Evaluation of a point of care prostate-specific antigen blood test on a mobile outreach service

BackgroundPoint of care (POC) tests may improve accessibility and reduce costs of blood tests including in prostate cancer. The Man Van project was a pilot designed to address health inequalities that affect prostate cancer with novel community-based targeting of high-risk groups on a mobile clinical unit.MethodsThe i-CHROMA-II™ POC machine is a quantitative assay for the measurement of total prostate specific antigen (PSA) from capillary blood using fluorescence immunoassay technology. Laboratory based Serum PSA testing was compared with capillary blood POC testing using the i-CHROMA-II™ to determine its accuracy and impact on clinical decision making on the Man Van.Results28 men participated. The median age was 53 years (range 45-74). One POC test result was invalid. Nine POCT samples gave a result of <0.5 μg/L and were not included in the analysis. Of the remaining results (N = 18) the median PSA was 1.97 μg/L (range 0.54-31.22 μg/L). Using Lin's Concordance Correlation Coefficient of Absolute Agreement gave a value of 0.392 (N = 17). A Bland-Altman plot showed a mean difference of 0.377 μg/L.ConclusionsWe report the first testing of PSA using the i-Chroma-II™ machine, and the first real-world mobile testing using any POC PSA test. Our study did not show correlation between the laboratory and i-Chroma-II™, although it did replicate the positive bias seen in previous studies. Further testing and refinement of POC tests may help to achieve the goal to developing reliable POC PSA tests.