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NLM Salutes National Center for Health Statistics on 50th Anniversary of National Health and Nutrition Examination Survey (NHANES)

Library Has Partnered with NHANES for Past 20 Years

The National Library of Medicine paid tribute to the National Health and Nutrition Examination Survey (NHANES) on the occasion of its 50th anniversary, September 29, 2009, acknowledging the program's many contributions to improving the health of Americans.

NHANES began in 1959 as the National Health Examination Survey. Since then, the program, under the National Center for Health Statistics (NCHS), a division of the US Centers for Disease Control and Prevention (CDC), has been a primary source of data on the nation's health.

NHANES data come from household interviews and standardized examinations and laboratory testing of a sample of the nation's civilian, non-institutionalized population. NHANES has expanded since the survey's inception to include a nutritional component now conducted in collaboration with the US Department of Agriculture, and measures of environmental exposure with the National Center for Environmental Health.

Based on NHANES survey results, scientists were able to detect abnormally high levels of lead in blood, which they traced to leaded gasoline. Those findings led to efforts to ban leaded gasoline and, as a result, lead levels in blood dropped dramatically.

NHANES also documented America's growing rates of obesity through direct physical measurements. And its scientific documentation of low levels of folic acid, a B vitamin, among women of child-bearing age, influenced the policy decision to fortify the food supply with folic acid, to reduce the number of infants born with neural tube defects, anencephaly and spina bifida. Rates of these serious birth defects have greatly decreased because women now get more adequate amounts of folate through foods in the crucial month following conception, a period before many women start taking prenatal vitamins.

A hallmark of NHANES is its partnerships with other CDC programs and the National Institutes of Health, among other government agencies. Among other NHANES-NIH collaborations, NLM has played a role in the last 20 years of the survey by taking on some of the digital tasks.

For example, in collaboration with the NCHS in the early 1990's, NLM's Lister Hill Center acquired text and x-ray films collected in the NHANES II and III surveys. The 17,000 films, of cervical and lumbar spine x-rays, were initially digitized for preservation, but found application in several research domains. These digital images and about 2,000 fields of alphanumeric data for each of several thousand survey subjects are made available to the public through the WebMIRS system used by researchers in epidemiology and other areas in biomedicine ( ). In addition, the data has been used to develop a digital atlas to serve as a reference tool for the interpretation of cervical and lumbar spine x-rays. The atlas contains representative images for several grades of severity for a number of spinal conditions on which expert rheumatologist readers have reached agreement in grading. Details may be found at

Parts of the NHANES collection is provided by the Lister Hill Center as validated reference ("truth") data for research in several areas of interest to the computer vision and image engineering communities, including: automated indexing by shape, texture and other image features; querying image databases by image example or sketch; advanced image compression algorithms; and classification of images according to the presence/absence of osteoarthritis features, such as disc space narrowing and subluxation (misalignment of the spine). Publications in these areas appear in