Total Prostate-Specific Antigen (PSA) Testing in Capillary Samples: Proof-of-Principle and Feasibility Study for Home Self-Testing for Prostate Cancer.

Background: There is growing interest in the use of capillary blood sampling (CBS) for testing biochemical analytes owing to the advantages it offers including home surveillance of chronic conditions. In this study, we aimed to determine whether the use of CBS was a viable and feasible method for testing total prostate-specific antigen (TPSA) concentrations in men with prostate disease.

Methods: Men with known prostate disease were recruited from a urology clinic where they were being treated or followed up. Samples were collected in serum separating tubes by the finger-prick method using validated devices. Simultaneously, venous blood was collected by venipuncture. We used validated immunoassays on both the Roche (Cobas 801) and Beckman (DXi) platforms to measure TPSA.

Results: In total, 66 adult men between 26 and 64 years of age were tested. Across the concentration range of normal (0.3 µg/L) to pathological (314 µg/L), the results between CBS and venous samples were highly comparable and correlated (r = 0.997). The average bias was 0.112 µg/L or 1.07% and was not significant (P = 0.274). Overall, there was no apparent proportional or constant bias observed. Our data showed that TPSA may be stable in CBS stored at ambient temperature for up to 8 days in the samples tested using either the Roche or Beckman assays.

Conclusions: This feasibility study shows that CBS and venous samples are highly correlated and there was negligible bias. Further validation work is now required for the measurement of TPSA in CBS and determining outcomes in men with prostate disease.