Palisano and colleagues, the first to apply the concept of classifying the extent of involvement of children with cerebral palsy (CP) primarily on the basis of self-initiated movements in their everyday lives, developed the Gross Motor Function Classification System (GMFCS).1,2 The GMFCS is a reliable and valid standard classification system for measuring the functional abilities of children with CP.3–5 The GMFCS was expanded and revised (GMFCS-E&R) in 2008.6 Including its most recent version, the GMFCS is an important contribution to the field of CP, providing common language for communication among professionals and parents. The Manual Ability Classification System (MACS), developed by Eliasson and colleagues in 2006,7 parallels the GMFCS in many ways.
The MACS is a 5-level classification system for the manual ability of children with CP on the basis of self-initiated ability to manipulate objects in the home, school, and community. Children at level I can perform all manual tasks and can handle objects easily and successfully, whereas children at level V are completely dependent and demonstrate very limited ability in performing even simple actions. The levels are determined by a parent or caregiver who regularly observes the child's functions in daily life, in collaboration with a health care professional.7
Similar to the GMFCS-E&R, the MACS is focused on the child's performance (ie, what the child does, rather than what the child can do). The MACS is designed for children between 4 and 18 years of age, and the levels are determined on the basis of age-appropriate activities using objects within the child's typical environment.7 Another important aspect of the GMFCS and the MACS is that they both consider the functional ability of children with CP rather than focusing on their disabilities. The MACS is an important classification system that provides a simple description of manual functioning in the everyday life of children with CP. Although many studies have been published including the MACS since its development in 2006, information about its use is lacking in the literature. The MACS is gaining international attention, and at this stage understanding the extent of its use in the literature, evidence of psychometric properties, and information about dissemination is important. Conducting a review on the above aspects also helps identify gaps, which may provide direction for future research. Therefore, the following research questions guided a scoping review: Has the use of the MACS increased over time since its publication? In what types of publications has the MACS been used? In which countries has the MACS been used? How has the MACS been used? What is the available evidence for the psychometric properties of the MACS? Has the MACS been correctly used? The purpose of this study was to understand the extent to which the MACS has been used and reported in written formats, and to identify gaps in the literature.
A scoping review is an excellent approach for identifying literature of interest in covering the broad scope of a research question. In addition to providing a breadth of knowledge, the scoping review also helps identify gaps in the literature allowing appropriate recommendations for future research. In this scoping review, the methodology developed by Arksey and O' Malley8 and recommendations made by Levac et al9 were followed. Specifically, the following first 5 stages were used: identifying the research questions, identifying relevant studies, study selection, charting the data, and collating, summarizing, and reporting the results.
After clarifying the research questions and purpose, consultation with the Health and Rehabilitation Science librarian at our institution on effective search strategies, databases, and search terms was undertaken to maximize the efficiency and quality of the literature search. An online literature search was performed on 15 databases including Abledata, Amed, CINAHL, Cochrane Library, Dissertations and Theses, EMBASE, Health and Psychosocial Instruments, PEDro the Physiotherapy Evidence Database, Physical Education Index, Proquest Nursing and Allied Health Source, PsycINFO, PubMed, Scopus, SocINDEX, and Sociological Abstracts, using the terms “Manual Ability Classification System” or “MACS.” Articles published since the inception of the MACS in 2006 until March 2013 were included in the scoping review.
Inclusion and Exclusion Criteria
Screening for eligibility was done in 2 stages. Because the purpose of this scoping review was to identify the dissemination of the MACS in written format, all types of publications including original contributions, review articles, case reports, conference presentations, commentaries, book sections, newsletters, and dissertations were included. In stage 1, all types of publications that used the term “Manual Ability Classification System” were included. Other publications were excluded that used the term “MACS” that did not represent the Manual Ability Classification System. Inclusion and exclusion criteria were derived after reading the abstracts of publications obtained in stage 1. In stage 2, publications in which the MACS was used as a variable or was the main focus were identified for inclusion in the review. Articles were excluded that were published in languages other than English, if the MACS was not used as a variable, or the main focus, as well as publications in which the MACS was used in populations other than CP. The MACS was originally developed for children up to 18 years of age; however, it has been validated for ages older than 18 years10; therefore, the articles in which the MACS was used in adult populations were included.
Review Process and Data Extraction
Each abstract was reviewed by 2 independent reviewers and screened for eligibility on the basis of a consensus process. A third reviewer was consulted when initial consensus was not reached. Each reviewer independently documented details on year of publication, type of publication, country of origin, psychometric properties, how the MACS was used, study design, and whether the MACS was used appropriately.
The publications for each full year (2006-2012) that included MACS were categorized into peer-reviewed and non-peer-reviewed publications. Articles published in 2013 were excluded for this part of the scoping review because the search was done only up to March 2013 and inclusion of these data would be misleading. Original research studies, review articles, and case reports were included in peer-reviewed publications. The conference presentations, commentaries, book sections, newsletters, letters to editor, and dissertations were included in non-peer-reviewed publications. Book sections were included in non-peer-reviewed publications because of the less rigorous nature of the peer review process. Conference presentation titles and abstracts were compared with the titles and abstracts of full-length articles to verify the proportion of conference presentations that were later published as full-length articles.
Full articles were categorized according to their country of origin. The country in which the research was conducted is an early indicator of adoption and use. Only full-length articles were included for this part of the review and all other types of publications were excluded because other types of publications did not indicate the country in which the research was done. For full-length articles in which the country of origin was not mentioned, the country of the first author was selected.
The uses of the MACS were classified into 5 categories: sample descriptor, independent variable, dependent variable, informative, and psychometric testing. The category sample descriptor refers to the articles in which the MACS was used to describe the sample. Publications in which the MACS was used as an independent variable were classified as “independent variable.” Publications were categorized as dependent variables if the MACS served as an outcome measure. Publications in which the MACS was used as a main variable of discussion such as reviews, commentaries, and letter to editor were classified as “informative,” and publications in which the psychometric properties of the MACS were tested or that used the MACS as a standard criterion were classified as “psychometric testing.”
In addition to the above categories, we documented information about study designs. Detailed descriptions of the definitions used to classify study designs are provided in Table 1.
Consensus between reviewers was achieved on every step of the scoping review process. Consensus between the 2 initial reviewers was reached immediately in 88% of cases, following discussion in 10% of cases, and a third reviewer was consulted in 2% of cases.
Figure 1 illustrates the process of screening the articles for eligibility. The literature search on 15 databases yielded 1133 articles; 519 duplicates were removed yielding a total of 614 publications. Of these 614 publications, 436 articles were excluded because the term “MACS” did not refer to the Manual Ability Classification System. The remaining 178 publications used the term “Manual Ability Classification System” appropriately, meeting the inclusion criteria. An additional 17 articles were excluded for a variety of reasons, including the MACS not being used as a variable, the MACS not being the primary focus (eg, referenced in background information or discussion), articles published in any language other than English, and the MACS not being used appropriately (with individuals with CP). Ultimately, 161 articles were included in the scoping review. All types of publications were included, which resulted in 106 original research studies, 36 conference presentations, 4 review articles, 3 case reports, 2 commentaries, 3 newsletters, 4 book sections, 2 dissertations, and 1 letter to the editor. A full reference list and details of the data extraction are contained in Supplemental Digital Content 1 (available at http://links.lww.com/PPT/A81).
Figure 2 illustrates the number of publications that used the MACS each year since its inception. A steady increase in peer-reviewed publications that included the MACS was observed from 2006 to a relatively steady state of 26 to 30 publications per year after 2010. The non-peer-reviewed publications reached a peak in 2010; however, the proportion of conference presentations that took the form of full-length articles and were disseminated in peer-reviewed publications (from 2006 to 2012) was only 28%. Figure 3 shows the adoption of the MACS in different continents. More publications including the MACS originated in Europe compared with any other continent.
Table 1 provides description of the research designs that employed the MACS. Table 2 contains a summary of the number of articles by use including articles that explored the psychometric properties of the MACS. The findings showed that the MACS was used as 1 of the criteria in sample selection and sample description, not only in experimental studies, but also in other research designs such as descriptive, measurement, correlational, comparative, and qualitative studies as well as in case reports. The MACS was used as 1 of the variables in various studies that focused on the relationship between the MACS and other measures or classifications. The MACS was used as an outcome variable in only 6 studies. Of the publications in which the MACS was used as a dependent variable, 3 were conference presentation abstracts, 2 were experimental studies, and 1 was a case report. The MACS was acknowledged as an important classification system in publications such as reviews, commentaries, and a letter to editor. The MACS was used in measurement studies that focused on the psychometric properties of the MACS and as a standard criterion to determine the validity of 3 upper extremity skills measures.
In previous studies, validation of the MACS was initially established through a literature search and consultation and consensus with expert groups.7 Content validity was further explored by interviews with parents and therapists.11 Findings in these validity studies demonstrated that the descriptions of each level and the difference between the levels of the MACS are clear and meaningful in describing the performance of manual tasks of children with CP. In this scoping review, 9 publications were identified, which focused on reliability of the MACS. Details on reliability values are provided in Table 3. The interrater and intrarater reliability of the MACS has been explored using the intraclass correlation coefficient (ICC) and kappa coefficient. In summary, the ICC values were greater than 0.9 for children aged between 4 and 18 years7,12–18 and 0.8 for adults.10 The kappa coefficient was 0.55 for children younger than 2 years and 0.67 for children between 2 and 5 years of age. The MACS is stable over a period of 12 months for children with CP aged 11 through 12 years (ICC = 0.92).19 Recently, Ohrvall and colleagues20 reported the stability of the MACS over time for children with CP between 4 and 17 years of age with an ICC value of 0.96 and 0.97 for ratings at 1-year interval and 3- to 5-year interval.
This review provides evidence on the adoption, inclusion, and use of the MACS as reported in the literature. The overall findings of the review demonstrate that there has been a relatively steady increase in the inclusion of the MACS in peer-reviewed publications since 2006 and that the MACS is used in many different types of publications. The MACS has captured international attention and is used worldwide, primarily as a sample descriptor and independent variable and less often as a dependent variable. The MACS is a reliable, stable, and valid classification system that can be used to classify children with CP aged 4 to 18 years on the basis of their hand function. In most cases, the MACS has been applied to children with CP, but in few instances its use has been generalized to other populations without sufficient psychometric testing for those groups.
Since its inception, the MACS has been used in various types of publications for many purposes. Knowledge translation emphasizes actual use of knowledge in practice; however, dissemination is an important and essential first step in knowledge synthesis and translation.21 The use of the MACS in different types of publications reveals different ways of spreading knowledge of the MACS. This scoping review supports the evidence of knowledge creation and dissemination; further work on actual use of the MACS may shed light on other aspects of the knowledge-to-action cycle.
“In health care, invention is hard, but dissemination is even harder”.22p. 2 Journals, conferences, seminars, books, newsletters, and reports are all venues of scholarly communication; however, the nature and the extent of peer review may differ. The early adopters typically obtain information from researchers through social interactions, including conferences.22 Therefore, the less rigorous peer-reviewed venues of scholarly communication and non-peer-reviewed publications should not be overlooked. Our scoping review identified a steady increase in the rate of peer-reviewed publications addressing the MACS each year since the development of the MACS to a relatively steady state in 2010. The review also identified a peak in the non-peer-reviewed publications in 2010, with subsequent peer-reviewed publications still pending for many of these research projects. This shows the effect of the adoption of the MACS by many researchers.
The country in which the research was conducted is an indicator of the adoption of a particular measure or technique. The findings of our review showed that the MACS has captured international attention and is used in all continents except Africa. The MACS is mostly used in Europe, perhaps because it was developed in Europe.
We are specifically interested in mapping the terrain to understand how the MACS is used in a variety of publications. The MACS was used as a sample descriptor or an independent variable in the majority of publications and as a dependent variable, informative, and to determine the psychometric properties in relatively fewer studies. Primarily, studies reported specific levels of the MACS, enabling generalization of the results of a specific study to a particular subgroup of the population of individuals with CP. The MACS level has been reported to be stable over time20 and therefore can be used for prognostic purposes. The use of the MACS to determine the validity of other measures supports the notion that the MACS is an accepted standard to describe manual functions.
The review supports the evidence for psychometric properties of the MACS. Relatively few studies addressed the validity of the MACS. On the basis of the available evidence, the MACS has good validity. Its content validity has been established through focus groups, literature review, and detailed interviews.7,11 Reliability is supported by ICC values greater than 0.75 (regarded as “excellent reliability”)23 for children between 4 and 18 years of age and adults aged between 18 and 24 years, although it was not originally designed for the adult population. Substantial agreement24 has been obtained for classification of children between 2 and 5 years of age but only moderate agreement21 for children under 2 years. Therefore, the MACS has to be used with caution with younger children. The MACS was originally developed for children with CP and must be validated before using it with other conditions. Our review identified a few studies in which the MACS was used in conditions other than CP; these articles were excluded.
Preliminary evidence on the use of the MACS to predict upper-extremity surgery outcomes has been reported on a small group of people by Gong et al.25 The findings of their study showed that individuals with CP with high and low MACS groups improved in different functional domains (ie, the high MACS group improved in the House functional scale and satisfaction and the low MACS group improved in hygiene status) after undergoing upper-extremity surgery. This was a retrospective study that was done on a sample of 27 participants, 6 to 54 years of age. Further studies on specific age groups using a prospective design and larger sample size are required to generalize the results of this study, or other studies focusing on prediction of future outcomes.
One objective of this scoping review was to identify gaps in the literature. The findings of this review showed that the construct validity of the MACS has not been fully explored in order for it to be considered as a reference standard although it is considered an “accepted standard” as previously discussed. The reliability of the MACS in adults with CP has been explored in only 1 study and ought to be replicated on a different sample. Our review did not identify any studies that explored the use of the MACS in clinical practice. Further work is required to elucidate the MACS's construct validity, reliability of use in adulthood and clinical uptake and utility.
The use of the MACS is emerging in the literature. The MACS possesses an acceptable standard for classifying the manual function of children with CP and is primarily used in the literature to describe the participants and as an independent variable. The MACS can be reliably used for children between 4 and 18 years and adults between 18 and 24 years. The use of MACS is expected to increase and further work is required to explore its use in clinical practice.
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