Centers for Disease Control and Prevention

About N C H S graphic and link
Información en Español
Fastats A-Z provides health statistics and links to additional sources of information
N C H S help graphic and link
Coming Events graphic and link
Surveys and Data Collection Systems graphic and link
National Health and Nutrition Examination Survey graphic and link
National Health Care Survey graphic and link
National Health Interview Survey graphic and link
National Immunization Survey graphic and link
Longitudinal Studies of Aging (LSOAs)
National Survey of Family Growth graphic and link
State and Local Area Integrated Telephone Survey graphic and link
National Vital Statistics System graphic and link
Initiatives graphic and link
Aging Activities graphic and link
Disease Classification graphic and link
Healthy People graphic and link
Injury graphic and link
Research and Development graphic and link
Research Data Center
NCHS Press Room
News Releases graphic and link
Publications and Information Products graphic and link
Statistical Export and Tabulation System
Listserv graphic and link
Graphic and link to FEDSTATS and other sites
Download graphic
Adobe Acrobat Reader graphic and link
PowerPoint Viewer 2003 graphic and link
National Center for Health Statistics 3311 Toledo Road Hyattsville, Maryland 20782
Toll Free Data Inquiries 1-800-232-4636

CDC Home Search Health Topics A-Z
N C H S home page graphic and link

Health Professionals

Participant Involvement and Benefits

The National Health and Nutrition Examination Survey is a population-based survey designed to collect information on the health and nutrition of the U.S. household population. You may have come across data gathered through NHANES during your professional education. NHANES data have been used to influence policy and improve the health of the U.S. population in many ways including: getting lead removed from gasoline; creating and updating the pediatric growth charts; and establishing national baseline estimates for cholesterol, blood pressure, and Hepatitis C in the U.S.

There are two parts to this survey: the home interview and the health examination. We obtain written informed consent from each participant for both the in-home interview and the health exam. During the in-home interview participants are asked questions about health status, disease history, and diet. The health examination is performed in a mobile exam center (MEC). The MEC is made up of four trailers, linked sideways, containing high-tech medical equipment. During the health examination many tests are performed; however, no internal exams or invasive procedures are done. Some of these tests (e.g. digital images of the retina) are not normally performed at a physician’s office and could give the participant and his/her doctor additional information on his/her health. The examinations a participant will have depend on that participant’s age and gender.

For a list of examinations, click here.  Participants are informed that the NHANES health exam is not a substitute for their regular health care visits.

All participants receive a written Report Of Findings approximately 12 weeks after the exam. If the survey program detects an abnormal value, the participant is notified immediately by letter.

For additional information on participant involvement and benefits please refer to the Participant Page.

Notification and Referral for Selected Infectious Diseases

The NHANES is conducted by the National Center for Health Statistics, which is part of the Centers for Disease Control and Prevention (CDC). The objective of the survey is to assess the health and nutritional status of adults and children in the United States. We gather and protect all information in keeping with the requirements of Federal Law. The Public Health Service Act (42 USC 242k) authorizes data collection. Section 308(d) of that law (42 USC 242 m) and the Privacy Act of 1974 (5 USC 552A) prohibit us from giving out information that identifies individuals in the survey without their consent.

Because the survey is for health research purposes only, our methods encompass procedures for measuring health status in the general population. These methods are not always similar to those used in clinical settings. Additionally, our survey physicians do not complete a history or physical exam on individual participants and therefore do not diagnose medical conditions. If a health problem is suspected based on findings from the survey protocol, participants are informed and referred to their local health care provider or health department clinic for evaluation and management. The legal obligation to report notifiable diseases to authorities will be fulfilled by the local provider or health department clinic if the participant’s clinical or laboratory assessment by the provider meets the case definition for infectious conditions under public health surveillance in their state.

The following is the survey protocol for notification and referral:

Participants are given STD/HIV test results by a health educator certified in HIV counseling by phone one month after their examination.  Adults who do not call in receive up to 3 reminder letters.  Teenagers are reminded by telephone.  Participant identity is confirmed by a password.  A participant with a positive test result based on the lab assays described below, is counseled and referred to his/her local doctor or health department STD clinic for repeat testing and evaluation.  Upon request, a results letter is mailed to the participant:  In addition to test results, laboratory assays used are reported in the letter as follows:

Explanation of the laboratory assays:

Chlamydia and gonorrhea

Urine is tested using a ligase chain reaction (LCR) test (Abbott) designed to detect the presence of DNA of chlamydia and/or gonorrhea.

Herpes Type 2

Blood is tested by type-specific immunodot assay developed and performed by scientists at the Emory University School of Medicine to detect andt-HSV-2 antibodies.


Blood is tested using an enzyme-linked immunoassay (ELISA) to detect antibody to HIV with a western blot confirmation of positive ELISA tests.

Human Papillomavirus

High-risk types
A vaginal swab is tested using the Digene Hybrid
â Capture II test to detect the presence of HPV types: 16/18/31/35/39/45/51/52/56/58/59/68.

Low-risk types

A vaginal swab is tested using the Digene Hybridâ Capture II test to detect the presence of HPV types: 6/11/42/43/44.


This page last reviewed October 15, 2008

H H S Health and Human Services logo and link
Centers for Disease Control and Prevention
National Center for Health Statistics
Hyattsville, MD