Sensitivity and specificity of Dried Blood Spot and Plasma Separation Card samples for Hepatitis C Virus RNA Testing

Dried blood spots (DBS) and plasma separation cards (PSC) have the potential to improve access to hepatitis C virus (HCV) testing. This multicenter study evaluated the performance of two HCV RNA assay platforms using capillary or venous DBS and PSC. Participants were enrolled in Cameroon, Rwanda, Georgia, and Greece. DBS and PSC prepared from capillary and venous blood samples were collected from three target populations; individuals at risk of HCV infection, persons living with HCV, and individuals previously treated for HCV. The diagnostic accuracy of DBS and PSC for detecting HCV RNA was assessed using the cobas HCV nucleic assay on the cobas 4800 and cobas 6800 platforms (Roche), with plasma samples tested using these platforms serving as the reference standard. A total of 936 participants were enrolled. Capillary, venous DBS and venous PSC demonstrated high diagnostic accuracy. Sensitivity and specificity were 97.2% (95% CI: 95.2-98.3) and 88.6% (95%CI: 85.4 -91.2) for capillary DBS, 96.1% (95%CI: 93.9 -97.5) and 87.8% (95%CI: 85.4 -90.4) for venous DBS and 95.2% (95%CI: 92.8 -96.8) and 99.6% (95%CI: 98.5 -99.9) for venous PSC, on the cobas 4800. The cobas 6800 platform had a sensitivity and specificity of 97.3% (95%CI: 95.4 -98.5) and 95.9% (95%CI: 93.7 -97.3) on venous DBS, 96.7% (95%CI: 94.6 -98.0) and 99.8% (95%CI: 98.8 - 100) on venous PSC, and 96.9% (95%CI: 94.8 -98.1) and 99.8% (95%CI: 98.8 - 100) on capillary PSC. The diagnostic accuracy of capillary and venous DBS and PSC for detecting HCV RNA was high on the two platforms evaluated. This study demonstrates that DBS and PSC sample types can be an alternative to plasma to screen for HCV infection, thus facilitating access to testing.

Although the use of point-of-care rapid antibody tests for hepatitis C virus (HCV) is increasing, people who test positive must still undergo a confirmatory test before receiving treatment. Confirmatory testing for HCV RNA can be performed using plasma, serum, or capillary whole blood, depending on the available diagnostic platforms and testing algorithms. Plasma samples are more commonly used; however, their collection, storage, transport, and handling can pose significant challenges in low-resource settings. To improve access to HCV testing, there is a need for alternative sample types. Blood samples dried on filter paper cards (dried blood spots, or DBS) can be collected at the community level, have low biohazard risk, can withstand exposure to ambient temperatures, and are easily stored and shipped. Plasma Separation Cards (PSC), which collect plasma rather than whole blood, have similar properties. This study demonstrated that the diagnostic accuracy of DBS and PSC for detecting HCV RNA using the Roche cobas 4800 and 6800 platforms was high, confirming that they could be viable alternatives to plasma sampling for HCV testing.