(PL24) EVALUATION OF THE PERFORMANCE OF DRIED BLOOD SPOTS VERSUS MICROVOLUME BLOOD TUBES IN SEROLOGICAL TESTING FOR SEXUALLY TRANSMITTED BLOODBORNE PATHOGENS

Background:
Remote testing for sexually transmitted infections may increase access to underserved and high-risk individuals who are unlikely to present to a health clinic for screening. Remote testing for sexually transmitted bloodborne pathogens (BBP) typically involves transfer of finger-pricked blood onto either dried blood spot (DBS) cards or into microvolume blood tubes (MVBT), but the performance of these devices in serological testing for BBPs remains unclear. We evaluated the performance of DBS vs MVBT using spiked samples in order to identify the optimal collection device for remote serological testing.

Methods:
Whole blood from four BBP-negative individuals was obtained by venipuncture, pooled, and separated into 420 aliquots. Mock samples were generated by spiking thirty aliquots in quintuplicate with increasing concentrations of BBP in human serum (very low – very high) per device; unspiked samples served as controls. 600 uL of mock blood were dispensed to MVBT. Two DBS/analyte were loaded with 50 uL of mock blood/spot, allowed to air dry, and then 3 punches were eluted using 300 uL of PBS. Serological testing for HIV-1 and HIV-2 antibodies, HIV p24 antigen, syphilis, hepatitis C (HCV) antibody and hepatitis B core antibody (HBVcAb) and HBV surface antigen (HBVsAg) was performed on the Roche cobas e801 platform.

Results:
Compared to MVBT, all serological tests of DBS samples resulted in a significant loss of sensitivity. By analyte, the percent positive agreements were: HIV antibodies 100%, HIV antigen 25%, syphilis treponemal antibody 40%, HCV antibody 28%, HBVcAb 0% and HBVsAg 100%. All analytes had 100% negative agreement.

Conclusion:
Compared to MVBT, using DBS for serological testing resulted in a significant loss in assay performance; these results confirm recent findings from Europe. The unacceptable false negative rate from DBS puts clients at increased risk for missed diagnoses, complications of untreated infections, and BBP transmission to partners.