Prospective evaluation of hepatitis C virus antibody detection in whole blood collected on dried blood spots with the INNOTEST® HCV Ab IV enzyme immunoassay

Abstract

Introduction: Dried blood spots (DBS) have potential to improve access to screening for antibodies to hepatitis C virus (HCV). However, although several studies on off-label use of DBS have been performed, to date no HCV antibody serology test is formally approved for use with DBS. This study evaluated the performance of the INNOTEST® HCV Ab IV enzyme immunoassay in paired DBS and plasma samples, to determine whether DBS may be added to the intended use.

Methods: Adults with no history of HCV treatment were prospectively enrolled from two sites in Ukraine. DBS were prepared from fingerstick whole blood (fDBS) and venous whole blood (vDBS) samples. Undiluted and serially diluted DBS and plasma samples were tested.

Results: Samples from 149 HCV positive and 151 HCV negative participants were included. Sensitivity and specificity of the INNOTEST® HCV Ab IV assay were both 100 % (95 % confidence intervals 95.7-100) for samples collected on fDBS or vDBS compared with plasma as the reference standard. In all undiluted samples, negative and positive percentage agreement and overall rate of agreement were 100 % between all sample types (Cohen's kappa coefficient of 1). In serially diluted samples, agreement was high (>95 %) between fDBS and vDBS, and as expected, positive percentage agreement between both DBS sample types and plasma was lower (>66 %).

Conclusions: Performance of the INNOTEST® HCV Ab IV assay in DBS was acceptable, thus whole blood collected on DBS may represent an alternative sample type for this assay in settings where venous blood collection is not possible.

Keywords: Dried Blood spot; Enzyme immunoassay; Hepatitis C virus; In vitro diagnostics; Sensitivity; Specificity.