The Manual Ability Classification System (MACS) - Wiley Online Library

29 downloads 0 Views 823KB Size Report
tional abilities in daily life. One recent classification with a clear functional approach is the Gross Motor Function Classification. System (GMFCS; Palisano et al.
The Manual Ability Classification System (MACS) for children with cerebral palsy: scale development and evidence of validity and reliability Ann-Christin Eliasson* PhD OT; Lena Krumlinde-Sundholm PhD OT, Department of Woman and Child Health, Karolinska Institute, Stockholm; Birgit Rösblad PhD PT, Department of Community Medicine and Rehabilitation, University of Umeå, Umeå; Eva Beckung PhD PT, Queen Silvia Children’s Hospital, Göteborg; Marianne Arner PhD MD, Hand Unit, Department of Orthopaedics, Lund University Hospital, Lund; Ann-Marie Öhrvall MSc OT, Department of Habilitation, Stockholm County Council, Stockholm, Sweden; Peter Rosenbaum MD FRCP, CanChild Centre for Childhood Disability Research, McMaster University, Hamilton, Ontario, Canada. *Correspondence to first author at Neuropaediatric Research Unit Q2:07, Astrid Lindgren Children’s Hospital, SE-171 76 Stockholm, Sweden. E-mail: [email protected]

The Manual Ability Classification System (MACS) has been developed to classify how children with cerebral palsy (CP) use their hands when handling objects in daily activities. The classification is designed to reflect the child’s typical manual performance, not the child’s maximal capacity. It classifies the collaborative use of both hands together. Validation was based on the experience within an expert group, a review of the literature, and thorough analysis of children across a spectrum of function. Discussions continued until consensus was reached, first about the constructs, then about the content of the five levels. Parents and therapists were interviewed about the content and the description of levels. Reliability was tested between pairs of therapists for 168 children (70 females, 98 males; with hemiplegia [n=52], diplegia [n=70], tetraplegia [n=19], ataxia [n=6], dyskinesia [n=19], and unspecified CP [n=2]) between 4 and 18 years and between 25 parents and their children’s therapists. The results demonstrated that MACS has good validity and reliability. The intraclass correlation coefficient between therapists was 0.97 (95% confidence interval 0.96–0.98), and between parents and therapist was 0.96 (0.89–0.98), indicating excellent agreement.

Cerebral palsy (CP) is the most common neurodisability in children. It has been defined as ‘a disorder of movement and posture due to a defect or lesion of the immature brain’ (Bax 1964) and as ‘a group of non-progressive, but often changing motor impairment syndromes secondary to lesions or anomalies of the brain arising in the early stages of development’ (Mutch et al. 1992). A proposed new definition of CP focuses on a broader perspective of activity restriction and disability (Bax et al. 2005). Classification of subtypes of CP has been proposed based on location of the lesion, part of the body involved, or degree of impairment (Ingram 1964). However, none of these descriptions provides information about the child’s functional abilities in daily life. One recent classification with a clear functional approach is the Gross Motor Function Classification System (GMFCS; Palisano et al. 1997). The GMFCS describes gross motor function in terms of self-initiated movements with emphasis on function in sitting and walking. This classification is based on the concept of disability (World Health Organization 1980) and of functional limitation (National Institutes of Health 1993). The GMFCS has been widely adopted internationally, suggesting that it has filled a gap in functional classification (Morris and Bartlett 2004). No similar classification of hand function has been available, but one is needed to broaden the functional perspective of CP beyond gross motor issues. Classification is the process of grouping data, persons, or objects into classes according to common characteristics, thereby reducing the number of data elements. The usefulness of a classification depends on how understandable and clear the descriptions are, and how meaningful different levels are. The most common way to classify hand function in CP has been to use terms like ‘mild’, ‘moderate’, and ‘severe’ impairment (Claeys et al. 1983). Although some other classifications are available (House et al. 1981, Zancolli and Zancolli 1981, Krägeloh-Mann et al. 1993, Beckung and Hagberg 2002), all of them classify aspects of grasping rather than functional performance and none has been tested for reliability. This proposed new classification, the Manual Ability Classification System (MACS), is designed to classify how children with CP use their hands when handling objects in daily activities. The focus is on manual ability, as defined in the International Classification of Functioning, Disability and Health (ICF; World Health Organization 2001). It has its starting point in upper limb function but is also influenced by environmental, personal, and contextual factors. MACS follows Penta and coworkers’ definition of manual ability as ‘the capacity to manage daily activities that require the use of the upper limbs, whatever the strategies involved, which can be observed from activity performance in the person’s everyday context’ (Penta et al. 2001). MACS is not designed to classify best capacity and does not mean to distinguish different capacities between hands. MACS reports the collaboration of both hands together: it is not an assessment of each hand separately. It looks for the children’s manual ability to ‘handle object(s) in daily life’. By that we mean those activities that are relevant and age appropriate for the child including, for example, eating, dressing, playing, writing, etc.; these are distinct from advanced skilled activities that require special training for performance, such as playing a musical instrument. Neither does it classify activities closely related to academic skills in school. The emphasis of MACS is on handling objects in an individual’s personal space, the space immediately close to one’s body, as

Developmental Medicine & Child Neurology 2006, 48: 549–554 549

distinct from objects that are not within reach, thus minimizing the potential confounding influence of limitations in gross motor function. Distinctions between the levels are based on the child’s ability to handle objects, i.e. the quantity and quality of performance and need for assistance or adaptations to perform manual tasks in everyday life. The aims of this report are to describe the development of MACS and provide evidence of its validity and reliability. Efforts were made to follow recommendations about accumulating evidence for scale validity according to guidelines published in Standards for Educational and Psychological Testing (American Educational Research Association 1999).

environments, mainly in their homes or schools. Using those videos, we discussed and defined the classification levels based on the assumption that five levels would be suitable, if possible, to correspond to the structure of GMFCS. To reduce the complexity of the work we agreed to start by developing a classification suitable for children aged 8 to 12 years. We have worked with a Swedish and an English language version of the classification in parallel. The study was conducted after approval from the Ethics Research Committee at the Karolinska Hospital, Sweden, and the State Government, Victoria, Australia. Informed consent was obtained from the parents of the children.

Method

External processes for validation When the first version of the classification was outlined an external validation process was initiated, by involving professionals within paediatric rehabilitation and parents of children with CP. To collect opinions from professionals we presented preliminary versions of the classification at national and international conferences (Sweden 2002, Canada 2003, Norway 2003). Interactive poster presentations were used where the participants were encouraged to classify children from video clips and to comment on the classification. Oral presentations were also given after which the audience was invited to discuss and offer feedback. Comments and suggestions collected on these occasions were brought back to the expert group and processed. The refinement of the wording and the distinctions between levels was a continuous process until the reliability study started. An additional step for validity testing was to investigate if this concept was meaningful for parents of children with CP (Öhrvall 2005). After a brief introduction, 25 parents classified their child according to the MACS leaflet (Appendix I). Thereafter, each parent participated in a semi-structured taperecorded interview following an interview guide (Kvale 1996). The questions focused on the parents’ thoughts about the classification. They were asked if this concept was meaningful for describing their child’s hand function. They were then asked for their rationale for choosing a particular level instead of others. A third set of questions concerned their judgement of the overall usefulness of the classification. The same procedure was repeated with the child’s occupational therapist or, sometimes, physiotherapist.

PROCESSES OF DEVELOPMENT AND VALIDATION OF THE CLASSIFICATION

The first step in developing MACS was to assemble an expert group, comprising six people (two occupational therapists, two physical therapists, one hand surgeon, and one developmental paediatrician), each with over 20 years of clinical experience and research in paediatric rehabilitation. It was considered important to involve people from different professional backgrounds and experience of research (Fink et al. 1984). The work in the expert group has proceeded through workshops, telephone conferences, and e-mail contacts for more than 3 years, with the construct development of the classification as an ongoing process. First, an inventory of available tests and classifications of hand function was constructed. An essential next step was to clarify the conceptual background and to define and formulate the basic underlying construct. Discussions occurred until consensus was reached in the expert group. It then became important to describe the content of the different levels of the classification. We video recorded children with different subtypes of CP and fields of functioning when performing various manual activities in their natural

Table I: Distribution of children by age and by Gross Motor Function Classification System (GMFCS) levels (n=164) Age (y)

4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Total Per cent

n

8 15 10a 12 16 13 29 16 16 3 7 10 4 3 6a 168 (164) –

I

II

3 3 2 1 9 4 9 4 5 2 1 – 2 1 – 47 28

2 4 2 4 1 3 2 4 5 – 2 2 1 – – 32 20

GMFCS levels III IV – 1 3 2 1 5 6 4 – – 3 2 – – 1 28 17

– 2 2 3 3 1 7 1 5 1 1 4 – – 2 32 20

V 3 5 – 2 2 – 5 3 1 – – 2 1 2 – 26 16

aGMFCS level missing for one child at 6y and three children at 18y.

550

Developmental Medicine & Child Neurology 2006, 48: 549–554

Data processing of the interviews Textual analysis of the materials from parents and therapists was performed separately (Kvale 1996), based on the three sets of questions, and for each level of MACS. The remarks were analyzed to understand if the distinction between levels was apparent or not (Polit and Hungler 1995). PROCESS OF TESTING THE RELIABILITY OF THE CLASSIFICATION

Design Interrater reliability was studied by asking pairs of therapists to classify the same child, and by asking parents and therapists to classify the same child. This meant that several therapists classified more than one child whereas each child was classified only once by each therapist. The parents and almost all therapists received a brief introduction to MACS with the MACS leaflet, which they were encouraged to read thoroughly (Appendix I). They were also invited to discuss uncertainties with the classification and

rating procedure with someone from the expert group before actually rating the children. Procedure and participants As originally planned, we started by classifying children aged between 8 and 12 years. During the process of developing MACS we frequently received comments from parents as well as therapists that the classification could be valid for children at other ages as well. We decided therefore to include children between 4 and 18 years in the reliability testing. In total 168 children between 4 and 18 years (98 males, 70 females) were classified by 93 therapists from six cities in Sweden and one city in Australia (Table I). The severity of disability, according to GMFCS, varies, as do the subtypes of CP (Tables I and II). The Swedish classification of CP subtypes was used (Hagberg and Hagberg 1993). Interrater reliability between therapists for children aged 4 to 18 years The 168 children were classified independently by two therapists (Table III). Twenty children from Melbourne, Australia, were analyzed first and separately to control for cultural differences, and were then included in further calculations. Interrater reliability between parents and therapists Twenty-five children between 8 and 12 years were classified independently by their parents and one therapist, in most cases an occupational therapist. The children were selected to cover what we assumed would be a wide range of functional abilities, with the intention of representing all levels of MACS. Statistics For analysis of interrater reliability a one-way random effects model (referred to as intraclass correlation coefficient [ICC] 1) was used, which, according to Shrout and Fleiss (1979), is suitable when different raters are assessing the children using average measures. The ICC result is equivalent to a weighted kappa (Fleiss and Cohen 1973). Rater agreement, the coefficient of total agreement between therapists (number of children with total agreement divided by total number of children; Polit and Hungler 1994) was calculated. For descriptive analysis, the result from the first rater of MACS was used. For correlation between MACS and GMFCS, Spearman’s rank correlation was used.

seemed to be related to the interpretation of certain words, for example ‘independence’. One parent emphasized that the child was independent in simple tasks, whereas the therapist thought about activities that were more complex where the child needed continuous support. When discussing the overall usefulness of the classification, parents suggested that MACS could be used for several purposes: e.g., in contact with the social services and local council to discuss the need for support and personal assistance; as information for parents of infants with CP; for newly employed staff working with the child; and as information between professionals working with the same person. The therapists expressed similar ideas but also emphasized the ability to use MACS in the clinic for planning of treatment and goal setting. INTERRATER RELIABILITY BETWEEN THERAPISTS

The classifications of 168 children between 4 and 18 years were analyzed. ICC was 0.97 (95% confidence interval [CI] 0.96–0.98) for the whole group, indicating excellent agreement (Table III). The total agreement was 84.5%. When ICC was calculated for the different ages, there were similar results (Table IV). A group of 20 children from Australia was included. When this group was analyzed separately no differences in the understanding of the MACS were found; however, ICC was slightly lower at 0.91 (95% CI 0.77–0.96). INTERRATER RELIABILITY BETWEEN PARENTS AND THERAPISTS

ICC between parents and therapists was 0.96 (95% CI 0.89– 0.98), indicating excellent agreement for the 25 children

Table II: Types of cerebral palsy (CP) by Manual Ability Classification System (MACS) rating by professionals Type of CP

Hemiplegia Diplegia Tetraplegia/quadriplegia Ataxia Dyskinetic CP Total %

I

II

III

MACS levels IV V Total

10 12 – 1 – 23 14

38 23 – 2 – 63 38

4 18 1 2 3 28 17

– 15 9 1 4 29 17

– 2 9 – 12 23 14

52 70 19 6 19 166a –

% 31 42 12 4 12 – –

aCP type was unavailable for two children.

Results VALIDATION OF THE CLASSIFICATION

All parents and therapists responded positively to the question about whether MACS was built on a useful construct for describing the child’s hand function. They also found the differences between the five levels meaningful and easy to understand. Parents emphasized the advantage of describing what the children actually can do instead of focusing on their limitations. The distinction between capacity and performance did not cause confusion for the families. Several therapists also emphasized that MACS was giving a structure to their thinking, and that it was important to have one classification for all kinds of CP. The rationale for choosing a particular level instead of others was most often clear for both parents and therapists. Although parents and therapists mainly agreed about the levels there were some disagreements (reported below). These

Table III: Numbers of children 4 to 18 years in each Manual Ability Classification System level as rated by two therapistsa

Therapist 1 I II III IV V Total

I

II

19 2 – – – 21

4 56 5 1 – 66

Therapist 2 III IV

– 6 22 3 – 31

– – 1 22 1 24

V

Total

– – – 3 23 26

23 64 28 29 24 168

aIntraclass correlation coefficient=0.97 (95% CI 0.96–0.98). Numbers in bold represent total agreement.

Manual Ability Classification System for Children with CP Ann-Christin Eliasson et al. 551

between 8 and 12 years. The total agreement was 72%. There was disagreement about one level for seven children, five of whom were rated on a higher level by the parents and two by the therapists. The disagreement was distributed across all levels of MACS.

Table IV: Distribution of intraclass correlation coefficient (ICC) for different age groups Age (y) 4–7 8–12 13–18 All: 4–18

n

ICC (95% CI)

45 90 33 168

0.98 (0.97–0.99) 0.96 (0.94–0.98) 0.98 (0.96–0.99) 0.97 (0.96–0.98)

Table V: Correlation between Manual Ability Classification System (MACS) and Gross Motor Function Classification System (GMFCS) level ratingsa

GMFCS levels I II III IV V Totalb

II

15 3 5 – – 23

29 22 10 2 – 63

MACS levels III IV

2 7 9 9 – 27

– – 4 17 6 27

Children with all different subtypes of CP were included in the study (Table II, Fig. 1). The children with hemiplegia were mainly seen in Level II but also in Levels I and III. Children with diplegia were found in Levels I to IV, whereas children with dyskinetic CP and tetra- or quadriplegia were apparent in Levels IV to V. RELATION BETWEEN MACS AND GMFCS

CI, confidence interval.

I

DISTRIBUTION OF MACS LEVELS AMONG SUBTYPES OF CP

V

Total

– – – 4 20 24

46 32 28 32 26 164

aSpearman’s correlation coefficient r=0.79. bGMFCS missing for

four children. Numbers in bold represent total agreement.

The correlation between GMFCS and MACS was 0.79 (p