Evaluation of dried blood spots as a feasible alternative to plasma for the detection and quantification of hepatitis c virus in a tropical setting: A pilot study.

Introduction: Confirmatory diagnosis of hepatitis C virus (HCV) infection (HCV RNA detection) is essential before start of the therapy. HCV RNA detection is not available in many parts of India. Shipment of plasma from distant places to referral laboratories may affect HCV RNA titres. Dried blood spots (DBS) provide an easy alternative for transporting samples to centres where HCV RNA testing is done.

Aim: Evaluation of DBS as a feasible alternative to plasma for HCV diagnosis.

Methods: In this cross-sectional study, 40 consecutive patients' blood samples were collected from patients referred from the Liver Clinic. Whole blood was spotted onto two Whatman 903 cards. One card was incubated at ≥37°C and other at 4°C for 15 days, after drying. DBS was eluted and run in Abbott RealTime HCV assay. HCV was also quantified using the Abbott ARCHITECT HCV core antigen assay for 29 of the study patients. Results were compared with normal plasma values.

Results: The median log HCV RNA value (in logIU/mL) of plasma was 5.74, with normalised DBS it was 4.92 (≥37°C) and 4.66 (4°C); difference in plasma and DBS median log values was 0.82 (≥37°C) and 1.08 (4°C) logs, respectively. Interclass correlation values were 0.943, P < 0.0001 (≥37°C) and 0.950, P < 0.0001 (4°C), showing high agreement. The median HCV core antigen value (in fmol/L) for plasma was 325.35, whereas it was 4.77 (≥37°C) and 4.64 (4°C) for DBS samples.

Conclusions: DBS can be used for sampling patients from distant resource-limited settings as an alternative to plasma for HCV RNA estimation. Larger studies are required to evaluate the feasibility of DBS in the Indian subcontinent, especially for HCV core antigen estimation.