Description of the condition
Conduct problems are a range of antisocial and disruptive behaviours that can be diagnosed as conduct disorder (CD) or oppositional defiant disorder (ODD), with ODD symptoms sometimes acting as a precursor to the onset of the more severe CD symptoms (Frick 2012; Moffitt 2008). CD is characterised by a repetitive and persistent pattern of behaviour in which the basic rights of others or major age-appropriate norms or rules are violated, whereas children with ODD demonstrate defiant behaviour, irritability, and vindictiveness (American Psychiatric Association 2013). Epidemiological studies have identified that between 5% to 10% of children and adolescents have significant problems with conduct and disruptive behaviour (Moffit 2009), making it the most common behavioural and mental health problem in children and young people globally (Collishaw 2004), and the most common reason for referral of young children to child and adolescent mental health services in the UK (NICE 2013).
Conduct problems are an important long-term condition of childhood as, when left untreated, they commonly persist (Murphy 2012). They predict not only the development of antisocial behaviour and substance misuse in adulthood, but also poor educational outcomes and increased physical health burden throughout life (Odgers 2007), and are the most common precursor of adult mental health problems across the spectrum (Copeland 2009; Kim-Cohen 2003). The 2010 Global Burden of Disease Study identified CD as a significant contributor to global years lived with disability (YLD), ranking it the 30th leading cause of nonfatal burden worldwide (Erskine 2014). Conduct disorder is ranked as the fourth leading cause of global YLDs for children aged five to nine years, and second for males in this age group. As well as the impact on the individual child and family, there is also an increased cost to the public purse, with each affected individual being associated with costs around 10 times that of children without the disorder (Murphy 2012). The early treatment and prevention of conduct problems is therefore of tremendous importance.
In recent years, there has been increasing awareness of substantial heterogeneity within conduct problems, so that it is now recognised that there are a number of ‘subgroups’ of children with conduct problems (Frick 2016; Klahr 2014). Variations include those in age-of-onset (Silberg 2015), level of aggression within antisocial behaviour (Loeber 1985), comorbidity with attention deficit hyperactivity disorder (ADHD; Waschbusch 2002), and influence of genetic and environmental factors in relation to level of callous-unemotional (CU) traits or ‘limited prosocial emotion’ (LPE; Viding 2005). These heterogeneous subgroups can exhibit differences in aetiology, developmental trajectory and likely prognosis (Frick 2016; Klahr 2014), with some studies reporting differential treatment outcomes (Hawes 2014; Reyno 2006).
Particular family characteristics have also been identified, both as risk factors for the development of conduct problems and as moderators of treatment effectiveness; for example, maternal mental health (Hutchings 2012) and contact with child protection services (Drugli 2010). Maternal ADHD symptoms have been associated with child ADHD and ODD symptoms (Zisser 2012) and may limit the improvement shown by children with ADHD in response to treatment (Chronis-Tuscano 2011; Sonuga-Barke 2002). It is therefore critical to identify subgroups defined by familial factors in addition to the recognition of heterogeneity on an individual level.
An example of the greater recognition of the importance of such subgroup heterogeneity is the decision by the American Psychiatric Association 2013 to incorporate a new specifier in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) to describe children and young people with conduct problems who present with LPE. LPE is characterised by the presence of two or more of the following criteria over at least 12 months and in multiple relationships and settings: (a) lack of remorse or guilt (b) callous - lack of empathy (c) shallow or deficient affect, and (d) lack of concern about performance (American Psychiatric Association 2013; Jambroes 2016). Recent reviews regarding chronic irritability and anger in ODD have also recommended the inclusion of a specific irritability subtype for ODD in the 11th revision of the International Classification of Diseases and Related Health Problems (ICD-11), in response to the greater level of severity and impairment experienced by some children (Evans 2017; Lochman 2014). This subtype will potentially act as an alternative to disruptive mood dysregulation disorder in the DSM-5, with the aim of enabling more accurate identification and treatment of heterogeneity within ODD (Evans 2017; Lochman 2014).
Such differences between subgroups have prompted debate as to whether a ‘one-size-fits-all’ model of intervention, which fails to take account of this heterogeneity, may be limited in its effectiveness. It is hoped, for example, that the addition of the LPE specifier into DSM-5 will encourage more precise diagnosis and the acknowledgement of ‘an emerging subgroup within conduct problems’ thereby promoting more targeted treatment research (American Psychiatric Association 2013).
Description of the intervention
Current recommended interventions
The gold standard, evidence-based intervention for the treatment of conduct problems in children is behavioural parent training (Scott 2009). While parent training programmes are recognised as an effective treatment (Dretzke 2009), personalisation seeks to address possible limitations in the effectiveness of such programmes. Evaluations of even the best parent training programmes estimate that a quarter to a third of families and their children do not benefit (Scott 2009). Parent training also requires substantial commitment and organisation from parents and can be undermined as a treatment due to dropout or failure to engage. Although some recent interventions have sought to trial new methods of delivery that could address particular issues with provision and attendance, such as internet-delivered parent training (Högström 2015; Sourander 2016), there are still inherent difficulties with implementing behavioural parent training. Families with children diagnosed with ODD, CD, or ADHD who are appropriate for behavioural parent training, commonly do not enrol, enrol but never attend treatment, drop out prematurely, or do not fully engage in within-session or between-session skills implementation (Chacko 2012; Fernandez 2011; Peters 2005). A recent review of 262 studies of behavioural parent training found a combined dropout rate of 51%, with 25% not enrolling despite being appropriate for the programme and 26% beginning but not completing the training (Chacko 2016). Limitations in the reach of parent training programmes are therefore a significant problem (NICE 2013; Pilling 2013).
In addition to such limitations in reach and effectiveness, differential outcomes of parent training have been associated with subgroups of children with conduct problems. High CU traits (or LPE) can predict poor outcomes across parent training interventions (Hawes 2014), and there is evidence that poor economic circumstances, marital discord, parental mental health problems, and parental hostility are associated with poorer outcomes (Reyno 2006). Paternal substance abuse and child comorbid anxiety or depression have also been identified as factors predicting poorer outcomes (Beauchaine 2005). However, the evidence in this area is not clear cut and a recent, comprehensive meta-analysis found that a range of family characteristics, which are usually associated with a poorer outcome from parent training, did not in fact moderate a less favourable response (Gardner 2016).
Although parent training is the primary recommended intervention for children with conduct or behavioural problems, other treatments, such as cognitive problem-solving programmes, are recommended (NICE 2013), and cognitive behavioural treatments have been investigated in the treatment of aggressive behaviour in children (Smeets 2015; Sukhodolsky 2004). Meta-analyses of Cognitive Behavioural Therapy (CBT) for aggression in children and adolescents have demonstrated medium effect sizes (Smeets 2015; Sukhodolsky 2004), and have suggested that further research is necessary to determine whether subgroups of individuals with predominantly reactive or proactive aggression may respond differentially to CBT intervention (Smeets 2015). Therefore, additional investigation is vital to clarify whether subgroup classification is associated with differential outcome across available interventions and, if so, whether understanding the underlying reasons for this could potentially lead to the development of more effective treatments.
Differences across developmental pathways and clinical presentations have been identified within the wider diagnostic classification of conduct problems (Frick 2016; Klahr 2014). Recognition of these differences could therefore aid the tailoring or personalisation of interventions to address the specific needs of particular subgroups (Frick 2016). Such personalisation aligns with the recent strategy of the Medical Research Council (MRC) to ‘embrace a stratified medicine approach’ (Medical Research Council 2017). Stratified medicine is described as "identifying groups of people with shared characteristics within or across specific disorders… looking beyond standard diagnostic categories to find new treatments and better ways of using existing treatments". Personalised interventions may therefore include novel treatments, or may involve additional or adjunctive interventions alongside existing standard evidence-based interventions. While the National Institute for Mental Health (NIMH) in the USA has called for mental health researchers to "expand and deepen the focus to personalise intervention research" (Fisher 2015), the science of personalisation in relation to child mental health is a novel field in the early stage of development (Ng 2016; Scott 2016).
How the intervention might work
How personalised interventions might work
Personalised interventions are likely to work by tailoring different aspects of treatment to the needs of particular subgroups of parents and children. It is possible that personalised treatments may include elements of parent training programmes, or supplement existing interventions with additional techniques to address subgroup heterogeneity. For example, a subgroup of children with conduct problems experiencing parental hostility could potentially benefit from a parenting programme tailored to include additional sessions focusing on hostility and offering particular techniques to address this issue. Alternatively, personalised interventions may be entirely novel treatments without any reference to parent training, or adaptations of existing non-parent training based interventions for conduct problems.
Subgroups of children with conduct problems that may benefit from personalisation
An example of a subgroup difference, which could be addressed by a personalised approach to intervention, is that of children who have high versus low CU traits (Frick 2014). Children with low CU traits are more likely to be sensitive to traditional disciplinary strategies employed in parenting programmes (Thapar 2015), whereas children with high CU traits appear genetically vulnerable to antisocial behaviour (Viding 2005) and relatively insensitive to punishment, threat and others’ distress (Pardini 2012). These vulnerabilities may cause insensitivity to certain critical components of traditional behavioural approaches (Hawes 2005), and children with high CU traits may benefit from programmes focusing on the positive dimension of parenting (Muratori 2016). Programmes that have been successful in the treatment of CU traits may contain elements that are more beneficial for this particular subgroup; for example, supporting an increase in parental warmth (e.g. Fast Track Intervention; Pasalich 2016).
Similarly, maternal ADHD symptoms have been associated with poorer parent training outcomes for children with ADHD (Chronis-Tuscano 2011; Sonuga-Barke 2002). Lack of reduction in negative parenting behaviours has been identified as a possible explanation for the relationship between maternal ADHD symptoms and poorer post-treatment child behavioural outcomes (Chronis-Tuscano 2011). The ability of parents to exhibit positive parenting behaviours is of vital importance for behavioural change, and has been shown to act as a protective factor against the development of conduct problems in children with ADHD (Chronis 2007). For these families, management of maternal ADHD symptoms to aid implementation of positive parenting strategies could be beneficial.
Targeting other aspects of parental mental health may also be beneficial; for example, treating maternal depression appears to improve outcomes for children with conduct problems (Hutchings 2012). Further, following evidence suggesting that subgroups of children presenting with emotional dysregulation may differentially respond to parent training programmes, Scott 2012 proposed that it may be worthwhile to pre-screen children prior to allocation of parenting interventions to ensure individual differences are accounted for. Personalised treatments, therefore, may have the potential to improve outcomes by targeting the specific needs of pre-defined subgroups.
Why it is important to do this review
While existing reviews have identified considerable heterogeneity within conduct problems and have investigated differential response to treatment (Gardner 2016; Hawes 2014; Klahr 2014; Shelleby 2014; Wilkinson 2016), to date, there has been no attempt to identify and synthesise the evidence on personalised interventions for subgroups of children with conduct problems. Previous Cochrane reviews focusing on the treatment of conduct problems have evaluated standard group-based parenting programmes for improving emotional and behavioural adjustment in young children (Barlow 2016), improving early-onset conduct problems in children aged three to 12 years (Furlong 2012), and improving conduct problems in older children and adolescents (Woolfenden 2001). This review, therefore, aims to address a gap in the treatment literature by systematically identifying and appraising the evidence for personalised psychosocial treatments for subgroups of children with conduct problems.