Background
Current diagnostic tests for Hepatitis C Virus (HCV) involve
phlebotomy and serologic testing for HCV antibodies (anti-HCV) and RNA,
which are not always feasible. Dried blood spots (DBS) present a minimally
invasive sampling method and are suitable for sample collection, storage and
testing.
Objectives
To assess the utility of DBS in HCV detection, we evaluated the
sensitivity and specificity of DBS for anti-HCV and HCV RNA detection
compared to plasma specimens.
Study design
This cross-sectional validation study was conducted in the context of
an existing prospective study of HCV in young injection drug users. Blood
samples were collected by venipuncture into serum separator tubes (SST) and
via finger stick onto Whatman 903® protein-saver cards. Plasma
samples and eluates from the DBS were tested for anti-HCV using
either a third generation enzyme-linked or chemiluminescent immunoassay
(IA), and HCV RNA using discriminatory HCV transcription-mediated
amplification assay (dHCV TMA). DBS results were compared to their
corresponding plasma sample results.
Results
148 participants were tested for anti-HCV and 132 participants were
tested for HCV RNA. For anti-HCV, the sensitivity of DBS was 70%,
specificity was 100%, positive predictive value (PPV) was 100%, negative
predictive value (NPV) was 76% and Kappa was 0.69. For HCV RNA, the
sensitivity of DBS was 90%, specificity was 100%, PPV was 100%, NPV was 94%
and Kappa was 0.92.
Conclusions
DBS are sensitive and very specific in detecting anti-HCV and HCV
RNA, demonstrate good correlation with plasma results, and have potential to
facilitate diagnosis of HCV infection.