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National Health & Nutrition Examination Survey (NHANES)


Key Web Links 

Home page

Introduction to NHANES

Data and documentation

Data structure and contents and variable locator

NHANES 1999-2010 survey contents

NHANES tutorials

Dataset summary 

NHANES is a nationally-representative study of adults and children in the United States. Data collection includes in-depth, in-person surveys, physical and physiological examinations, and laboratory tests. Survey information is extensive, including demographic, socioeconomic, dietary, health-related, and many other questions, while the examination component includes a wide variety of medical and dental exams, physiological measurements, and laboratory tests. NHANES began in the 1960s and has been through several iterations through the present. Since 1999, NHANES has collected data using a serial, cross-sectional design in ongoing 2-year cycles (“Continuous NHANES”). In prior years, data was collected in discontinuous fashion (NHANES I, II, and III). The survey samples approximately 5,000 individuals each year. Data are free and directly downloadable from the website. Data years can be combined (using different sampling weights) to maximize sample sizes and evaluate for time trends.

Expert Comments
NHANES is an extensive and reliable source of information on the health of the nation at any given point. Because it combines interviews, examinations, and tests, the data collected are quite extensive, providing a rich data source for wide ranging areas of research. There is not much focus on healthcare use and access. To appropriately account for the sampling design, different weights are available depending on which data components are being used since many assessments are conducted only on a subsample of participants.

Dataset details 

Dataset Owner / Manager

National Center for Health Statistics (NCHS)

Study and sample characteristics

Since 1999, NHANES has collected serial cross-sectional data on approximately 5000 adults and children per year. Data is collected using in-person interviews, as well as extensive physical and physiological examinations and laboratory testing conducted in special Mobile Examination Centers. Subjects are selected and sampling weights are provided to allow investigators to generate nationally representative results. Persons age 60 and older, African-Americans, and Hispanics are oversampled.

Prior to 1999, NHANES comprised a series of non-continuous study samples (NHANES I, II, and IIII).

Statistical adjustment for sampling strategy and patient weights is essential to produce accurate results. Methods for making these adjustments are described in several places on the NHANES website, including:

Major Foci

NHANES contains a wide range of foci, combining interview data, physiologic measurements, and laboratory tests.

Clinical conditions of special interest include:
• Anemia
• Cardiovascular disease
• Diabetes
• Environmental exposures
• Eye diseases
• Hearing loss
• Infectious diseases
• Kidney disease
• Nutrition
• Obesity
• Oral health
• Osteoporosis
• Physical fitness and physical functioning
• Reproductive history and sexual behavior
• Respiratory disease (asthma, chronic bronchitis, emphysema)
• Sexually transmitted diseases
• Vision

Various components collected between 1999-2010 are shown below. Not all components are collected on all participants or in all years; details can be found in:

• Acculturation (ACQ)
• Allergy (ARQ)
• Audiometry ( AUQ)
• Balance (BAQ)
• Blood Pressure (BPQ)
• Cardiovascular Disease (CDQ)
• Demographics (DMQ)
• Dermatology (DEQ)
• Diabetes (DIQ)
• Diet Behavior and Nutrition (DBQ)
• Dietary Supplements & Medications (DSQ)
• Digit Symbol Substitution Test (CFQ)
• Early Childhood (ECQ)
• Health Insurance (HIQ)
• Hospital Utilization & Access to Care (HUQ)
• Immunization (IMQ)
• Introduction & Verification (IVQ)
• Kidney Conditions (KIQ)
• Medical Conditions (MCQ)
• Miscellaneous Pain (MPQ)
• Occupation (OCQ)
• Oral Health (OHQ)
• Osteoporosis (OSQ)
• Physical Activity & Physical Fitness (PAQ)
• Physical Functioning (PFQ)
• Respiratory Health & Disease (RDQ)
• Sleep Disorders (SLQ)
• Smoking and Tobacco Use (SMQ)
• Social Support (SSQ)
• Tuberculosis (TBQ)
• Vision (VIQ)
• Weight History (WHQ)

• Family questionnaire
o Consumer Behavior (CBQ)
o Demographic Background/Occupation (DMQ)
o Food Security (FSQ)**
o Health Insurance (HIQ)
o Housing Characteristics (HOQ)
o Income (INQ)
o Pesticide Use (PUQ)
o Smoking (SMQ)

• Mobile exam center self-administered questionnaires
o Alcohol Use
o Bowel Health
o Current Health Status
o Depression Screener
o Kidney Conditions—Urology
o Pesticide Exposure
o Physical Activity
o Prostate Conditions
o Reproductive Health
o Tobacco Use
o Volatile Toxicants
o Weight History
o Alcohol Use
o Conduct Disorders
o Food Security
o Drug Use
o Sexual Behavior
o Tobacco Use
o Prostate Conditions

Clinical and physiological examinations
• Audiometry
• Balance
• Bioelectrical Impedance Analysis
• Body Measurements
• Cardiovascular Fitness
• Dermatology
• Dietary
• Dual Energy X-Ray Absorptiometry:
• Body Composition
• Bone Density—Hip and Spine
• FCBS Phone Follow-up Module
• Food Frequency
• Hair Collection
• Lower Extremity Disease:
• Peripheral Neuropathy
• Peripheral Vascular Disease
• Mental Health evaluations
• Parental evalution of child mental health
• Opthomologic and vision examination
• Oral health evaluation
• Physical activity
• Physical function
• Vital signs
• Pulmonary function
• Tuberculosis screen

Laboratory examinations
• Multiple tests

Special supplements and resources

Various questions and examination components are rotated in and out of the survey. See the following link for details:

Links to other datasets

NHANES includes linkages to Medicare claims data, Social Security Administration data, and mortality files.

NHANES Medicare Utilization and Expenditure Linked Files

NHANES linked Social Security Administration Files

NHANES linked Mortality Files

Papers Published

Click here for a PubMed search for articles using this dataset.

Customized search link for finding NHANES studies in PubMed:

NHANES Data Briefs: Statistical publications by NCHS/CDC on current public health topics

Examples of papers published using NHANES data include:

Demographic differences and trends of vitamin D insufficiency in the US population,1988-2004.
Ginde AA, Liu MC, Camargo CA Jr.
Arch Intern Med. 2009 Mar 23;169(6):626-32.

Use of inexpensive technology to enhance adolescent health screening and counseling.
Olson AL, Gaffney CA, Hedberg VA, Gladstone GR.
Arch Pediatr Adolesc Med. 2009 Feb; 163(2):172-7.

Association of hypertension, diabetes, dyslipidemia, and metabolic syndrome with obesity: findings from the National Health and Nutrition Examination Survey, 1999 to 2004.
Nguyen NT, Magno CP, Lane KT, Hinojosa MW, Lane JS.
J Am Coll Surg. 2008 Dec; 207(6):928-34.

Vitamin and mineral supplement use by children and adolescents in the 1999-2004 National Health and Nutrition Examination Survey: relationship with nutrition, food security, physical activity, and health care access.
Shaikh U, Byrd RS, Auinger P.
Arch Pediatr Adolesc Med. 2009 Feb; 163(2):150-7.

Diabetes and hearing impairment in the United States: audiometric evidence from the National Health and Nutrition Examination Survey, 1999 to 2004.
Bainbridge KE, Hoffman HJ, Cowie CC.
Ann Intern Med. 2008 Jul 1;149(1):1-10.

Dataset accessibility and cost

Data is free and publicly-accessible for downloading.

NHANES Data release and access policy

Access to non-publicly released data sets is available through the NCHS Research Data Center after completing steps outlined in the following link:

Data Release FAQ

Help Desk

Write to for questions about NHANES data and to submit data requests.

Request a consultation (SGIM members only)
Members of SGIM may request a one-time consultation with an expert in this dataset, for example, to explore research ideas or to troubleshoot a problem or vexing question. Please click here for guidelines and the request process.