Myasthenia Gravis: from Functioning and Disability evaluation ...

SSD Neurologia, Salute Pubblica, Disabilità (HEADNET) - Direzione Scientifica

Myasthenia Gravis: from Functioning and Disability

evaluation towards new healthcare approaches

Alberto Raggi

Raggi A, Leonardi M, Antozzi C, Confalonieri P, Maggi L, Cornelio F, Mantegazza R.

Neurological Institute C. Besta IRCCS Foundation


Disability in MG

Disability evaluation in MG patients, has been performed focussing on neuromuscular symptoms’ severity (with no or poor consideration of impairments not directly linked to MG), and on limitations in executing a limited set of ADL, directly linked to MG symptoms (e.g. MG-ADL. Wolfe, 1999).

These approaches fail in establishing a connection between MG symptoms, patients difficulties in executing tasks or activities and the environmental factors that contribute to reducing difficulties and improving patients’ ability in performing daily activities and participating to social situations (leisure activities as well as work activities).


Disability in MG: a biopsychosocial approachThe biopsychosocial approach endorsed by WHO’s ICF Classification

(International Classification of Functioning, Disability and Health, 2001) is a useful approach to evaluate patients’ disability status in connection to the context they live in.

Myasthenia

Symptoms (weakness, mood disturbances…)

Limitations and restrictions in performing activities and in participating to social

situations

Adequate environment (good treatments, positive context…): improvement

Unfavourable environment (hindering context…): worsening


Quality of Life in MG

Since 2000, when MGFA recommended to evaluate HRQoL in MG patients to evaluate intermediate levels of clinical improvement, there has been a strong interest towards its evaluation.

Research that employed the SF-36 demonstrated HRQoL to be compromised in MG patients both in its physical and mental components (Paul, 2001; Rostedt, 2006).

In 2008, two MG-specific HRQoL instruments have been developed to capture aspects of quality of life specific to MG patients (Burns, 2008; Mullins, 2008).


Disability and HRQoL in MG: Besta Institute experience

We administered the ICF Checklist (a selection of 128 ICF codes), the SF-36 and the WHO-DAS II (WHO Disability Assessment Schedule, 2nd version) to 102 MG patients.– ICF codes describe the presence of a problem (from no problem to mild-

complete) in body functions/structures and activities. They also describe the presence of barriers/facilitators within the environment.

– SF-36: evaluates HRQoL – two main indexes: PCS and MCS– WHO-DAS II: evaluates disability – 6 areas and a global score

MG patients were classified with the MG Score System, that describes MG muscle involvement in four areas – ocular, generalized, bulbar and respiratory – and with MGFA classification.


Sample characteristics

102 MG patients (68,8% females), aged 18-78 (mean 47.2)• 24.5% symptom-free• 28.4% with ocular symptoms• 25.4% with generalized symptoms• 21.7% with bulbar symptoms

Following MGFA’s classification• 24.5% in Pharmacological Remission• 28.4% in Class 1• 12.7% in Class II• 10.8% in Class III• 23.6% in Class IV

52% of patients was not employed (or student) at the timepoint of evaluation, although only 32.4% was retired.


Relationship between Disability, HRQoL and MG severity

WHO-DAS II total score and SF-36 composite scores have been used to define groups of patients with similar features through a k-means cluster analysis. Three groups have been identified– Cluster A: 51 cases, with low levels of disability and low QoL decrement;

– Cluster B: 28 cases, with intermediate levels of disability and intermediate QoL decrement;

– Cluster C: 23 cases with high levels of disability and high QoL decrement.

Cluster F

A B C

Dtot 8.9 16.6 42.6 115.6

PCS 48.0 48.6 32.7 29.6

MCS 51.4 36.8 29.3 73.3



There is a strong relationship between these clusters and MG severity: Cramer’s V=0.456 (P<0.001); Contingency Coefficient=0.542 (P<0.001). Clusters A and C are well defined. In cluster B there is an intermediate area with patients whose disability and HRQoL levels – and therefore whose problems – are not described by traditional severity measurements.

MGFA Cluster Total

A B C

PR 19 6 0 25

class 1 15 12 2 29

class 2 6 5 2 13

class 3 6 2 3 11

class 4 5 3 16 24

Total 51 28 23 102



The correlation between disability and HRQoL life tools is strongly significant (*P<.01), but generally moderate. WHO-DAS II SF-36

PF RP BP GH VT SF RE MH PCS MCS

Understandin & communicating -0,37* -0,30* -0,2 -0,23 -0,51* -0,31* -0,44* -0,37* -0,28* -0,43*

Getting around -0,67* -0,58* -0,46* -0,31* -0,54* -0,32* -0,32* - -0,70* -

Self care -0,53* -0,57* -0,28* -0,36* -0,63* -0,43* -0,41* -0,42* -0,49* -0,41*

Interactions -0,21 -0,33* - -0,27* -0,39* -0,34* -0,27* -0,29* -0,25 -0,31*

Household act. -0,59* -0,61* -0,42* -0,37* -0,55* -0,44* -0,38* -0,31* -0,64* -0,29*

Work act. - -0,36 - -0,31 -0,53* -0,44* -0,45* -0,42* - -0,48*

Participation -0,39* -0,53* -0,38* -0,39* -0,56* -0,55* -0,45* -0,48* -0,45* -0,50*

Total score -0,62* -0,65* -0,43* -0,44* -0,68* -0,54* -0,50* -0,43* -0,64* -0,46*

PF physical functioning, RP role physical, BP bodily pain, GH general health, VT vitality, SF social functioning, RE role emotional, MH mental health, PCS physical composite score, MCS mental composite score


Relationship between Disability, HRQoL and MG features

Mann-Whitney U test reports significant differences, consistent with MG features, in WHO-DAS II and in PCS scale. No inter-group difference is observed in MCS scale.

0

25

50

75

SF Ocular Generalized Bulbar

WD

PCS

MCS

P<0.01 P<0.05


The description of Disability in MG

Through a direct application of the ICF checklist to MG patients, we identified 54 relevant categories (i.e. those reported as a problem by more than 30% of patients):

– 14 Body Functions

– 2 Body Structures

– 22 Activities and Participation

– 16 Environmental Factors


ICF relevant categories from Body Functions and Structures domain

Most of impaired functions are mental (emotional, energy and drive, sleep..).

MG-specific functions (seeing functions, muscle endurance, voice, ingestion…) are all reported as a problem.

Around 60% of our sample reports pain as a problem.

ICF category description %

b435 Immunological system functions 100.0

b210 Seeing functions 83.3

b740 Muscle endurance functions 77.5

b152 Emotional functions 72.6

s220 Structure of eyeball 67.6

s420 Structure of immune system 63.7

b130 Energy and drive functions 62.7

b510 Ingestion functions 61.8

b280 Sensation of pain 60.8

b134 Sleep functions 58.8

b730 Muscle power functions 54.9

b440 Respiration functions 48.0

b144 Memory functions 41.2

b310 Voice functions 41.2

b235 Vestibular functions 37.3

b140 Attention functions 33.1


ICF relevant categories from Activities and

Participation domainMost of problematic activities refer to

mobility (carrying objects, driving, walking….), to self care and to activities requiring a physical effort (doing housework, acquisition of goods and services…).

Approximately one-third of the identified areas deal with relational abilities and skills (conversation, formal relationships, remunerative employment…).

ICF category description %

d430 Lifting ad carrying objects 87.3

d110 Watching 86.3

d475 Driving 79.5

d640 Doing housework 81.3

d450 Walking 78.5

d220 Undertaking a multiple task 78.4

d350 Conversation 77.5

d620 Acquisition of goods and services 77.4

d330 Speaking 74.5

d560 Drinking 74.5

d550 Eating 73.5

d630 Preparing meals 72.5

d510 Washing oneself 71.5

d440 Fine hand use 57.9

d520 Caring for body parts 47.1

d540 Dressing 48.0

d730 Relating with strangers 46.0

d470 Using transportation 44.1

d920 Recreation and leisure 41.2

d740 Formal relationships 39.2

d750 Informal social relationships 31.4

d850 Remunerative employment 30.4


ICF relevant categories from Environmental

factors domain

The majority of EF are herein reported as facilitators: health SSP, drugs, support from family members and doctors.

Several areas, generally not covered by established assessment tools are evidenced. Among them, attitudes and support from friends and colleagues, as well as transportation SSP.

ICF category description % (% barriers)

e580 Health services systems and policies 100 (11.8)

e110 Products or substances for personal consumption

99.0 (0)

e310 Immediate family 99.0 (3.0)

e355 Health professionals 98.0 (1.0)

e450 Individual attitudes of health professionals 98.0 (6.9)

e320 Friends 92.2 (6.9)

e410 Individual attitudes o immediate family members

93.1 (10.8)

e540 Transportation services systems and policies 81.4 (16.7)

e125 Products and technology for communication 77.5 (1.0)

e420 Individual attitudes of friends 75.7 (8.8)

e325 Acquaintances, peers, colleagues and community members

71.6 (11.9)

e570 General social support services systems and policies

65.7 (10.8)

e330 People in position of authority 41.2 (10.8)

e120 Products and technology for personal indoor and outdoor mobility and transportation

36.4 (2.0)

e225 Climate 37.2 (25.5)

e590 Labour and employment services systems and policies

30.4 (7.8)


The effect of Environmental Factors on disability in MG

Through an ICF-based approach to the evaluation of functioning and disability of MG patient, we recognized the positive effect of Environmental Factors (EF) in determining MG patients disability staus.

Impairments have play a primary role in the definition of disability of MG patients: but their functional status is also improved by the effect of some relevant EF.

Therefore, future studies on MG patients’ health status should endorse this new perspective.


HRQoL and Disability in MG

We stressed that physical aspects of HRQoL are more closely related to disability profiles than mental health ones.

Clinical status is also a relevant issue: the impact of MG on disability and HRQoL increases consistently with the disease’s severity.

If worsening of HRQoL’s physical aspects is predictable by the disease, less evidence supports hypotheses on the decrement of mental aspects. This decline might be a consequence of the disease itself: however, the role of the context in which daily activities are carried out should be considered too.


Why functioning and disability data in MG?

Clinical evaluation answers to the need of highlighting disease features and providing medical treatment, through the description of muscle strength and resistance.

On the contrary, functioning and disability data, as well as HRQoL ones, report information on the lived experience of disability of patients, and on their needs to overcome some of their difficulties: for this reason, such kind of measures should be employed in MG research.


Future directions

The results of this research could be used to develop MG-specific assessment measures, able to distinguish MG features from activity limitations and participation restrictions that patients experience. At the same time, such assessment tools should be able to provide a measure of the facilitating/hindering role of the environment.

Once such measures are developed, they could be employed to evaluate treatment effectiveness, as well as other health and social interventions, not only on MG clinical status, but also on patients’ everyday lives.

Myasthenia Gravis: from Functioning and Disability evaluation ...

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