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NCHS

National Health Interview Survey on Disability

Background

In the United States there are an estimated 35-43 million people with physical and mental disabilities. The Americans with Disabilities Act (ADA), which was signed into law in July 1990, is one of the catalysts prompting legal and policy reforms in the area of disability. However, policy-relevant data on disability needed to understand its many aspects and impacts is either very limited or nonexistent, particularly on a national level.

In an effort to meet some of these data needs, four Federal offices (Office of the Assistant Secretary for Planning and Evaluation, Health and Human Services; Office of Supplemental Security Income, Social Security Administration (SSA); Office of Disability, SSA; and Bureau of Maternal and Child Health, Health Resources Administration) planned several national surveys about various aspects of disability in the early 1990's.

Because many of their interests overlapped, these agencies decided to merge their efforts into developing one survey to be included with the National Health Interview Survey (NHIS) for 2 consecutive years. As plans for this survey evolved, other organizations with an interest in disability participated including:

  1. Office of the Assistant Secretary for Health, DHHS
  2. Administration on Developmental Disabilities, DHHS
  3. Administration on Aging, DHHS
  4. Disability Prevention Program, CDC
  5. National Center for Medical Rehabilitation Research, NICHD
  6. Center for Mental Health Services, SAMHSA
  7. Rehabilitation Services Administration, Department of Education
  8. National Institute for Disability and Rehabilitation Research, Department of Education
  9. Office of Research and Demonstrations, Health Care Financing Administration
  10. Office of Research and Statistics, SSA
  11. Bureau of Transportation Statistics, DOT
  12. Robert Wood Johnson Foundation

Survey Goals and Objectives

One important goal of the National Health Interview Survey-Disability Survey (NHIS-D) was to develop a series of questionnaires that would provide a useful set of measures while maintaining a balance between the social, administrative, and medical considerations involved in disability measurement. The NHIS-D is not limited to one definition of disability; therefore, it will allow analysts from varying programs to combine data items in different ways to meet specific agency or program needs. It is designed to collect data that can be used to understand disability, to develop public health policy, to produce simple prevalence estimates of selected health conditions, and to provide descriptive baseline statistics on the effects of disabilities.

Questionnaire Development and Data Collection Methods

Given such broad objectives for the NHIS-D, it was apparent very early in the planning process that it would be impossible to collect all of the data needed about disability in one interview. Thus, it was decided to use a two phase data collection plan with a series of disability questionnaires.

Development of these questionnaires involved extensive input from Federal agencies as well as consultants from the research community. Drafts of the questionnaires were reviewed by an outside panel of experts from the academic and private research community. Questionnaires were also tested extensively in the NCHS Questionnaire Design Research Laboratory and in field tests.

Introduction to NHIS-D Phase I

The Phase I Disability questionnaire was administered at the same time as the NHIS Core, and collected information about all members of the NHIS households. For more information about the NHIS Core, please refer to Current Estimates. As with the NHIS Core, the NHIS-D Phase I questions were answered by any available adult in the household who was knowledgeable about the health of other household members. The Phase I questionnaire collected basic data on disability and was used as a screening device to determine eligibility for the second phase of the survey.

Although the NHIS-D Phase I questionnaire collected information on persons of all ages, for children, a broader perspective on disability was taken. In addition to impairments, information was also collected on children with chronic illness or special health needs. In order to examine these issues in detail, the Phase I questionnaire had 3 sections exclusively for children: a section on special health needs of children, a section on special education services for children, and a section on early childhood development for children under 5 years of age.

Because of the low frequency of occurrence of disabilities within the noninstitutionalized civilian population, Phase I of the NHIS-D was fielded over a 2-year period from 1994-95.

Content of the 1994 and 1995 NHIS-D - Phase I Data

Information collected with the NHIS-D Phase I questionnaire has been organized into two data files.

  1. Disability Phase I Person File - this file contains information about each person in the NHIS-D Phase I sample. Topics covered in this file include:
    • Sensory, Communication, and Mobility
      • Vision, hearing, and mobility aids - all ages
      • Communication, understanding, and learning - age 5+
      • Dizziness, balance, ringing in ears, and sense of smell + taste - age 18+
    • Developmental Disability Conditions (includes polio) - all ages
    • Disability
      • Activities of daily living (ADL) - age 5+
      • Instrumental activities of daily living (IADL) - age 18+
    • Functional limitation - age 18+
    • Mental health - age 18+
    • Services and benefits - age 18+
    • Special health needs of children - primarily age under 18
    • Early child development - questions vary by specific age under 5
    • Education - two sets of questions for those age 3-17 and those under 3
    • Relationship to respondent - age under 18
    • Perceived disability - all ages
  2. Disability Phase I Condition File - This file contains detailed information on each condition reported as being related to certain disabilities. There are 29 places in the NHIS-D Phase I questionnaire that ask for the name of the main condition causing that health problem, impairment, limitation, or disability. Each of these 29 items is considered a "source", that is, a source from which a condition name emanated. In most cases, only one attributable condition could be accepted. The reported condition could be one that was mentioned in the NHIS Core or it could be first mentioned in the NHIS-D. Information about each condition mentioned, regardless of its source, is contained in this file. The file structure is similar in format to the NHIS Core Condition File. It should be noted that the Disability Phase I Condition File is NOT intended to make national prevalence estimates of conditions contained in that file. The purpose of this file is to provide more detail on reported conditions for which there is some specific or possible relevance to a source of disability.

Content of the 1994 and 1995 NHIS-D - Phase II Data

Eligibility for the second phase of the NHIS-D (termed the "Disability Followback Survey or DFS") was based not only on responses to the Phase I questionnaire, but also on responses to other parts of the NHIS on activity limitation and receipt of disability benefits. The specific inclusion criteria for Phase II are summarized in a table. These sample selection criteria were applied to the unedited data from Phase I. Interviewing for Phase II began in August 1994. Only a brief description of this second phase is included here.

There are 4 DFS questionnaires: one for children, one for adults, one for elderly persons (69 years of age and over) without any indication of disability (also called the Supplement on Aging or SOA), and one for persons with a past history of polio.

For children in Phase II, additional information was collected on utilization and need for services, functional assessment, including emotional and behavioral development, and the impact of the child's disability on the family. The respondent for this component was the parent or the adult in the household who knew the most about the selected child's health.

For adults, the Phase II questionnaire obtained more extensive information about the persons with disabilities on issues such as employment, use of services and benefits, transportation and personal assistance needs, housing characteristics, environmental barriers, and participation in social activities. The respondent for the Phase II Adult questionnaire was the individual defined from the Phase I interview whenever possible.

Since disabilities increase with age, detailed information on older persons, even those currently not experiencing any type of disability, is needed for planning purposes. The SOA questionnaire included a number of items identical or similar to those on the Adult DFS questionnaire because many of the topics are very relevant to the elderly population. In most cases, these older adults responded for themselves.

The Polio Questionnaire collected additional information about the symptoms and impact of the illness at the time of initial diagnosis of polio and at various times after the diagnosis. Information on current health problems was also obtained. Whenever possible, self response by the polio survivor was required for this component.

News Releases and Fact Sheets

Data Highlights

Bibliography

Methods

Survey Instruments

1994 Disability Followback Survey

Questionnaires for: 1995 Phase I

1995 Phase 2

1994 Phase 1

1994 Phase 2

Data Analysis

Variance Estimation: Using SUDAAN

Public-use Data Files (Micro-data)

Downloadable data files via ftp

Downloadable documentation via ftp

Related Links

Related Sites

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