A Comparative Study of Prostate Specific Antigen (PSA) Point-of-Care-Testing (POCT) Techniques

Abstract

Background: Prostate Specific Antigen (PSA) testing is widely used to diagnose and monitor clinical progress in patients with prostate cancer. The availability of various new Point-of-Care-Testing (POCT) equipment for PSA demands that the performance characteristics of these equipment be assessed before introducing them into clinical use to ensure accuracy and reliability.

Objectives: To compare the i-CHROMA^® automated immunofluorescence serum total PSA assay with the Accubind^® Enzyme Linked Immuno-Sorbent Assay (ELISA) as POCT among patients with suspected prostate cancer.

Methods: The study was conducted at the Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC), Ile-Ife, Nigeria. Blood samples drawn from 20 consecutively selected patients were analysed for PSA using the i-CHROMA^® immunofluorescence kit once and with the Accubind^® ELISA protocol twice.

Results: The mean PSA using Accubind^® ELISA was 12.9ng/ml, while it was 14.5ng/ml with the i-CHROMA^® immunofluorescence assay. The bias between the two methods was 1.6ng/ml. The two methods had a good correlation: Passing Bablok regression equation was y = 1.264604x – 0.0300469, and the Spearman correlation coefficient between the two measurements was high (r = 0.956; Confidence Interval 0.889 - 0.983; p<0.0001). Agreement between the two methods was statistically satisfactory as the mean values of the samples fell within the 95% Confidence Interval of the differences on the Bland Altman plot.

Conclusion: The i-CHROMA^® POCT assay showed good correlation and agreement with the well-known ELISA method. Therefore, the method is recommended for use in monitoring PSA in patients with prostatic cancer.