Objectives: To analyze the relationship of age and race to prostate-specific antigen (PSA) levels among participants in a community-based study.
Methods: A total of 77,700 records of men aged 40 to 79 years were analyzed from a longitudinal study of PSA conducted during Prostate Cancer Awareness Week 1993 and 1994. Records from 1994 were not included for men who were tested in 1993. All cases of prostate cancer were excluded. Records with outlier PSA values greater than 20 ng/mL were eliminated from the analysis (n = 190; 24%).
Results: Mean PSA values (ng/mL) of 10-year age groups differed significantly (P < 0.0001) between each group (ages 40-49, 0.83; 50-59, 1.23; 60-69, 1.83; 70-79, 2.31). In each successively older age group, PSA variance increased significantly (P = 0.0001). Standard deviations (SD) by age group were: 40-49, 0.79; 50-59, 1.33; 60-69, 1.94; and 70-79, 2.35. Significant differences in mean PSA by race were found. Pairwise differences in mean PSA were found between whites and blacks, whites and Latinos, blacks and Asians, and Asians and Latinos (P < 0.0001). No statistically significant differences in PSA variance between racial groups were found. Age-within-race analysis resulted in consistent statistical significance when comparing variance among age cohorts in each race.
Conclusions: Age-specific PSA reference ranges are a result of the increasing mean PSA and increasing PSA variance in successively older cohorts of men. Mean PSA values differ significantly by race, but differences in PSA variance do not. The clinical significance of race-specific PSA reference ranges has yet to be determined.