Table of Contents

Locator Record

Title: Prostate specific antigen (PSA_F )
Contact Number: 1-866-441-NCHS
Years of Content: 2009 - 2010
First Published: September, 2011
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Total, free and complex prostate specific antigens (PSA) were measured among men age 40 years and older. PSA exclusion questions (KIQ115, KIQ185, KIQ191, KIQ195, KIQ201, KIQ241, KIQ282, KIQ301, and KIQ311) were asked during the physician examination.
Record Source: NHANES 2009 - 2010
Survey Methodology: NHANES 2009 - 2010 is a stratified multistage probability sample of the civilian non-institutionalized population of the U.S.
Medium: NHANES Web site; SAS transport files

Component Description

Prostate cancer is the most common non-skin malignancy among men with approximately 180,000 new cases diagnosed and 37,000 deaths in 1999. The total and free PSA tests have been recognized as tumor markers for the screening, diagnosis and management of prostate cancer.

Total, free and complex prostate specific antigens (PSA) were measured among men age 40 years and older. PSA exclusion questions (KIQ115, KIQ185, KIQ191, KIQ195, KIQ201, KIQ241, KIQ282, KIQ301, and KIQ311) were asked during the physician examination. PSA immunoassays were performed on blood specimens using the Hybritech tests (Beckman Coulter, Fullerton, CA).

Eligible Sample

Male participants aged 40 years and older were tested for PSA. Those who reported having any of the following conditions were not eligible for PSA testing:

Current infection or inflammation of the prostate gland (KIQ115)
Rectal exam in the past week (KIQ185)
Prostate biopsy in the past month (KIQ191)
Cystoscopy in the past month (KIQ195)
History of prostate cancer (KIQ201)

Description of Laboratory Methodology

Serum specimens are processed, stored and shipped to University of Washington, Seattle, Washington.

Free prostate specific antigen
The Access Hybritech free PSA assay is a two-site immunoenzymatic "sandwich" assay. A sample was added to a reaction vessel with mouse monoclonal anti-free PSA alkaline phosphatase conjugate, and paramagnetic particles coated with a second mouse monoclonal anti-free PSA antibody. The free PSA in the sample bound to the immobilized monoclonal anti-free PSA on the solid phase while, at the same time, the monoclonal anti-PSA conjugate reacted with a different antigenic site on the sample free PSA. Separation in a magnetic field and washing removes material not bound to the solid phase. A chemiluminescent substrate, Lumi-Phostm 530 was added to the reaction vessel and light generated by the reaction was measured with a luminometer. The light production was proportional to the concentration of free PSA in the sample. The amount of analyte in the sample was determined by means of a stored, multi-point calibration curve.

Total prostate specific antigen
Total PSA values were obtained using the Hybritech PSA method on the Beckman Access. A second sample was added to a reaction vessel with mouse monoclonal anti-PSA alkaline phosphatase conjugate and paramagnetic particles coated with a second mouse monoclonal anti-PSA antibody. The PSA in the sample bound to the immobilized monoclonal anti-PSA on the solid phase while, at the same time, the monoclonal anti-PSA conjugate reacted with a different antigenic site on the sample PSA. The light production was proportional to the concentration of PSA in the sample.

Complex prostate specific antigen (cPSA)
The Centaur XP cPSA assay quantitatively measures complexed prostate-specific antigen (cPSA) in human serum. Free PSA present in the sample is prevented from reacting with the total PSA antibodies by incubating the sample at 37°C with a free-PSA-specific monoclonal mouse antibody (Pretreatment Reagent), which blocks the free PSA so that it is nonreactive in the Centaur XP cPSA assay. The cPSA in the sample is then measured in the two-site sandwich immunoassay using direct chemiluminometric technology, which uses constant amounts of two antibodies. The first antibody, in the Lite Reagent, is a polyclonal goat anti-PSA antibody labeled with acridinium ester. The second antibody, in the Solid Phase, is a monoclonal mouse anti-PSA antibody, which is covalently coupled to paramagnetic particles. The immunocomplexes of sample cPSA sandwiched and coupled to paramagnetic particles are magnetically separated from unbound components and washed in the cuvette incubation ring. The addition of hydroxyl groups to complete the flash reaction is accomplished by the addition of Acid and Base. The chemiluminescent reaction occurs in the luminometer. The photomultiplier tube (PMT) measures the chemical light reaction that takes place. A direct relationship exists between the amount of cPSA present in the patient sample and the amount of relative light units (RLUs) detected by the system. The amount of cPSA in the sample is determined by means of a stored, multi-point calibration curve.

This assay was developed to aid in the detection of prostrate cancer in men. Biopsy of the prostate is required for the diagnosis of prostate cancer. Further studies are needed to confirm that measuring cPSA is more sensitive than total PSA levels in cancer detection. The concentration of cPSA in a given specimen, as determined by assays from different manufacturers, can vary due to differences in assay methods and reagent specificity and cannot be used interchangeably.

Free Prostate Percent:
This free prostate percent was calculated by dividing the free PSA by the total PSA:
LBDP3 = round ((LBXP2/LBXP1)*100) (whole number)

There were no changes (from the previous 2 years of NHANES) to equipment, lab methods or lab site for total and free PSA. However, for complexed PSA the Siemens Centaur Advia immunoassay was used in 2007-2008 and the Siemens Centaur XP immunoassay was used in 2009-2010. 

A detailed description of the laboratory method used can be found at NHANES web page.

Data Processing and Editing

Read the General Documentation on Laboratory Data file for detailed data processing and editing protocols. The analytical methods are described in the Description of Laboratory Methodology section above.

The prostate specific antigen ratio is a derived variable.

Laboratory Quality Assurance and Monitoring

The NHANES quality control and quality assurance protocols (QA/QC) meet the 1988 Clinical Laboratory Improvement Act mandates.Detailed QA/QC instructions are discussed in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM) .

Read the General Documentation on Laboratory Data file for detailed QA/QC protocols.

Analytic Notes

NHANES Survey Design:

The analysis of NHANES laboratory data must be conducted with the key survey design and basic demographic variables. The Demographic file contains: Status Variables providing core information on the survey participant including examination status, Recoded Demographic Variables including age, gender, race etc., and Interview and Examination Sample Weight Variables and Survey Design Variables. The Questionnaire Data Files contain socio-economic data, health indicators, and other related information collected during household interviews. The Phlebotomy Examination file includes auxiliary information on duration of fasting, the time of day of the venipuncture, and the conditions precluding venipuncture. The Demographic, Questionnaire and Phlebotomy Examination files may be linked to the laboratory data file using the unique survey participant identifier SEQN.

Data on health conditions that would make a sample person ineligible for PSA testing are missing for some people with non-missing PSA lab data. This happened mainly because some sample persons did not attend the physician’s examination component of the MEC examination where such data were collected. It is advisable to exclude these observations for PSA analyses.

Detection Limits:

The detection limits were constant for the analytes in the data set. The lower detection limits for Total PSA was 0.10 ng/mL, 0.05 ng/mL for Free PSA, and 0.06 for Complex PSA.

In cases where the result was below the limit of detection, the value for that variable is the detection limit divided by the square root of two.

Weights:

Exam sample weights should be used for analyses.

Please refer to the NHANES Analytic Guidelines  and the on-line NHANES Tutorial  for further details on the use of sample weights and other analytic issues.

Regression equation to compare 2009-2010 and 2007-2008 Complexed PSA data:

A crossover study was performed to compare the 2009-2010 Complexed PSA data to the 2007-2008 Complexed PSA data. The Siemens Centaur Advia immunoassay was used in 2007-2008 and the Siemens Centaur XP immunoassay was used in 2009-2010. A Deming regression analysis was performed and the following regression was obtained for the Complexed PSA (ng/mL):

Y (2009-2010, Centaur XP) = 1.047*X (2007-2008, Centaur Advia)

The regression was based on 117 paired values with a Pearson r = 0.999. The researcher may want to use this regression equation to trend Complexed PSA data.

References

Codebook and Frequencies

SEQN - Respondent sequence number

Variable Name:
SEQN
SAS Label:
Respondent sequence number
English Text:
Respondent sequence number.
Target:
Males only 40 YEARS - 150 YEARS

KIQ110 - Willing to have blood tested for PSA

Variable Name:
KIQ110
SAS Label:
Willing to have blood tested for PSA
English Text:
Are you willing to have your blood tested for PSA?
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 1743 1743
2 No 32 1775
7 Refused 0 1775
9 Don't know 0 1775
. Missing 201 1976

KIQ115 - Infection or inflammation of prostate

Variable Name:
KIQ115
SAS Label:
Infection or inflammation of prostate
English Text:
{Do you/does SP} have an infection or inflammation of the prostate gland at the present time?
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 28 28
2 No 1884 1912
7 Refused 0 1912
9 Don't know 2 1914
. Missing 62 1976

KIQ185 - Rectal exam in the last 7 days

Variable Name:
KIQ185
SAS Label:
Rectal exam in the last 7 days
English Text:
{Have you/Has SP} had a rectal exam in the last 7 days?
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 16 16
2 No 1896 1912
7 Refused 0 1912
9 Don't know 2 1914
. Missing 62 1976

KIQ191 - prostate biopsy or surgery in last 4 wks

Variable Name:
KIQ191
SAS Label:
prostate biopsy or surgery in last 4 wks
English Text:
{Have you/Has SP} had a prostate biopsy or other prostate surgery in the last 4 weeks?
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 6 6
2 No 1906 1912
7 Refused 0 1912
9 Don't know 2 1914
. Missing 62 1976

KIQ195 - Cystoscopy in the last 4 weeks

Variable Name:
KIQ195
SAS Label:
Cystoscopy in the last 4 weeks
English Text:
{Have you/Has SP} had a cystoscopy in the last 4 weeks? (Cystoscopy is an internal examination of the prostate and bladder using a flexible tube-like instrument with a lens inserted through the penis.)
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 11 11
2 No 1901 1912
7 Refused 0 1912
9 Don't know 2 1914
. Missing 62 1976

KIQ201 - Diagnosed with prostate cancer

Variable Name:
KIQ201
SAS Label:
Diagnosed with prostate cancer
English Text:
{Have you/Has SP} ever been told by a doctor or health professional that {you/he} had prostate cancer?
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 95 95
2 No 1815 1910
7 Refused 0 1910
9 Don't know 4 1914
. Missing 62 1976

KID221 - Age at diagnosis of prostate cancer

Variable Name:
KID221
SAS Label:
Age at diagnosis of prostate cancer
English Text:
How old {were you/was SP} when {you were/he was} first told that {you/he} had prostate cancer?
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
8 to 85 Range of Values 95 95
777 Refused 0 95
999 Don't know 0 95
. Missing 1881 1976

KIQ241 - Ever had prostate surgery

Variable Name:
KIQ241
SAS Label:
Ever had prostate surgery
English Text:
{Have you/Has SP} ever had surgery on {your/his} prostate?
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 54 54
2 No 41 95
7 Refused 0 95
9 Don't know 0 95
. Missing 1881 1976

KIQ282 - Surgery for prostate cancer?

Variable Name:
KIQ282
SAS Label:
Surgery for prostate cancer?
English Text:
{Have you/Has SP} had surgery for prostate cancer?
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 53 53
2 No 1 54
7 Refused 0 54
9 Don't know 0 54
. Missing 1922 1976

KIQ301 - Radiation treatment for prostate cancer

Variable Name:
KIQ301
SAS Label:
Radiation treatment for prostate cancer
English Text:
{Have you/Has SP} ever had radiation treatments for prostate cancer?
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 49 49
2 No 46 95
7 Refused 0 95
9 Don't know 0 95
. Missing 1881 1976

KIQ311 - Taken medicines for prostate cancer

Variable Name:
KIQ311
SAS Label:
Taken medicines for prostate cancer
English Text:
{Have you/Has SP} ever taken prescribed medicines for prostate cancer?
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Yes 27 27
2 No 68 95
7 Refused 0 95
9 Don't know 0 95
. Missing 1881 1976

LBXP1 - Total prostate specific antigen (ng/mL)

Variable Name:
LBXP1
SAS Label:
Total prostate specific antigen (ng/mL)
English Text:
Total prostate specific antigen (ng/mL)
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.07 to 73.97 Range of Values 1746 1746
. Missing 230 1976

LBXP2 - Free prostate specific antigen (ng/mL)

Variable Name:
LBXP2
SAS Label:
Free prostate specific antigen (ng/mL)
English Text:
Free prostate specific antigen (ng/mL)
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.04 to 20.08 Range of Values 1746 1746
. Missing 230 1976

LBDP3 - Prostate specific antigen ratio (%)

Variable Name:
LBDP3
SAS Label:
Prostate specific antigen ratio (%)
English Text:
Prostate specific antigen ratio (%)
Target:
Males only 40 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
4 to 84 Range of Values 1746 1746
. Missing 230 1976

LBXPS4 - Complex prostate specific antigen(ng/mL)

Variable Name:
LBXPS4
SAS Label:
Complex prostate specific antigen(ng/mL)
English Text:
Complexed prostate specific antigen (ng/mL)
Target:
Males only 40 YEARS - 150 YEARS
Hard Edits:
0 to 999999.99
Code or Value Value Description Count Cumulative Skip to Item
0.04 to 44.38 Range of Values 1746 1746
. Missing 230 1976