N H A N E S I Epidemiologic Followup Study (N H E F S) Public-Use Data Files

Survey description
The NHANES I Epidemiologic Follow-up Study (NHEFS) is a national longitudinal study that was jointly initiated by the National Center for Health Statistics and the National Institute on Aging in collaboration with other agencies of the Public Health Service. The NHEFS was designed to investigate the relationships between clinical, nutritional, and behavioral factors assessed in the first National Health and Nutrition Examination Survey NHANES I and subsequent morbidity, mortality, and hospital utilization, as well as changes in risk factors, functional limitation, and institutionalization.

The NHEFS cohort includes all persons 25-74 years of age who completed a medical examination at NHANES I in 1971-75 (n = 14,407). It is comprised of a series of follow-up studies, four of which have been conducted to date. The first wave of data collection was conducted for all members of the NHEFS cohort from 1982 through 1984. It included tracing the cohort; conducting personal interviews with subjects or their proxies; measuring pulse rate, weight, and blood pressure of surviving participants; collecting hospital and nursing home records of overnight stays; and collecting death certificates of decedents.

Continued follow-up of the NHEFS population was conducted in 1986, 1987, and 1992 using the same design and data collection procedures developed in the 1982-84 NHEFS, with the exception that a 30-minute computer-assisted telephone interview was administered rather than a personal interview; and no physical measurements were taken. The 1986 NHEFS was conducted for members of the NHEFS cohort who were 55-74 years of age at their baseline examination and not known to be deceased at the 1982-84 NHEFS (n = 3,980). The 1987 NHEFS was conducted for the entire nondeceased NHEFS cohort (n = 11,750). The fourth wave of data collection, the 1992 NHEFS, includes the entire nondeceased NHEFS cohort (n = 11,195). Tracing and data-collection rates in the NHEFS have been very high. Ninety-six percent of the study population has been successfully traced at some point through the 1992 follow-up. Tracing rates for each completed wave ranged from 90 to 94 percent and interview rates ranged from 91 to 96 percent of those traced.

Data file description
The NHEFS public use data files are divided into four components. These are:

Vital and Tracing Status Data
The 1992 Vital and Tracing Status contains tracing, vital status, and demographic data for all 14,407 subjects for each wave of data collection.

Interview Data
The 1982-84, 1986, 1987, and 1992 Interview data contain information collected from the subject and proxy interviews conducted during each follow-up period. When merged together, these files provide a complete follow-up history for each subject from baseline through the last completed interview.

Health Care Facility Stay Data
The 1982-84, 1986, 1987, and 1992 Health Care Facility Stay data contain information collected during each follow-up period regarding overnight stays in health care facilities, including diagnostic and summary information abstracted from hospital and nursing home records. Supplemental Health Care Facility Stay data is used to provide information on overnight facility stays that occurred outside the reported follow-up period. When these five Health Care Facility Stay data files are merged together, they provide a history of all reported hospitalizations and institutionalizations from baseline through 1992.

Mortality Data
The 1992 Mortality Data contains death certificate information collected during each follow-up period coded according to ICD-9 multiple-cause-of-death procedures for all 4,497 decedents identified through 1992.

List of data file variables at a glance

See section on "Data file description."

Data file technical characteristics
Each NHEFS public-use data file contains fixed-length records.

Type of file	Number of records
Interview	9,281
Health care facility stay	10,535
Supplemental health care facility stay	70
Mortality	4,497
Vital and tracing status	14,407

Type of file	Number of records
Interview	12,220
Revised health care facility stay	25,436

Geographic coverage
In the first National Health and Nutrition Examination Survey (NHANES I), data were collected from a national probability sample of the civilian noninstitutionalized population. The NHANES I Epidemiologic Follow-up Study attempts to trace and interview all study subjects at their current location.

Data availability
NHEFS data are available on CD-ROM. Data from the 1992 study can be downloaded from the CDC/FTP server. The NHANES I public-use data files can be used with NHEFS public-use data to access health outcomes. Data for both surveys were collected as follows:

Ordering information
Data from the NHEFS can only be purchased through the National Technical Information Service (NTIS) on CD-ROM. Please call NTIS for current pricing. The NTIS order numbers are as follows:

Data year	Title	NTIS order no.
1992	Interview	PB96-502752
	Health care facility stay	PB96-502760
	Supplemental health care facility stay	PB96-502786
	Mortality	PB96-502778
	Vital and tracing status	PB96-502703

1987	Interview	PB92-501154
	Health care facility stay	PB92-501147

1986	Interview	PB90-501677
	Health care facility stay	PB90-501669

1982-84	Interview	PB88-121298
	Revised health care facility stay	PB90-504077

Documentation contents
NHEFS Public-Use Data documentation is available on each CD-ROM and documentation for the 1992 study can be downloaded from the CDC/FTP server.

Cohen BB, Barbano HE, Cox CS, et al. Plan and operation of the NHANES I Epidemiologic Follow-up Study, 1982-84. National Center for Health Statistics. Vital and Health Statistics report Series 1, No. 22. 1987.

Finucane FF, Freid VM, Madans JH, et al. Plan and operation of the NHANES I Epidemiologic Follow-up Study, 1986. National Center for Health Statistics. Vital and Health Statistics report Series 1, No. 25. 1990.

Cox CS, Rothwell ST, Madans JH, et al. Plan and operation of the NHANES I Epidemiologic Follow-up Study, 1987. National Center for Health Statistics. Vital and Health Statistics report Series 1, No. 27. 1992.

Cox CS, Mussolino M, Rothwell ST, et al. Plan and operation of the NHANES I Epidemiologic Follow-up Study, 1992. National Center for Health Statistics. Vital and Health Statistics report Series 1, No. 35. 1997.

Madans JH, Cox CS, Kleinman JC, et al. 10 Years after NHANES I: Mortality experience at initial follow-up, 1982-84. Public Health Reports 101(5):474-481, Sept.-Oct. 1986.

Madans JH, Kleinman JC, Cox CS, et al. 10 Years after NHANES I: Report of initial follow-up, 1982-84. Public Health Reports 101(5):465-73, Sept.- Oct. 1986.

Cornoni-Huntley JC, Huntley RR, Feldman JJ, editors. Health status and well-being of the elderly, National Health and Nutrition Examination Survey I Epidemiologic Follow-up Study. Oxford University Press, New York, N.Y. 1990.

Contact
Christine S. Cox
Division or Epidemiology
Office of Analysis, Epidemiology, and Health Promotion
National Center for Health Statistics
Centers for Disease Control and Prevention
3311 Toledo Road, Room 6425
Hyattsville, Maryland 20782
(301) 458-4164