Evaluation of dried blood spot testing using the Abbott Alinity i

Abstract

Background: The West of Scotland Specialist Virology Centre currently uses the Abbott Architect for DBS serology. The new Abbott Alinity i will replace the Architect in our laboratory. In this study, mock and stored patient DBS samples were tested on both platforms and results compared.

Study design: Mock DBS were made from whole blood where patient results were known (38 negative samples and 141 positive samples; 39 HIV Antigen/Antibody (Ag/Ab), 35 HCV IgG antibody (HCVG), 34 HBV core IgG (HBCG) and 33 HBsAg). Mock DBS were tested on both Abbott platforms. Stored patient DBS samples (132 negative and 263 positive: 9 HIVAg/Ab, 10 HBsAg, 52 HBCG and 60 HCVG) previously tested on the Architect were retested on the Alinity i.

Results: Mock DBS showed good correlation between the Architect and Alinity i for the HIV Ag/Ab,HBCG and HCVG assays. A poorer correlation occurred with HBsAg, the Alinity i reported HBsAg positives at a lower value compared to the Architect. The coefficient of variation for intra-assay variation was 1.69 % (HIVAg/Ab), 3.25 % (HCVG), 1.68 % (HBsAg) and 1.95 % (HBCG). The sensitivity and specificity was determined based on results from the mock and patient samples. At S/Co cut-off 1.0 both HIV and HBsAg had a sensitivity of 100 %. A cut-off 0.8 gave a sensitivity of 95.83 % (95 % CI 89.67%-98.85%) for HCVG and 0.3 gave a sensitivity of 98.8 % (CI 93.69%-99.97%) for HBCG.

Discussion: The alinity i compared well against the architect and can be used to test DBS samples.

Keywords: Abbott; Alinity; DBS; HBV; HCV; HIV.