DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY
REVIEW
Efficacy of interventions to improve motor performance in children with developmental coordination disorder: a combined systematic review and meta-analysis BOUWIEN C M SMITS-ENGELSMAN 1 , 2 | RAINER BLANK 3 | ANNE-CLAIRE VAN DER KAAY 2 | RIANNE MOSTERD-VAN DER MEIJS 2 | ELLEN VLUGT-VAN DEN BRAND 2 | HELENE J POLATAJKO 4 | PETER H WILSON 5 1 Department of Kinesiology, KU Leuven, Leuven, Belgium. 2 Avansplus University for Professionals, Breda, the Netherlands. 3 University of Heidelberg and Child Centre, Maulbronn, Germany. 4 Department of Occupational Science and Occupational Therapy, University of Toronto, Canada. 5 School of Psychology, Australian Catholic University, Melbourne, Australia. Correspondence to Dr Bouwien Smits-Engelsman at Department of Kinesiology, KU Leuven, Tervuursevest 101, 3001 Heverlee, Leuven, Belgium. E-mail:
[email protected]
PUBLICATION DATA
AIM The aim of this study was to review systematically evidence about the efficacy of motor inter-
Accepted for publication 25th July 2012. Published online.
ventions for children with developmental coordination disorder (DCD), and to quantify treatment effects using meta-analysis. METHOD Included were all studies published between 1995 and 2011 that described a systematic review, (randomized) clinical trial, or crossover design about the effect of motor intervention in children with DCD. Studies were compared on four components: design, methodological quality, intervention components, and efficacy. Twenty-six studies met the inclusion criteria for the review. Interventions were coded under four types: (1) task-oriented intervention, (2) traditional physical therapy and occupational therapy, (3) process-oriented therapies, and (4) chemical supplements. For the meta-analysis, effect sizes were available for 20 studies and their magnitude (weighted Cohen’s d [dw]) was compared across training types. RESULTS The overall effect size across all intervention studies was dw=0.56. A comparison between classes of intervention showed strong effects for task-oriented intervention (dw=0.89) and physical and occupational therapies (dw=0.83), whereas that for process-oriented intervention was weak (dw=0.12). Of the chemical supplements, treatment with methylphenidate was researched in three studies (dw=0.79) and supplementation of fatty acids plus vitamin E in one study (no effect). The post hoc comparison between treatment types showed that the effect size of the task-oriented approach was significantly higher than the process-oriented intervention (p=0.01) and comparison (p=0.006). No significant difference in the magnitude of effect size between traditional physical and occupational therapy approaches and any of the other interventions emerged. INTERPRETATION In general, intervention is shown to produce benefit for the motor performance of children with DCD, over and above no intervention. However, approaches from a task-oriented perspective yield stronger effects. Process-oriented approaches are not recommended for improving motor performance in DCD, whereas the evidence for chemical supplements for children with DCD is currently insufficient for a recommendation.
ABBREVIATIONS
CO-OP Cognitive orientation to daily occupational performance DCD Developmental coordination disorder NTT Neuromotor task training
Children with developmental coordination disorder (DCD) are identifiable by the difficulties they have in performing fine and gross motor tasks, which affect their performance in the classroom and in activities of daily living.1 According to the DSM-IV,2 in DCD the level of motor coordination is below that expected given the child’s chronological age and intelligence, and may lead to problems in activities of daily living and ⁄ or academic performance.3 The estimated prevalence of children with DCD is between 6 and 13% of all school-aged children,4 with some reports finding that males experience a higher incidence than females.5 Forty per cent of the children diagnosed as having delayed motor development before start-
ing school continue to have this problem 10 years later.6 These figures indicate that DCD is not a condition that exists only in earlier childhood. Several comorbid problems are common in children with DCD including a substantial overlap with attention-deficit– hyperactivity disorder (ADHD), dyslexia, and autistic spectrum disorders.7,8 Children with DCD show higher rates of social difficulties, low self-esteem, and associated behavioural problems during childhood and adolescence.9 In particular, children with combined DCD and ADHD show poorer outcomes when evaluated in early adulthood, in terms of academic achievement and psychosocial adjustment.10 Indeed,
ª The Authors. Developmental Medicine & Child Neurology ª 2012 Mac Keith Press
DOI: 10.1111/dmcn.12008 1
the persistent nature of DCD in around one-half of individuals first diagnosed in childhood emphasizes the importance of targeted intervention.11–13 Therapeutic approaches are drawn from occupational therapy,14–20 physiotherapy,21–30 medicine31–33 (e.g. methylphenidate), diet34 (e.g. fatty acids plus vitamin E supplementation,), and education21,35,36 (teachers, parents, physical education). Although different terms can be found in the literature to describe interventions for DCD, approaches can be grouped under three main types: process-oriented, task-oriented, and conventional physical and occupational therapy. Chemical treatments (e.g. fatty acids) represent a newer, fourth type. Process-oriented approaches target the components or body functions needed to perform activities. Sensory integration, kinaesthetic training, perceptual training, or combinations are examples of these bottom-up approaches. For DCD, the hypothesis is that the improvement of body functions such as sensory integration, kinaesthesia, muscle strength, core stability, visual–motor perception, and so on leads to better skill performance.37,38 By comparison, task-oriented approaches tend to focus on motor performance, i.e. on learning particular motor skills, with attention given to specific aspects of task performance that are causing the child difficulty. Leading examples are neuromotor task training (NTT),26,35,39,40 the cognitive orientation to daily occupational performance (CO-OP) approach,37,38,41 and imagery training.29 In reality, these taskoriented approaches are all based on a combination of current motor control or motor learning and ecological principles, with the relative contribution of these frameworks varying from one method to another.42 NTT can be considered a true hybrid: from motor learning theory, it draws strongly on the notion that task structure and scheduling are fundamental to the way skills are assembled over repeated learning trials and sessions; from the ecological approach, it considers how task and environmental constraints can be manipulated to provide some leverage for the individual child whose motor impairment does not enable direct and seamless movement in a particular workspace.20,35–38 CO-OP can be considered the most pure example of a topdown approach. It focuses particularly on the use of cognitive strategies to facilitate skill acquisition, and uses a collaborative, problem-solving approach adapted from cognitive-behavioural therapy, particularly the work of Meichenbaum. The child is encouraged to form a mental model of how to attack a movement task; they are led to generate a movement goal, plan its implementation, and reflect on how their performance was or was not successful (goal, plan, do, check).37,38,42 From a traditional physical therapy or occupational therapy training perspective, individuals with DCD are trained in the most important fundamental gross motor and fine motor skills (hopping, jumping, throwing, and catching; cutting, drawing, writing), and in the basic motor abilities that are thought to be prerequisite for skills (e.g. trunk stability for certain fine-motor skills). These approaches combine underlying process-oriented approaches with direct skill training; the underlying assumptions are that motor skills are 2 Developmental Medicine & Child Neurology 2012
What this paper adds • Children with DCD benefit from some form of motor intervention. • Task-oriented interventions and traditional motor-based skill training yield significant effects. • Task-oriented interventions improve motor performance more than processoriented interventions. • Few intervention studies capture changes in the level of participation. • Higher-quality studies are needed on optimal intensity and treatment duration.
developed in a sort of hierarchical fashion. Basic abilities (such as postural control, in-hand manipulation, visual–perceptual skills) need to be refined in conjunction with teaching complex motor skills. Although many different intervention strategies have been used and studied, it remains unclear which best improve motor performance or activities in children with DCD and alleviate the associated problems. To determine the most effective intervention strategy, we searched the literature on interventions in children with DCD published between 1995 and December 2011. The longer an intervention method has existed, the larger the possibility that it has been investigated for its treatment effects. This is certainly true for sensory integration and kinaesthetic training.5,26 Studies investigating sensory integration and kinaesthetic training occurred mainly between the early 1970s and 1996, with very few since 1996. Several studies published after 1996 have investigated taskoriented approaches like CO-OP and NTT, both of which are relatively new. No meta-analysis has been conducted so far that includes this work. The main aim of this meta-analysis was to synthesize the literature from 1995 to December 2011, a period during which DCD gained greater recognition as a diagnosis in its own right. In 1994 the London Consensus group43 produced a more detailed description of DCD compared with the DSM-III-R (1987)44 and DSM-IV (1994).2 This was an important milestone in the research into DCD. It meant the beginning of a uniform approach to children with motor impairment, not otherwise specified by a medical diagnosis. From 2004 to 2006, several professionals from different countries met to obtain a new agreement about the diagnosis, research, and intervention characteristics and comorbidities of DCD, resulting in the Leeds Consensus statement in 2006.45 From these meetings, several issues emerged: there was no consistency in the interpretation and application of diagnostic tests, and no uniformity in the application of the various evidence-based intervention methods. The Leeds Consensus set the following guidelines that intervention approaches should meet: (1) activities should be functional, based on goals that are relevant to daily living and meaningful to the child; (2) they should enhance generalization and application in the context of everyday life; and (3) interventions must be evidence-based and grounded in theories that are applicable to understanding children with DCD.38,45 Thereafter, various (inter-)national professionals inside and outside Europe, some of whom participated in the seminars in Leeds, decided to write a directive for diagnosis, prognosis, and intervention for children with DCD. This resulted in the
European Academy for Childhood Disability recommendations for diagnosis and treatment of DCD, issued in January 2012.46 In support of these recommendations for intervention, a systematic review on treatment efficacy was initiated. It was the aim of this review to rate both the scientific quality of the studies and compare the magnitude of differences across treatment types, highlighting the most effective.
METHOD Criteria for inclusion and exclusion In advance of the actual literature search, selection criteria were set for the abstracts. Abstracts of meta-analysis, systematic reviews, randomized controlled trials (RCTs), clinical trials, and narrative reviews were included. The papers had to be written in English, German, or Dutch and published between 1995 and 2011. The populations included in the studies were children of any age, diagnosed with DCD or with possible DCD. DCD was defined either according to the criteria of the DSM-IV2 or as motor impairment not otherwise specified by a medical diagnosis, but examined with standardized motor tests confirming motor impairment. Studies reporting on children with poor motor performance, which was defined as 1SD below the mean, were also included. Studies investigating a sample of children with a syndrome (like ADHD or dyslexia), were included in the descriptive part of the study but excluded from the meta-analysis. The included studies had to have motor outcome measures with standardized and internationally accepted assessments, for example, the Movement Assessment Battery for Children, the Concise Assessment Method for Children’s Handwriting, or the Test of Gross Motor Development-2. Literature search The literature search spanned the period January 1995 to December 2011. The following databases were consulted: Medline, the Cochrane Library, PubMed, CINAHL, PsychInfo, PsychLit, OTDBase, OTseeker, PEDRO, ERIC, Embase, and HealthSTAR. The search terms were agreed upon at a meeting of the international working group for the EACD recommendations for DCD in 2008. The following search terms were used (connected with ‘OR’): motor skills disorder, developmental coordination disorder, clumsiness, clumsy, clumsy child syndrome, clumsy child, in-coordination, dys-coordination, minimal brain dysfunction, minor neurological dysfunction ⁄ disorder, motor delay, perceptual-motor impairment, motor coordination difficulties ⁄ problems, motor learning difficulties ⁄ problems, mild motor problems, non-verbal learning disability ⁄ disorder ⁄ dysfunction, sensorimotor difficulties, sensory integrative dysfunction, physical awkwardness, physically awkward, psychomotor disorders, motor control and perception, apraxias, developmental dyspraxia, perceptual motor dysfunction, minimal cerebral dysfunction. These search terms above where combined (with ‘AND’) with the general terms (connected with OR) ‘physical therapy’, ‘physiotherapy’, ‘occupational therapy’, ‘intervention’, ‘treat-
ment’, and the more specific treatment approaches (connected with OR) sensory integration, Neuro-Developmental Treatment (NDT): Neuromotor Task Training (NTT), Cognitive Orientation to daily Occupational Performance (CO-OP), Perceptual Motor Training (PMT), motor imagery training (MIT), sensory integration training (SIT), task-specific training, cognitive training, timing control, kinaesthetic training. The following exclusions (‘NOT’) were used to obtain more pure DCD studies: cerebral palsy, stroke, traumatic brain injury, leukodystrophia or muscular disorders. Additionally, references of all selected articles were checked for further papers suitable for inclusion. Each abstract resulting from the search was individually screened for inclusion by at least two of four independent experts (BS-E, A-CvdK, RM-vdM, EV-vdB). When consensus existed, the full-text articles were evaluated. Each full-text article was again rated by two independent experts who needed to reach a consensus to include the paper in the study. If consensus was not reached, a third expert was consulted. Next, for each of the included studies, the experts had to agree on the level of evidence rated according to levels of evidence (Oxford Centre for Evidence-Based Medicine,47 or in case of an RCT, the PEDro scale;48 Tables I and II). If consensus was not reached by the two experts, a third was consulted. Authors did not rank their own studies. Moreover, all conclusions and recommendations were reviewed by the international DCD guideline group in several meetings.46
Data analysis All abstracted study characteristics are shown in Table SI (online supporting information). These include population description, number of participants, age and relevant baseline testing results, type of intervention, description of the intervention, frequency, intensity and duration, outcome measures, description of results of the populations, short description of the conclusion and limitations, main conclusions. Included articles were assessed by members of project group for methodological quality using the instruments mentioned, and results were added to Table SI results. To classify their efficacy, the results were characterized by either a ‘+’ for significant improvement in the experimental group(s) or ‘0’ for no significant change. Estimates of effect size were calculated for each comparison of pre- and post-test results of a given treatment. The preferred estimate was Cohen’s d.49 To calculate estimates of effect size, means and standard deviations for pre- and posttest results were used whenever they were reported. The inclusion of multiple dependent measures (and associated statistics) was allowed for each study. Mean effect sizes are not unduly affected by non-independence in most instances,50 and many authors choose not to weight studies according to the number of effect sizes. Pseudo-independence of effect size was assumed here. Outcome measures were therefore analysed at the level of each finding; there were 54 effect sizes, distributed among four treatment types, plus one for comparison groups, pre- and post test. Review 3
Table I: Levels of evidence (modified according to Oxford Centre for Evidence-Based Medicine), March 200947 Level of evidence
Grade
Oxford level
Oxford definition (intervention studies)
1 (high)
Evidence from a meta-analysis of randomized controlled trials
Ia
Evidence from at least one randomized controlled trial (intervention study) or well-controlled trial with well-described sample selection (diagnostic study); confirmatory data analysis. QUADAS rating >10. Evidence from at least one controlled study without randomization or QUADAS rating >7.
Ib
Evidence from a meta-analysis or systematic review of randomized controlled trials (with homogeneity). Evidence from at least one randomized controlled trial.
2 (moderate)
3 (low) 4 (very low)
IIa
Evidence from at least one other type of quasi-experimental study.
IIb
Evidence from observational studies. QUADAS rating >4. Evidence from expert committee reports or experts.
III IV ⁄ V
Evidence from systematic review of cohort studies (with homogeneity); or evidence from at least one controlled study without randomization. Individual cohort study (including low-quality randomized studies, e.g.
