4.20 Health

NLSY79 questionnaires contain a variety of health questions. NLSY79 health sections are divided into two periods. From 1979 to 1996, most of the questions focus on health concerns that restrict or inhibit the respondent’s ability to work. From 1998 on, as respondents reached middle age, the "Health" section was expanded to provide a baseline profile of the respondent’s overall health as they turn 40 years old.

Ability to Work

From 1979 to 1982 a standard set of health questions was administered during each survey. The focus of these questions was on health problems that restricted or prohibited a respondent’s ability to work. For example, in each year the survey asked three questions: (1) Respondents not currently working were asked “Would your health keep you from working on a job for pay now?” (2) All respondents were asked, “(Are you/Would you be) limited in the kind of work you (could) do on a job for pay because of your health?” (3) All respondents were asked “(Are you/Would you be) limited in the amount of work you (could) do because of your health?” If an individual answered ‘yes’ to being limited in either the kind or amount of work they could do because of health, the NLSY79 then probed for specific details on the health ailment.

While information is collected on up to three health conditions, the respondent is asked to identify which of the conditions is the “main” condition. Follow-up questions regarding the main condition include the month and year the condition began and how long the respondent has been limited in this way. In addition, the name of the condition is gathered and later coded using a modified version of the International Classification of Diseases (ICD-9) codes taken from the World Health Organization, International Classification of Diseases, Ninth Revision, 2 vols., WHO, Geneva, 1977 (vol. 1) and 1978 (vol. 2). See Attachment 8 of the NLSY79 Codebook Supplement for a detailed description of these codes.

Additional details collected on respondent health conditions include information on whether the youth ever saw or talked to a medical person regarding the condition, what the cause of the condition was, what part of the body was affected, and when the respondent first noticed the condition. If the condition was caused by an accident or injury, the date of the accident/injury, as well as information on the parts of the body that were hurt, was collected. A description of the coding scheme used for the body part information is also contained in Attachment 8 of the NLSY79 Codebook Supplement.

From 1983 to 1987, the amount of data collected on health was significantly reduced to basic information on whether the respondent had a work-limiting health problem and the duration of any limitation. While this same short series of questions has been asked in virtually every NLSY79 survey, significant additions were made in the late 1980s. For example, beginning with the 1988 survey, an extensive series of questions was initiated on work-related injuries or illnesses. The respondent is asked specifically for the most recent and most severe work injury. The questions are asked to determine the nature and extent of the condition, whether or not the respondent received Workers Compensation payments, and the impact of the condition on the respondent. A sample of the impact questions include whether there were lost wages, missed days at work, or whether the worker had to quit work, change occupations, or was fired from the job, etc., as a result of the injury/illness. Finally, beginning in 1998, all respondents are asked about their participation in regular physical activity on and off the job.

Health Profile

Examining the raw unweighted data shows that approximately three percent of NLSY79 respondents each year are limited in the amount of work they do by health reasons. Additionally, approximately three percent of all respondents are limited in the kind of work they do by health problems. While these questions provide a detailed picture of a respondent’s current health restrictions, they offer little insight into chronic health problems that will affect their labor force activity in the future. For example, a serious ailment that slowly develops over time will not be picked up by these questions until the respondent actually drops out of the labor market. For this reason and because of the aging of the cohort, an extended health module was administered to respondents age 40 and over and general questions on physical activity and exercise were administered to all respondents beginning with the 1998 survey. This extended module was created to provide a baseline health profile of the respondent for examining the interrelationship of health and labor market activity in advance of the retirement years. To broaden the usefulness of the NLSY79 health data, this extended module, comprising four major parts, is not restricted to work-related health problems, and all questions are asked irrespective of the respondent’s labor force status.

The first part of the 40-and-over module asks respondents to answer the Center for Epidemiological Studies Depression Scale (CES-D). This scale measures symptoms of depression, discriminates between clinically depressed individuals and others, and is highly correlated with other depression rating scales (see Radloff 1977; Ross and Mirowsky 1989). The 1998 and 2000 surveys collected a reduced set of seven items from the original 20 item CES-D scale. The number of items was increased to nine in the 2002 survey; the full 20-item scale was last administered in 1992.

The second part of the extended health profile asks respondents when they last saw a health care professional. These questions provide researchers with the date of the respondent’s last physical exam and last visit to the doctor for any reason. Information on individuals who never visit a doctor is available as well. This subsection also gathers information about the health and life status of the NLSY79 respondents’ biological parents. Questions which ask respondents about their parent’s health are designed to improve researchers’ understanding of hereditary health problems. Respondents are asked whether their biological parents are alive and if not, their parent’s age at death and cause of death. Information is also gathered about any major health problems afflicting either parent.

The third section reproduces the SF-12 scale, a 12-question health survey designed by John Ware of the New England Medical Center Hospital. The SF-12 is designed to provide a measure of the respondents’ mental and physical health irrespective of their proclivity to use formal health services. Detailed information on the SF-12 is available from QualityMetric Incorporated  (http://www.sf36.com/ or 640 George Washington Highway, Lincoln, RI 02865). QualityMetric also provides researchers with software and algorithms to score the SF-12.

The last section of the 40-and-over health module asks respondents if they suffer from an extensive list of health conditions. Respondents with certain major conditions, such as cancer, hypertension, diabetes, etc., are probed on the date at which the condition was first diagnosed and other details relevant to the particular condition.

Respondent Characteristics

A respondent’s height and weight are natural indicators of health. Height questions were asked in 1981, 1982, 1983 (only to females who were ever pregnant), and 1985. Users should exercise caution because the height questions have been collected in a variety of formats. The 1981 question combines feet and inches into a single number. Hence, respondents range from 400 (four feet and zero inches) to 611 (six feet and eleven inches). The 1982 and 1985 questions convert all answers into just inches. The 1983 height questions are found under two different reference numbers: female height in feet is provided in R09989., while height in inches is provided in R09990.

Since weight fluctuates more than height, questions on weight are asked more frequently. Weight questions appear in the 1981, 1982, 1985, 1986, 1988–90, and 1992–2004 surveys. Weight in all years is recorded in pounds. The weight data are normally distributed from 50 to 400 pounds in all years except 1989. In 1989, there are 11 individuals marked as weighing 996 pounds. This number is not a true weight but rather an out-of-range code. Users are advised to examine height and weight distributions prior to analysis in order to make informed decisions as to how to handle outliers.

Respondent hair and eye colors were collected during the 1985 interview and information on whether they were born left or right handed was collected in the 1993 interview.

In 2004 a series of questions about asthma was added to the survey. These included the onset and diagnosis of asthma, whether the respondent missed work, when they had an attack and methods of prescribed treatment.  Also included were question regarding onset in the respondent's children.

Health Insurance

The NLSY79 provides researchers with a variety of insurance information. Almost every survey asked working respondents if their current or most recent job provided health insurance benefits. Table 4.20.1 is taken from the fringe benefits series and shows that, over time, an increasing number of NLSY79 respondents work in jobs that are covered by health insurance benefits. While only 39.3 percent were working in covered jobs in 1979, by 2004 more than 82 percent had health insurance available.

Table 4.20.1 Percentage of Respondents Whose Current or
Most Recent Job Provided Health Insurance Benefits

There are a number of problems with using the fringe benefits question series in the CPS and ES section to understand and track health insurance coverage. First, respondents who are not working are excluded from these questions. Second, not all health insurance is employer provided. Some individuals pay directly for health insurance, while others are covered by their spouse’s or partner’s plans. Lastly, while an employer may offer this benefit, workers might not participate in the plan and therefore may not be aware of its availability. To overcome these limitations, the health section of the NLSY79 was expanded beginning in 1989 to directly ask about sources of health insurance coverage.

The health section of the questionnaire in 1989, 1990, and 1992–2004 asks respondents if they are covered by a health plan. If the respondent answers “yes,” the interviewer asks who pays for the plan. Responses include current employer, previous employer, spouse’s employer, purchased directly, and Medicaid or welfare source. If the respondent is married, the same set of questions on medical coverage are asked about the wife or husband (and beginning in 1994, about the non-marital, opposite-sex partner, if any). Additionally, if the respondent has any children, the same questions are asked about the children’s health insurance coverage.

Related Variables: Additional information on the relationship between health and labor force status can be found in the CPS section. The CPS section contains questions allowing respondents to state that they are not in the labor force because of health problems. Unfortunately, these questions do not describe the specific problem, when the problem started, or how long the problem has lasted. Information on substance use (smoking, drugs, alcohol) is collected as part of a largely self-administered report in selected survey years. See the "Alcohol Use," "Cigarette Use," and "Drug Use" sections of this guide for further information on these topics. Information on health practices related to sexual activity and pregnancy can be found in the fertility section of selected surveys. For further information see the "Fertility" and "Sexual Activity and Contraception" sections of this guide. Information on self-perceptions and self-esteem measures can be found in the "Attitudes and Expectations" section of this guide.

Survey Instruments: Health and health insurance questions are located within the "Health" section of each questionnaire.

Documentation: Documentation augmenting the questionnaire and codebook include Attachment 8 in the NLSY79 Codebook Supplement.

Data Files: Data related to health can be found in the following NLSY79 main file areas of interest: "Health," "Alcohol," "Drugs," "CPS," "Birth Record," "Birth Record xxxx," and "Misc. xxxx."

Comparison to Other NLS Cohorts: Maternal prenatal care information and health-related characteristics are provided on the NLSY79 Child and Young Adult data set. As part of the child data collection, the Mother Supplement (MS) survey instrument includes a selection of scales measuring the child's temperament, motor and social development, and behavior problems. Information on the child's health is also collected from the mother in the Child Supplement (CS) survey instrument.

Respondents in the other cohorts have answered questions about their health; however, the specific questions have varied widely as the health sections were modified to reflect the respondents’ varying life cycle stages. Health insurance information has been collected from respondents in these cohorts except the Young Men. The round 1 NLSY97 interview included a series of questions, addressed to youths born in 1983, on respondents’ health practices and knowledge. Users should refer to the BLS website at http://www.bls.gov/nls or the appropriate cohort’s User’s Guide for more precise information.

References

Radloff, Lenore. “The CES-D Scale: A Self Report Depression Scale for Research in the General Population.” Applied Psychological Measurement 1 (1997): 385–401.

Ross, Catherine E. and John Mirowsky. “Explaining the Social Patterns of Depression: Control and Problem Solving - or Support and Talking?” Journal of Health and Social Behavior 30 (June 1989): 206–9.