA; VitMin Lab, Germany) and the Quansys Q-Plex™ Human Micronutrient Array (7-Plex) are multiplex serum assays that are used to assess population micronutrient status in low-income countries. We aimed to compare the agreement of five analytes, α-1-acid glycoprotein (AGP), C-reactive protein (CRP), ferritin, retinol binding protein 4 (RBP4), and soluble transferrin receptor (sTfR) as measured by the 7-Plex and the s-ELISA. Serum samples were collected between March 2016 and December 2017. Pregnant women (n=249) were recruited at primary healthcare clinics in Johannesburg and serum samples were collected between March 2016 and December 2017. Agreement between continuous measurements was assessed by Bland-Altman plots and concordance measures. Agreement in classifications of deficiency or inflammation was assessed by Cohen's kappa. Strong correlations (r>0.80) were observed between the 7-Plex and s-ELISA for CRP and ferritin. Except for CRP, the 7-Plex assay gave consistently higher measurements than the s-ELISA. With the exception of CRP (Lin's ρ=0.92), there was poor agreement between the two assays, with Lin's ρ <0.90. Discrepancies of test results difference between methods increased as the serum concentrations rose. Cohen's kappa for all the five analytes was <0.81 and ranged from slight agreement (vitamin A deficiency) to substantial (inflammation, iron deficiency) agreement. The 7-Plex 1.0 is a research and or surveillance tool with potential for use in low-resource laboratories but cannot be used interchangeably with the s-ELISA. Further optimising and validation is required to establish its interchangeability with other validated methods.

Original languageEnglish
Pages (from-to)248 - 255
Number of pages8
JournalBritish Journal of Nutrition
Volume131
Issue number2
Early online date10 Aug 2023
DOIs
Publication statusPublished - 28 Jan 2024

Keywords

  • C-reactive protein
  • ferritin
  • Keywords:
  • Quansys 7-Plex assay
  • retinol-binding protein
  • soluble transferrin receptor
  • α-1-acid glycoprotein

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