Relationship of demographic and clinical factors to free and total prostate-specific antigen

Objectives. To characterize the role of demographic and clinical parameters in the measurements of prostate-specific antigen (PSA), free PSA (fPSA), a nd percent free PSA (%fPSA). Methods. This was a cohort study of volunteers to a randomized screening tr ial. A central laboratory determined PSA and fPSA for the Prostate, Lung, C olorectal and Ovarian (PLCO) Cancer Screening Trial. A baseline evaluation of free and total PSA was done for 7183 white, black, Asian, Hispanic, and other male volunteers, aged 55 to 74 years. Comparisons were made across ra cial and ethnic groups and across a set of clinical parameters from a basel ine questionnaire. Results. The median levels of serum PSA were less than 2.1 ng/mL in each ag e-race grouping of the study participants. The levels of free and total PSA were higher in black (n = 868, 12%) participants than in white (n = 4995, 70%) and Asian (n = 849, 11.8%) participants. Individuals who identified th emselves as ethnically Hispanic (n = 339, 4.7%) had median PSA levels highe r than whites who were not Hispanic. The free and total PSA levels increase d with age, particularly among men 70 to 74 years old. However, the %fPSA l evels showed less variation among the four racial groups or by age. The fre e and total PSA levels were higher among those who had a history of benign prostatic disease. Conclusions. Demographic (age and race/ethnicity) and clinical (history of benign prostatic disease) variables had a moderate effect on the measures o f PSA and fPSA and very little effect on %fPSA. (C) 2001, Elsevier Science Inc.