may 151 the definition and measurement of disability the work of the washington group on disability...
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Apr 18, 2023 1
The Definition and Measurementof DisabilityThe Work of the Washington Group on Disability Statistics
Jennifer H. MadansNational Center for Health Statistics, USAfor the Washington Group on Disability Statistics
Apr 18, 2023 2
This presentation will cover:
• Disability definition and the International Classification of Functioning, Disability and Health – ICF
• Disability measurement and the Washington Group on Disability Statistics – WG
Apr 18, 2023 3
The Washington Group on Disability Statistics (WG)• In June of 2001, the UN International
Seminar on the Measurement of Disability recommended the development of principles and standard forms for global indicators of disability to be used in censuses
• There was a broad consensus on the need for population based measures of disability for country use and for international comparisons
Apr 18, 2023 4
Global disability prevalence rates*
High-income countries Low-income countries
Year % Year %
Canada 1991 14.7 Kenya 1989 0.7
Germany 1992 8.4 Namibia 1991 3.1
Italy 1994 5.0 Nigeria 1991 0.5
Netherlands 1986 11.6 Senegal 1988 1.1
Norway 1995 17.8 South Africa 1980 0.5
Sweden 1988 12.1 Zambia 1990 0.9
Spain 1986 15.0 Kenya 1989 0.7
UK 1991 12.2 Zimbabwe 1997 1.9
USA 1994 15.0 Malawi 1983 2.9
* Sources and methodologies are country specific
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The WG was created to: • Foster international cooperation in the area of
health and disability statistics• Untangle the web of confusing and conflicting
disability estimates• Develop a small set of general disability
measures suitable for use on Censuses• Develop extended set/s of items to measure
disability on population surveys• Address methodological issues associated
with disability measurement
Apr 18, 2023 6
Our understanding of disability has changed:
from: a medical definition – based on a medical
condition as an individual pathology
to:a concept based on the consequences of
diseases - on functional capacity and/or social participation
Apr 18, 2023 7
Moving from Concept to Definition to Measurement:
The Conceptual Model
ICF selected as the conceptual model:• Common point of reference • Common vocabulary• Does NOT provide an operational
definition or a way to measure the concepts
Apr 18, 2023 8
Health Condition(disorder/disease)
Body Function &Structure (Impairment)
Activities(Limitation)
Participation(Restriction)
EnvironmentalFactors
PersonalFactors
Source: World Health Organization, 2001
The ICF Model
Apr 18, 2023 9
Moving from Concept to Definition to Measurement:
The Definitional Paradox• There is no single operational definition
of disability• Different operational definitions lead to
different estimates• The question you are trying to answer
(the purpose) will determine which definition to use
• Source of data can impact choice of purpose and definition
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Purpose of Data Collection3 major classes of purposes at aggregate level:• Service provision• Monitoring functioning in the population• Assess equalization of opportunities/
participation
2 criteria for selection of a purpose:• Relevance - particularly for policy makers and
program officials• Feasibility - especially for international
comparability
Apr 18, 2023 11
Purpose: Service provision
• Seeks to identify those with specific needs, usually the most serious problems
• Requires detailed information about the person and the environment
• Influenced by the organization and structure of service organizations within a particular culture
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Needs assessment/service provision• Benefit eligibility• Income support / social security• Subsidies
• Device manufacture• Formal rehabilitation services• Education programs• Medical rehabilitation• Vocation rehabilitation
• Personal assistant services• Advocacy services
Apr 18, 2023 13
Purpose: Monitoring functioning in the population
• Seeks to identify all those with activity limitations or participation restrictions due to ‘health’ – e.g. ‘are you limited in the work you can do because of a health problem?’
• Difficult to craft questions• Response comparability is problematic
since participation is culturally and environmentally determined
Example: Monitoring trends in functioning
• Information is used to characterize population functioning
• Focus on the interaction of people and environment
0
5
10
15
20
25
Pro
port
ion (
%)
2005 2010 2015 2020 2025
Population reporting limitation in work
Apr 18, 2023 15
Purpose: Equalization of opportunities
• Seeks to identify all those at greater risk than the general population of experiencing restrictions in social participation, for example in employment, education or civic life
• Disability as a demographic• Civil rights definition
Apr 18, 2023 16
UN Convention on the Rights of Persons with Disabilities?
UN Convention (2006): Persons with disabilities include those who have long-term physical, mental, intellectual or sensory impairments which in interaction with various barriers may hinder their full and effective participation in society on an equal basis with others.
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Moving from Concept to Definition to Measurement:
Measurement of equalization of opportunities
• Locate the definition of disability at the most basic level of activity in core domains
• Defined as the ability or inability to carry out basic actions at the level of the whole person (i.e. walking, climbing stairs, lifting packages, seeing a friend across the room)
Apr 18, 2023 18
Moving from Concept to Definition to Measurement:
Measurement of equalization of opportunities
• Measure functioning that defines disability status without accommodations to the extent possible (e.g., use of assistive devices, personal assistance)
• Participation outcomes are measured with accommodations (e.g., are you employed)
• Connection between ‘disability’ and participation is made during data analysis
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Health Condition(disorder/disease)
Body Function &Structure (Impairment)
Participation(Restriction)
EnvironmentalFactors
PersonalFactors
Source: World Health Organization, 2001
Locating Risk in the ICF Model
?
Example: Equalization of opportunities
• Compares actual participation by level of risk for limitations in activity or participation
• Disability used as a demographic
% Employed
0
30
60
90
Pro
port
ion (
%)
Nondisabled Disabled
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Criteria for inclusion of domains
• Cross cultural comparability• Suitability for self-report• Parsimonious• Validity across various methodological
modes
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Possible question optionsMobility• Walking• Climbing stairs• Bending or stooping• Reaching or lifting• Using handsSensory• Seeing• HearingCommunicating• Understanding• Speaking
Cognitive functions• Learning• Remembering• Making decisions• ConcentratingEmotional functioning• Interpersonal interactions• Psychological well-being
Apr 18, 2023 23
WG short set of questions for censuses:Because of a Health problem:1) Do you have difficulty seeing even if wearing glasses?2) Do you have difficulty hearing even if using a hearing
aid?3) Do you have difficulty walking or climbing stairs?4) Do you have difficulty remembering or concentrating?5) Do you have difficulty with (self-care such as) washing
all over or dressing?6) Using your usual (customary) language, do you have
difficulty communicating (for example understanding or being understood by others)?
Response categories: No - no difficulty; Yes - some difficulty; Yes - a lot of difficulty; Cannot do at all
Apr 18, 2023 24
What do we end up with?
• Identify persons with similar types and degree of limitations in basic actions regardless of nationality or culture
• Represent the majority (but not all) persons with limitations in basic actions in any one nation—no psychological or upper body functioning
• Represent commonly occurring limitations in domains that can be captured in the Census context
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Intended use of data• Compare levels of participation in
employment, education, or family/social life for those with disability versus those without disability to see if persons with disability have achieved social inclusion
• Monitor effectiveness of programs / policies to promote full participation can be monitored – UN Convention
• Monitor prevalence trends for persons with limitations in specific basic activity domains
Apr 18, 2023 26
Limitations• One set of measures will not satisfy the
multiple needs for disability data• Excluded populations:
• very young children• institutionalized population• homeless• floating populations
• It is not our purpose to:• identify every person with a disability within
every community • replicate a population evaluated across a wider
range of domains that would be possible with other forms of data collection – extended set
Apr 18, 2023 27
Work on Extended Measures• The WG is developing an extended set of
questions that:• goes into greater depth on the same 6
domains covered by the short set of questions, and
• includes additional domains of functioning such as learning, affect, pain and fatigue,
• includes questions about age at onset and impact of the difficulty,
• is currently being cognitively tested in preparation for subsequent field testing.
Apr 18, 2023 28
RowVision (1) Hearing (1) Mobility
Communi-cation
Cognition/ remembering
Upper Body
Learning/ understanding
Affect Pain FatigueADL/ IADL
Getting Along with
People
Life Activities
Participation in Society
Short SetSingle Questions (1) d a d
Extended SetMultiple Questions (1) c c c c
Use of Assistive DevicesMicro-E (2)
Functioning with Assistance, Micro-E (2)
5 Age at Onset
6 Cause
7 Duration
8 Impact ? ? ?
9Meso-Environment
(3)
10Macro-Environment
(4)
ICF Chapter Reference - Activities/Participation
ICF-1 ICF-1 ICF-4 ICF-3 ICF-1,2 ICF-4 ICF-1 ICF-2 ICF-5,6 ICF-7 ICF-8 ICF-9
Capacity Perform
ance
Basic Activity Domains Complex Activity Domains
(5) See Note below
Washington Group/Budapest Initiative/UNESCAP Activities and Workplan
QuestionnaireTopic/Type
To be obtained through other sources, not personal survey data collections
b
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