Appendix D

Public-Facing Background Materials: Workshop Primer: Background and Context about the National Health and Nutrition Examination Survey (NHANES)

Created by: Workshop planning committee and staff

Document Purpose: To provide key information about the NHANES to inform the 2022 workshop on “Considerations for Returning Individual Genomic Results from Population-Based Surveys: Focus on the NHANES.” This document is not intended to be comprehensive. Readers who need additional information are encouraged to visit the NHANES website to find additional information (www.cdc.gov/nchs/nhanes).

ABOUT THE NHANES DATA COLLECTION¹

• The NHANES program began in the early 1960s and is a continuous program that has a changing focus on a variety of health and nutrition measurements to meet emerging needs.
• This survey is cross sectional and there is no active tracking of participants following their participation in the survey.
• NHANES is a complex sample survey which involves “the identification [of] and data collection [based on] a sample of population units [e.g., individuals, institutions]”²

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¹ https://www.cdc.gov/nchs/nhanes/about_nhanes.htm

² Saavedra, P. (2011). Complex sample surveys. In P. J. Lavrakas (Ed.) Encyclopedia of survey research methods. https://doi.org/10.4135/9781412963947; see also National Center for Health Statistics. (2020). National Health and Nutrition Examination Survey, 2015–2018: Sample design and estimation procedures. Vital and Health Statistics, 2(184). Centers for Disease Control and Prevention, U.S. Department of Health and Human Services. Saavedra, P. (2011). Complex sample surveys. In P. J. Lavrakas (Ed.) Encyclopedia of survey research methods. https://www.cdc.gov/nchs/data/series/sr_02/sr02-184-508.pdf

• The current survey examines a nationally representative sample of about 5,000 persons each year. These persons are located in counties across the country, 15 of which are visited each year.
• Oversampling of certain population subgroups is also done to increase the reliability and precision of health status indicator estimates for these particular subgroups.
• The NHANES interview includes demographic, socioeconomic, dietary, and health-related questions. The examination component consists of medical, dental, and physiological measurements, as well as laboratory tests administered by highly trained personnel.
• Findings from this survey are used to determine the prevalence of major diseases and risk factors for diseases. Data from this survey are used in epidemiological studies and health sciences research, which help develop sound public health policy, direct and design health programs and services, and expand the health knowledge for the nation.

REPORTING FINDINGS TO NHANES PARTICIPANTS³

• All survey participants receive a report of findings approximately 12–16 weeks after their participation in the main survey (household interview and to visit mobile examination) and this is generally the last contact NHANES initiates with survey participants.
• NHANES provides health measurement and test results to all participants who have completed at least one component of the health examination.
• For a NHANES test result to be reported, it must be “clinically actionable” for participant and/or medical provider.
• To be clinically actionable or reportable, the test result must either:
  • Inform clinical decision-making

  OR

  • Inform participants so that precautions and/or changes to health behavior can be made
  • Labs: Historically to be eligible for reporting to participants must be FDA approved and a Clinical Laboratory Improvement Amendments (CLIA)-certified test from CLIA-certified laboratory. (Also see “Laboratory Developed tests” in the Workshop Glossary.)
• NCHS has an in-house survey response team available to answer calls from sample participants regarding questions about test results from the Report of Finding System.

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³ https://www.cdc.gov/nchs/data/bsc/nhanes_reports_of_findings_overview_for_bsc.pdf

INFORMED CONSENT⁴

• When NHANES last collected DNA (2011–2012), there was a separate informed consent
  • DNA Specimens were collected in NHANES III, 1999–2002 and 2007–2012. Since 1999, this collection consists of adults only.
  • Consent for Specimen Storage and Continuing Studies for DNA⁵
• NHANES currently has informed consent for two separate components⁶ as follows:
  • Home interview and Examination Consent⁷
  • Consent/Assent and Parental Permission for Specimen Storage and Continuing Studies (e.g., plasma, sera, and urine)⁸

BIOSPECIMEN PROGRAM⁹

• Serum, Plasma, and Urine Specimens¹⁰
• DNA Specimens and Genetic Data Program¹¹
• Access
  • Specimens
    • Proposal Process: Including ensuring that research does not generate clinically significant results (i.e., traditionally American College of Medical Genetics and Genomics for DNA specimens)
  • Resulting data
    • Public-use data are available on the NHANES website¹²
    • To guarantee the confidentiality of the survey participants, Limited Access data¹³ are available in the NCHS’s Research Data Center.¹⁴ This includes Personally Identifiable Information (PII) and genetic data, indirect PII, and other sensitive data.

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⁴ https://wwwn.cdc.gov/nchs/nhanes/continuousnhanes/documents.aspx?BeginYear=2011

⁵ https://wwwn.cdc.gov/nchs/data/nhanes/2011-2012/documents/2011_dna_consent_english.pdf

⁶ https://wwwn.cdc.gov/nchs/nhanes/continuousnhanes/documents.aspx?BeginYear=2019

⁷ https://wwwn.cdc.gov/nchs/data/nhanes/2019-2020/documents/2019-Home-Interview-Consent-English-508.pdf

⁸ https://wwwn.cdc.gov/nchs/data/nhanes/2019-2020/documents/2019-Specimen-Storage-and-Continuing-Studies-Consent-508.pdf

⁹ https://www.cdc.gov/nchs/nhanes/biospecimens/biospecimens.htm

¹⁰ https://www.cdc.gov/nchs/nhanes/biospecimens/serum_plasma_urine.htm

¹¹ https://www.cdc.gov/nchs/nhanes/biospecimens/dnaspecimens.htm

¹² https://wwwn.cdc.gov/nchs/nhanes/Default.aspx

¹³ https://wwwn.cdc.gov/nchs/nhanes/search/datapage.aspx?Component=LimitedAccess&CycleBeginYear=2017

¹⁴ https://www.cdc.gov/rdc/

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