Table 4.

History of prostate-specific antigen (PSA) screening among participants in the 2005 to 2006 National Health and Nutrition Examination Survey*

Characteristics	Nonshiftworkers, mean (SD)	Shiftworkers, mean (SD)
No.	506	67
Age, y	51.0 (6.9)	50.6 (6.9)
Age of first PSA test, y	47.9 (7.6)	45.1 (7.2)
Months since last PSA test	658 (847)	1146 (1650)
Number of PSA tests in the last 5 years	2.4 (2.2)	2.5 (2.4)
	No. (%)	No. (%)
Ever had a PSA test	199 (41.6)	27 (40.9)
Ever had an abnormal PSA test	7 (3.5)	2 (7.4)

* SD = standard deviation.