Comparison of cross-sectional HIV incidence assay results from dried blood spots and plasma

Katherine E. Schlusser, Christopher Pilcher, Esper G. Kallas, Breno R. Santos, Steven G. Deeks, Shelley Facente, Sheila M. Keating, Michael P. Busch, Gary Murphy, Alex Welte, Thomas Quinn, Susan H. Eshleman, Oliver Laeyendecker

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Background Assays have been developed for cross-sectional HIV incidence estimation using plasma samples. Large scale surveillance programs are planned using dried blood spot (DBS) specimens for incidence assessment. However, limited information exists on the performance of HIV cross-sectional incidence assays using DBS. Methods The assays evaluated were: Maxim HIV-1 Limiting Antigen Avidity EIA (LAg-Avidity), Sedia HIV-1 BED-Capture EIA (BED-CEIA), and CDC modified BioRad HIV-1/2 Plus O Aviditybased Assay (CDC-BioRad Avidity) using pre-determined cutoff values. 100 matched HIV-1 positive plasma and DBS samples, with known duration of infection, from the Consortium for the Evaluation and Performance of HIV Incidence Assays repository were tested. All assays were run in duplicate. To examine the degree of variability within and between results for each sample type, both categorical and continuous results were analyzed. Associations were assessed with Bland Altman, R2 values and Cohen's kappa coefficient (?). Results Intra-assay variability using the same sample type was similar for all assays (R2 0.96 to 1.00). The R2 values comparing DBS and plasma results for LAg-Avidity, BED-CEIA, and CDC-BioRad Avidity were 0.96, 0.94, and 0.84, respectively. The concordance and κ values between DBS and plasma for all three assays were >87% and >0.64, respectively. The Bland-Altman analysis showed significant differences between plasma and DBS samples. For all three assays, a higher number of samples were classified as recent infections using DBS samples. Conclusions DBS and plasma sample results were highly correlated. However, when compared to plasma, each assay performed somewhat differently in DBS at the lower and higher ends of the dynamic range. DBS samples were more likely to be classified as recently infected by all three assays, which may lead to overestimation of incidence in surveys using performance criteria derived for plasma samples. This is an open access article, free of all copiright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

Original languageEnglish
Article numbere0172283
JournalPLoS ONE
Issue number2
Publication statusPublished - Feb 2017


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