National Health and Nutrition Examination Survey

2007 - 2008 Data Documentation, Codebook, and Frequencies

Blood Pressure (BPX_E)

Data File: BPX_E.xpt

First Published: September, 2009

Last Revised: NA

Locator Record

Title: Blood Pressure (BPX_E )
Contact Number: 1-866-441-NCHS
Years of Content: 2007 - 2008
First Published: September, 2009
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:The data in this file provide interview questions and blood pressure measurements taken in the mobile examination center by two physicians on sample persons eight years of age and older.
Record Source: NHANES 2007 - 2008
Survey Methodology: NHANES 2007 - 2008 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

Accurate measurement of blood pressure (BP) is a major public health concern; it is essential for hypertension screening, as well as for disease management. This section provides data for three consecutive blood pressure (BP) measurements and other methodological measurements to obtain an accurate blood pressure.

 

Eligible Sample

Heart rate is measured on all children 0-4 years of age; radial pulse is measured on examinees 5 years and older; and blood pressure (BP) is measured on all examinees 8 years and over.

Exclusion criteria: presence of the following on both arms: rashes, gauze dressings, casts, edema, paralysis, tubes, open sores or wounds, withered arms, a-v shunts, or if blood has been drawn from arm within last week.

Protocol and Procedure

After resting quietly in a sitting position for 5 minutes and determining the maximum inflation level (MIL), three consecutive blood pressure readings are obtained. If a blood pressure measurement is interrupted or incomplete, a fourth attempt may be made. All BP determinations (systolic and diastolic) are taken in the mobile examination center (MEC).

 

Quality Assurance & Quality Control

The BP examiners are certified for blood pressure measurement through a training program from Shared Care Research and Education Consulting. Certification is achieved when physician examiners meet all requirements of the training program. The initial training includes:

• didactic instruction about BP measurement and propensity for error; 
• practice listening to systolic and diastolic BP sounds using a standardized audio-video tape presentation; 
• audio-video tape test;
• written exam;
• examiner and gold standard instructor simultaneously listening to BP of a minimum of 20 volunteers of all ages through a Y- stethoscope to compare measures; and
• observation of protocol technique using a checklist.

Certification requires a score of 100 per cent on the audio-video tape test. Correct answers on the audio-video tape test require the examiner’s answers and the standardized test answers to be within +/- 2mm mercury (Hg) on 92 per cent of 24 measures (12 systolic, 12 diastolic), and within +/- 4mm Hg on 100 percent of 24 measures (12 systolic, 12 diastolic). For more information on quality assurance and control, see Ostchega et al. (Ostchega et al, 2003).

For more details on the QA/QC process for this component, please refer to the Physician Section of the MEC Operations Manual.

Data Processing and Editing

The following are some required specifications used in capturing the blood pressure data:

• systolic blood pressure and maximum inflation level cannot be greater than 300 mmHg;
• systolic and diastolic blood pressure and maximum inflation level can be even numbers only;
• systolic blood pressure must be greater than diastolic blood pressure;
• if there is no systolic blood pressure, there can be no diastolic blood pressure;
• diastolic blood pressure can be zero

Analytic Notes

Changes Since 2005-2006:

The exam variable BPXDB is not continued in the 2007-2008.

Exam sample weights should be used for analyses. Please refer to the Analytic Guidelines for further details on the use of sample weights and other analytic issues. The Analytic Guidelines are available on the NHANES website.

References

• Ostchega Y, Prineas RJ, Paulose-Ram R, Grim CM, Willard C, Collins C. National Health and Nutrition Examination Survey (NHANES) 1999-2000: Effect of observer training and protocol standardization on reducing blood pressure measurement error. J Clinical Epidemiology. 2003 Aug; 56 (8): 768-774

Codebook and Frequencies