Background: Elimination of Hepatitis C virus (HCV) relies on increasing HCV diagnostic rates in hard to reach populations. Dried blood spot (DBS) samples are a convenient sample type for HCV testing, as they can be collected in non-traditional settings such as drug services and prison settings, increasing access to HCV testing.
Objectives: Herein we investigate an off-label DBS protocol for use on the Abbott Alinity m platform.
Study design: A dilution series of HCV RNA positive blood was used to determine the analytical sensitivity of the test. We assess the sensitivity and specificity of HCV RNA detection in 50 mock DBS specimens compared to associated plasma viral load, and re-test 66 clinical DBS, previously tested on the m2000 to determine the clinical sensitivity and specificity of the assay.
Results: The dilution panel suggested that the Alinity m DBS assay is one log more sensitive than our current DBS HCV RNA assay. Mock DBS demonstrated 100% specificity, and 100% sensitivity for samples with plasma HCV RNA viral loads > 2.7 log10 IU/mL, however four samples with viral loads between 1.3 and 2.4 log10 IU/mL were not detected. The clinical sensitivity and specificity of previously tested DBS was 94% and 100% respectively, with two samples reported as low level RNA positive on the m2000 testing negative on Alinty m.
Conclusions: The data suggests that DBS can be used as an off-label specimen type on the Alinity m HCV assay. Allowing continuous, random access testing of DBS simultaneously alongside other Alintiy m assays, potentially improving test turn-around times.
Keywords: Alinity m; Dried blood spots; HCV elimination; Hepatitis C virus; Off-Label assay.
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