Intervention for Children with Developmental Coordination Disorder: A Systematic Review

Prevalence of children with developmental coordination disorder (DCD) is high (6-13% of all school children) and the negative impact of their movement difficulties on their participation in recreation and academic pursuits is well documented. This secondary research systematically reviewed the available literature for evidence of effectiveness of interventions that aim to improve the movement capability of children with DCD. Specified databases were searched for appropriate studies, these were retrieved and two reviewers appraised the level and quality of evidence. Thirty one studies were included between levels I and III-3 of the NH & MRC protocol. Scoring using an established critical appraisal tool demonstrated variable quality. Meta-analysis was not possible due to the clinical heterogeneity of the primary studies. A best evidence synthesis of results was conducted, producing clear evidence that no intervention has poor results when compared to any intervention. The high number of purportedly different interventions and variable quality make definitive conclusions about the merits of specific approaches difficult. There may be generic qualities or factors in the studied interventions that are more important for effectiveness than specific content. More information is needed on the underlying mechanisms of DCD, factors influencing effectiveness and the broader pragmatics of intervention delivery. Introduction Developmental coordination disorder (DCD) encompasses a complex presentation of sensory and motor impairments in children that can result in significant restrictions of daily activities and participation in life roles. The estimated prevalence (depending on severity criteria) is between 6 and 13% of all school aged children1, with some reports finding that boys experience a higher incidence than girls2 and that social disadvantage may also increase incidence3. Nomenclature for children experiencing motor difficulties in this group varies internationally although the current term – DCD – was accepted at the International Consensus on Children with DCD in 1994.4 Other terms used (and possibly reflecting subor allied groups) include minimal motor dysfunction, deficits in attention, motor control and perception (DAMPS), minimal cerebral/brain dysfunction, developmental dyspraxia, motor (dys)praxia, “clumsy child” and perceptual motor dysfunction.4 The current consensus for diagnosis of DCD is based on the DSM-IV (American Psychiatric Association) and includes: marked impairment of the development of motor coordination, significantly interfering with academic achievement of activities of daily living, not due to a general medical condition (e.g. Cerebral Palsy), criteria are not met for Pervasive Developmental Disorder and if mental retardation is present, the motor difficulties are in excess of those usually associated with it.5 Macnab, et al. (2001) identified five sub-types of children with DCD, characterised by varying proportions of impairment in gross and fine motor function, and/or sensory acuity. Other authors have reported varying characteristics such as information processing deficits (particularly visuo-spatial); reliance on visuo-spatial memory for learning movements; being perceived externally as having poor effort and reduced motivation, secondary effects of lower fitness levels or restricted social skills; and co-morbidity with learning delay (LD), Intervention for children with developmental coordination disorder: a systematic review 2 © The Internet Journal of Allied Health Sciences and Practice, 2007 developmental language disorder (DLD) and attention deficit and hyperactivity disorder (AD/HD).6-13 Not surprisingly with such a heterogenous group, identification and diagnosis of children with DCD is difficult. Observations by the parent/s, and/or teacher/s may be reported and followed up with any number of professionals including paediatricians, occupational and physical therapists and psychologists. It is generally accepted that no one test is sufficient to identify all children; rather a problem solving approach, plus an exclusion of other disorders, is required.14 Geuze, et al. (2001) reviewed the clinical and diagnostic literature and recommend scores on standardised motor tests below the 15 percentile, coupled with IQ scores over 69, as the diagnostic criteria, in compliance with the DSM-IV definitions. 14 The underlying mechanisms for DCD are still under investigation. By definition there are no ‘hard’ neurological signs or pathology; in other words, no macroscopic anomalies. Abnormal microscopic function – at the neurotransmitter or receptor level within the central nervous system is a matter for conjecture.1 Earlier theories focused on sensory-integration deficits (the hierarchical or neurodevelopmental perspective), that postulated issues with integrating sensory information.15 These early ideas arose from the view that DCD may be a minimalist form of Cerebral Palsy.16 These were followed by more cognitive based theories suggesting difficulties with the problem solving aspect of motor control.16 Current understandings are influenced by the inclusion of recent information from the motor learning literature and dynamic systems theories including the influence of task and environment on an individual’s development.17, 18 Neuronal group selection theory ties in with neuroplasticity research, which suggests that children may have impoverished repertoires of movement and sensing and that this can be exacerbated by reduced opportunities for experience and learning (also linked with social disadvantage)1 . Intervention approaches to assist children with DCD to establish more skilled action in home and school activities are based on the several theories. Barnhart, et al. (2003) and Wilson (2005) have provided summaries of the interventions currently in the literature, discussing the content and theoretical standpoint of the various paradigms.16,19 International consensus meetings have agreed that intervention should be holistic, child-centered and individualized for the unique characteristics of the child.4 Broader questions of when to intervene, at what age, in which environment and who should intervene have not been as well investigated as the specific approaches. Research into the effectiveness of these varied interventions for DCD has produced extensive literature, with narrative reviews produced by several authors.15,16, 20 Three meta-analyses have pooled data using an evidence based framework. The first by Kaplan, et al. in 1993, combined data from two studies both specifically investigating perceptual-motor versus sensory integration approaches versus no intervention, finding that both groups who received intervention improved similarly compared to little change with the no intervention group.21 Miyahara (1996) produced a meta-analysis of four DCD intervention studies, concluding motor intervention per se is better than nothing but that there was no evidence for one approach over another.22 The inclusion criteria for the identified studies were not systematic. The author also categorized the studies into task-oriented versus process oriented. The more recent meta-analysis that reported exclusively on children with DCD found 21 studies comparing three different approaches (general, sensory integration and specific skill) and included 13 of these in a meta analysis.23 These authors concluded that some form of intervention is useful, particularly using the specific skill approach, targeting children five years and over, either in groups or at home, with a frequency of at least 3-5 times per week. This paper only included research until 1996 and, because of the selection process for meta analysis, only drew conclusions from a sample of the evidence. Therefore it was considered timely to revisit the literature and perform a systematic review of all investigations to date concerning interventions for children with DCD. Systematic reviews involve a priori search methodologies to ensure all relevant literature are found (no search bias) and analyzed in a standardized and repeatable fashion (no reporting bias). The appraisal usually involves two stages to ascertain levels of bias (and therefore trustworthiness or validity) of individual clinical trials. Results can then be considered as a body of evidence, either combined narratively, in a discussion, or statistically (if studies are sufficiently similar and report the requisite data). Systematic reviews therefore offer consumers, service providers and researchers a single point of reference when considering the effectiveness of interventions for given conditions. Summary table/s offer individual readers the opportunity to make decisions based on their individual circumstances and to seek further information within individual trials as needed. As such, the aims of this secondary research were to: 1. Systematically identify all intervention based research investigating the effectiveness of defined approaches with children with DCD. 2. Identify the levels and quality of evidence for effectiveness. 3. Formulate implications for management and future research Intervention for children with developmental coordination disorder: a systematic review 3 © The Internet Journal of Allied Health Sciences and Practice, 2007 Methods Criteria for review Preferred studies for this review were identified from the published literature as systematic reviews (and/or metaanalyses) of randomised controlled trials (RCT’s), RCT’s, pseudo-randomised / controlled clinical trials (CCT), nonrandomised clinical trials (NRCT) or comparative studies (levels I-III)24. Study participants were children of any age, identified with DCD (or allied terms) by recognized tests, and exclusion of children with other neurological diagnoses or significant intellectual disability.14 Interventions could be of any type provided they were defined, and did not involve pharmacology or surgical intervention. Possible comparisons could include the intervention with a placebo, a control, another intervention or no intervention. Types of outcome assessment accepted included a change in motor performance as demonstrated by a recognized test (at minimum) evaluating impairment, activity or participation restriction. Search Strategy Databases searched included AMED, Australasian Medical Index, Austhealth, Cinahl, Cochrane Controlled Trials Register, Current