RESEARCH PAPER

Assessing disability in morbidly obese individuals: the Italian Society ofObesity test for obesity-related disabilities

LORENZO M. DONINI1, AMELIA BRUNANI2, ANNA SIRTORI2, CLAUDIA SAVINA3,

SETTIMIO TEMPERA1, MASSIMO CUZZOLARO1, GIOVANNI SPERA1,

VERONICA CIMOLIN2,4, HELMER PRECILIOS2, ALBERTO RAGGI5,

PAOLO CAPODAGLIO2 & THE SIO-ISDCA TASK FORCE*

1Department of Medical Physiopathology (Food Science Section) –‘Sapienza’ University of Rome, Italy, 2Rehabilitation Unit

and Research Lab in Biomechanics and Rehabilitation, Istituto Auxologico Italiano IRCCS, Piancavallo, Verbania, Italy,3Villa delleQuerce Clinical Rehabilitation Institute – Nemi, RM – Italy, 4Bioengnerring Department, Politecnico di Milano,

Milano, Italy, and 5Neurology, Public Health and Disability Unit, Neurological Institute C. Besta IRCCS Foundation,

Milan, Italy

Accepted March 2011

AbstractPurpose. To validate a new obesity-specific disability assessment test: the Obesity-related Disability test (Test SIO DisabilitaObesita Correlata, TSD-OC).Methods. Adult obese individuals were assessed with the TSD-OC, 36-Item Short-Form Health Survey (SF-36), 6-minwalking test (6MWT) and grip strength. The TSD-OC is composed of 36 items divided into seven sections (pain, stiffness,activities of daily living and indoor mobility, housework, outdoor activities, occupational activities and social life). Statisticalcorrelations between the TSD-OC, functional assessment (6MWT and grip strength) and quality of life parameters (SF-36)were analysed. Internal consistency was assessed with Cronbach’s a test. Test–retest reliability was evaluated in a subgroup of30 individuals. A linking exercise between TSD-OC items and categories of the International Classification of Functioning,Disability and Health was performed.Results. Test–retest showed excellent stability (r¼ 0.90) and excellent internal consistency was reported (Cronbach’sa4 0.90). Significant low to moderate correlations between TSD-OC, SF-36 scores, 6MWT and grip strength wereobserved. A total of 26 ICF categories were linked, mostly related to the area of mobility.Conclusions. The TSD-OC is a reliable and valid instrument for measuring self-reported disability in obese subjects. It mayrepresent an important tool for establishing rehabilitation needs in individuals with obesity-related disability, for planningappropriate rehabilitation programmes and for evaluating their effectiveness.

Keywords: Obesity, assessment, TSD-OC

Introduction

Obesity is a clinical condition characterised by

significant clinical implications, such as co-morbid-

ities and somatic fragility, which seriously affect

independence, psychological well being and overall

quality of life (QoL) at all ages [1,2]. The 2000–2001

Health Survey for England [3] revealed that many of

the encountered disabling conditions were signifi-

cantly correlated with obesity. Conditions such as

osteoarthritis, diabetes mellitus and chronic obstruc-

tive pulmonary disease, which are often associated

with obesity, were ranked among the 10 most

burdensome diseases for high-income countries in

the last update of WHO’s Global Burden of Disease

study [4]. Obesity is in fact associated with an

Correspondence: Veronica Cimolin, Department of Bioengineering, Politecnico di Milano, P.zza Leonardo Da Vinci 32, 20133, Milano, Italy.

Tel: þ39 02 2399 3359. E-mail: Veronica.cimolin@polimi.it

*SIO-SISDCA Task Force Collaborators are as follows: Maria RosaBollea, Emanuela Castellaneta, Roberto Dalle Grave, Ezio Di Flaviano, Maria Gabriella

Gentile, FabrizioJacoangeli, Cecilia Invitti, Carla Lubrano, Fausto Manara, Barbara Mezzani, RobertoOstuzzi, GianluigiPanzolato, FabrizioPasanisi, Maria

Letizia Petroni, Ferruccio Santini, Felice Strollo, Patrizia Todisco, and Mauro Zamboni.

Disability and Rehabilitation, 2011; Early Online, 1–10

ISSN 0963-8288 print/ISSN 1464-5165 online ª 2011 Informa UK, Ltd.

DOI: 10.3109/09638288.2011.575529

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increased risk of disability after the age of 50 years in

terms of limited mobility and activities of daily living

(ADL) and with a significantly lower number of

disability-free years (5.7 years for males and 5.02

years for females) [5]. As body mass index (BMI)

and age increase, these activities are bound to be

limited.

Disability associated with obesity may be predo-

minantly due to motor or cardiorespiratory compli-

cations, as well as a combination of the two

according to the coexistence of a range of related

conditions (i.e. osteoarthritis, cardiorespiratory dis-

orders, etc.). Some articles [6–10] reported difficul-

ties for obese subjects in ADL (i.e. personal hygiene

and dressing), indoor mobility, household chores

(i.e. rising from a couch, getting onto a high stool

and taking objects from a cupboard or picking them

up from the floor), outdoor activities (i.e. lifting and

carrying bags, walking4100 m and standing in a

queue) and occupational activities. As for the latter

point, obesity seems to be significantly related to sick

leave, reduction in productivity, the need to be

assigned to less demanding jobs and represents a

significant risk factor for work inability [11–14].

One of the major problems in the research area on

obesity-related disability is the lack of widely used

obesity-specific scales able to provide a thorough

understanding of the physical difficulties and limita-

tions in everyday life. Standardised functional

assessments are often non-specifically validated in

the obese population and are not designed to

measure clinical appropriateness, which heightens

the risk of underestimating the problems. Functional

status measures (i.e. the Barthel Index) assess only

physical disability as reflected by ADL or Instru-

mented ADL scales and thus fails to detect

functional status changes until disability is extreme

[15]. The association between the Functional In-

dependence Measure (FIM), the gold standard for

measuring outcomes in rehabilitation and BMI has

been recently investigated in unfit individuals with

medical complications who are undergoing intensive

rehabilitation: they showed higher gains in FIM

scores, mostly accounted for by the motor subscale,

as compared with normal weight patients [16].

Some evidence exists that obese individuals under-

going intensive rehabilitation do not have suboptimal

outcomes as compared with their leaner counterparts

[17]. Vincent and Vincent [18] showed that a high

BMI does not prevent FIM gains during inpatient

rehabilitation after total knee replacement. However,

these gains were achieved less efficiently and at a

higher cost than when BMI is normal. Two small

studies also reported no association between BMI

and FIM scores in post-acute stroke and joint

arthroplasty rehabilitation patients [19]. Since post-

acute rehabilitation individuals may encompass a

range of diagnoses, it is likely that the BMI-FIM

association may vary within subgroups. Those

studies investigate whether a high BMI might

actually impede the rehabilitation process after

surgery or stroke and the gains in physical function.

The FIM scale has never been used for the

assessment of obesity-related disability, which ap-

pears to be an entity backed by a consistent body of

recent literature, independent of recent acute events.

In 2002, the United States Task Force on Develop-

ing Obesity Outcomes and Learning Standards

(TOOLS) [20] recommended a summary of out-

come measures for the obese patient, which included

the use of the Medical Outcome Survey 36-Item

Short-Form Health Survey (SF-36) or its 12-items

version (SF-12) [21,22]. The use of such scales

allows researchers to compare the burden associated

with obesity against that associated with other

disorders. The SF-36 physical composite score

(PCS) also taps lower extremity functions likely to

be impaired by osteoarthritis and may be useful for

identifying obese individuals who would benefit from

a more intensive follow-up with disease-specific

scales. However, the SF-36 content is not restricted

to functional status, but includes a conflation of

symptom, function and health-perception scales or

items that, moreover, are not specific to the obese

individuals’ situation. Obesity-specific measures, on

the contrary, have the potential advantage of captur-

ing experiences frequently reported by obese indivi-

duals, which are not, in turn, assessed by generic

QoL or mood inventories measures, and tend to be

more sensitive to change [23].

The Impact of Weight on Quality of Life Ques-

tionnaire is a 74-item self-report obesity-specific

measure [24] that describes the effect of body weight

on functioning in areas such as health, social status,

work, mobility, self-esteem, sexual activities, ADL

and eating. Both the long and the reduced 31-item

versions of the questionnaire have shown good test–

retest reliability and internal consistency and re-

vealed significant improvements in all domains

following weight reduction [25]. Other obesity-

specific instruments suffer the disadvantage of being

used in limited settings and of lacking empirical

validation: the ORWELL97 suffers from limited and

unfocused content [26], and the Swedish Obese

Subjects Intervention Trial Battery is very psychoso-

cial oriented and lengthy [27]. The TOOLS Task

Force (2002) recommends the use of an existing

symptom-specific scale in addition to the more

general measure when the goal is to provide an in-

depth evaluation of one specific obesity-related

symptom.

In 2001, the WHO released the International

Classification of Functioning, Disability and Health

(ICF) as an international reference for understanding

2 L. M. Donini et al.

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functioning and disability [28]. Disability in ICF is

understood as the relationships between impairments

at the level of the body, which determine limitations

and restrictions in undertaking activities and in

engaging in social situations and interaction with

environmental factors. Acting as facilitators, environ-

mental factors contribute to an increase in functional

level and a reduction in disability, if they are barriers

to the individual then they contribute to an increase in

disability. As a recent literature review has shown

[29], several experiences with the use of ICF in a

clinical context exist, and ICF-related tools like the

ICF-Core Set have been developed. The Compre-

hensive ICF-Core Set for obesity consists of 109

categories [30] mainly covering aspects related to

cardiovascular and metabolic functions (and their

related structures) as well as activities related to

mobility and self-care. The ICF is also useful as a

background to describe the content of existing

assessment tools, through standardised linking

rules [31].

Previous studies on obesity implications evidenced

different areas of impairments in body functions and

structures, as well as an increase in disability risk;

mobility limitations were reported in several studies

[9,23–27,32,33]. Daily activities appear to be re-

duced or limited as a direct expression of the

intrinsic health state, with a limited intervention of

external factors. Impairments in emotional func-

tions, even without a diagnosis of depression, are

reported together with impairments in body image as

well as in energy level. Such findings support known

evidence of the implications of emotional and

psychological factors in obese individuals’ eating

behaviours [34–37]. Disability in the area of inter-

personal interactions and social isolation, with

difficulties in creating and maintaining intimate

relationships, and in relating to strangers, are also

recognised features of obese individuals. Social

stigma and discrimination were frequently deemed

to underlie relational problems, jointly with personal

characteristics such as guilt and shame [34,35,38].

Multidimensional rehabilitation approaches have

been proposed to treat morbidly obese subjects [11].

Measuring disability with instruments reflecting the

full range of functional status appears therefore

crucial in order to initiate rehabilitation programmes

for obese subjects and to assess their effectiveness. In

2009, it was with this goal in mind that the Italian

Society of Obesity (SIO) developed a new scale for

assessing disability correlated to obesity in adult

populations, the short-form questionnaire the Obe-

sity-related Disability test (Test SIO Disabilita

Obesita Correlata, TSD.OC) [39]. This instrument

is intended to target the most important obesity-

specific functional status dimensions such as physi-

cal, emotional functioning and social functioning.

The aim of our study was to verify the extent to

which this new instrument is linked to the different

ICF components and to evaluate its validity and

reliability in a group of obese individuals.

Materials and methods

Subjects

A multi-centric study coordinated by the SIO and

involving 16 Italian hospitals (SIO-SISDCA Task

Force) was performed. Obese individuals under-

going multidisciplinary rehabilitation for obesity in

different settings (outpatient, day-hospital and in-

patient) were enrolled between January and June

2009. To be enrolled, individuals had to be aged over

20 years, have a BMI higher than 30 kg/m2 and be

able to walk a distance of at least 30 m indepen-

dently. Exclusion criteria were, to have undergone

orthopaedic surgery on the lower limbs and spine in

the 2 years prior to the start of the study, the presence

of neurological disturbances, the assumption of

pharmacological treatment for equilibrium and vestib-

ular disturbances, cardiological and respiratory dis-

turbances. The study protocol was approved by the

Ethical Committee of the Sapienza University of

Rome and all subjects gave written informed consent

prior to enrolment. A subsample of 30 randomly

selected individuals completed the TSD-OC a second

time 24 h after the first assessment.

Methods

The TSD-OC is composed of 36 items divided into

seven sections (pain: 5 items; stiffness: 2 items; ADL

and indoor mobility: 7 items; housework: 7 items;

outdoor activities: 5 items; occupational activities: 4

items and social life: 6 items), which reflect the

domains in which individuals experience the most

common problems. Individuals are requested to

provide a subjective assessment of their disability

for each item on a 0–10 visual analogue scale (VAS),

where 10 indicates the highest level of disability and

0 no difficulties in performing the task. In this

preliminary application, we decided to define arbi-

trary provisional ‘disability scores’ as the sum of each

item’s raw score divided by the maximum possible

score, expressed as a percentage according to the

following linear transformation: (raw score/max

score)6 100. For example, a raw score of 90, being

25% of the total possible score (which corresponds to

360), results in a final disability score of 25. In this

way, disability scores can be calculated for each

subsection, thus enabling a preliminary section-by-

section comparison.

The SIO test for obesity-related disabilities 3

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The SF-36 [40] is a multi-purpose general health

survey with 36 questions, generally used to evaluate

health-related quality of life (HRQoL). It is com-

posed of 36 items grouped into eight scales and of

two additional summary measures, the PCS and the

mental composite score (MCS). The scores of the

scales range between 0 and 100, with higher scores

reflecting greater HRQoL, while PCS and MCS are

norm-based scores with a mean of 50 and a standard

deviation of 10.

Objective measures of health status included

handgrip strength and walking speed. Grip strength

was measured by a handgrip (Jamar1 Hydraulic

Hand Dynamometer – 5030J1). The maximum

value (kg) out of three trials using the dominant

hand was recorded. Between two consecutive trials,

a 1-min recovery was provided. In the 6-min

walking test (6MWT) [41], subjects were in-

structed to walk as fast as they could along an

even, undisturbed 30 m hospital corridor marked

every 5 m with coloured tape on the floor. They

were allowed to stop or rest during the test if

necessary. The distance walked in 6 min was

computed. The subject’s pulse, respiratory rate,

blood pressure and perceived fatigue on Borg’s

scale were measured before the test, at 1, 3 and

5 min after the start and at test completion.

Statistics

For assessing retest reliability, Spearman’s rank

order correlation (rs) between the first and the

second administration of the TSD-OC in the

subsample was used. An rs of 0.80 was set as the

minimum level of acceptable stability [41]. Wilcox-

on’s signed-rank test was used to test the difference

between test and retest scores. Internal consistency

of the test was assessed using Cronbach’s a. The avalues of 0.6–0.7 indicate acceptable reliability,

while values higher than 0.8 indicate good reliability

[42]. To assess validity, Pearson’s correlation was

calculated between the TSD-OC score, SF-36

scores and objective physical assessments. Statistical

significance was set at P50.05. Data were analysed

using the SPSS for Windows 10.0 (SPSS Inc.,

1989–1999) statistical software package. SF-36,

6MWT and handgrip strength were also compared

against normative values [43–45], describing the

percentage of subjects who reported values lower

than normative ones.

Given the taxonomy of ICF and its coding rules,

‘rolling-up’ procedures have been applied to move

from detailed information to more generic, and

therefore to more wide open, second-level codes

(e.g. from d4200 to d420) that are more useful for

exploring the content of the questionnaire.

Results

The study group consisted of 501 subjects with a

mean BMI of 43.8 (SD 5.8) kg/m2 and mean age of

48.3 (SD 12.4) years (Table I). Thirty individuals

repeated the TSD-OC for the retest 24 h after the

first administration. Their characteristics did not

differ from the whole study population.

Mean values for each TDS-OC scale are reported

in Table II. Cronbach’s a and the overall standar-

dised Cronbach’s coefficient a showed the excellent

internal consistency of the test, which appeared

higher than the suggested minimum value of 0.70

in each scale. Test–retest analysis showed acceptable

stability in five scales (rs4 0.80), while in Stiffness,

Instrumental Activities of Daily Living (IADL) and

Occupational Activities scales, rs was 0.65, 0.76 and

0.67, respectively. In none of the TDS-OC scales,

statistically significant differences between the first

and the second test were observed.

Results of the SF-36, 6MWT and handgrip

strength, compared to normative values, are reported

in Table III. Lower scores compared to normative

values were reported by 35% of individuals for the

SF-36 PCS and by 34.5% for the MCS. In the

6MWT, 98.9% of the individuals exhibited a deficit,

while handgrip strength values were lower than

reference values in 52.5% of the individuals.

The correlations between the TSD-OC and the

other measures are presented in Table IV. Moderate

correlations were observed between the TSD-OC

total score and SF-36’s PCS and MCS scales, with

the latter showing a lower correlation. The TSD-OC

was also moderately correlated with handgrip

strength, while the correlation with 6MWT was low.

The results of the linking exercise are reported in

Table V. After rolling-up information to the second

level, a total of 26 categories were linked: six from

Body Functions, 18 from Activities and Participation

and two from Environmental Factors. The majority

Table I. Clinical characteristics of the sample (n¼ 501).

Variable Whole sample, n (%) Retest sample, n (%)

Sex

Female 348 (69.5) 21 (70)

Male 153 (30.5) 9 (30)

Age (year)

Mean (SD) 48.77 (12.19) 50.39 (11.83)

Range 20.75–70 24.56–65.12

BMI (kg/m2)

Mean (SD) 42.36 (7.92) 48.36 (8.15)

Range 30.02–75.28 36.60–70.90

Setting

Outpatient 163 (32.5) 0 (0)

Day hospital 91 (18.2) 0 (0)

Inpatient 247 (49.3) 30 (100)

4 L. M. Donini et al.

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of categories are related to the area of mobility: 10

from Activities and Participation and two from Body

Functions.

Discussion

Disability is a condition that limits an individual’s

interaction with the environment, independence in

performing ADL and in participating in social life

activities. The risk of disability is known to be

significantly higher in obese persons with a

BMI4 30 [33]. Since the reduction in disability

[12,46,47] is a major goal in treating obese subjects,

the obesity-related disability needs to be clearly

defined and appropriately assessed.

The structure of the TSD-OC considers all

the domains of disability that are reported in the

literature to be obesity related. Each section of the

TSD-OC (pain, stiffness, ADL and indoor mobility,

housework, outdoor activities, occupational activities

and social life) has a different weight on the global

score, depending on the number of items included.

We had also speculated whether the number of items

could be reduced without affecting the value of the

whole test. Statisticians tend to prefer mathematical

models or screening/predictive tests with the smallest

possible number of parameters, as each parameter

introduced into the model adds some degree of

uncertainty. From a clinical point of view, reducing

the items may mean ignoring some daily life

situations that are difficult to cope with and thus

lead to underestimating the disability level of the

obese population. Therefore, we opted not to reduce

them because every single item in the TSD-OC

relates to an aspect that has the potential to unveil the

subject’s difficulty in coping with everyday situations.

In the TSD-OC, the items aimed at defining the level

Table II. Reliability, internal consistency and stability of TSD-OC (n¼501).

TSD domain n items Means (SD)

Internal consistency

Cronbach’s a

Test–retest (stability) (n¼ 30)

rs Wilcoxon P-value

Pain 5 19.17 (12.59) 0.93 0.87 0.53

Stiffness 2 7.08 (5.45) 0.95 0.65 0.71

ADL 7 25.78 (19.63) 0.92 0.87 0.67

Housework 7 25.34 (19.95) 0.92 0.86 0.48

IADL 5 16.54 (13.62) 0.92 0.76 0.42

Occupational activities 4 11.02 (10.88) 0.94 0.67 0.86

Social life 6 19.08 (15.91) 0.93 0.80 0.43

Total score 36 35.64 (24.54) 0.92 0.90 0.67

Note: ADL, Activities of daily living; IADL, Instrumental activities of daily living.

Table III. Comparison between study sample and reference values

(males and females) for SF-36, 6MWT and handgrip strength.

Test Sample study score Normative score

SF-36; n¼ 394; mean (SD)

PCS

Males (n¼123) 45.91 (21.57) 51.0 (9.2)

Females (n¼271) 44.71 (21.59) 48.9 (10.7)

MCS

Males (n¼21) 46.83 (21.29) 48.5 (9.9)

Females (n¼271) 44.75 (22.18) 45.0 (11.1)

6MWT; n¼287; mean (SD)

20–40 years

Males (n¼18) 477.17 (118.92) 800 (83)

Females (n¼59) 462.25 (130.68) 699 (37)

40–60 years

Males (n¼46) 452.15 (128.28) 671 (56)

Females (n¼128) 404.40 (115.55) 670 (85)

60–80 years

Males (n¼7) 329.43 (146.96) 687 (89)

Females (n¼29) 296.83 (131.09) 583 (53)

Handgrip; n¼ 183; mean (range)

20–30 years

Males (n¼3) 40.33 (34–50) 53.6 (44.3–63.6)

Females (n¼12) 29.38 (20–37) 32.2 (26.7–38.1)

30–40 years

Males (n¼8) 41.25 (32–50) 53.05 (44.0–62.6)

Females (n¼19) 27.87 (12–37) 33.5 (28.6–38.6)

40–50 years

Males (n¼13) 37.65 (32–50) 52.25 (42.5–61.2)

Females (n¼38) 28.58 (8–42) 33.35 (28–39)

50–60 years

Males (n¼12) 37.42 (26–54) 47.35 (36.7–56.9)

Females (n¼43) 24.65 (12–40) 30.4 (26.4–35.2)

60–70 years

Males (n¼7) 35.43 (16–54) 41.7 (35.4–47.9)

Females (n¼28) 22.29 (8–31) 25.75 (22.2–29.6)

Table IV. Correlation between TSD-OC, SF-36, handgrip

strength and 6MWT.

TSD-OC

domain

SF-36

PCS

SF-36

MCS

Handgrip

strength 6MWT

Pain 70.46** 70.30** 70.19 70.27**

Stiffness 70.32** 70.24** 70.15 70.22**

ADL 70.48** 70.30** 70.08 70.24**

Housework 70.51** 70.34** 70.21 70.27**

IADL 70.53** 70.35** 70.13 70.29**

Occupational

activities

70.32** 70.23** 70.06 70.11

Social life 70.49** 70.38** 70.21 70.21**

Total score 70.56** 70.38** 70.34** 70.25**

Note: **P5 0.01.

The SIO test for obesity-related disabilities 5

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Table V. Linking exercise between TSD-OC and ICF categories.

Sections Items Linking to items Linking to section

Pain Pain when walking b280 Sensation of pain b134 – Sleep

d450 Walking b280 – Sensation of pain

Night pain b280 Sensation of pain d430 – Lifting and carrying objects

b1343 Quality of sleep

Pain when carrying weights b280 Sensation of pain d450 – Walking

d430 Lifting and carrying objects d455 – Moving around

Pain in going up the stairs b280 Sensation of pain

d4551 Climbing

Pain at rest b280 Sensation of pain

Stiffness Stiffness at morning awakening b7800 Sensation of muscle stiffness b710 – Mobility of joints functions

b7102 Mobility of joints generalized b780 – Sensations related to

muscle and movement functions

Stiffness during the day b7800 Sensation of muscle stiffness

b7102 Mobility of joints generalized

Function and

autonomy in

daily life

activities

Difficulty in using the bathroom d530 Toileting d410 – Changing basic body

position

d4103 Sitting d420 – Transferring oneself

d4200 Transferring oneself while

sitting

d455 – Moving around

d4101 Squatting d510 – Washing oneself

Difficulty to get dressed (put on and

off socks or stockings)

d540 Dressing d530 – Toileting

d5402 Putting on footwear d540 – Dressing

d5403 Taking off footwear

Difficulty in foot care and hygiene d5100 Washing body parts

Difficulty in personal hygiene (bidet,

washing the back, getting in and out

the bath)

d5100 Washing body parts

d4103 Sitting

d4101 Squatting

d410 Changing basic body position

Difficulty in putting on and off the

shoes or lacing them

d5402 Putting on footwear

d5403 Taking off footwear

Difficulty in going up and down the

stairs (two flights of 10–12 steps

each)

d4551 Climbing

Difficulty in lying down or getting up d4100 Lying down

Housework Difficulty in picking up objects from

the ground

d4300 Lifting d430 – Lifting and carrying objects

d4400 Picking up d440 – Fine hand use

Difficulty in lighter housework d640 Doing housework d445 – Hand and arm use

Difficulty in cleaning windowpanes d6402 Cleaning living area d455 – Moving around

Difficulty in climbing onto a stool d4551 Climbing d640 – Doing housework

Difficulty in ironing d6403 Using household appliances

Difficulty in moving pieces of

furniture or in heavier housework

d640 Doing housework

Difficulty in taking an object from an

higher place

d4452 Reaching

d4300 Lifting

Function and

autonomy in

outdoor

activities

Difficulty in lifting and carrying the

shopping bags (5 kg weight)

d620 Acquisition of good and services d410 – Changing basic body

position

d430 Lifting and carrying objects d415 – Maintaining a body

position

Difficulty to get into and out a car d410 Changing basic body position d430 – Lifting and carrying objects

d4701 Using private motorized

transportation

d450 – Walking

d4702 Using public motorized

transportation

d470 – Using transportation

Difficulty in queuing (i.e. at the post

office)

d4154 Maintaining a standing position d475 – Driving

Difficulty in driving a car d4751 Driving motorized vehicles d620 – Acquisition of good and

services

Difficulty in walking for at least 200 d450 Walking

Function and

autonomy at

work

Difficulty at work (and the need of

being assigned to lighter tasks)

d850 Remunerative employment b280 – Sensation of pain

e5900 Labour and employment

services

d410 – Changing basic body

position

(continued)

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of disability are based on VAS scores. The 10

(maximum level of disability) to 0 score (absence of

difficulty in performing a specific function) defines

the subjective/perceived level of disability. Future

studies should be aimed at defining the cut-off values

of the TSD-OC by comparing it with sensitive

performance tests in the obese population.

The validation of TSD-OC was performed against

the SF-36, which has several dimensions and,

although not obesity specific, has shown sensitivity

to the impact of weight loss on HRQoL in severely

obese persons [47]. Unsurprisingly, the TSD-OC

showed better correlations with the SF-36 items

related to physical than mental health component

and the mental health component. However, a

significant, although not so strong, correlation was

also found with the items describing the mental

health component. These data confirm that disability

in obesity is not only a physical issue, but one which

also brings about relevant psychological conse-

quences that also affect QoL.

The TSD-OC showed a significant correlation

also with the chosen functional parameters: grip

strength and distance walked in 6 min. The latter

test has been extensively used as an outcome

measure of the functional status and response to

treatment in individuals with cardiorespiratory dis-

orders as well as in the geriatric population and its

reproducibility in obese subjects has been recently

demonstrated [48].

The correlation between functional parameters

and the TSD-OC score, although statistically sig-

nificant, was not very strong. This may be due to the

fact that the TSD-OC and functional testing

measures two different aspects of disability: the

TSD-OC targets participation in the different

aspects of everyday life, while the latter measures

objective physical performance. The TSD-OC and

functional parameters therefore depict different but

complementary aspects of disability from a subjective

and an objective perspective, respectively, and

should both be used in a comprehensive assessment

of the disabling status of obesity. This also implies

that participation is not so strictly connected with

functional limitations: rather, it deals with the

engagement in social situations, which constitutes a

relevant problem for obese individuals. The relation-

ships found between disability profiles and HRQoL

are significant, but generally low or moderate,

meaning that QoL and disability reflect different

constructs, which therefore should not be considered

as transposable.

The linking exercise to ICF categories showed a

wide coverage in particular of activities related to

mobility and self-care, and of impairments of mental

functions. A few previous articles attempted to use or

Table V. (Continued).

Sections Items Linking to items Linking to section

Pain after a day of work b280 Sensation of pain d415 – Maintaining a body

position

Difficulty in maintaining a posture d415 Maintaining a body position d850 – Remunerative employment

d850 Remunerative employment e590 – Labour and employment

SSP

Need to be often absented from work e5901 Labour and employment

systems

d850 Remunerative employment

Function and

autonomy in the

social life

Necessity to avoid sofas, reclining

seats for fear of not getting up

d4103 Sitting b152 – Emotional functions

b152 Emotional functions b160 – Thought functions

Fear of falling and not being able to

get up

b152 Emotional functions d410 – Changing basic body

position

Feeling criticized for being obese b160 Thought functions d470 – Using transportation

Fear of having difficulty in going to the

cinema, to the theatre or in getting

on an airplane

b152 Emotional functions d750 – Informal social

relationships

d9202 Art and culture d920 – Recreation and leisure

d4702 Using public motorized

transportation

e115 – Products and technology

for personal use in daily living

Need to find armchairs to get up more

easily

e1150 General products and

technology for personal use in daily

living

d4103 Sitting

Difficulty in going round with ‘non-

obese’ friends or acquaintances

d7500 Informal relationship with

friends

d7502 Informal relationship with

acquaintances

Note: Linking to items was performed to the most specific category possible, linking to section was performed to second-level ICF

categories.

The SIO test for obesity-related disabilities 7

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implement the ICF in obesity rehabilitation pro-

grammes. A first experience mapped ICF categories

onto a full diagnostic and therapeutic protocol,

evidencing a total of 166 ICF cross-walked categories,

of which 106 mapped onto standardised assessment

tools [49]. An analysis of the prevalence of problems in

obese individuals showed that 43 ICF categories

reported relevant information (i.e. reported as a

problem) in at least 20% of subjects [50]. The

majority of these categories are covered by the TSD-

OC; however, some of them were not reported. In

particular, the TSD-OC covers information related to

two categories from Body Functions (b160 – Thought

Functions; b780 – Sensations related to muscle and

movement functions) and eight from Activities and

Participation (d420 – Transferring oneself, d440 –

Fine hand use, d445 – Hand and arm use, d470 –

Using transportation and d475 – Driving) that were

not reported in the ICF-based problems’ prevalence.

Finally, a third article [51] showed that impairments at

the level of the body are much more closely related to

limitations in performing activities than the effect of

environmental factors. All these studies support a

multidisciplinary approach to the evaluation of dis-

ability, which is a key element in the rehabilitation

programme, which however needs to rely upon valid

and solid assessment tools.

This study has some limitations. The first lies in

the cross-sectional design that does not allow us to

state that the TSD-OC is sensitive to change: future

studies should be planned to measure its reliability in

capturing differences in a pre- vs. post-rehabilitation

longitudinal design, at different time points. A

second limitation lies in the selection of our subjects

who were all individuals enrolled in specialty clinics

for obesity rehabilitation. However, age and BMI

range should reduce this limitation. For the linking

exercise, the instrument proposed appears in line

with the ICF bio-psychosocial model of disability.

However, only two environmental factors are con-

sidered while our previous results on the application

of such a methodology show that five categories were

more frequently rated as barriers and eight as

facilitators.

Conclusions

The results of the present study demonstrate the

validity of the TSD-OC as a tool able to measure the

aspects of disability described by obese subjects: in

particular, the TSD-OC proved to be significantly

correlated with functional and QoL parameters. Its

use within a multidisciplinary assessment should

be implemented by specific instruments able to

establish the role of environmental factors. This

new scale may represent an important instrument

for the description of obesity-related disability and

for planning and measuring the effectiveness of

rehabilitation programmes in obese subjects. Fu-

ture longitudinal studies should be planned to

assess its sensitivity to change at different time

points.

Acknowledgements

The authors are indebted to Prof GajVidmar for his

invaluable statistical assistance.

Declaration of interest: The authors report

no conflicts of interest. The authors alone are

responsible for the content and writing of the paper.

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