Incorrect identification of recent HIV infection in adults in the United States using a limiting-antigen avidity assay

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Abstract

Objectives: To evaluate factors associated with misclassification by the limiting-antigen avidity (LAg-avidity) assay among individuals with long-standing HIV infection. Design: Samples were obtained from the Multicenter AIDS Cohort Study and AIDS Linked to the IntraVenous Experience cohort (1089 samples from 667 individuals, 595 samples collected 2-4 years and 494 samples collected 4-8 years after HIV seroconversion). Paired samples from both time points were available for 422 (63.3%) of the 667 individuals. Methods: Samples were considered to be misclassified if the LAg-avidity assay result was 1.5 or less normalized optical density (OD-n) units. Results: Overall, 4.8% (52/1089) of the samples were misclassified, including 1.8% [16/884, 95% confidence interval (CI) 1.09-3.06%] of samples from individuals with viral loads above 400 copies/ml and 1.4% (10/705) of samples from individuals with viral loads above 400 copies/ml and CD4+ cell counts above 200 cells/ml (95% CI 0.68-2.60%). Age, race, sex, and mode of HIV acquisition were not associated with misclassification. In an adjusted analysis, viral load below 400 copies/ml [adjusted odds ratio (aOR) 3.72, 95% CI 1.61-8.57], CD4+ cell count below 50 cells/ml (aOR 5.41, 95% CI 1.86-15.74), and low LAg-avidity result (≥1.5 OD-n) from the earlier time point (aOR 5.60, 95% CI 1.55-20.25) were significantly associated with misclassification. Conclusions: The manufacturer of the LAg-avidity assay recommends excluding individuals from incidence surveys who are receiving antiretroviral therapy, are elite suppressors, or have AIDS (CD4+ cell count <200 cells/ml). The results of this study indicate that those exclusions do not remove all sources of assay misclassification among individuals with long-standing HIV infection.

Original languageEnglish (US)
Pages (from-to)1227-1232
Number of pages6
JournalAIDS
Volume28
Issue number8
DOIs
StatePublished - 2014

Keywords

  • HIV
  • Incidence
  • Limiting-antigen avidity
  • MSM
  • Misclassification
  • People who inject drugs

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Infectious Diseases

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