Reproducibility of low galactomannan enzyme immunoassay index values tested in multiple laboratories

Arlo Upton, Anja Gugel, Wendy Leisenring, Ajit Limaye, Barbara Alexander, Randall Hayden, Kieren Marr

Research output: Contribution to journalArticle

Abstract

The Platelia galactomannan enzyme immunoassay is a commercially available nonculture method for diagnosing invasive aspergillosis. Recently, steps have been taken to improve sensitivity; specifically, a low (0.5 to 0.7) galactomannan index (GMI) value to determine positivity has been validated by multiple groups. We evaluated the intra-assay and interassay reproducibility at low index levels using three different kit lots on three different days in three different microbiology laboratories. Clinical and spiked sera were blinded and sent with galactomannan enzyme immunoassay (EIA) kits to the participating laboratories. We also prospectively collected data on all galactomannan EIAs performed between 1 September 2003 and 21 July 2004 at the University of Washington Medical Center microbiology laboratory to assess reproducibility of clinical samples analyzed in "real time." From the multilaboratory study, a total of 836 results were available for evaluation. Reproducibility was excellent between laboratories and on different days. Significant variability was seen between runs/lots, which may in part be associated with different threshold control values in different kits. Among the 1,410 clinical samples that were prospectively analyzed, 168 (90%) were confirmed to be positive on repeat testing (GMI, ≥0.5). Among the 19 (10.2%) initially positive samples not confirmed on repeat testing, the majority had a GMI at the threshold of the assay (between 0.5 and 0.7). Our findings suggest that the Platelia galactomannan immunoassay has good reproducibility. However, changes in GMI levels when different kit lots are used, and single samples with low-positive (GMI of 0.5 to 0.7) indices, should be interpreted with caution.

Original languageEnglish (US)
Pages (from-to)4796-4800
Number of pages5
JournalJournal of Clinical Microbiology
Volume43
Issue number9
DOIs
StatePublished - Sep 2005
Externally publishedYes

Fingerprint

Immunoenzyme Techniques
Microbiology
galactomannan
Aspergillosis
Immunoassay
Serum

ASJC Scopus subject areas

  • Microbiology (medical)
  • Microbiology

Cite this

Reproducibility of low galactomannan enzyme immunoassay index values tested in multiple laboratories. / Upton, Arlo; Gugel, Anja; Leisenring, Wendy; Limaye, Ajit; Alexander, Barbara; Hayden, Randall; Marr, Kieren.

In: Journal of Clinical Microbiology, Vol. 43, No. 9, 09.2005, p. 4796-4800.

Research output: Contribution to journalArticle

Upton, Arlo ; Gugel, Anja ; Leisenring, Wendy ; Limaye, Ajit ; Alexander, Barbara ; Hayden, Randall ; Marr, Kieren. / Reproducibility of low galactomannan enzyme immunoassay index values tested in multiple laboratories. In: Journal of Clinical Microbiology. 2005 ; Vol. 43, No. 9. pp. 4796-4800.
@article{fbdef1abf3014fe7b83954deab5e004f,
title = "Reproducibility of low galactomannan enzyme immunoassay index values tested in multiple laboratories",
abstract = "The Platelia galactomannan enzyme immunoassay is a commercially available nonculture method for diagnosing invasive aspergillosis. Recently, steps have been taken to improve sensitivity; specifically, a low (0.5 to 0.7) galactomannan index (GMI) value to determine positivity has been validated by multiple groups. We evaluated the intra-assay and interassay reproducibility at low index levels using three different kit lots on three different days in three different microbiology laboratories. Clinical and spiked sera were blinded and sent with galactomannan enzyme immunoassay (EIA) kits to the participating laboratories. We also prospectively collected data on all galactomannan EIAs performed between 1 September 2003 and 21 July 2004 at the University of Washington Medical Center microbiology laboratory to assess reproducibility of clinical samples analyzed in {"}real time.{"} From the multilaboratory study, a total of 836 results were available for evaluation. Reproducibility was excellent between laboratories and on different days. Significant variability was seen between runs/lots, which may in part be associated with different threshold control values in different kits. Among the 1,410 clinical samples that were prospectively analyzed, 168 (90{\%}) were confirmed to be positive on repeat testing (GMI, ≥0.5). Among the 19 (10.2{\%}) initially positive samples not confirmed on repeat testing, the majority had a GMI at the threshold of the assay (between 0.5 and 0.7). Our findings suggest that the Platelia galactomannan immunoassay has good reproducibility. However, changes in GMI levels when different kit lots are used, and single samples with low-positive (GMI of 0.5 to 0.7) indices, should be interpreted with caution.",
author = "Arlo Upton and Anja Gugel and Wendy Leisenring and Ajit Limaye and Barbara Alexander and Randall Hayden and Kieren Marr",
year = "2005",
month = "9",
doi = "10.1128/JCM.43.9.4796-4800.2005",
language = "English (US)",
volume = "43",
pages = "4796--4800",
journal = "Journal of Clinical Microbiology",
issn = "0095-1137",
publisher = "American Society for Microbiology",
number = "9",

}

TY - JOUR

T1 - Reproducibility of low galactomannan enzyme immunoassay index values tested in multiple laboratories

AU - Upton, Arlo

AU - Gugel, Anja

AU - Leisenring, Wendy

AU - Limaye, Ajit

AU - Alexander, Barbara

AU - Hayden, Randall

AU - Marr, Kieren

PY - 2005/9

Y1 - 2005/9

N2 - The Platelia galactomannan enzyme immunoassay is a commercially available nonculture method for diagnosing invasive aspergillosis. Recently, steps have been taken to improve sensitivity; specifically, a low (0.5 to 0.7) galactomannan index (GMI) value to determine positivity has been validated by multiple groups. We evaluated the intra-assay and interassay reproducibility at low index levels using three different kit lots on three different days in three different microbiology laboratories. Clinical and spiked sera were blinded and sent with galactomannan enzyme immunoassay (EIA) kits to the participating laboratories. We also prospectively collected data on all galactomannan EIAs performed between 1 September 2003 and 21 July 2004 at the University of Washington Medical Center microbiology laboratory to assess reproducibility of clinical samples analyzed in "real time." From the multilaboratory study, a total of 836 results were available for evaluation. Reproducibility was excellent between laboratories and on different days. Significant variability was seen between runs/lots, which may in part be associated with different threshold control values in different kits. Among the 1,410 clinical samples that were prospectively analyzed, 168 (90%) were confirmed to be positive on repeat testing (GMI, ≥0.5). Among the 19 (10.2%) initially positive samples not confirmed on repeat testing, the majority had a GMI at the threshold of the assay (between 0.5 and 0.7). Our findings suggest that the Platelia galactomannan immunoassay has good reproducibility. However, changes in GMI levels when different kit lots are used, and single samples with low-positive (GMI of 0.5 to 0.7) indices, should be interpreted with caution.

AB - The Platelia galactomannan enzyme immunoassay is a commercially available nonculture method for diagnosing invasive aspergillosis. Recently, steps have been taken to improve sensitivity; specifically, a low (0.5 to 0.7) galactomannan index (GMI) value to determine positivity has been validated by multiple groups. We evaluated the intra-assay and interassay reproducibility at low index levels using three different kit lots on three different days in three different microbiology laboratories. Clinical and spiked sera were blinded and sent with galactomannan enzyme immunoassay (EIA) kits to the participating laboratories. We also prospectively collected data on all galactomannan EIAs performed between 1 September 2003 and 21 July 2004 at the University of Washington Medical Center microbiology laboratory to assess reproducibility of clinical samples analyzed in "real time." From the multilaboratory study, a total of 836 results were available for evaluation. Reproducibility was excellent between laboratories and on different days. Significant variability was seen between runs/lots, which may in part be associated with different threshold control values in different kits. Among the 1,410 clinical samples that were prospectively analyzed, 168 (90%) were confirmed to be positive on repeat testing (GMI, ≥0.5). Among the 19 (10.2%) initially positive samples not confirmed on repeat testing, the majority had a GMI at the threshold of the assay (between 0.5 and 0.7). Our findings suggest that the Platelia galactomannan immunoassay has good reproducibility. However, changes in GMI levels when different kit lots are used, and single samples with low-positive (GMI of 0.5 to 0.7) indices, should be interpreted with caution.

UR - http://www.scopus.com/inward/record.url?scp=24744463130&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=24744463130&partnerID=8YFLogxK

U2 - 10.1128/JCM.43.9.4796-4800.2005

DO - 10.1128/JCM.43.9.4796-4800.2005

M3 - Article

C2 - 16145143

AN - SCOPUS:24744463130

VL - 43

SP - 4796

EP - 4800

JO - Journal of Clinical Microbiology

JF - Journal of Clinical Microbiology

SN - 0095-1137

IS - 9

ER -