Evaluation of rapid one-step prostate specific antigen test against an established ELISA method

Abstract

Main Objective: To evaluate the analytical performance of the rapid one-step immunochromatographic PSA assay against an established ELISA method.

Design: A comparative study was conducted in the Department of Chemical Pathology at the University of Zimbabwe, College Health Sciences, between June 2012 and May 2013.

Setting: Department of Chemical Pathology, University of Zimbabwe, College Health Sciences, Harare, Zimbabwe.

Samples: Serum samples from patients referred for routine Prostate Specific Antigen (PSA) assays. Serum samples from female patients were used as negative controls.

Results: The rapid test correctly classified 46 (97.9%) as negative (PSA <4ng/ml) and 94 (95%) as positive (PSA ≥4ng/ml). However one (2.1%) sample and 5 samples (5%) were wrongly classified as positive and  negative respectively.

All 18 (100%) of PSA Rapid Test Devices (RTD) performed on female samples were correctly judged as negative. Accuracy, sensitivity, specificity negative and positive predictive values of PSA RDT were 95.9%, 94.95%, 97.87%, 90.2% and 98.95% respectively. There was a strong positive correlation between the ELISA PSA values and the semiquantitative PSA values from the RDT (r=0.91)

Conclusion: The rapid one-step immunochromatographic test is a useful preliminary screening tool from which positive results can be quantified to give an indication of the magnitude of PSA elevation by semiquantitative estimation. The test is cheap, simple to perform and avails results within a short period of time.