Health Measures in the 1997 Redesigned National Health Interview Survey (NHIS)
This document describes the general health
measures included in the Redesigned NHIS Basic Module starting in January 1997.
Information in the Family Core questionnaire is collected on all household members. A
household adult reports information for a randomly selected child less than 18 years of
age in the Child Core questionnaire, and a randomly selected adult reports for him/herself
in the Adult Core questionnaire.
Limitation of Activity
Questions in thissection are designed to retain comparability to previous NHIS
surveys for reporting of activity limitation due to physical, mental, or emotional
problems. Information on activity limitation is collected on each family member and can be
categorized to four major groups including: 1) unable to perform major activity, 2)
limited in major activity, 3) limited in other activity, and 4) not limited. Included in
this section are questions about the need for assistance with personal care needs such as
eating, bathing, dressing or getting around, or assistance handling routine needs such as
everyday household chores, doing necessary business, shopping or getting around for other
purposes. If any limitations are identified, the respondents are asked to specify the
health condition causing the limitation and indicate how long they have had the condition.
Since cognitive impairment is increasingly recognized as a source of activity limitation
among older adults, a new question has been added to determine if anyone in the family is
limited because of difficulty remembering or periods of confusion. Other new measures in
this section include determining if any family members have difficulty walking without any
special equipment and identifying children who receive Special Education or Early
Intervention Services. At the end of this section, the general health status of each
household member is reported as excellent, very good, good, fair, or poor.
Questions on limitation of activity in
the Adult Core are used to determine the number of work-loss days and bed days reported
during the 12 months prior to the interview. In addition, respondents are asked if their
health is better, worse, or the same compared with 12 months ago. There are also nine Nagi
items which attempt to measure physical functioning in a context that is not activity
specific. The questions allow persons to report the degree of difficulty they experience
doing activities such as walking 3 city blocks, standing for 2 hours, or lifting or
carrying something as heavy as 10 pounds such as a bag of groceries. Respondent are also
asked to rate the difficulty they experience in engaging in social activities and
Questions on limitation of activity in
the Child Core are used to determine limitations in movement such as walking, running, or
playing and whether or not the causal impairment is expected to last a year or more.
Respondents are asked whether the child has a health problem that requires prescription
medicine for a duration of 3 months or longer. This question is designed to assess
chronicity of the health problem. Respondents are also asked if they had ever been told by
a school official or health care provider that the child has a learning disability.
Questions in this section are designed to improve injury surveillance by asking about the
external causes and circumstances of injury. Two screening questions capture injury and
poisoning events that occurred in the 3 months prior to interview and required medical
attention. The recall period was lengthened from 2 weeks (old NHIS) to 3 months in order
to obtain larger numbers of events. Verbatim responses on how the injury happened, the
kind of injury, and the body part or parts affected are recorded by the interviewers and
are then coded to ICD 9-CM e-codes during data processing. Additional information related
to activity and place of occurrence of the injury is being collected to be used in new
external cause-of-injury groupings for reporting injury morbidity data.
The purpose of this section is to classify all household members by type of health care
coverage. Information is provided by an adult knowledgeable about the family's health
insurance, when available; else, information is collected from the family respondent.
Questions are asked about who in the family is covered and the kind of coverage (private,
Medicare, Medicaid, Military/Champus/Tricare, Indian Health Service, State-sponsored or
government plan) he/she receives. When indicated, respondents are asked to provide the
full names of the plans which are recorded verbatim by the interviewers. Plan names are
coded into known types such as fee-for-service, HMO, PPO, POS, etc., during data
processing by means of an updated list of U.S. health plans maintained by NCHS. Other
information collected from respondents includes the source of coverage, i.e., the
workplace or direct purchase, and the annual amount spent for health insurance premiums
including payroll deductions. Information is also collected on noncovered household
members on the length of time without coverage as well as the reasons that coverage
stopped. The last question in the health insurance section asks respondents to estimate
the annual household expenditure for medical care, including dental care.
Access to health care
Many of the questions in this section are derived from the 1993-1995 NHIS Access to Care
supplements. Items in the family core assess the extent of access problems resulting from
cost considerations. Questions on access in the Adult and Child cores are designed to
identify persons who have a usual source of care and to determine the nature of that
source. Respondents are also asked if this usual source is also the place where preventive
care is received, or if it is received elsewhere. These questions are typical of usual
source questions used in many access surveys. Persons are asked if they have recently
changed their usual source(s) of care. In the past, respondents were asked to indicate a
variety of reasons for such changes. In this survey, respondents are asked directly about
reasons related to health insurance only. The last two questions identify persons who have
delayed care for reasons other than costs (couldn't get through on the phone, couldn't get
an appointment, etc.) and/or who have not gotten specific types of care that they needed
(prescription medicines, mental health, or dental care).
Health Care Utilization
The Family Core contains questions on hospitalizations that are used to monitor trends and
differentials in inpatient stays and length of stay by sociodemographic, health status,
and health insurance variables. Information on past 12 month hospitalizations including
the total number of days hospitalized is collected for all family members. A question
identifies hospitalization for childbirth that will allow analysts to exclude deliveries
from estimates of hospital stays. The Family Core also contains questions on health care
received in the 2 weeks prior to the interview. Respondents are asked whether they have
received care of any kind from medical doctors or any other health professionals such as
nurses, physical therapists, and chiropractors. Health care contacts are categorized by
home visits, phone contacts, and office/clinic or ER visits.
Items in the Adult and Child core
include questions on the length of time since last contact with 1) a dentist or 2) a
doctor or other health care professional. Individuals report whether they have seen or
talked to specific types or categories of health care providers during the 12 months prior
to the interview. Categories of providers include mental health professionals, eye
doctors, foot doctors, chiropractors, allied health professional such as physical
therapist and speech therapists, and physician assistants or nurse practitioners.
Respondents are also asked about the type of medical doctor seen during encounters in the
12 months prior to the interview. The purpose of these questions is to track the
proportion of visits to generalists and to specialists. Additional information is
collected on the number of health care provider visits in each of the following places in
the 12 months prior to interview: hospital emergency room, home, and other places
including physician offices. Information on the number of inpatient or outpatient
surgeries during the 12 months prior to interview is also collected.
The section on health conditions was designed with the goals of substantially reducing the
length of the NHIS survey and eliminating the analytic complexity of the data while
preserving the ability to produce national estimates of disease prevalence. Questions that
use to cover 133 conditions in six condition lists have been reduced to a single list
consisting of several domains which are in the Adult and Child cores. The domains for
adults are organized by organ system or health topic and include the following:
cardiovascular disease, respiratory conditions, cancer, diabetes, gastrointestinal
conditions, renal conditions, joint symptoms, oral health, sensory impairments, pain, and
mental health. The mental health section consists of a brief symptom screening battery
using a Likert scale with a 30 day reference period. General distress symptoms are known
predictors of service utilization. There is also one question on the impact of these
symptoms on a persons activities to assess the severity of distress. Pain questions
in the NHIS are designed to assess pain a person experienced in the 3 months prior to the
interview. Respondents are asked about pain that lasted a whole day or more. Sample adults
are asked about neck pain, back pain, facial ache, or pain and headaches/migraines.
Information on conditions are
self-reported in the Adult Core and proxy reported in the Child Core. Questions on health
conditions for children include those that are associated with disabilities such as
cerebral palsy, mental retardation, Downs syndrome, among others; and those associated
with learning disabilities such as Attention Deficit Disorder. Information is also
collected on important childhood illnesses or impairments including, but not limited to,
asthma, allergic conditions, ear infections, headaches/migraines, seizure disorders,
hearing and visual impairments and stuttering. The redesigned NHIS also includes a brief
child behavior scale, or mental health indicator. These questions are derived from the
Child Behavior Check List. Items selected for inclusion were those that best discriminated
between children referred for mental health care and those who were not. Specific sets of
questions were developed for boys and girls by age groups.
Questions on health behaviors include tobacco use, physical activity, and alcohol use.
They are in the Adult Core questionnaire.
The NHIS has long been an important part of national tobacco use surveillance. Questions
have been designed to monitor self-reported cigarette smoking behavior. Respondents are
asked if they ever smoked 100 cigarettes, and if so, the age at which they started
smoking. Information on smoking behavior is collected to categorize respondents as former,
current, or never smokers. Former smokers are asked to provide the length of time
since quitting. Current smokers are asked about the average number of cigarettes smoked
per day, and the number of days they smoked in the past month, and quit attempts.
A program of regular physical activity is known to prevent a number of chronic health
conditions and enhance good health. Persons are asked about physical activities (exercise,
sports, or physically active hobbies) that are done during leisure time. Respondents are
asked about 2 levels of activity: 1) how often they do VIGOROUS activities lasting at
least 10 minutes that cause heavy sweating or large increases in breathing or heart rate,
2) how often they do LIGHT or MODERATE activities that cause light sweating or slight to
moderate increase in breathing or heart rate. Information on the duration of the activity
is ascertained for each of these levels. In addition, respondents are asked how often they
do physical activities designed to STRENGTHEN muscles such as lifting weights or doing
Questions are similar to previous NHIS items on self-reported alcohol use. Respondents are
asked whether they have had at least 12 drinks in ANY ONE YEAR or in their ENTIRE LIFE.
Persons reporting alcohol use are asked about consumption in the past year. Respondents
are asked how often they drink, how much they drank on the days that they drank, and how
many days in the past year they had 5 or more drinks.
Both the Adult and Child Core questionnaires contain questions on immunizations. The Adult
questionnaire includes questions on receipt of a flu shot during the past 12 months and
ever having a pneumonia vaccine. These items are used to track progress toward a national
health objective for the year 2000, which is to increase pneumococcal and influenza
vaccination levels to greater than or equal to 60 percent for persons at high risk for
complications from these diseases, including older persons.
Questions in the Child Core are
identical to those in previous NHIS Immunization Surveys, with the addition of new
questions on chicken pox vaccination and adolescent immunizations. The NHIS has been an
important part of the Childhood Immunization Initiative and is critical for monitoring
vaccination coverage of 2 year old children. Information is collected from a knowledgeable
adult about doses of DTP, Polio, MCV, Hib, Hep B, and Varicella given to sample children
under 7 years of age as well as all 12-35 month old children in the household. This
information is collected from a shot record, if available, or by history. Information on
children 7-17 years old is obtained for the following antigens: MCV, Hep B, Varicella and
Td (tetanus diphtheria booster). An ongoing National Immunization Provider Record Check
Study is done in conjunction with the NHIS to adjust the estimates of vaccination coverage
for children 12-35 months of age.
The NHIS has included questions on AIDS since 1987, with a primary focus on AIDS knowledge
and attitudes from 1988 through 1995. As AIDS prevention programs have emphasized early
detection and treatment of HIV infection, the 1997 NHIS questions are designed to monitor
voluntary HIV counseling and testing. Respondents are asked about their blood donation
history and about any tests they may have had for HIV infection exclusive of blood
donation. Persons who have been tested for HIV are asked about the location of the test,
the reason they were tested, whether or not they received the results of their tests, how
the test results were received (by mail, telephone, or in person), and if they received
counseling at the time they received their results. Respondents who indicate that they
have not been tested are asked about any intentions to get tested in the next year, where
they are likely to be tested, and the likely reason they would have the test. Two
questions ask about self-perceived risk of infection, and whether or not any of a list of
risk items applies to the respondent (including being a hemophiliac, having used IV drugs,
and being a homosexual male).