How accurate is Color’s PSA test?
Color’s partner laboratory, US Specialty Labs (USSL), uses the Beckman Coulter UniCel DxI 800 Access Immunoassay System with the Access Hybritech PSA assay. This highly sensitive instrument can detect concentrations of PSA in serum as low as 0.1ng/mL.
A PSA test is quantitative, with a reportable range from 0-20. Over the reportable range, Color’s at-home blood test to measure PSA was 98% correlated with a venous blood draw (i.e. phlebotomy).
Clinical sensitivity of the PSA test is understood from prior clinical literature. The clinical sensitivity of a PSA test depends on the threshold defined as ‘abnormal’. We currently plan to use a PSA of 4.0 ng/mL as the threshold for ‘elevated’ and requiring a referral – this is in accordance with guidelines from the American Cancer Society (ACS). The American Cancer Society conducted a systematic review to estimate sensitivity and specificity of PSA testing for detecting prostate cancer. It is estimated that a PSA cutoff of 4.0 ng/mL has a sensitivity of 21% and specificity of 91% for detection of any stage prostate cancer.