Measuring Disability Prevalence

Daniel Mont, HDNSPDisability and Development TeamJune 6, 2007

World Bank and Disability – What is the link?World Bank and Disability – What is the link?

The World Bank’s mission is to eliminate povertyThe World Bank’s mission is to eliminate poverty Disability leads to poverty, and poverty leads to Disability leads to poverty, and poverty leads to

disabilitydisability Disability affects not just disabled people, but Disability affects not just disabled people, but

their families and communitiestheir families and communities Doing a good job on poverty alleviation requires Doing a good job on poverty alleviation requires

taking disabled people into accounttaking disabled people into account

Problems with existing data

Often not available Definitions and measures not

standard and often outdated Quality is poor

Prevalence Rates Vary Dramatically (Censuses)

United States 19.4%

United Kingdom 12.2%

Uganda 3.5%

Mexico 2.3%

India 2.1%

Kenya 0.7%

Prevalence Rates Vary Dramatically – (Surveys)

New Zealand 20.0%

Spain 15.0%

Ecuador 12.1%

Nicaragua 10.3%

China 5.0%

Egypt 4.4%

Medical Model vs. Social Model

Medical model – Disability is a physical, mental or psychological health condition that limits a person’s activities

Social model – Disability arises from the interaction of a person’s functional status with the environment

Medical versus Social Model

PERSONAL vs. SOCIAL Medical care vs. Social integration Individual treatment vs. Social action Professional help vs. Individual and collective

responsibility Personal adjustment vs. Environmental

adjustment Behavior vs. Attitude Care vs. Human rights Individual adaptation vs. Social change

WHO’s International Classification of Functioning, Disability and Health (ICF) Incorporates social model approach Describes facets of human functioning that

may be affected by a health condition Purpose:

provide a scientific basis for the consequences of health conditions

establish a common language to improve communications

permit comparisons of data across countries and health care disciplines,

provide a systematic coding scheme for health information systems

ICF Domains – Body Function and Structure

Physiological and psychological function of body systems

Very specific recording of detailed functional abilities and impairments

Not linked to cause. For example, fluency and rhythm of speech functions – could be from stuttering, stroke, or autism

Activities and Participation

Describes individual’s functioning as a whole person

Range from Basic to Complex Basic: e.g., walking, eating, and bathing Complex: e.g., work and schooling

Activities – tasks an individual can do that require multiple body functions

Participation – higher order activities that involve integration in the community

ICF is a Functionally Based System

ICF does not measure disability It describes people’s functional abilities in various

domains

Health conditions that affect functional status are not part of classification system

Disability is not an “all or nothing” concept Disability arises out of the environmental

context

Health Condition Health Condition ((disorder/diseasedisorder/disease))

International Classification of International Classification of Functioning, Disability and Health Functioning, Disability and Health

(ICF)(ICF)

Environmental Environmental FactorsFactors

Personal Personal FactorsFactors

Body Body function&structurefunction&structure (Impairment(Impairment))

ActivitiesActivities(Limitation)(Limitation)

ParticipationParticipation(Restriction)(Restriction)

How can we capture such a complex concept of disability in a single measure?

Why not ask this old question?

Do you have a physical, mental, or emotional health condition that limits the amount or type of work you can do?

Because…

In some sense, the answer for everyone is “YES”

The answer is a function of the environment the respondents live in Physical environment Cultural environment Policy environment

The answer is a function of their particular circumstances at the time

The question is very complex and easily misinterpreted

Why not ask this question?

Do you have a disability?

Under counts what most people consider disability

People think of disability as very serious and won’t report minor or moderate disabilities

“Disability” creates shame and stigma so people do not want to identify themselves that way, especially for mental and psychological

People think of disability relative to their expectations of normal functioning so it undercounts the elderly

Why not ask detailed diagnosis questions?

Many people don’t have or don’t know their diagnosis Some diagnoses have intense stigma A diagnosis doesn’t tell you much about ability to

function Can miss age related disabilities If people have multiple diagnoses they’ll often report

only one The one with less stigma The one that occurred first The one that’s most visible

Ability and willingness to report often depends on their interaction with health services and thus other socio-demographic factors

Census-based Disability Rates

Do you have a disability?

Nigeria 0.5

Jordan 1.2

List of conditions

Mexico 1.8

Uganda 3.5

Activity Based

Poland 10.0

Brazil 14.5

Where we focus on this model depends on the purpose of measurement

Health Condition Health Condition ((disorder/diseasedisorder/disease))

Environmental Environmental FactorsFactors

Personal Personal FactorsFactors

Body Body function&structurefunction&structure (Impairment(Impairment))

ActivitiesActivities(Limitation)(Limitation)

ParticipationParticipation(Restriction)(Restriction)

National prevalence rates

Internationally comparable Capture broad spectrum of those with

disabilities Questions suitable for census To examine the relationship between

disability and socio-economic outcomes

Equalization of Opportunity

UN Washington Group concluded that Equalization of Opportunities was most appropriate for a census.

So ask participation questions? No. That identifies the segment of the

population that is not participating so can’t look at progress of inclusion

Not internationally comparable

Activity level questions indicate whether a person is having difficulty with important tasks

If these activity limitations are correlated with outcome measures (e.g., poverty) this indicates there are important barriers to participation

WG Questions Because of a physical, mental or emotional health

condition… Do you have difficulty seeing, even if wearing

glasses? Do you have difficulty hearing, even if wearing

hearing aid/s? Do you have difficulty walking or climbing stairs? Do you have difficulty remembering or

concentrating Do you have difficulty with self-care, such as

washing all over or dressing? Do you have difficulty communicating (for example,

understanding or being understood by others)? Response categories: No, Some, A lot, Unable

Cognitive Testing

To examine interpretation of questions

Conducted in about 15 countries Performed very well Issues:

Difficulty with glasses and hearing aid/s clause

Communication question

Field Testing

Vietnam and South Africa UNESCAP testing in Philippines, Fiji,

India, Indonesia and Mongolia Again, responses fairly robust

Responses

Scaled responses No, Some, A lot, and Unable Allows user to shift threshold as desired Captures heterogeneity of disability

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Non-disabled

Activity Limitation Scores - Zambia

Recommendations for General Prevalence Measures

Questions should be based on functionality Questions should focus on core activities

Equalization of opportunity International comparability

Do not use the word “disability” Responses should be scaled A range of prevalence should be reported

for various levels of severity, rather than a single prevalence rate

Do you have difficulty walking or climbing steps?

PctCumulative

Pct

Some difficulty 16.6 16.6

A lot of difficulty 5.2 21.8

Unable 0.7 22.5

Mobility Limitations in Vietnam

UNESCAP Field Testing

India Indonesia MongoliaSeeing

Mild 4.7 14.9 12.4Severe/Unable 4.4 7.3 4.2

Cognitive

Mild 8.1 16.3 9.7Severe/Unable 3.7 2.9 4.0

Disability Rates in LAC

Total Male Female

Brazil 14.5 13.7 15.3

Ecuador 12.1 11.8 12.4

Nicaragua 10.3 9.1 11.3

Disability Prevalence Ecuador 12.1% Nicaragua 10.3% Brazil 14.5% Zambia 13.1% Vietnam 10.5% (preliminary) India 8% Roughly, 10-12% is reasonable estimate

with less than half “severe” and about 1-2% incapable of self-care