Defining Abnormal Prostate-Specific Antigen Values for Prostate Cancer Screening in the Spinal Cord Injury Population

Abstract

Purpose: Men with spinal cord injury (SCI) experience frequent urinary tract inflammation and manipulation as well as chronic hypogonadism, all of which may artifactually alter PSA values. Thus, established PSA reference ranges and age-adjusted values may not be accurate in this population. This study's objective was to use national Department of Veterans Affairs data to establish threshold values for PSA in the SCI population to guide decision-making in prostate cancer screening.

Materials and methods: All PSA values in the national Department of Veterans Affairs system in men with SCI were collected between 1999 and 2019. Values collected before a diagnosis of SCI and after a diagnosis of prostate cancer were excluded. Determination of SCI was based on a list of International Classification of Diseases, 9th Revision and 10th Revision codes. Mixed-effect quantile regression was used to estimate percentile PSA values adjusted by age and time since SCI. These values were then compared with published values in the non-SCI population.

Results: A total of 34,899 male veterans with SCI were included in the analysis with a total of 240,131 PSA values. Using the best-fit model, age-adjusted PSA values for the 25th, 50th, 75th, and 95th percentiles were created. The 95th age-adjusted percentile values for PSA in the SCI population were 40 to 49 years: 2.5 ng/mL; 50 to 59 years: 2.6 ng/mL; 60 to 69 years: 2.6 ng/mL; and 70 to 79 years: 2.8 ng/mL.

Conclusions: Using a large, geographically diverse database, age-adjusted PSA values in the SCI population can be generated. While PSA values of the SCI population are comparable in younger men, as the SCI population ages, PSA fails to rise and stagnates at around 3 ng/mL.

Keywords: PSA; cancer screening test; laboratory diagnoses; prostate cancer; spinal cord injury.