• Component Description
• Eligible Sample
• Description of Laboratory Methodology
• Data Processing and Editing
• Laboratory Quality Assurance and Monitoring
• Analytic Notes
• Codebook
  • SEQN - Respondent sequence number
  • KIQ110 - Willing to have blood tested for PSA
  • KIQ115 - Infection or inflammation of prostate
  • KIQ185 - Rectal exam in the last 7 days
  • KIQ190 - Prostate biopsy in the last 4 weeks
  • KIQ195 - Cystoscopy in the last 4 weeks
  • KIQ201 - Diagnosed with prostate cancer
  • KID221 - Age at diagnosis of prostate cancer
  • KIQ241 - Ever had prostate surgery
  • KIQ281 - Was surgery for prostate cancer?
  • KIQ301 - Radiation treatment for prostate cancer
  • KIQ311 - Taken medicines for prostate cancer
  • LBXP1 - PSA. total (ng/mL)
  • LBXP2 - PSA, free (ng/mL)
  • LBDP3 - Prostate specific antigen ratio (%)

National Health and Nutrition Examination Survey

2003-2004 Data Documentation, Codebook, and Frequencies

Prostate Specific Antigen (PSA) (L11PSA_C)

Data File: L11PSA_C.xpt

First Published: February 2006

Last Revised: NA

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 prostate-specific antigen (PSA) tests have been recognized as tumor markers for the screening, diagnosis, and management of prostate cancer.

Total and free PSAs were measured among men age 40 years and older. PSA exclusion questions (KIQ115, KIQ185, KIQ190, KIQ195, KIQ201, KIQ241, KIQ281, KIQ301, and KIQ311) were asked during the physician’s examination. PSA immunoassay was 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 (KIQ190)
• Cystoscopy in the past month (KIQ195)
• History of prostate cancer (KIQ201)

Description of Laboratory Methodology

Free PSA

The Access Hybritech free PSA assay is a two-site immuno-enzymatic "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-Phos 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 PSA

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.

PSA ratio

This ratio was calculated by dividing the free PSA by the total PSA:

LBDP3 = round ((LBXP2/LBXP1)*100)

There were no changes to the equipment, lab method, or lab site from the previous 2 years.

A detailed description of the laboratory method used can be found on the NHANES website.

Data Processing and Editing

Blood specimens are processed, stored and shipped to University of Washington, Seattle, WA. Detailed specimen collection and processing instructions are discussed in the NHANES LPM. Read the LABDOC file for detailed data processing and editing protocols. The analytical methods are described in the Analytic methodology section.

Because of a potential disclosure risk, the KID221 question was recoded by creating an “85 or greater” response category. Any participant reported as being diagnosed with prostate cancer at age 85 years or older was recoded to an “85 or greater” years response.

One derived variable was created in this data file. This PSA ratio was calculated by dividing the free PSA by the total PSA:

LBDP3 = round ((LBXP2/LBXP1)*100).

Detailed instructions on specimen collection and processing can be found on the NHANES website.

Laboratory Quality Assurance and Monitoring

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

A detailed description of the quality assurance and quality control procedures can be found on the NHANES website.

Analytic Notes

The analysis of NHANES 2003–2004 laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES 2003–2004 Questionnaire Data Files contain demographic data, health indicators, and other related information collected during household interview and MEC examination. They also contain sample weights for these age groups. The phlebotomy file includes auxiliary information, such as the conditions precluding venipuncture. The household questionnaire and phlebotomy 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 omission exists 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.

Codebook and Frequencies