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Abstract Background In Sweden, men =50 years of age are offered participation in Organized Prostate cancer Testing (OPT) by monitoring of prostate-specific antigen (PSA). Currently, the participation rate is 35%.The aim of this study was to validate an at-home sampling procedure for PSA monitoring. The long-term aim is to investigate the effect on the OPT participation rate when offering this at-home sampling as an alternative to venous routine blood sampling. This at-home sampling is based on a quantitative dried blood spot disc device, named Capitainer®B (qDBS), allowing sampling of a precise volume of blood via a capillary finger-prick. The device is then mailed to a clinical laboratory for PSA quantification. Methods The developed method was based on extraction of blood from dried qDBS discs in PBS for 1h in room temperature during shaking. The extracts were then analyzed on Siemens Atellica IM. The validation focused on venous blood qDBS comparison to reference method (PSA in venous plasma), in anonymized samples. Also, precision between two individual dried qDBS discs and limit of quantification (LOQ) were validated. The final part of method validation is an ongoing clinical study, where capillary blood on qDBS are sampled by lay-persons in parallel to routine venous plasma sampling. Results An excellent correlation (R=0.998, n=106) between PSA-concentrations in qDBS extracts of venous blood versus the reference method in plasma was demonstrated. The PSA concentration range in plasma was 0.3-307 µg/L (median 3.2). The regression line equation was used to recalculate qDBS concentrations to corresponding plasma concentration. The action limit cut-off for PSA in the Swedish national OPT program is 3.0 µg/L in plasma. Applying this cut-off for the recalculated qDBS concentrations resulted in 98% sensitivity and 100% specificity. The method coefficient of variance (CV) was 4, 6, 12 % in the low, mid and high PSA concentration range, and the LOQ was 0.3 µg/L. In an interim analysis of the ongoing clinical study (n=40), promising results were obtained, showing similar statistics for capillary blood on qDBS with a correlation of 0.99 and CV of 6.1%. Conclusion The results show that the qDBS method delivers satisfactory analytical performance supporting implementation as an alternative sampling method for monitoring of PSA. Next steps are to complete the ongoing clinical study, followed by a randomized clinical study within the OPT program.