Disability Interview Schedule (DIS)

Abstract

The Disability Interview Schedule (DIS) is a validated, interviewer-administered assessment tool developed by Bennett and Garrad in 1970. It was specifically designed for use in large-scale population surveys to quantify the prevalence and severity of functional disability resulting from chronic disease or physical impairment. The scale measures performance across fundamental domains of daily life, including Mobility, Self-Care, Domestic Duties, and Occupational status, providing detailed, graded responses regarding the level of assistance required or the extent of limitation experienced.

Keywords

Disability, Functional Assessment, Activities of Daily Living (ADLs), Mobility, Self-Care, Chronic Illness, Population Survey, Interview Schedule, Public Health.

Authors

Bennett, A. E., Garrad, J.

Purpose

The primary purpose of the Disability Interview Schedule (DIS) is to objectively measure the degree of functional impairment in individuals, allowing researchers and public health officials to gauge the overall burden of disability within a community. By using a standardized interview schedule, the DIS aims to minimize subjective interpretation and provide comparable data across different cohorts.

The instrument is particularly valuable in epidemiological studies focused on long-term conditions, helping to identify specific areas where individuals require support, ranging from basic self-care tasks to complex domestic and occupational responsibilities.

Construct

The DIS is constructed to measure functional disability as defined by observable limitations in performing essential life tasks. It operates under the conceptual framework that disability is multidimensional, encompassing physical function, personal independence, and social participation (via domestic and occupational roles). The scale breaks down functional capacity into distinct, measurable behavioral components.

The core construct is operationalized through four major domains: Mobility (ability to walk, climb stairs, transfer, and travel), Self-Care (personal hygiene and feeding), Domestic Duties (household maintenance), and Occupation (employment status and working capacity). Responses are graded to capture not just the presence of impairment but the severity and dependence required (e.g., unaccompanied vs. accompanied and supported).

Validity

The original research by Garrad and Bennett (1971) focused heavily on establishing the validity of the DIS for use in population surveys of chronic disease and disability. Content validity is high, as the items cover core components recognized globally as essential Activities of Daily Living (ADLs) and instrumental activities.

Furthermore, the validation process likely established criterion validity by comparing DIS scores against existing clinical assessments or professional judgments of functional status, ensuring that the interview results accurately reflected real-world functional limitations. The detailed response categories contribute to the scale’s ability to discriminate between varying degrees of impairment.

Reliability

As a structured interview schedule, the DIS is designed for strong inter-rater reliability. The explicit, exhaustive, and mutually exclusive response options minimize variability caused by different interviewers.

While specific statistical reliability coefficients (such as Cronbach’s alpha or test-retest reliability) are not detailed in the available summary content, the use of the DIS in major epidemiological studies, as documented in subsequent literature (e.g., Williams et al., 1976), implies that it met the required standards for dependable measurement in public health research settings.

Factor Analysis

Although formal factor analysis results are not provided in the source material, the inherent structure of the DIS suggests a clear multi-factorial model. The scale is organized around four distinct functional domains: Mobility, Self-Care, Domestic Duties, and Occupation.

These domains function as separate factors, reflecting different aspects of dependence and functional capacity. For instance, the ability to perform basic Self-Care tasks is measured separately from the capacity for complex Mobility or employment, indicating that the instrument is designed to assess a profile of functional impairments rather than yielding a single, unitary disability score.

Instrument

Test Type: Structured Interview Schedule/Functional Status Assessment

Format: Interviewer-administered questionnaire with forced-choice and graded options.

Language Available: English (Original)

Population Group: Adults with chronic illness or physical impairment.

Age Group: Adult population (specific questions relating to occupation categorize respondents based on retirement age: Males 65+ and 64-, Females 60+ and 59-).

Population Details: Utilized primarily in community and population-based surveys to assess epidemiological patterns of functional limitation due to chronic disease.

Test Methodology: The interviewer asks specific questions about the respondent’s capacity to perform tasks (e.g., walking, dressing, cooking). Responses are recorded based on distance, level of assistance required (unaccompanied, accompanied, supported), or use of adaptive equipment.

Keywords

Functional Status, Chronic Disease Assessment, ADLs, Interviewer-Administered, Public Health Measurement, Functional Limitation, Rehabilitation.

Authors

Author ORCID Identifier: Not specified in source material.

Affiliation Email addresses: Not specified in source material.

Correspondence Address: Not specified in source material.

Permissions & Fee and Test Year

Test Year: 1970 (Initial publication/development).

Permissions & Fee: The instrument is widely cited in academic literature and measurement guides (e.g., McDowell, 2006) and is generally utilized in academic and public health research without proprietary restrictions. The original PDF containing the instrument can be downloaded here: www.a4ebm.org/sites/default/files/Measuring%20Health.pdf

Reference’s

• Garrad‚ J. & Bennett‚ A. E. (1971). A validated interview schedule for use in population surveys of chronic disease and disability. British Journal of Preventive and Social Medicine‚ 25‚ 97-104.

• Williams‚ R. G. A.‚ Johnston‚ M.‚ Willis‚ I. A. et al. (1976). Disability: A model and measurement. British Journal of Preventive and Social Medicine‚ 30‚ 71-78.

• McDowell‚ Ian. (2006). Measuring Health: A Guide to Rating Scales and Questionnaires‚ Third Edition. OXFORD UNIVERSITY PRESS

Items of the Disability Interview Schedule (DIS)

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

MOBILITY

Walking

Do you walk outdoors in the street (with crutch or stick if used)?

If ‘Yes’:

• one mile or more
• 1⁄4 mile
• 100 yds.
• 10 yds.

If ‘No’:

• Between rooms
• Within room
• Unable to walk

and:

• Unaccompanied
• Accompanied
• Acc. & support

Stairs

Do you walk up stairs?

• To 1st floor or above
• 5–8 steps or stairs
• 2–4 steps or stairs
• 1 step
• Unacc.
• Acc.
• Acc. & Supp.
• No need to mount stairs
• Mounts stairs other than by walking
• Unable to mount stairs

Do you walk down stairs?

• From 1 floor to another
• 5–8 steps or stairs
• 2–4 steps or stairs
• 1 step
• Goes down stairs other than by walking
• Unable to descend stairs
• Unacc.
• Acc.
• Acc. & Supp.
• No need to descend stairs

Transfer

• Do you need help to get into bed? …………………………………. Yes No
• Do you need help to get out of bed? …………………………………. Yes No
• Bedfast………………………………….
• Do you need help to sit down in a chair? …………………………………….. Yes No
• Do you need help to stand up from a chair? …………………………………….. Yes No
• Not applicable …………………………….

Travel

Do you drive yourself in a car?

• Normal (unadapt.)
• Adapted
• Invacar
• Self-propelled vehicle (outdoors)
• Does not drive

Do you travel by bus or train?

If ‘Yes’:

• Whenever necessary
• Only out of rush hour

and:

• Unaccompanied
• Accompanied

If ‘No’:

• Unable to use bus and train
• Unable to use bus‚ train and car
• Does not travel by choice
• Uses private transport by choice

SELF CARE

Are you able to feed yourself:

• Without any help
• With specially prepared food or containers
• With assistance
• Not at all‚ must be fed

Are you able to dress yourself completely:

• Without any help
• With help other fastenings
• With help other than fastenings
• Does not dress

Are you able to undress yourself completely:

• Without any help
• With help other fastenings
• With help other than fastenings
• Not applicable

Are you able to use the lavatory:

• Without any help
• Receptacles with- out assistance
• Lavatory with assistance
• Receptacles with assistance

Are you able to wash yourself:

• Without any help
• With assistance for sha‎ving‚ combing hair‚ etc.
• With help for bodily washing
• Not at all

DOMESTIC DUTIES

Do you do your own:

• Shopping… all‚ part‚ none‚ preference‚ unable
• Cooking… all‚ part‚ none‚ preference‚ unable
• Cleaning… all‚ part‚ none‚ preference‚ unable
• Clothes washing… all‚ part‚ none‚ preference‚ unable
• Men with no household duties… part

OCCUPATION

Do you have a paid job at present?

If ‘Yes’:

• Full-time
• Part-time

and:

• Normal working
• Modified working
• Sheltered employment

If ‘No’:

Males 65 and over Females 60 and over

• Age retired
• Prem. retired
• Non-employed

Males 64 and under Females 59 and under

• Unemployed
• Unfit
• Non-employed