In their systematic review and meta-analysis Smits-Engelsman et al (2018) «Smits-Engelsman B, Vinçon S, Blank R, ym. Evaluati...»1 reviewed the evidence published from January 2012 to February 2017 regarding the effectiveness of motor based interventions in children with DCD, quantified treatment effects using a meta-analysis and examined the available information on different aspects of delivery including use of group intervention, duration and frequency of therapy and identified gaps in the literature and made recommendations for future intervention research.
Initially, any study reporting new data on the motor outcomes of intervention for children or adults with DCD (or those labeled probable-DCD) was selected for review. 30 studies covering 25 datasets were included of which 19 provided outcomes on standardized measures of motor performance. From these 25 datasets 10 was randomized control trials (RCT) and 11 controlled clinical trials (CCT) also there was two case studies and four studies without any standardised tests. 30 Studies were selected with any intervention study that aimed to improve motor functions, activities and/or participations outcomes. Studies were included regardless of the type of intervention or delivery mode (one to one or group). DSM criteria were cited frequently 22/25, but in many cases it was not mentioned whether participating children had a clinical referral for intervention. 30 studies included a total of 807 participants with DCD (range 4-12 years of age) of which 509 received interventions and the rest received usual care or no intervention. Mean duration of the interventions was 671 min (median 540, range 120-2400 min) and median frequency was 1.5 times per week (1-5) over 9 weeks (4-18) and 12 sessions (5-48). Interventions were grouped in ICF terms according to the main orientation or target of interventions; Body functions oriented (strength training, aerobic fitness training, selective muscle activation, visual training), Activity oriented (Task oriented Intervention; NTT/CO-OP, General Skill Training, Sport/play related skill training, virtual reality training) and Participation oriented (real life situation). Two studies reported outcomes only on body functions level, 16 on body function and activity level (MABC-2 and BOT-2), and five on all 3 ICF levels (body function, activity and participation). The following three parameters were used to determine the strength of evidence for a given intervention approach: (1) the quality of individual studies, (2) quantity of studies, and (3) consistency of outcomes across all reviewed studies. The quality of individual studies was assessed in two steps: first, the integrity of design features, and second, a rating of the risk of bias that may have contributed to an outcome.
Effect sizes and their confidence intervals were calculated for individual studies. The overall effect size (Cohen's d) on the standardized motor tests across intervention studies was large (1.06) but the range was wide (0.21-4.37): for 12 interventions, the observed effect was large (>0.80), in eight studies moderate (>0.50) and in five it was small or regligible (<0.50). When compared across the main intervention types, the mean effect size was 1.81 (range 0.60-4.37) for body-function oriented approaches and 0.96 (range 0.21-2.77) for activity oriented. A significant moderate correlation was found between effect size on standardized tests and duration (rs=0.58, p=0.003). Positive benefits were evident for activity-oriented approaches, body function –oriented combined with activities, active video games, and small group programs. The risk of bias of included studies was evaluated and it showed some major concerns (see comment).