The ICF and statistics on disability and health

Classification, Assessment, Surveys and Classification, Assessment, Surveys and Terminology (CAS/EIP)Terminology (CAS/EIP)

World Health OrganizationWorld Health OrganizationGenevaGeneva

T Bedirhan Ustun and Marguerite SchneiderT Bedirhan Ustun and Marguerite Schneider

Washington City Group on Measurement of Disability Washington City Group on Measurement of Disability Washington D C, Washington D C,

18 - 20 February 200218 - 20 February 2002

UN Disability Statistics

010203040

Country

% o

f pop

UN Disability rates

Wide inter-country variationWide inter-country variation– 60 fold difference (0.2 - 30%)60 fold difference (0.2 - 30%)

ReliabilityReliability

– unknown - not measuredunknown - not measured

Construct validityConstruct validity– not sure what is being measured not sure what is being measured

Possible explanations for between country variations

real differencesreal differences– levels of developmentlevels of development– different environmentsdifferent environments– population age structurepopulation age structure– time of data collectiontime of data collection

Methodological differencesMethodological differences– Census vs surveysCensus vs surveys– different concepts of ‘disability’different concepts of ‘disability’– different domainsdifferent domains– different questionsdifferent questions– different levels of severitydifferent levels of severity

Life expectancy at birth 2000

0 10 20 30 40 50 60 70 80 90

Country

Year

s

Life expectancy

Measuring number of years people are expected to live Measuring number of years people are expected to live based on mortality statistics in countriesbased on mortality statistics in countries

Reliability: GoodReliability: Good– different measurements give similar resultsdifferent measurements give similar results

Differences indicate real and expected differences Differences indicate real and expected differences between countriesbetween countries

– developed vs developingdeveloped vs developing– responsive to health interventionsresponsive to health interventions– internationally recognised consensus measureinternationally recognised consensus measure– used in different indices: Human development index; Health system used in different indices: Human development index; Health system

performanceperformance Need indicators with similar properties for disabilityNeed indicators with similar properties for disability

Life Expectancy and % disabled

0

5

10

15

20

25

30

35

country

%

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

year

s

% disabled Life Expec.

Life expectancy and % disabled

No relationship between country differences in % No relationship between country differences in % disabled and life expectancydisabled and life expectancy

disability measure lacks face validitydisability measure lacks face validity

Country % disabled LE (yrs)

Japan 2.7 73.8

Malawi 2.9 30.9

LE and % disabled (2)

Disability levels cannot be explained by other Disability levels cannot be explained by other covariates, such ascovariates, such as

– age structureage structure– development leveldevelopment level– life expectancylife expectancy– education leveleducation level– economic leveleconomic level– other contextual variables...other contextual variables...

as disability % goes up, more face validityas disability % goes up, more face validity

Current disability statistics are not clearCurrent disability statistics are not clear

What is wrong with disability statistics

Not holistic Not holistic – focus more on the physical (vision, hearing and mobility and focus more on the physical (vision, hearing and mobility and

severe mental handicap) than mental health severe mental handicap) than mental health

not multi-dimensionalnot multi-dimensional– usually activity limitation or impairments or mixusually activity limitation or impairments or mix– very limited in terms of participation and environmental factorsvery limited in terms of participation and environmental factors

not comparable mainly because not using common not comparable mainly because not using common conceptual frameworkconceptual framework

What is wrong with disability statistics (2)

poor reliability and validity - even if measure is poor reliability and validity - even if measure is reliable cannot compare if not same conceptual reliable cannot compare if not same conceptual frameworkframework

traditionally, used set definitions of disability as traditionally, used set definitions of disability as input (blind, deaf, physically disabled, etc. ) - no input (blind, deaf, physically disabled, etc. ) - no measure of individual domains within each categorymeasure of individual domains within each category

threshold is set at outset and cannot be changed threshold is set at outset and cannot be changed and need new set of data for each purposeand need new set of data for each purpose

Disability and health surveys:

Same and differentHealth surveysHealth surveys health conditionhealth condition cause of health cause of health

conditioncondition risk factorsrisk factors prognosisprognosis health system health system

interventionsinterventions satisfactionsatisfaction

Disability surveysDisability surveys health conditionhealth condition level of functioning at level of functioning at

body, person and body, person and societal levelsocietal level

assistance requiredassistance required other facilitators and other facilitators and

barriers barriers satisfactionsatisfaction

WHO World Health Survey

Uses ICF domainsUses ICF domains these domains are based on international these domains are based on international

consensusconsensus domains lend themselves to empirical validation for domains lend themselves to empirical validation for

cross-population comparabilitycross-population comparability– calibration testscalibration tests– vignettesvignettes

20% of domains explain 80% of variance in health 20% of domains explain 80% of variance in health levellevel

summarise data into summary measures of summarise data into summary measures of population healthpopulation health

Level of health across 6 core ICF domains

6 core ICF domains used to measure level of health6 core ICF domains used to measure level of health– CognitionCognition understanding - communicationunderstanding - communication– MobilityMobility moving aroundmoving around– Self-careSelf-care washing, toileting, eatingwashing, toileting, eating– AffectAffect depression, anxietydepression, anxiety– PainPain physical bodily painphysical bodily pain– Usual activitiesUsual activities housework, work, schoolhousework, work, school

Measured in standard surveysMeasured in standard surveys– WHO multi-country Survey Study in 61 countries 2000-2001WHO multi-country Survey Study in 61 countries 2000-2001– Adjusted for self-report biasAdjusted for self-report bias

Level of health across 6 core ICF domains (2)

Aggregate the level across whole populationAggregate the level across whole population

Cross country comparisonsCross country comparisons

Less variation than current disability statistics Less variation than current disability statistics because:because:

– identical concepts being measuredidentical concepts being measured– same method of measurementsame method of measurement– reliability measured and ensuredreliability measured and ensured– self-report bias is adjusted forself-report bias is adjusted for

Average levels of health(yrs lived with disability expressed as fraction of total number of years)

0.00000.02000.04000.06000.08000.10000.12000.14000.16000.1800

Using ICF for both disability and health statistics

According to ICF, disability and health are defined According to ICF, disability and health are defined across the same domainsacross the same domains

Surveys assess the same set of domainsSurveys assess the same set of domains questions measuring the same thing at different questions measuring the same thing at different

levelslevels– impairmentimpairment– capacity & performancecapacity & performance

Key issue is the definition of a threshold level for Key issue is the definition of a threshold level for which you define any disability for a given domainwhich you define any disability for a given domain

Threshold is arbitrary and can be set at different Threshold is arbitrary and can be set at different levels for different purposeslevels for different purposes

ICF Checklist

One component- One pageOne component- One page Salient Categories (169 out of Salient Categories (169 out of

1494) at-a-glance1494) at-a-glance-Impairments with Body Functions-Impairments with Body Functions-Impairments with Body Structures-Impairments with Body Structures-Capacity and Performance in -Capacity and Performance in Activity and Participation DomainsActivity and Participation Domains-Environmental Factors-Environmental Factors-Other Contextual information-Other Contextual information

Additional notesAdditional notes Available for CliniciansAvailable for Clinicians

WHO Disability Assessment Schedule - WHO-DAS II

Validated across number of countries and Validated across number of countries and conditionsconditions

based on ICF domainsbased on ICF domains

What is disability?

Outcome of interaction:Outcome of interaction: person’s health condition + contextual factors = DISABILITYperson’s health condition + contextual factors = DISABILITY

This outcome of disability can be described at 3 levels: This outcome of disability can be described at 3 levels:

– body (impairment of body function or structure)body (impairment of body function or structure)– person (activity limitations measured as capacity) person (activity limitations measured as capacity) – society (participation restrictions measured as performance)society (participation restrictions measured as performance)

Plus description of contextual factors - personal and Plus description of contextual factors - personal and environmentalenvironmental

Body functions and structures

Body functionsBody functions (b - codes) are the physiological (b - codes) are the physiological functions of body systems (including psychological functions of body systems (including psychological functions)functions)

Body structuresBody structures (s -codes) are anatomical parts of (s -codes) are anatomical parts of the body such as organs, limbs and their components the body such as organs, limbs and their components

ImpairmentsImpairments – are problems in body function or structure as a significant deviation are problems in body function or structure as a significant deviation

or lossor loss– are the manifestation of an underlying pathologyare the manifestation of an underlying pathology– can be temporary or permanent; progressive, regressive or static; can be temporary or permanent; progressive, regressive or static;

intermittent or continuous; slight through to severeintermittent or continuous; slight through to severe

Activities and Participation

ActivityActivity is the execution of a task or action by an is the execution of a task or action by an individualindividual

ParticipationParticipation is involvement in a life situation is involvement in a life situation

Activity limitationsActivity limitations are difficulties an individual may are difficulties an individual may have in executing activitieshave in executing activities

Participation restrictionsParticipation restrictions are problems an individual are problems an individual may experience in involvement in life situationsmay experience in involvement in life situations

Constructs for A and P: Capacity

‘‘Just me’ - inherent abilityJust me’ - inherent ability person’s ability to execute a task or person’s ability to execute a task or

action action notion is independent of environment notion is independent of environment measurement within an environment measurement within an environment

(standard environment) (standard environment) compared to individual without a compared to individual without a

similar health condition similar health condition

Constructs for A and P: Performance

‘‘Me plus my context’ - outcome Me plus my context’ - outcome what a person does or what happens in his what a person does or what happens in his

or her current environment or her current environment notion is dependent on environment - notion is dependent on environment -

– when the environment is facilitating, the outcome is improved when the environment is facilitating, the outcome is improved functioning; functioning;

– when the environment is hindering, the outcome is worsening when the environment is hindering, the outcome is worsening disability. disability.

compared to individual without a similar compared to individual without a similar health condition health condition

Environment

ICF Part 2: Contextual factors has two components:ICF Part 2: Contextual factors has two components:– personal factorspersonal factors (not classified in ICF)(not classified in ICF)– environmental factorsenvironmental factors (ICF EF Section)(ICF EF Section)

Environmental factors (EFs) are Environmental factors (EFs) are external factorsexternal factors that that make up the physical, social and attitudinal make up the physical, social and attitudinal environment in which people live and conduct their environment in which people live and conduct their liveslives

EFs form part of both the immediate and distant or EFs form part of both the immediate and distant or background environmentsbackground environments

Environment and functioning

Body Function/Structure and Activity: Body Function/Structure and Activity: – independent of E for definitionindependent of E for definition– manifestation of latent health condition manifestation of latent health condition maymay occur through impact of occur through impact of

EFs EFs – aggravation of existing impairment or Activity Limitationaggravation of existing impairment or Activity Limitation– measurement of function, structure or activity within an measurement of function, structure or activity within an

environmental context environmental context

Participation:Participation:– environment is integral to the definitionenvironment is integral to the definition– description of environmental factors is part of description of description of environmental factors is part of description of

participationparticipation– changes in environment causes changes in participationchanges in environment causes changes in participation

The added value of ICF... comprehensive approach for describing functioning at comprehensive approach for describing functioning at

body, person and societal level.body, person and societal level. common framework forcommon framework for

– needs assessment needs assessment – selection of a targeted population (e.g. eligibility for selection of a targeted population (e.g. eligibility for

benefits)benefits)– comparison within and across different peoplecomparison within and across different people– monitoring and evaluation within and between monitoring and evaluation within and between interventionsinterventions– prioritisation of interventionsprioritisation of interventions

common language for communicationcommon language for communication

Conclusion on ICF

Descriptive tool (not evaluative)Descriptive tool (not evaluative)

provides common frameworkprovides common framework

allows for clear continuum: health and disability allows for clear continuum: health and disability statistics use the same frameworkstatistics use the same framework

provides profile of individual domainsprovides profile of individual domains

allows different thresholds for same data setallows different thresholds for same data set

Conclusions: general

Current international ‘Disability Statistics’ are Current international ‘Disability Statistics’ are problematicproblematic

Census and survey data could be expressed in ICF Census and survey data could be expressed in ICF terms, thereby:terms, thereby:

– increasing conceptual clarityincreasing conceptual clarity– reliabilityreliability– comparabilitycomparability

ICF domains as basis for health and disability ICF domains as basis for health and disability statisticsstatistics

www.who.int/classification/icfwww.who.int/classification/icf

Contacting WHOContacting WHO

How can we include the information matrix and EFs?

Wording and sequence of questionsWording and sequence of questions– ‘‘What difficulty do you have in….?’What difficulty do you have in….?’– ‘‘What happens in your usual/current environment?’What happens in your usual/current environment?’– ‘‘What features of the environment make it easier or more difficult What features of the environment make it easier or more difficult

for you to…?’for you to…?’ Cognitive testing of what context people have in Cognitive testing of what context people have in

mind when reporting difficultiesmind when reporting difficulties Ask about a wider range of domains and Ask about a wider range of domains and

environmental factorsenvironmental factors – involvement in civil society, friendships, caring for others, etc.involvement in civil society, friendships, caring for others, etc.– attitudes, natural environment, design of land areas, systems and attitudes, natural environment, design of land areas, systems and

policies, services such as housing, political, legal, etc. policies, services such as housing, political, legal, etc.

Disability and health surveys: common ground

Health of a populationHealth of a population List of domainsList of domainsVisionVision CommunicationCommunicationHearingHearing Mobility and dexterityMobility and dexteritySpeech Speech Self-care Self-care Digestion Digestion Usual activitiesUsual activitiesBodily excretion Bodily excretion Social functioningSocial functioningFertility Fertility Skin & disfigurementSkin & disfigurementBreathing Breathing Pain Pain Affect Affect Sleep Sleep Energy/vitality Energy/vitality Cognition Cognition