• Component Description
• Eligible Sample
• Description of Laboratory Methodology
• Data Processing and Editing
• Laboratory Quality Assurance and Monitoring
• Analytic Notes
• Codebook
  • SEQN - Respondent sequence number
  • WTSAF2YR - Fasting Subsample 2 Year MEC Weight
  • LBXAPB - Apolipoprotein (B) (mg/dL)
  • LBDAPBSI - Apolipoprotein (B) (g/L)

National Health and Nutrition Examination Survey

2007-2008 Data Documentation, Codebook, and Frequencies

Apolipoprotein B (ApoB_E)

Data File: ApoB_E.xpt

First Published: July 2010

Last Revised: NA

Component Description

The goals of this component are: 1) to monitor the prevalence and trends in major cardiovascular conditions and risk factors in the U.S.; and 2) to evaluate prevention and treatment programs targeting cardiovascular disease in the U.S.

The main element of the cardiovascular disease laboratory component in NHANES is blood lipid levels. Cardiovascular disease is the leading cause of death in the United States. The data will be used to monitor the status of hyperlipidemia and the success of the National Cholesterol Education Program.

Eligible Sample

Participants aged 12 years and older who were examined in the morning (AM) session were tested.

Description of Laboratory Methodology

In an immunochemical reaction, Apolipoprotein B in the human serum sample form immune complexes with specific antibodies. These complexes scatter a beam of light passed through the sample. The intensity of the scattered light is proportional to the concentration of Apolipoprotein B in the sample. The result is evaluated by comparison with a standard of known concentration.

Apolipoprotein B is the main protein component of LDL and accounts for approximately 95% of the total protein content of LDL. Apo B is necessary for the reaction with LDL receptors in the liver and on cell walls, and is thus involved in transporting cholesterol from the liver to the vessel cell. Elevated levels of Apo B are frequently found in patients with atherosclerotic vascular changes and are a risk factor for atheroscelerosis.

There were changes to the lab site and lab instrument and methodology from 2005-2006. The University of Minnesota began testing in 2007-2008.

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

Data Processing and Editing

Blood specimens were processed, stored and shipped to University of Minnesota for analysis. 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 Description of the Laboratory Methodology section.

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

Laboratory Quality Assurance and Monitoring

The NHANES quality assurance and quality control (QA/QC) protocols 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 LABDOC file for detailed QA/QC protocols.

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

Analytic Notes

Regression equations to compare 2007-2008 and 2005-2006 Apolipoprotein B data:

A crossover study was performed to compare the 2007-2008 Apolipoprotein B data to the 2005-2006 Apolipoprotein B data. The Dade-Behring BN100 nepholometric immunoassay was used in 2005-2006. The Dade-Behring BN ProSpec nepholometric immunoassay was used in a different laboratory in 2007-2008. A Deming regression analysis was done and the following regressions were obtained for Apolipoprotein B (mg/dL):

Y (2005-2006, BN100) = 1.084*X (2007-2008, ProSpec)

Y (2007-2008, ProSpec) = 0.923*X (2005-2006, BN100)

The regressions were based on 168 paired values with a r=0.984.

These regression equations should be used to trend the Apolipoprotein B data.

General Analytic Notes:

The analysis of NHANES laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES Household Questionnaire Data Files contain demographic data, health indicators, and other related information collected during household interviews. They also contain all survey design variables and 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.

Sampling Weights

The analyst should use the special sampling weights in this file to analyze Apolipoprotein B (ApoB). 

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

Codebook and Frequencies