• Component Description
• Eligible Sample
• Protocol and Procedure
• Quality Assurance & Quality Control
• Data Processing and Editing
• Analytic Notes
• References
• Codebook
  • SEQN - Respondent sequence number
  • BPAOARM - Arm selected - oscillometric
  • BPAOCSZ - Coded cuff size - oscillometric
  • BPAOMNTS - Minutes between mercury & oscillometric
  • BPXOSY1 - Systolic - 1st oscillometric reading
  • BPXODI1 - Diastolic - 1st oscillometric reading
  • BPXOSY2 - Systolic - 2nd oscillometric reading
  • BPXODI2 - Diastolic - 2nd oscillometric reading
  • BPXOSY3 - Systolic - 3rd oscillometric reading
  • BPXODI3 - Diastolic - 3rd oscillometric reading
  • BPXOPLS1 - Pulse - 1st oscillometric reading
  • BPXOPLS2 - Pulse - 2nd oscillometric reading
  • BPXOPLS3 - Pulse - 3rd oscillometric reading

National Health and Nutrition Examination Survey

2017-2018 Data Documentation, Codebook, and Frequencies

Blood Pressure - Oscillometric Measurements (BPXO_J)

Data File: BPXO_J.xpt

First Published: April 2021

Last Revised: NA

Component Description

Blood pressure (BP) measurements have traditionally been obtained in NHANES using a mercury sphygmomanometer and a stethoscope with an auscultatory protocol, in which the examiner listens for sounds in the brachial artery to determine BP. Due to increased environmental concerns about the disposal of mercury-contaminated medical waste and the risk of spills from mercury sphygmomanometers, mercury devices have been phased out of clinical use. Alternative BP devices based on oscillometric protocols are increasingly used in clinical and epidemiological studies.

During the 2017-2018 survey cycle, a BP methodology study was conducted to compare BP measurements obtained by a physician using a mercury sphygmomanometer to those obtained by a health technician using an oscillometric device. In this methodology study, blood pressure was measured twice on survey participants by the two different protocols with a randomly assigned order of administration. This data file (variable name prefix BPXO) includes BP readings from the study obtained using the oscillometric protocol. BP measurements obtained using the auscultatory protocol are available in a separate dataset: Blood Pressure (BPX_J).

Additional details and the results from the BP methodology study are available in an NCHS Vital and Health Statistics Series 2 Report at NCHS website (Ostchega et al, 2021).

Eligible Sample

Participants aged 8 years and older were eligible. Participants with any of the following on both arms were excluded from the exam: rashes, gauze dressings, casts, edema, paralysis, tubes, open sores or wounds, withered arms, and A-V shunts. Also, women who have had an axillary nodal biopsy or resection, or a unilateral radical mastectomy do not have their blood pressure measured in the affected arm.

Protocol and Procedure

All BP measurements (systolic and diastolic) are taken in the mobile examination center (MEC). Prior to obtaining BP measurements, upper arm circumference is measured, which is done to guide selection of cuff size. Details on the protocol for obtaining upper arm circumference is described in the Anthropometry Procedures Manual.

After resting quietly in a seated position for 5 minutes; three consecutive BP measurements (systolic and diastolic) were taken 60 seconds apart using a digital upper-arm electronic blood pressure measurement device, Omron HEM–907XL. This device has been previously validated by both the Association for the Advancement of Medical Instrumentation (AAMI) and the International Protocol of the European Society of Hypertension for taking BP measurements in populations aged 13 years and older (White et al, 2002; Ombani et al, 2007; Ostchega et al, 2010).

BP measurements were taken in the right arm unless specific conditions prohibited the use of the right arm, or if participants reported any reason that the BP measurements should not be taken in the right arm.

For more details on the BP measurement using the oscillometric device, please refer to the Blood Pressure – Oscillometric Measurements Manual.

Quality Assurance & Quality Control

The BP examiners were certified for BP measurement through a training program and followed a strict standardized BP protocol. In addition, every three months the BP examiners were observed by subject matter experts to assure that BP readings were obtained following the standardized protocol.

Data Processing and Editing

The following are some specifications used in capturing the BP data:

• Systolic BP cannot be greater than 300 mmHg;
• Systolic blood pressure must be greater than diastolic BP;
• If there is no systolic BP, there can be no diastolic BP. However, there can be a systolic measurement without a diastolic measurement.

In the methodology study, the participant was assigned randomly to have the BP measured using the auscultatory protocol first or using the oscillometric protocol first. The two BP measurements were not done consecutively; instead, they were separated by other examination components while in the MEC. The variable BPAOMNTS describes the difference in minutes between BP readings obtained by the auscultatory protocol and reading obtained by the oscillometric protocol. A positive value in BPAOMNTS indicates the measurement using auscultatory protocol was conducted first, and a negative value indicates the measurement using oscillometric protocol was conducted first.

Analytic Notes

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.

References

• Ombani S, Riva I, Giglio A, Caldara G, Groppelli A, Parati G. Validation of the Omron M5–I, R5–I and HEM–907 automated blood pressure monitors in elderly individuals according to the international protocol of the European Society of Hypertension. Blood Press Monit 12(4):233–42. 2007.
• Ostchega Y, Nwankwo T, Chiappa M, Wolz M, Graber J, Nguyen DT. Comparing blood pressure values obtained by two different protocols: National Health and Nutrition Examination Survey, 2017–2018. National Center for Health Statistics. Vital Health Stat 2(187). 2021. https://www.cdc.gov/nchs/data/series/sr_02/s02-187-508.pdf
• Ostchega Y, Nwankwo T, Sorlie PD, Wolz M, Zipf G. Assessing the validity of the Omron HEM–907XL oscillometric blood pressure measurement device in a national survey environment. J Clin Hypertens (Greenwich) 12(1):22–8. 2010
• White WB, Anwar YA. Evaluation of the overall efficacy of the Omron office digital blood pressure HEM–10. El Assaad MA, Topouchian JA, Darné BM, Asmar RG. Validation of the Omron HEM–907 device for blood pressure measurement. Blood Press Monit 7(4):237–41. 2002.

Codebook and Frequencies