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Developing the World Health Organization Disability Assessment Schedule 2.0

Developing the World Health Organization Disability Assessment Schedule 2.0 - Clinical Hub, UW Health Clinical Tool Search, UW Health Clinical Tool Search, Questionnaires, Related


815
Research
Bull World Health Organ 2010;88:815–823 | doi:10.2471/BLT.09.067231
Introduction
Information on disability is an important component of health
information, as it shows how well an individual is able to func-
tion in general areas of life. Along with traditional indicators of a
population’s health status, such as mortality and morbidity rates,
disability has become important in measuring disease burden, in
evaluating the e�ectiveness of health interventions and in plan-
ning health policy. De�ning and measuring disability, however,
has been challenging. e World Health Organization (WHO)
has tried to address the problem by establishing an international
classi�cation scheme known as the International Classi�cation
of Functioning, Disability and Health (ICF).
1
Nevertheless, all
standard instruments for measuring disability and health need
to be linked conceptually and operationally to the ICF to allow
comparisons across di�erent cultures and populations.
To address this need for a standardized cross-cultural mea-
surement of health status and in response to calls for improving
the scope and cultural adaptability of the original World Health
Organization Disability Assessment Schedule (WHODAS),
2–9

WHO developed a second version (WHODAS 2.0) as a general
measure of functioning and disability in major life domains.
is paper reports on the development strategy and the metric
properties of the WHODAS 2.0.
Conceptual framework for WHODAS 2.0
e WHODAS 2.0 is grounded in the conceptual framework
of the ICF and captures an individual’s level of functioning in
six major life domains: (i) cognition (understanding and com-
munication); (ii) mobility (ability to move and get around);
(iii) self-care (ability to attend to personal hygiene, dressing
and eating, and to live alone); (iv) getting along (ability to in-
teract with other people); (v) life activities (ability to carry out
responsibilities at home, work and school); (vi) participation in
society (ability to engage in community, civil and recreational
activities). All domains were developed from a comprehensive set
of ICF items and made to correspond directly with ICF’s “activ-
ity and participation” dimension (Table 1), which is applicable
to any health condition. For all six domains, the WHODAS
2.0 provides a pro�le and a summary measure of functioning
and disability that is reliable and applicable across cultures in
adult populations.
e WHODAS 2.0 is used for many purposes. It can be
used for conducting population surveys,
10–15
for registers
16
and
for monitoring individual patient outcomes in clinical practice
and in clinical trials of treatment e�ects.
17–27
Methods
e WHODAS 2.0 was constructed through a process involving
extensive review and �eld-testing, as described in the following
sections.
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Objective To describe the development of the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) for
measuring functioning and disability in accordance with the International Classification of Functioning, Disability and Health. WHODAS
2.0 is a standard metric for ensuring scientific comparability across different populations.
Methods A series of studies was carried out globally. Over 65 000 respondents drawn from the general population and from specific
patient populations were interviewed by trained interviewers who applied the WHODAS 2.0 (with 36 items in its full version and 12
items in a shortened version).
Findings The WHODAS 2.0 was found to have high internal consistency (Cronbach’s alpha, _ 0.86), a stable factor structure; high
test-retest reliability (intraclass correlation coefficient: 0.98); good concurrent validity in patient classification when compared with other
recognized disability measurement instruments; conformity to Rasch scaling properties across populations, and good responsiveness
(i.e. sensitivity to change). Effect sizes ranged from 0.44 to 1.38 for different health interventions targeting various health conditions.
Conclusion The WHODAS 2.0 meets the need for a robust instrument that can be easily administered to measure the impact of health
conditions, monitor the effectiveness of interventions and estimate the burden of both mental and physical disorders across different
populations.
Developing the World Health Organization Disability
Assessment Schedule 2.0
T Bedirhan Üstün,
a
Somnath Chatterji,
a
Nenad Kostanjsek,
a
Jürgen Rehm,
b
Cille Kennedy,
c
Joanne Epping-
Jordan,
d
Shekhar Saxena,
a
Michael von Korff
e
& Charles Pull
f
in collaboration with WHO/NIH Joint Project
a
World Health Organization, avenue Appia 20, 1211 Geneva 27, Switzerland.
b
University of Toronto, Toronto, Canada.
c
National Institutes of Health (NIH), Department of Health and Human Services, Washington, United States of America (USA).
d
Independent health consultant (formerly with the World Health Organization), Geneva, Switzerland.
e
Group Health Cooperative, Seattle, USA.
f
Centre Hospitalier de Luxembourg, Luxembourg.
Correspondence to T Bedirhan Üstün (e-mail: ustunb@who.int).
(Submitted: 13 August 2009 – Revised version received: 27 April 2010 – Accepted: 30 April 2010 – Published online: 20 May 2010 )

Bull World Health Organ 2010;88:815–823 | doi:10.2471/BLT.09.067231816
T Bedirhan Üstün et al.WHO assessment schedule for measuring disability
Research
Table 1. World Health Organization Disability Assessment Schedule 2.0, 36 items over six domains with the corresponding
International Classification of Functioning, Disability and Health (ICF) codes
a
Domain Domain question ICF code
1: Cognition In the last 30 days, how much difficulty did you have in:
1.1 Concentrating on doing something for 10 minutes d160 Focusing attention; b140 Attention functions;
d110-d129 Purposeful sensory experiences
1.2 Remembering to do important things b144 Memory functions
1.3 Analysing and finding solutions to problems in day to day life d175 Solving problems; d130-d159 Basic learning
1.4 Learning a new task, for example, learning how to get to a
new place
d1551 Acquiring complex skills
1.5 Generally understanding what people say d310 Communicating with - receiving - spoken messages
1.6 Starting and maintaining a conversation d3500 Starting a conversation; d3501 Sustaining a
conversation
2: Mobility In the last 30 days, how much difficulty did you have in:
2.1 Standing for long periods such as 30 minutes d4154 Maintaining a standing position
2.2 Standing up from sitting down d4104 Standing
2.3 Moving around inside your home d4600 Moving around within the home
2.4 Getting out of your home d4602 Moving around outside the home and other buildings
2.5 Walking a long distance such as a kilometre (or equivalent) d4501 Walking long distances
3: Self-care In the last 30 days, how much difficulty did you have in:
3.1 Washing your whole body d5101 Washing whole body
3.2 Getting dressed d540 Dressing
3.3 Eating d550 Eating
3.4 Staying by yourself for a few days d510-d650 Combination of multiple self-care and domestic
life tasks
4: Getting along In the last 30 days, how much difficulty did you have in
4.1 Dealing with people you do not know d730 Relating with strangers
4.2 Maintaining a friendship d7500 Informal relationships with friends
4.3 Getting along with people who are close to you d760 Family relationships; d770 Intimate relationships;
d750 Informal social relationships
4.4 Making new friends d7500 Informal relationships with friends;
d7200 Forming relationships
4.5 Sexual activities d7702 Sexual relationships
5: Life activities In the last 30 days, how much difficulty did you have in:
5.1 Taking care of your household responsibilities d6 Domestic life
5.2 Doing most important household tasks well d640 Doing housework; d210 Undertaking a single task;
d220 Undertaking multiple tasks
5.3 Getting all the household work done that you needed to do d640 Doing housework; d210 Undertaking a single task;
d220 Undertaking multiple tasks
5.4 Getting your household work done as quickly as needed d640 Doing housework; d210 Undertaking a single task;
d220 Undertaking multiple tasks
5.5 Your day-to-day work/school d850 Remunerative employment; d830 Higher education;
d825 Vocational training; d820 School education
5.6 Doing your most important work/school tasks well d850 Remunerative employment; d830 Higher education;
d825 Vocational training; d820 School education; d210
Undertaking a single task; d 220 Undertaking multiple tasks
5.7 Getting done all the work that you needed to do d850 Remunerative employment; d830 Higher education;
d825 Vocational training; d820 School education; d 210
Undertaking a single task; d220 Undertaking multiple tasks
5.8 Getting your work done as quickly as needed d850 Remunerative employment; d830 Higher education;
d825 Vocational training; d820 School education; d210
Undertaking a single task; d220 Undertaking multiple tasks
6: Participation How much of a problem do you have:
6.1 Joining in community activities d910 Community life
6.2 Because of barriers or hindrances in the world d9 Community, social and civic life
6.3 Living with dignity d940 Human rights
6.4 From time spent on health condition Not applicable (impact question)
6.5 Feeling emotionally affected b152 Emotional functions
6.6 Because health is a drain on your financial resources d8700 Personal economic resources
6.7 With your family facing difficulties due to your health Not applicable (impact question)
6.8 Doing things for relaxation or pleasure by yourself d920 Recreation and leisure
a
The WHO DAS 2.0 also includes two preliminary sections that ask about demographic variables and general health. These sections are to be used if the WHO DAS
2.0 is used alone, but may be dropped or modified if WHO DAS 2.0 is used in conjunction with other instruments that already collect such information. A final
optional section asks about the attributes and impact of identified problems.

Bull World Health Organ 2010;88:815–823 | doi:10.2471/BLT.09.067231 817
T Bedirhan Üstün et al.
WHO assessment schedule for measuring disability
Research
Existing measures
In preparation for the development of the
WHODAS 2.0, we conducted a review
of existing measurement instruments
and of the literature on the conceptual
aspects and measurement of functioning
and disability. e instruments we chose
included various measures of disability,
handicap, quality of life and other aspects
of health, such as the ability to perform
the activities of daily living (including
instrumental ones), as well as global and
speci�c measures of well-being (including
subjective well-being).
28,29
We compiled
information from more than 300 instru-
ments in a database showing a common
pool of items, along with the origin and
known psychometric properties of each
instrument. An Instrument Development
Task Force composed of international
experts reviewed the database and pooled
the items in it using the ICF as the com-
mon framework.
Research study and field testing
Since the WHODAS 2.0 was developed
primarily to allow cross-cultural com-
parisons, it was based on an extensive
cross-cultural study spanning 19 countries
around the world.
30
e items included
in the WHODAS 2.0 were selected ašer
exploring how health status is assessed in
di�erent cultures through a process that
involved linguistic analysis of health-relat-
ed terms, interviews with key informants
and focus group discussions, as well as
qualitative methods (e.g. pile sorting and
concept mapping).
e development of the WHODAS
2.0 also involved �eld testing across
countries in two waves (Appendix A,
available at: http://www.who.int/icidh/
whodas/). Wave 1 focused on 96 items
proposed for inclusion in the instrument
being developed. In these initial �eld
testing studies, empirical feedback was
obtained on the metric qualities of the
proposed items, possible redundancy,
screener performance in predicting the
results of the full instrument, rating
scales and the suitability of di�erent
disability recall time frames (e.g. 1 week,
1 month, 3 months, 1 year or lifetime).
e studies also included cognitive
interviews to determine how well the
respondents understood the questions
and reacted to the contents of the in-
strument. e second of �eld testing
studies involved checking the reliability
of a shortened, 36-item version of the
WHODAS 2.0 by means of a standard
statistical procedure, in line with classic
test and item response theory (IRT).
For each wave of �eld testing, the
overall study design required the presence
of four di�erent groups at each site, all
having an equal number of subjects. e
groups were composed of: (i) members
of the general population in apparent
good health; (ii) people with physical
disorders; (iii) people with mental or
emotional disorders; and (iv) people with
problems related to alcohol or drug use.
Subjects 18 years of age or older, divided
equally into males and females, were re-
cruited at each site.
Statistical analysis
Reliability was assessed by having a di�er-
ent interviewer repeat the interviews one
week later, on average. e results were
expressed in terms of kappa and intraclass
correlation coežcients. Internal consis-
tency was assessed by calculating Cron-
bach’s alpha (α) coežcient for patients at
baseline. Pearson’s correlation coežcient
(r) was used to determine concurrent
validity between the WHODAS 2.0 and
other generic health status and disability
measures. Principal components analysis
was used to assess the construct validity
of the scales. All items in the WHODAS
2.0 were tested against the Partial Credit
Model for ordinality. e paired t-test
was used for assessing the responsive-
ness of WHODAS 2.0 scores to clinical
intervention.
Results
General application
e WHODAS 2.0 was found to per-
form well in widely di�erent cultures,
among di�erent subgroups of the gen-
eral population, among people with
physical disorders and among those with
mental health problems or addictions.
Respondents found the questionnaire
meaningful, relevant and interesting.
e WHODAS 2.0 has already been
translated into 27 languages following
a rigorous WHO translation and back-
translation protocol. Linguistic analy-
sis and expert opinion survey results
showed the content to be comparable
and equivalent in di�erent cultures, as
was later con�rmed by psychometric
tests. e interview time was 5 minutes
for the 12-item version and 20 minutes
for the 36-item version. e 96-item ver-
sion was found to require an interview
time of 63−94 minutes.
In cognitive interviews, most respon-
dents preferred the 30-day time frame and
many pointed out problems in remember-
ing with longer time frames. Regarding
the concept of “dižculty”, some respond-
ers reported reasons other than health,
including having too little time, too little
money or too much to do – all of which
were outside the de�nition of limitation
in functioning due to a health condition.
Item reduction
Using the �eld trials data, we reduced to
34 the 96 items proposed for inclusion
in the WHODAS 2.0 in accordance
with classic test theory and item response
theory. We also added two more items
– one about sexual activity and another
about the impact of the health condition
on the family – based on suggestions from
�eld interviewers and on the results of the
expert opinion survey. A repeat survey
con�rmed the face validity of the resulting
36-item version. Scores in the six selected
domains explained more than 95% of the
variance in the total score on the 96-item
version. Repeated factor analysis showed
the same structure for all domains.
36-item factor structure
In all cultures and populations tested,
factor analysis of the WHODAS 2.0
revealed a robust factor structure on two
levels: a �rst level consisting of a general
disability factor, and a second level com-
posed of the six WHODAS representing
di�erent life areas (Fig. 1). On con�rma-
tory factor analysis, the factor structure
was similar across the di�erent study sites
and populations tested. e results of in-
dependent wave 2 �eld testing essentially
replicated this factor structure as well.
Internal consistency
Internal consistency, a measure of the
correlation between items in a proposed
scale, was very good for WHODAS 2.0
domains. Cronbach’s α coežcients for the
di�erent domains were as follows: cogni-
tion (6 items), 0.86; mobility (5 items),
0.90; self-care (4 items), 0.79; getting along
(5 items), 0.84; life activities for home
(4 items), 0.98; life activities for work
(4 items), 0.96; and participation in society
(8 items), 0.84. Total internal consistency of
the WHODAS 2.0 was 0.96 for 36 items.
IRT characteristics
WHODAS 2.0 showed very good IRT
characteristics, indicative of the compa-

Bull World Health Organ 2010;88:815–823 | doi:10.2471/BLT.09.067231818
T Bedirhan Üstün et al.WHO assessment schedule for measuring disability
Research
rability of the assessment across di�erent
populations. In wave 1 of �eld testing,
good response functions were one of the
criteria for selecting items.
In �eld testing wave 2, items in the
36-item version ful�lled the Rasch char-
acteristics. All items were compatible with
speci�c objective measurements using a
Partial Credit Model.
Test-retest reliability
e WHODAS 2.0 showed good test-
rest reliability, a measure of the instru-
ment’s stability in repeated applications.
Results of the reliability analysis are
shown in Fig. 2 at the item, domain and
general instrument levels. e intraclass
correlation coežcient ranged from 0.69
to 0.89 at the item level and from 0.93
to 0.96 at the domain level, and it was
0.98 overall. More detailed analyses by
country, region and demographic and
other variables are reported separately.
31
Concurrent validity
Concurrent validity results, a measure
of how well the WHODAS 2.0 results
correlate with the results of other in-
struments that measure the same dis-
ability constructs, are summarized in
Table 2. e table shows the correlation
coežcients for relevant domains in
comparisons with other instruments
that are less widely known, such as the
WHO ¨uality of Life measure (WHO
QOL),
32
the London Handicap Scale
(LHS),
33
the Functional Independent
Measure (FIM)
34
and the Short Form
Health Survey (SF).
35–37
As expected,
the highest correlation coežcients were
found for speci�c domains measuring
similar constructs, such as the FIM and
WHODAS 2.0 mobility domains. Most
other coežcients were between 0.45 and
0.65, which suggests not only that the
WHODAS 2.0 and other recognized
tests have similar constructs, but also
that the WHODAS 2.0 is measuring
something di�erent. In addition, the
WHODAS 2.0 score showed correlation
in the number of days in which household
tasks were reduced (r = 0.52) and in the
number of absences from work lasting half
a day or more (r = 0.63), respectively. e
overall score on the WHODAS 2.0 was
highly correlated with the overall score
on the LHS (r = 0.75), the WHOQOL
(r = 0.68) and the FIM (r = 0.68). It was
less strongly correlated with SF mental
health component scores (r = 0.17) be-
cause the SF measures signs of depression
rather than functioning per se. What is
important is that WHODAS 2.0 do-
main scores correlate highly with scores
on comparable instruments designed
to measure disability in speci�c areas
(e.g. the FIM motor scale, r = 0.67 and
the SF-36 Physical Component Score,
r = 0.66). e correlation coežcients
obtained indicate that the WHODAS
2.0 is measuring what it aims to measure
(i.e. day-to-day functioning across a range
of activity domains).
Subgroup analysis
WHODAS 2.0 is able to di�erentiate
between special types of disabilities in
patients belonging to di�erent clinical
subgroups. Domain and total scores are
shown in Fig. 3. Results for disability
domain pro�les for di�erent populations
were all in the expected direction. For
example, the group with physical health
problems showed higher scores in “get-
ting around”, whereas groups with mental
Fig. 1. Factor structure of the World Health Organization Disability Assessment
Schedule 2.0, 36-item version, in formative field studies
6 items
0.94
D1: Cognitive
0.82–0.92
5 itemsD2: Mobility
0.83–0.96
4 itemsD3: Self care
0.85–0.92
5 itemsD4: Getting along
0.82–0.94
4 itemsD5: Life activities
0.98
8 itemsD6: Participation
0.88–0.92
General disability factor
0.95
0.93
0.99
0.91
0.97
ICC, intraclass correlation coefficient.
Fig. 2. Test–retest reliability of the World Health Organization Disability Assessment
Schedule 2.0, 36-item version
a
6 items D1: Cognitive
0.69–0.80
5 items D2: Mobility
0.83–0.89
4 items D3: Self care
0.72–0.88
5 items D4: Getting along
0.72–0.82
4 items D51: Household
0.83–0.84
4 items D52: Work
0.75–0.80
Total domain ICCDomainItem ICC
0.94
0.96
0.95
0.93
0.94
0.94
0.98
8 items D6: Participation
0.75–0.80
Overall
ICC
0.95
ICC, intraclass correlation coefficient.
a
Field testing wave 2 (n
total
= 1565; n for the ICC depends on the domain, e.g. on how many subjects responded to
all items at both time points: D1, 1448; D2, 1529; D3, 1430; D4, 1222; D5(1), 1399; D5(2), only with remunerated
work, 808; D6, 1431).

Bull World Health Organ 2010;88:815–823 | doi:10.2471/BLT.09.067231 819
T Bedirhan Üstün et al.
WHO assessment schedule for measuring disability
Research
health problems and drug problems
showed higher scores in “getting along
with people”. is con�rms that the in-
strument has face validity. People drawn
from the general population got lower
scores in all domains and a lower general
score than people in speci�c treatment
subgroups. Individuals on treatment for
mental problems or addictions reported
more dižculty with cognitive activities
and with getting along than patients on
treatment for physical problems, who
showed greater dižculty (i.e. scored
higher) getting around and performing
self-care. Participation in community
activities was most dižcult for drug users.
Screening properties
In wave 2 �eld trials, the 12-item short
version of the WHODAS 2.0 explained
81% of the variance of the 36-item
version. For each domain, the 12-item
version included two sentinel items with
good screening properties that identi�ed
over 90% of all individuals with even mild
disabilities when tested on all 36 items.
Scoring WHODAS 2.0
Multiple ways to score WHODAS 2.0
were compared in terms of their informa-
tion value and practicality in daily use. As
a result, two ways to compute the sum-
mary scores, namely simple and complex
scoring, were found useful. In simple
scoring, the scores assigned to each of
the items (none, 1; mild, 2; moderate, 3;
severe, 4; and extreme, 5) are summed up
without recoding or collapsing response
categories. Simple scoring is as practical
as hand scoring and may be preferable
for busy clinical settings or interviews.
e simple scoring of WHODAS 2.0 is
only speci�c to the sample at hand and
should not be assumed to be comparable
across populations. e psychometric
properties of the WHODAS 2.0, namely
its one-dimensional structure with high
internal consistency, make it possible to
add the scores.
38
In complex scoring, also
known as item response theory-based
scoring,
39
multiple levels of dižculty
for each WHODAS 2.0 item are al-
lowed for. Complex scoring makes more
�ne-grained analyses possible, since the
information for the response categories
is used in full for comparative analysis
across populations or subpopulations.
With item response theory-based scoring
for WHODAS 2.0, each item response
(none, mild, moderate, severe and ex-
treme) is treated separately and the sum-
mary score is generated with a computer
by di�erentially weighting the items and
the levels of severity.
In addition to the total scores,
WHODAS 2.0 also makes it possible
to compute domain-speci�c scores for
cognition, mobility, self-care, getting
along, life activities (at home and at work)
and social participation. We used SPSS
sošware, version 10 (SPPS Inc., Chicago,
United States of America), to compute
the summary score. Both the program and
the domain scores are available at: http://
www.who.int/icidh/whodas/
Table 2. Concurrent validity coefficients for the World Health Organization Disability Assessment Schedule 2.0, 36-item and 12-item
versions, versus other recognized disability measurement instruments
Domain Instrument
SF 36
(n = 608–658)
c
SF 12
a

(n = 93–94)
c
WHO QOL
(n = 257–288)
c
LHS
(n = 662–839)
c
FIM
b

(n = 68–82)
c
1 Cognition: understanding and communicating −0.19 −0.10 −0.50 −0.62 −0.53
2 Mobility: getting around −0.68 −0.69 −0.50 −0.53 −0.78
3 Self-care −0.55 −0.52 −0.48 −0.58 −0.75
4 Interpersonal: getting along −0.21 −0.21 −0.54 −0.50 −0.34
5.1 Household −0.54 −0.46 −0.57 −0.64 −0.60
5.2 Work −0.59 −0.64 −0.63 −0.52 −0.52
6 Participation in society −0.55 −0.43 −0.66 −0.64 −0.62
FIM, functional independent measure; LHS, london handicap scale; SF, short form health survey; WHO QOL, world health organization quality of life scale.
a
For correlations in domains 1 and 4, the SF mental scores were used. For all other domains the SF physical scores were used.
b
For domain 1, the FIM cognition score was used as the basis of the correlation. For domain 2, the FIM mobility score was used. For all other domains, the overall FIM
score was used.
c
Then in parentheses represents the minimum and maximum number of subjects on which the correlations are based.
Fig. 3. World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0):
domain profile by subgroup
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Bull World Health Organ 2010;88:815–823 | doi:10.2471/BLT.09.067231820
T Bedirhan Üstün et al.WHO assessment schedule for measuring disability
Research
WHODAS 2.0 provides standard
scores for the general population derived
from large international samples against
which individuals or groups can be com-
pared, as was done in the reliability and
validity study conducted in wave 2 of the
WHODAS 2.0 development process;
and the WHO Multi-Country Survey
Study.
12
Fig. 4 gives the population stan-
dard scores for IRT-based scoring of the
36-item WHODAS 2.0. Accordingly, an
individual with 22 positive item responses
would represent the 80th percentile. Sum-
mary scores and population percentiles
for item response theory-based scoring
of the 12-item WHODAS 2.0 are also
available. Details are available in the
WHODAS 2.0 training manual
40
and
at: http://www.who.int/icidh/whodas/
Responsiveness
When the mean standardized response
(that is, the change in mean score divided
by the standard deviation of the change in
score) was used as a measure of e�ect size,
the WHODAS 2.0 was found to be at
least as sensitive to change as comparable
functioning scales, For example, Fig. 5
shows WHODAS 2.0 responsiveness
as noted in the case of treatment for de-
pression in patients from four di�erent
countries. E�ect sizes for the WHODAS
2.0, which ranged from 0.44 to 1.07,
are comparable to those obtained with
established functioning scales. Similar
e�ect sizes (0.44–1.38) were obtained for
interventions targeting individuals with
schizophrenia, osteoarthritis, back pain
and alcohol dependence.
41
Discussion
Stringent tests performed during WHO-
DAS 2.0 development have shown that
the WHODAS 2.0 can be used across
cultures, sexes and age groups, as well as
for di�erent types of diseases and health
conditions. e instrument covers key life
activities well. e12-item version of the
WHODAS 2.0 can be administered in
less than 5 minutes and the 36-item ver-
sion in less than 20 during interviews and
in 5 to 10 minutes when self-administered
or administered by proxy. Scores are easily
obtained and interpreted. ey represent
multidimensional disability based on the
ICF, and the underlying factor structure
is robust. Details and instructions on how
to administer di�erent versions of the
WHODAS 2.0 and compute its scores
can be found in the WHODAS 2.0 train-
ing manual.
40
WHODAS 2.0 has good psychomet-
ric qualities, including good reliability
and item-response characteristics, and its
robust factor structure remains the same
across cultures and in di�erent patient
populations. It shows concurrent validity
when compared with other measures of
disability or health status or with clinician
ratings. ese �ndings have been replicat-
ed across di�erent countries and in a wide
range of patient and general population
samples. us, the WHODAS 2.0 can be
used to assess individual patients as well
as to explore di�erences between groups.
Field trials of the use of WHODAS
2.0 in health services research have fo-
cused on responsiveness, that is, on how
well WHODAS 2.0 can detect changes
following treatment under speci�c con-
ditions. We use the WHODAS 2.0 to
predict disability-related outcomes such
as health care utilization, costs and work
productivity, and we have compared its
Fig. 4. Population distribution of scores on the World Health Organization Disability
Assessment Schedule 2.0 (WHODAS 2.0), 36-item version
G
e
n
e
r
a
l

p
o
p
u
l
a
t
i
o
n

p
e
r
c
e
n
t
i
l
e
0
100
40
WHODAS 2.0 IRT-based score
90
80
70
60
50
3 6 12 22 41 100
IRT, item response theory.
Fig. 5. Responsiveness (sensitivity to change) of the World Health Organization
Disability Assessment Schedule 2.0 (WHODAS 2.0), 36-item version (SF 36), as
noted in the case of treatment for depression
Outpatient care
(Mexico City, Mexico)
WHODAS 2.0
Comparator
Effect size
a
0
0.8n = 100
0.74SF -36 (MCS)
Outpatient care
(Ibadan, Nigeria)
1.07n = 60
0.81LHS
Outpatient care
of elderly
(London, England)
0.44n = 40
0.23LHS
Primary
health care
(Seattle, USA)
0.72n = 73
1.32SF -36 (MCS)
0.2 0.4 0.6 0.8 1 1.2 1.4
LHS, London Handicap Scale; MCS, mental component summary.
a
The effect size represents the change in mean value divided by one standard deviation.

Bull World Health Organ 2010;88:815–823 | doi:10.2471/BLT.09.067231 821
T Bedirhan Üstün et al.
WHO assessment schedule for measuring disability
Research
predictive validity to that of other dis-
ability measures.
In the Multi-country Survey Study
that was conducted in 12 WHO Member
States, WHODAS 2.0 was adminis-
tered to randomly selected adults from
the general population in face-to-face
interviews.
12
ese surveys have been
used to formulate a descriptive system of
disability weights (i.e. utilities) for use in
summary measures of population health,
such as disability-adjusted life years.
Econometric methods, such as time trade-
o� or person trade-o� tools, have proved
useful in eliciting disability weights. How-
ever, the application of these methods in
general population surveys is problematic.
Descriptive methods, such as application
of WHODAS 2.0, are not only easier to
apply but also yield more reliable indices
for disability weights.
e WHODAS 2.0 has several
limitations. It covers mainly the activities
and participation domains of the ICF, so
bodily impairments and environmental
factors are not included. is design de-
cision was made during the initial phase
of development. However, work is under
way to develop an additional module for
bodily impairments.
40
Furthermore, the
WHODAS 2.0 is only applicable to adult
populations. Ašer the ICF for children
and youth (ICF-CY) was published in
2007, plans were initiated to develop a
version of the WHODAS 2.0 for children
and youth.
42
e WHODAS 2.0 framework can
be applied in di�erent formats for uses
such as clinical interviews or telephone
interviews. e feasibility and reliability
of these applications are currently being
determined. Computer-adaptive test-
ing, a novel method for shortening the
application, will enhance the feasibility
of using the WHODAS 2.0 in di�erent
studies. Population standard norms will
be continuously improved during future
applications of the WHODAS 2.0. Simi-
larly, item banking for di�erent clinical
intervention trials will enable compara-
tive e�ectiveness studies.
In summary, WHODAS 2.0 has
the potential to serve as a reliable and
valid tool for assessing functioning and
disability across countries, populations
and diseases. It provides data that are
culturally meaningful and comparable.
us, it can be used as a common metric
for assessing the level of functioning in
individuals with di�erent health condi-
tions as well as in the general population.
e WHODAS 2.0 can be used in surveys
and in clinical research settings and it can
generate information of use in evaluat-
ing health needs and the e�ectiveness
of interventions to reduce disability and
improve health. �
Acknowledgements
e Task Force on Assessment Instru-
ments also included: Elizabeth Badley,
Cille Kennedy, Ronald Kessler, Michael
Von Kor�, Martin Prince, Karen Ritchie,
Ritu Sadana, Gregory Simon, Robert
Trotter and Durk Wiersma.
e following are the WHO col-
laborative investigators involved in
the WHO/NIH Joint Project: Gavin
Andrews (Australia); omas Kugener
(Austria); Kruy Kim Hourn (Cambo-
dia); Yao Guizhong (China); Jesús Saiz
(Cuba); Venos Malvreas (Greece); R
Srinivasan Murty (India, Bangalore);
R ara (India, Chennai); Hemraj Pal
(India, Delhi); Matilde Leonardi, Ugo
Nocentini (Italy); Miyako Tazaki ( Ja-
pan); Elia Karam (Lebanon); Charles
Pull (Luxembourg ); Hans Wyirand
Hoek (Netherlands); AO Odejide
(Nigeria); José Luis Segura García
(Peru); Radu Vrasti (Romania); José
Luis Vásquez Barquero (Spain); Adel
Chaker (Tunisia); Berna Ulug (Turkey);
Nick Glozier (United Kingdom); Patrick
Doyle, Katherine McGonagle, Michael
von Kor� (United States of America).
A full list of collaborators is available
at: http://www.who.int/icidh/whodas/
Funding: e WHODAS 2.0 develop-
ment was funded through the WHO/
National Institutes of Health (NIH) Joint
Project on Assessment and Classi�cation
of Disability (MH 35883–17).
Competing interests: None declared.
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��� ��
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Bull World Health Organ 2010;88:815–823 | doi:10.2471/BLT.09.067231822
T Bedirhan Üstün et al.WHO assessment schedule for measuring disability
Research
Resumen
Evolución del Programa de evaluación de la discapacidad 2.0 de la Organización Mundial de la Salud
Objetivo Describir la evolución del Programa de evaluación de la
discapacidad 2.0 de la Organización Mundial de la Salud (WHODAS
2.0) para medir la funcionalidad y la discapacidad de acuerdo con la
Clasificación Internacional del Funcionamiento, la Discapacidad y la Salud.
El WHODAS 2.0 es una medida normalizada para garantizar la posibilidad
de comparar científicamente las diversas poblaciones.
Métodos Se han llevado a cabo varios estudios a nivel mundial.
Encuestadores cualificados entrevistaron a más de 65 000 personas de
la población general y de poblaciones específicas de pacientes aplicando
el WHODAS 2.0 (con 36 apartados en su versión completa y 12 apartados
en la versión abreviada).
Resultados Se descubrió que el WHODAS 2.0 presentaba una elevada
congruencia interna (coeficiente _ de Cronbach: 0,86), una estructura
factorial estable; una fiabilidad elevada de las pruebas realizadas en dos
ocasiones (coeficiente de correlación intraclase: 0,98); validez simultánea
adecuada en la clasificación de los pacientes, en comparación con otros
instrumentos reconocidos de medición de la discapacidad; concordancia
con las propiedades del modelo de Rasch a través de las poblaciones
y buena capacidad de respuesta (es decir, sensibilidad al cambio). Las
magnitudes del efecto oscilaron entre 0,44 y 1,38 para diferentes
intervenciones sanitarias dirigidas a diversas dolencias.
Conclusión El WHODAS 2.0 satisface la necesidad de contar con un
instrumento consistente que se pueda administrar fácilmente para medir
el impacto de las enfermedades, controlar la eficacia de las intervenciones
y calcular la carga de los trastornos mentales y físicos en diferentes
poblaciones.
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Développement de l’outil Disability Assessment Schedule 2.0 de l’OMS
O b j e c t i f D é c r i r e l e d é v e l o p p e m e n t d e l ’ o u t i l
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