The knowledge and practices of urologists in the United States (US) about standardization of PSA assays.
Gupta A., Shariat SF., Eastham JA., Scardino PT., Vickers AJ., Lilja H.
207 Background: PSA assays can be calibrated to either the WHO or the Hybritech standard. Studies of PSA-based prostate cancer screening have used Hybritech-standardized assays and prostate cancer risk calculators are based on these studies. Testing of patient samples with a WHO calibrated assay gives values that are 22% lower than from those with Hybritech-calibrated assays. Up to 60% of the labs in the US use WHO calibrated assays. We evaluated whether US urologists are aware of the different calibrators and the differences in PSA values. METHODS: A random sample of 1,742 US urologists were invited by email to participate in a web-based survey of their knowledge and practices regarding PSA assay standardization. No mention was made of assays or calibration in the invitation. 419 responses were received. RESULTS: Many (56%) US urologists thought that different standards may lead to clinically relevant differences in PSA values. Although 62% reported awareness of the two PSA calibrators, 67% did not know the difference between the two. Only 17% correctly reported the difference between the two standards. Nationally almost 60% of the labs use WHO standardized assays, but in this survey only 5% of the urologists thought that the hospital where they practice used a WHO standardized assay. The rest reported either not knowing the standard (46%) or use of the Hybritech standard (49%). The majority of urologists did not look at the reference range (64%) or for the PSA standard (74%) in the lab reports. Only 25% reported considering the PSA-calibration in their clinical decisions about prostate biopsy, but only a third of them correctly knew the difference between the calibrators. CONCLUSIONS: Many US urologists are unaware of the difference caused by WHO versus Hybritech based PSA-assay calibration. Although 60% of clinical laboratories use WHO-calibrated assays, only 5% of urologists are aware of this use in their practice, and a majority of urologists could not correctly explain the difference between the different calibrators. A greater awareness is needed amongst US urologists about the different PSA calibrators, the calibrator in use at their practice, and means to account for different calibrators in clinical decision making. [Table: see text].