Child Psychiatry Hum Dev (2018) 49:244–267 DOI 10.1007/s10578-017-0745-9 ORIGINAL ARTICLE Systematic Review and Meta-analysis of Parent Group Interventions for Primary School Children Aged 4–12 Years with Externalizing and/or Internalizing Problems Sarah Buchanan‑Pascall1 · Kylie M. Gray1,2,4 · Michael Gordon1,3 · Glenn A. Melvin1,2 Published online: 11 July 2017 © Springer Science+Business Media, LLC 2017 Abstract This systematic review and meta-analysis evaluates the efficacy of parent training group interventions to treat child externalizing and/or internalizing problems. A search identified 21 randomized controlled trials of parent group interventions aimed at ameliorating child externalizing and/or internalizing problems in children aged 4–12 years. Random effects meta-analyses yielded significant pooled treatment effect size (g) estimates for child externalizing (g = −0.38) and internalizing problems (g = −0.18). Child anxiety symptoms or internalizing problems evident in children with externalizing behavior problems did not change significantly following intervention. Study quality was a statistically significant moderator of treatment response for child externalizing problems, however hours of planned parent group treatment and treatment recipient were not. Findings support the use of parent group interventions as an effective treatment for reducing externalizing problems in children aged 4–12 years. Whilst statistically significant, programs had a limited impact on internalizing symptoms, indicating a need for further investigation. * Kylie M. Gray kylie.gray@monash.edu 1 Centre for Developmental Psychiatry & Psychology, Department of Psychiatry, School of Clinical Sciences at Monash Health, Monash University, Melbourne, Australia 2 Centre for Educational Development, Appraisal and Research, University of Warwick, Coventry, UK 3 Early in Life Mental Health Service, Monash Health, Melbourne, Australia 4 Centre for Developmental Psychiatry & Psychology, 1/270 Ferntree Gully Road, Notting Hill, VIC 3168, Australia 13 Vol:.(1234567890) Keywords Parent training · Group therapy · Early intervention · Externalizing disorders · Internalizing disorders Introduction Internationally, the prevalence of child mental health problems is high. Research suggests that up to one in five children worldwide experience mental health problems [1, 2]. Children’s mental health problems have high social, personal and economic costs [3], in both the short and long term [4]. Child mental health problems often continue into adolescence and then adulthood, adding further costs related to areas such as school dropout, substance abuse, poor vocational outcomes, family violence and suicide, along with sick leave, unemployment and crime [5, 6]. The financial cost arising from mental health problems in young people places significant burden on health services, social, and education systems [7, 8]. For instance, Scott et al. [9] estimated the mean individual total cost of publicly resourced services for those aged 28 who continued to experience behavioral problems associated with early onset Conduct Disorder to be £70 019 (£114 475.51 inflated to 2017, ten times higher than for those with no behavioral problems). Given such costs, it is vital that evidence-based, early intervention treatments are adopted with the aim of ameliorating these problems before they incur greater burden to the child, family and society. Broadly speaking, mental health problems in childhood can be categorized into two broad types: externalizing (behavioral) and internalizing (emotional) problems. Externalizing problems are characterized by an under-controlled behavioral pattern, a tendency to act out and respond in a way that disturbs or is harmful to others [10]. Some of Child Psychiatry Hum Dev (2018) 49:244–267 the most common mental health disorders considered to be externalizing problems are attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder (ODD) and conduct disorder (CD) [11]. Internalizing problems, on the other hand, is a broad term that refers to a range of difficulties characterized by personal emotional distress and described as over-controlled or inhibited behaviors [12]. Internalizing problems in childhood may manifest as, for example, anxiety or depressive disorder [13]. Together, internalizing and externalizing disorders are among the most common difficulties of early childhood, affecting approximately 15% of those aged 8–15 years [14]. Community-based studies have confirmed this high prevalence, along with a strong stability of internalizing symptoms across early to mid-childhood [15]. Without effective intervention, these children are at great risk of experiencing deterioration in their presenting difficulties as they move towards and through the adolescent years and into adulthood [16, 17]. Interventions for Child Externalizing Problems There is evidence that psychological treatments are effective in reducing externalizing problems in children and adolescents with clinical conduct problems [18]. Metaanalyses [19–21] and reviews [22, 23] have provided evidence to suggest that parent training interventions are effective at reducing children’s externalizing behavior problems. Lundahl et al. [19] conducted a meta-analysis of 63 peerreviewed studies that evaluated the ability of parent training programs (including group, individual, self-directed delivery) to modify disruptive child behaviors and parental behavior and perceptions. Effects immediately following treatment for behavioral and non-behavioral programs were small to moderate. However, studies included in the review were limited to years spanning 1974–2003 and the authors conducted an analysis of child (externalizing) behavior outcomes only. Kaminski et al. [20] meta-analytic review of the components associated with effective parenting programs indicated larger effects on children’s externalizing behaviors for programs that included training in behavioral strategies such as time-out and parental consistency, as well as training in positive interactions (e.g., positive reinforcement for appropriate behavior) and in vivo practice with the parent’s own child. However, the programs included in this review varied widely in their mode of delivery (e.g., individual, group, self-directed) and the review was restricted to treatment of children aged 0–7 years and studies published from 1990 to 2002. Research has also focused on a wide range of early intervention programs and have produced evidence indicating that group-based parenting interventions, many based on social learning theory, offer an effective treatment for 245 externalizing behavior problems in children [24–26]. One group-based parenting program, Group Triple P [27], is based on theory that suggests that coercive patterns of parent–child interaction lead to child problem behaviour [28]. Previous studies have indicated that Group Triple P results in significant reductions in negative child behaviors (e.g., aggression, tantrums, and oppositionality) [27]. Recently, Furlong et al. [29] systematic review of randomized controlled trials (RCTs) or quasi-randomized controlled trials of behavioral and cognitive-behavioral group-based parenting interventions for parents of children aged 3–12 years with conduct problems found both types of interventions were effective and cost-effective for improving child conduct problems, parental mental health and parenting skills in the short-term. However, limitations of the review were the lack of long-term assessment of outcomes, limited data on child emotional problems, and the fact that 9 of the 13 included studies evaluated the effectiveness of the Incredible Years intervention [30]; meaning results are most applicable to studies of interventions that share components similar to the Incredible Years program. Interventions for Child Internalizing Problems While there has been extensive past research into parent training for early intervention of children with externalizing problems, the same cannot be said for children with internalizing problems [22]. Children with serious internalizing disorders such as anxiety represent some of the most severely impaired group of students in schools and those most in need of comprehensive services. Despite this, few studies have tested parent-only interventions for childhood anxiety and among these existing studies [31–33] the emphasis has been on training parents as lay therapists to implement cognitive behavioral therapy (CBT) with the child. One recent exception is a therapist-led, parent-based treatment intervention for childhood anxiety called the supportive parenting for anxious childhood emotions program (SPACE) [34]. The SPACE program is a parent-only intervention that moves away from teaching parents specific sets of skills and aims to target the fundamental dynamics underlying the interaction between parents and anxious children. However, the SPACE program is yet to be adapted or trialed in a group setting. More promising is recent evidence that supports the theorized cross-impact effects of group-based parent interventions on child outcomes. That it, there is theoretical and empirical evidence to suggest that disruptive behaviors and internalizing symptoms have similar developmental antecedents (i.e., exposure to negative parenting practices) and may respond to like interventions [35, 36]. For instance, Webster-Stratton and Herman [37] found that the Incredible Years (IY) Parent Training (PT) program 13 246 reduced internalizing symptoms in children in addition to its well-established effects on child conduct problems. In a recently conducted randomized control trial, Niec et al. [38] investigated the relative efficacy of a novel group format of parent–child interaction therapy (PCIT) versus individual PCIT with parents of 3–6-year-old children with oppositional defiant or conduct disorder. Study results demonstrated that in addition to experiencing a significant reduction of conduct problems, children in both group and individual PCIT experienced a significant reduction of internalizing symptoms from intake to post-treatment and from intake to follow-up. While such results are encouraging, a paucity of research trials that focus on implementation of parent training programs that specifically target internalizing problems in early primary school aged children or that evaluate child internalizing outcomes resulting from group-based parent programs with primary school aged children remains a major shortcoming in the knowledge base. Current Review This review seeks to address several gaps in knowledge of evidence-based parent group interventions. First, it includes the breadth of group-based parent interventions, such as studies in which parent group training is delivered as a stand-alone group treatment, parallel group intervention (i.e., with concurrent child group treatment) or part of a multi-systemic intervention. Second, it includes studies delivered in ‘real world’ settings (i.e., school settings) rather than being restricted to clinic or research settings only. Third, while clinical work directed at parents has been advocated as a potential enhancer of treatment outcomes for internalizing problems such as anxiety in children and adolescents, there have been inconsistent findings in the research literature regarding whether parent involvement in treatment significantly improves child anxiety outcomes [39]. Therefore, group-based parent treatments aimed at ameliorating child internalizing problems will be encompassed within this review. Finally, in the last decade a number of more recently developed parent group programs have been trialled that have not been included in prior systematic reviews. This paper aims to encompass and review such programs. Given group-based parent training programs may arguably enhance efficiency and provide parents with increased peer support and reassurance, this systematic review and meta-analysis of the current literature examined the efficacy of identified parent group interventions to reduce externalizing and internalizing problems in children aged 4–12 years. This review had the overarching aim of evaluating the efficacy of parent group interventions to treat externalizing and/or internalizing problems in children. 13 Child Psychiatry Hum Dev (2018) 49:244–267 Specifically, this review also aimed to: (1) describe and summarize characteristics of the included studies; (2) examine whether there is a cross-impact treatment effect on internalizing problems evident in children with externalizing behavior problems whose parents participated in group programs; and (3) explore if treatment efficacy varies as a function of treatment recipient (i.e., parent group versus parent group +/− teacher and/or child intervention components), study quality (i.e., summary risk assessment), and planned number of hours of parent group intervention. Method Identification of Trials A systematic review and meta-analysis was conducted in keeping with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) [40]. A literature search was conducted for all peer reviewed studies from 01 January 2005 to 21 October 2016, with the aim of locating trials of parent group interventions for children aged 4–12 years with externalizing and/or internalizing problems. Earlier studies (i.e., those published prior to 2005) were excluded to ensure that the results of our analysis were representative of trials of contemporaneous parent group programs as well as more recently developed programs not encapsulated in prior reviews. An electronic search of the databases PsycINFO, Medline and CINAHL was performed using key words for child externalizing (behaviour, conduct, externalizing, oppositional, aggressive, impulsivity, hyperactive, or antisocial) and internalizing (emotional, internalizing, anxiety or depression) problems, combined with keywords for group-based parent training (parent, group, training, intervention, education, outcome, program, or treatment). Searches were limited to peer reviewed papers and children aged 0–12 years. In addition, reference lists of articles located by this search were hand searched for additional papers to be included in the review. Studies met selection criteria for this systematic review if they (a) included a therapist-led, manualized parent group intervention aimed at improving externalizing and/or internalizing problems for children aged 4–12, (b) evaluated the parent group intervention in comparison with a control (active or inactive), (c) included a standardized measure of child externalizing and/or internalizing outcomes, (d) included quantitative analysis of outcomes, (e) were published in a peer-reviewed journal, and (f) excluded children with primary or co-morbid diagnoses of intellectual disability, communication disorder, or autism spectrum disorder. Studies reporting on findings from the same trial were included in the systematic review, provided they reported on different child Child Psychiatry Hum Dev (2018) 49:244–267 externalizing and/or internalizing outcome measures and otherwise met criteria for inclusion in the review. The review authors took care to ensure that the participant characteristics from articles reporting outcomes from the same trial were not ‘double counted’ (i.e., when reporting on the total number of participants included in the review). To accurately reflect the breadth of contemporaneous methods of delivery of parent group training, studies in which parent group training was delivered as a standalone group treatment, parallel group intervention (i.e., with concurrent child group treatment) or part of a multisystemic intervention were considered for inclusion. Due to the high levels of co-morbidity between oppositional and conduct problems and attention deficit hyperactivity disorder (ADHD), samples including children with comorbid ADHD or ADHD alone were included in the systematic review provided a primary concern for the child participants was externalizing behavior problems such as aggression, conduct problems or oppositional behavior and the parent group intervention component was designed to teach parents skills to manage externalizing behavior separate from skills learned to manage specific ADHD symptoms. However, samples including children with primary or co-morbid diagnoses of intellectual disabilities, communication disorders, or autism spectrum disorder were excluded, as children with these conditions require specialized and often modified approaches to intervention. Studies in which child- or family-focused interventions were the primary focus were not included in this review. Studies were also excluded if it was evident that they were not experimental in nature or examined a question other than the efficacy of parent group training in improving child externalizing and/or internalizing problems. Studies were not excluded on the basis of theoretical orientation of the parent group intervention of interest. One author (SB-P) independently reviewed all abstracts located in the electronic database searches and conducted an initial elimination of studies based on selection criteria. Eligibility assessment was performed on all remaining studies in a non-blinded standardized manner by three authors (SB-P, KMG and GAM). One author (SB-P) then independently extracted data from the included studies into a format for systematic review based on existing guidelines [41, 42]. Study authors were contacted to obtain further information about data or details not reported for the included papers. The other authors then reviewed this extracted information for accuracy and completeness. Risk of bias was assessed for each study by three authors (SB-P, KMG and GAM) using The Cochrane Collaboration’s tool [41]. One author (MG) conducted all meta-analyses undertaken in this review. 247 Ratings of Study Quality Evaluating potential risks of bias in a body of research evidence is an important yet complicated task. The PRISMA statement recommends that systematic reviews and metaanalyses include assessments of risk of bias within and across studies [40]. Based on PRISMA recommendations, all included studies in this review were assessed using a standardized risk of assessment tool. The current review authors assessed study quality using two approaches. First, in accordance with guidelines from the Cochrane Handbook for Systematic Reviews of Interventions [41], the quality of each RCT was rated in eight criterion categories: random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, attrition bias, reporting bias, and any other bias deemed important. Bias can occur in any of these areas and can affect the interpretation of the study’s results. Based on guidelines, each of the eight criterion categories within an individual study was judged as ‘high’ (plausible bias that seriously weakens confidence in results), ‘low’ (plausible bias unlikely to seriously alter the results), or ‘unclear’ risk of bias (plausible bias that raises some doubt about the results) by the reviewing authors. For the second assessment of study quality, the three criterion categories related to blinding of participants, personnel and outcome assessors (i.e., performance and detection bias) were excluded and a summary risk assessment for each study was based on ratings across the remaining five criterion categories (random sequence generation; allocation concealment; incomplete outcome data; selective reporting; and, any other bias). The rationale for excluding performance and detection bias criterion categories from this second assessment of study quality is that almost invariably parents and study personnel (i.e., therapists) in parent group intervention studies are not completely blinded; they are usually aware whether or not they or their child have received a particular intervention or intervention arm in a trial. Further, parent report of child externalizing and internalizing problems is the most common outcome source and often the most appropriate and feasible way to obtain assessment of key outcomes. The summary risk assessment for each study based on these remaining five criterion was rated as follows: ‘low risk’ of bias (‘low risk’ of bias for all five criterion); ‘unclear risk’ of bias (‘unclear risk’ of bias for one or more criterion); and, ‘high risk’ of bias (‘high risk’ of bias for one or more criterion). Meta‑analyses Data from parent- and clinician-reported measures of child externalizing and internalizing problems were used in meta-analyses using a random effects model. 13 248 Under the random effects model, the true effect size is assumed to vary from study to study and the summary effect is the estimate of the mean of the distribution of effect sizes. Data were analyzed using a random effects model as it was expected that the studies included in this meta-analysis would differ on their study characteristics, resulting in varying true effect sizes [43]. Separate metaanalyses were conducted to examine the effects of parent group interventions on child externalizing and internalizing outcome measures, child anxiety, and cross-impact treatment effect of parent group interventions on internalizing symptomatology evident in children with externalizing problems. All randomized controlled trials that met inclusion criteria and provided sufficient data with post and control variables to calculate an effect size were included. Where more than one active treatment arm was reported, the numbers, means and standard deviations were converted to a single treatment outcome using the formula reported by Cochrane [41]. Where standard errors were reported, standard deviations were calculated using the formula reported by Cochrane [41]. Standardized mean differences were calculated with a random effects model using Hedges’ g. Hedges’ g was used, as it corrects for biases due to small sample sizes, which is not assumed under Cohen’s d. Hedges’ g < 0.5 indicate a small effect size, g = 0.5–0.8 indicate a moderate effect size and g > 0.8 indicate a large effect size [44]. Heterogeneity was assessed using visual inspection of the forest plots and the I2 index. The I2 index was computed to provide a measure of the degree of heterogeneity, where I2 is interpreted as the percentage of variability among effect sizes that exists between studies relative to the total variability among effect sizes [45]. The I2 index can be interpreted as follows: 0% indicates homogeneity; 25% indicates small heterogeneity; 50% is medium; and 75% is large [45]. The level of significance was set for p < 0.1 for the heterogeneity of the studies. Publication bias was assessed using a funnel plot. Meta-regression was conducted on those meta-analyses that were significant (p < 0.05). The I2 residual was computed to provide a percentage of residual heterogeneity that is attributable to between-study heterogeneity. Independent variables of (1) hours of planned parent group treatment as a continuous measure, (2) treatment recipient (parent only versus parent +/− teacher and/ or child intervention components) as a categorical variable, and (3) study quality (summary risk assessment of ‘unclear risk’, ‘low risk’ or ‘high risk’) as a categorical variable were entered in the regression as single variables. Statistical analyses were conducted using Stata 12 [46]. 13 Child Psychiatry Hum Dev (2018) 49:244–267 Results Study Selection As seen in Fig. 1, a total of 3992 articles were identified through the initial database searches, 746 of which were duplicates. An additional four potential studies were identified by hand searching the reference lists of included studies. When duplicates were removed and a review of the titles and abstracts of the remaining 3250 abstracts completed, 3153 papers were excluded because they did not meet the criteria. Of the remaining 97 articles, a further 74 papers were excluded (see Fig. 1 for reasons). Overall, a total of 23 articles involving parent group interventions from 21 RCTs were identified for inclusion in the review. These articles were published between March 2006 and April 2016. Articles by Duncombe et al. [47] and Havighurst et al. [48] reported findings from the same trial. Both articles were included in the current review as they measured child externalizing problems using different outcome measures. Articles by Chacko et al. [49] and Rajwan et al. [50] also reported findings from the same trial using different outcome measures and were therefore both included in the review. Study Characteristics Characteristics of each study are included in Table 1 and summarised below. Study Design and Treatment Focus As seen in Table 1, 19 of the 23 (82.6%) studies included in this review were RCTs and the remaining four studies (17.4%) were cluster RCTs. In regard to treatment focus, 20 studies (87.0%) evaluated outcomes of intervention programs aimed primarily at addressing child externalizing problems [47–53, 55–58, 60–66, 68, 69]. The remaining three studies [54, 59, 67] evaluated outcomes of interventions aimed exclusively at parents of children with internalizing problems. Number of Treatment Sessions The number of group treatment sessions completed by parent participants ranged from 3 to 28 sessions across studies. Session length ranged from 60 min (1-h) to 150 min (2.5-h) across studies. Booster Sessions Of the 23 studies included in this review, four (17.4%) of studies described use of booster sessions post treatment Included Eligibility Screening Identification Child Psychiatry Hum Dev (2018) 49:244–267 249 Records identified through database searching (n = 3992) Additional records identified through hand searches of reference lists of located papers or via contact with field authors (n = 4) Records screened after duplicates removed (n =3250) Full-text articles assessed for eligibility (n = 97) Studies included in review (n = 23) Records excluded as did not meet criteria (n =3153) Articles excluded (n = 74) because: Outside specified age range (n = 23) No therapist-led parent group intervention (n = 18) Not an RCT (n = 14) Did not target child emotional/behavioral problems (n = 8) Non-English language and no translation located (n = 4) Sample included children with known diagnoses of Pervasive Developmental Disorders, ID or Communication Disorders (n = 3 ) Moderator analyses of data only (n = 2) No measure of child emotional/behavioral problems (n = 1) Study protocol only (n = 1) Fig. 1 PRISMA flow chart describing identification and selection of studies for inclusion in the systematic review adapted from Moher et al. [40] [54, 57, 59, 67]. Havighurst et al. [57] incorporated two parent booster sessions offered at two-monthly intervals post intervention. Waters et al. [67] offered booster sessions to parent and child participants in both active treatment conditions 8 weeks after the final sessions. De Groot et al. [54] conducted one booster session with children approximately 3–4 weeks following completion of the child program. Finally, Holmes et al. [59] offered two booster sessions to parents and children at 1 and 3 months after completion of the initial program. Settings Studies were based on trials conducted in a variety of settings, including: university clinics [49, 50, 52, 54, 58, 59, 67–69], social service organizations [55], primary school or kindergarten settings [47, 48, 53, 56, 64, 65], community settings [57], community or school sites [61, 63], outpatient child mental health clinic settings [51, 60, 66], and insufficiently described settings [62]. Seven (30.4%) studies were based on trials conducted in Australia [47, 48, 54, 57, 59, 67, 69], five (21.7%) studies were based on trials conducted in the USA [49, 50, 58, 61, 68], and four (17.4%) were based on trials conducted in the United Kingdom [62–65]. The remaining trials were conducted in Belgium [52], Hong Kong [55], Ireland [56], Norway [60], the Netherlands [66], Romania [53], and Sweden [51]. Participants The included studies involved a total of 2197 eligible participants. The total sample size per study varied greatly, ranging from 18 to 320 across studies. Trial samples 13 13 Group CBT program Individual CBT program Tuning in to kids (TIK) Triple P—Positive Parenting Program (Triple P) Anger Coping Training (ACT) Parents Plus Children’s Program (PPCP) TIK TIK 5. de Groot et al. [54] 6. Duncombe et al. [47]b 8. Hand et al. [56] 9. Havighurst et al. [47] 10. Havighurst et al. [56] 7. Fung & Tsang [55] RCT Cluster RCT RCT TIK (n = 31) WL (n = 23) TIK (n = 91) WL (n = 113) PPCP (n = 44) No treatment CG (n = 31) Cluster RCT TIK (n = 91) Triple P (n = 116) WL (n = 113) RCT ACT program (n = 12) Control group (n = 6) RCT Group CBT (n = 15) Individual (n = 14) Standard program (n = 47) Enhanced program (n = 45) Wait-list (n = 38) RCT 4. David et al. [53] Traditional BPT (n = 40) STEPP (n = 40) WL (n = 40) RCT Traditional behavioral parent training STEPP (Strategies to Enhance Positive Parenting) program Standard Cognitive Behavioral Parenting Program (Standard) Rational Positive Parenting Program (Enhanced) 3. Chacko et al. [49]a RCT Parent Management Training (PMT) Conditions 2. Braet et al. [52] Design PT (n = 37) WL (n = 24) PMT (n = 34) WL (n = 30) Parent group program(s) 1. Axberg and Broberg [51] Incredible Years BASIC PT RCT Study Table 1 Summary of study characteristics Pre, post, 3 mo FU Pre, post, 12 mo FU Pre, post, 12 mo FU Measure times Parents of children (aged 4–9 years) screened for conduct problems Parents of children (aged 8–10 years) screened for aggressive behaviors Parents of children (aged 6–11 years) self-selected to participate Primary caregivers of children (aged 4–9 years) screened for conduct problems Parents of children (aged 4–5 years) who presented with externalizing behavior difficulties Parents of children with a principal diagnosis of an anxiety disorder 8, 2.5-hr weekly sessions. (B) 8, 2-hr parent group sessions. (B) 6, 2-hr weekly sessions. (B) Baseline 6 mo FU Pre, Post 6 mo FU Standard : 10, 90-min sessions. (B) Enhanced: 10, 90-min sessions, incorporating an emotion-regulations strategies module. (B) Group CBT: 12-session (60–90 min) manualized program including 6 parent-focussed sessions. (E) TIK: 8, 2-hr weekly parent group sessions. (B) PPP: as above. (B) 10 sessions, 1.5 h per session. (B) Traditional BPT: 9, 2.5-hr weekly sessions. (B) STEPP: 9, 2.5 h weekly sessions. (B) 6–8 parents, weekly 2-h sessions, 12–14 weeks. (B) 8–10 parents, 11 (2-hr) sessions, spread over 24 weeks. (B) Parent group program description and treatment aim Pre, post 6 mo FU Pre, post 3 mo FU Baseline 6 mo FU Pre, post, 3 mo FU 6 mo FU Pre, mid, post Parents of children (aged 4–12 years) with external- 1 mo FU izing behavior problems Parents of children (aged 4–8 years) with ODD Parents of children (aged 4–7 years) exhibiting problematic or externalizing behavior Single mothers of children with ADHD Participants 250 Child Psychiatry Hum Dev (2018) 49:244–267 Triple P (n = 73) Waitlist and services as usual (n = 73) Traditional BPT (n = 40) STEPP (n = 40) RCT No Worries! Program Basic IY Parenting Program IY Parenting Program Group Triple P Traditional Behavioral Par- RCT ent Training STEPP Program 1-2-3 Magic Parenting Program IY Parenting Program 12. Holmes et al. [59] 13. Larsson et al. [60] 14. Lau et al. [61] 15. Little et al. [62] 16. Rajwan et al. [50] 17. Sayal et al. [63] 18. Scott, O’Connor et al. [64] IY Parenting Program (n = 32) Delayed treatment (n = 22) PT (n = 51) PT + CT (n = 55) WL condition (n = 30) Cluster RCT Parent only arm (n = 67) Parent + Teacher arm (n = 60) Control arm (n = 72) RCT IY Program plus six-week literacy program (n = 88) Usual community services (control group; n = 86) RCT RCT Cluster RCT PT (n = 31) PT + TT (n = 24) CT (n = 30) CT + TT (n = 23) PT + CT + TT (n = 25) WL (n = 26) RCT WL (n = 22) Treatment group (n = 20) Incredible Years (IY) Series Conditions 11. Herman et al. [58] Design Parent group program(s) Study Table 1 (continued) Pre Parents of children (aged 5–6 years) in the screened 12 mo FU population who scored above the cut-off level for ODD symptoms or conduct problems Baseline 3 mo and 6 mo after baseline 4, 2.5-hr parent sessions plus four individual telephone consultations (15–30 min duration each). (B) Baseline 6 mo FU Parents of children (aged 4–8 years) at risk of ADHD 5–10 parents, 14 (2-hr) sessions. (B) Pre, post 6 mo FU 18, 2-hr sessions were offered, interleaving a 12-week parenting program with a 6-week literacy program. (B) Traditional BPT: 9, 2.5-hr weekly sessions. (B) STEPP: 9, 2-5hr weekly sessions. (B) 1–7 parents, 3 (2-hr) weekly sessions. (B) 10–12 parents, 12–14 weeks, 2-hr sessions. (B) Baseline, post 12 mo FU Baseline Post 7 weekly (1.5-hr) sessions. (E) Pre, post, 3 mo FU Parents of children (aged 7–12 years) with a primary clinical diagnosis of GAD Parents of children (aged 4–8 years) with subthreshold or definitive diagnosis of ODD and/ or CD Chinese American parents and their children (aged 5–12 years) referred for PT due to concerns about parental discipline or child behavior problems Parents of children (aged 4–9 years) whose symptoms indicated a potential social-emotional or behavioral disorder Single mothers of children with ADHD 10–12 parents, 22–24 weekly (2-hr) sessions. (B) Pre, post 12 mo FU Parents of children (aged 4–8 years) with ODD Parent group program description and treatment aim Measure times Participants Child Psychiatry Hum Dev (2018) 49:244–267 251 13 13 Behavioral parent training (BPT) ‘‘Take ACTION’’ Program RCT Incredible Years (IY) treatment condition Pathways Triple P (PTP) 20. van den Hoofdakker et al. [66] 21. Waters et al. [67] 22. Webster-Stratton et al. [68] 23. Wiggins et al. [69] PTP intervention (n = 30) WL (n = 30) IY treatment condiction (n = 49) WL (n = 50) PO condition (n = 25) P + C condition (n = 24) WL (n = 11) BPT + uncontrolled Routine Clinical Care (RCC) (n = 47) Uncontrolled RCC alone (n = 47) IY Program plus six-week literacy program (n = 61) Control (Helpline; n = 51) Conditions 28 weeks of intervention, including parent group program and literacy program, delivered to 4–8 parents for 2.5 h one morning per week. (B) 12, 120-min sessions. Six children’s parents could participate in each group. (B) Pre 12 mo FU Parents of children (aged 5–6 years) in the screened population who scored above the cut-off level for ODD symptoms or conduct problems Parents of children (aged 4–12 years) with ADHD who had been referred to an outpatient mental health clinic by their general practitioners Parents of children (aged 4–8 years) with specific phobia, social phobia, generalized anxiety disorder and/or separation anxiety disorder Parents of children (aged 4–6 years) with ADHD (hyperactive or inattention) Parents of children (aged 4–10 years) with parent–child relationship disturbance and parentreported child emotional or behavioral problems 10 parents, 9 weekly (2-hr) sessions. (B) Pre, post, 3 mo FU Pre, Post Parents of children in the PO and P + C conditions received 10 weekly sessions of group-based cognitive-behavioral treatment (GCBT). (E) IY treatment condition: 6 parents, 20 weekly (2-hr) sessions. (B) Pre, post, 6 mo FU, 12 mo FU Pre, post, 6 mo FU Parent group program description and treatment aim Measure times Participants Duncombe et al. [47] and Havighurst et al. [48] studies based on the same trial b Chacko et al. [49] and Rajwan et al. [50] studies based on the same trial a B behavioral problems, CG control group, CT child therapy, E emotional problems, FU follow-Up, mo months, P + C parent + child, PD professional development, PO parent only, PT parent training, RCT randomized control trial, TT teacher training, WL waitlist control RCT RCT RCT RCT IY Parenting Program 19. Scott, Sylva et al. [65] Design Parent group program(s) Study Table 1 (continued) 252 Child Psychiatry Hum Dev (2018) 49:244–267 Child Psychiatry Hum Dev (2018) 49:244–267 included a majority of male child participants with exception of four studies [53, 59, 64, 67]. Data pertaining to sex of child participants was not stated in Hand et al. [56]. The majority of parent participants were female however parent gender was not stated in five studies [59, 62–64, 66]. The majority of studies (16/23 or 69.6%) included samples of children with diagnoses of or sub-threshold symptoms of externalizing or internalizing disorders. Specifically, nine (39.1%) studies focused on evaluation of interventions with parents of children with diagnoses of ADHD [49, 50, 66, 68], ODD [51, 58], or anxiety disorders [54, 59, 67]. Seven (30.4%) studies evaluated interventions with parents of children with specific difficulties such as oppositional or conduct problems [47, 48, 60, 64, 65], aggressive behaviors [55], or sub threshold symptoms of ADHD [63]. Four studies (17.4%) evaluated interventions with parents of children with general externalizing behavior concerns [52, 53, 57, 61] and two studies (8.7%) included samples of children at risk of social-emotional or behavioral disorders [62, 69]. One study (4.4%) included children whose parents self-selected to participate in parent training [56]. Economic status of participants varied across studies. For instance, samples ranged from being, on average, markedly disadvantaged [64, 65] to majority of participants reporting they had no significant financial problems [69]. Four studies (17.4%) involved participants from predominantly low income families [52, 55, 61, 62], three studies (13.0%) had samples that were predominantly from a low to middle socioeconomic demographic [47, 48, 57], one study [68] had a sample of parents with predominantly middle socioeconomic status, and two studies had samples of parents with predominantly middle to high socioeconomic status [53, 59]. Economic status of participants was not explicitly stated for 10 (43%) studies [49–51, 54, 56, 58, 60, 63, 66, 67]. Selection Criteria Inclusion criteria relating to child characteristics included specified age range for child [47–53, 58, 60, 62, 63, 66, 69]; elevated child scores on parent/teacher-rated behavioral and/or emotional problem measures [47–50, 52, 53, 55, 62–65, 69]; parent-reported child misconduct or child met sub threshold or definitive diagnosis of DSM-IV criteria for ODD or CD [51, 58, 60]; child met DSM-IV criteria for ADHD [49, 50, 66, 68] or an anxiety disorder [54, 67]; child met DSM-IV criteria for primary diagnosis of GAD with clinical severity rating (CSR) of at least 4 (on a 0–8 scale) [53] and, minimum reading level of 7 years [53]. Inclusion criteria across studies for parent characteristics consisted of parent and/or clinician identified need for parent training [61]; both parents (if present) willing and/ 253 or able to participate in the group program [65, 66]; parent–child relationship disturbance in borderline to clinically significant range [69]; parent ability to understand English [65] or Swedish [51] language; and single mother as primary caregiver [49, 50]. Four studies [56, 57, 63, 68] did not specify parental inclusion criteria. Children were excluded if they had intellectual disability/developmental delay [58–60, 64–66]; IQ less than 80 [49, 50]; organic brain damage [67] communication disorder [57]; pervasive developmental disorder [47–50, 57, 59, 60, 67]; debilitating physical impairment [58, 60]; sensory deprivation [60]; history or evidence of psychosis [49, 50, 58, 67]. One study [67] excluded children with a co-morbid externalizing disorder, as the CBT-based group treatment was focused on children with anxiety disorders. A further study [53] excluded children referred for internalizing disorders as the primary problem, as the focus of treatment was for child externalizing behavior problems. Children were also excluded if they were taking medication to treat ADHD [57, 68] or were already in receipt of psychological, pharmacological or medical treatment [53, 54, 58–60, 67]; had significant medical problems [54]; had severe learning difficulties [54, 59]; met diagnostic criteria for a clinically significant non-anxiety diagnosis ([54]; treatment focused on treatment of child anxiety); had behavioural problems more impairing than anxiety ([59]; study focused on treatment of child anxiety); and had substance abuse, self harm or suicidal ideation [59]. Two studies did not specify child exclusion criteria [51, 63]. Other exclusion criteria across studies included criteria not specifically stated [51, 52, 55, 58, 61–63, 65, 66, 68, 69]; no exclusionary criteria applied [56]; insufficient parent English skills to complete assessment or understand content of intervention [57, 64]; parent presenting with psychotic disorders, current substance abuse or intellectual disability [53]; parent declined invitation to participate [47, 48]; and, schools withdrew from study following screening [47, 48]. Interventions In regard to parent group programs evaluated, seven (30.4%) studies evaluated versions of the Incredible Years program [51, 58, 60, 61, 64, 65, 68], two studies evaluated versions of the Triple P Program—Positive Parenting Program [62, 69], and two studies evaluated the Tuning into Kids (TIK) program [48, 57]. Duncombe et al. [47] evaluated both the Triple P Parenting—Positive Parenting Program and TIK programs. Other programs evaluated included Parent Management Training [52], behavioral parent training [66], Anger Coping Training (ACT) parent–child parallel group program [55], Parents Plus Children’s Program (PPCP) [56], and the Take Action Program 13 254 [67], Behavioral Parent Training (BPT) versus Strategies to Enhance Positive Parenting (STEPP) [49, 50], No Worries! Program (cognitively-focused program) [59], Standard Group based Cognitive-Behavioral Parent Program versus Enhanced Cognitive-Behavioral Parent Programs [53], Do as I do program for parents (group CBT) [54] and, 1-2-3 Magic parenting program [63]. Outcome Measures Child externalizing and internalizing problems were measured using a variety of outcome measures. All of the included studies used parent report measures. Teacherreported measures were used in ten (43.5%) studies [47, 48, 51–53, 55, 57, 59, 64, 68]. Investigator-based parent interview was used in five (21.7%) of studies [54, 59, 64, 65, 67]. Child assessed measures were used in three studies [47, 54, 59]. Refer to Table 1 for details of timing of outcome assessment for individual studies. Treatment Fidelity Of 23 studies included within this review, 20 (87.0%) studies reported efforts or measures taken to ensure treatment fidelity [47–51, 53, 54, 57–69]. Nineteen studies (82.6%) reported satisfactory or high treatment fidelity. One study [62] reported poor treatment fidelity. Child Psychiatry Hum Dev (2018) 49:244–267 Child Externalizing Problems Twenty studies (87.0%) reported on child externalizing problem outcomes using parent report [47–53, 55–57, 60–69]. Clinician-rated diagnostic interviews with parents were used to measure child externalizing problems in two studies [64, 65]. Of the 20 studies that measured child externalizing problems, 16 (80.0%) of the included studies reported statistically significant findings that favored the parent group intervention over control (or alternative treatment) for child externalizing problems [47–51, 53, 55–57, 60, 61, 63, 65, 66, 68, 69]. Four of the studies [52, 62, 64, 67] reported no statistically significant difference between groups. Three studies [54, 58, 59] did not measure child externalizing problems. Effect size values reported with Cohen’s d for difference in outcomes between intervention groups versus control on parent-reported measures [70–74] of child externalizing problems ranged from negligible to large (d = 0–1.26). Effect size values reported with partial eta squared for difference in outcomes between intervention groups versus control on parent-reported measures [70, 71, 74] of child externalizing problems ranged from medium to large (partial η2 = 0.04–0.24). Effect size values reported with Cohen’s d for difference in outcomes between intervention groups versus control on clinician-reported measures [75] of child externalizing problems showed medium treatment effect (d = 0.44–0.52). Study Outcomes Child Internalizing Problems The results of the 23 included papers are listed in Table 2. Results are based on post/follow-up treatment outcomes for parent- and clinician-reported measures of child externalizing and internalizing problems. Statistically significant differences (p values) in outcome between intervention group(s) versus control have been indicated where available throughout. Effect sizes for differences in outcome between intervention group(s) versus control are also reported where available. Effect sizes were presented using partial eta squared (partial η2; [44]) in four studies [59, 67–69] and Cohen’s d [44] in 13 studies [47–49, 51–53, 56–58, 60, 61, 65, 66]. Effect sizes were not reported in six studies [50, 54, 55, 62–64]. According to Cohen [44], guidelines for magnitude of partial eta squared are that 0.02, 0.13 and 0.26 indicate small, medium and large effect sizes respectively, whereas guidelines for magnitude of Cohen’s d are that 0.2, 0.5 and 0.8 indicate small, medium and large effect sizes respectively. The following component of this section of the review provides a narrative summary of the effects of the parent group interventions on the two key child outcome variables of interest. Fourteen studies (60.9%) reported on child internalizing problem outcomes [51, 52, 54, 56, 58–62, 65–69]. All fourteen studies used parent-rated measures. Four studies [54, 59, 65, 67] used clinician-rated diagnostic interviews with parents to measure severity of child anxiety symptoms. Of the fourteen studies that measured child internalizing problems, five (35.7%) studies included statistically significant findings that favored the parent group intervention over control (or alternative treatment) for child internalizing problems [58–60, 66, 67]. Nine of the fourteen studies (64.3%) reported outcomes showing no statistically significant difference between groups [51, 52, 54, 56, 61, 62, 65, 68, 69]. Little et al. [61] reported that emotional disorders for some children whose parents participated in the TripleP groups increased in severity compared with those in the control group receiving services as usual. Nine studies did not measure child internalizing outcomes [47–50, 53, 55, 57, 63, 64]. Effect size values reported with Cohen’s d for difference in outcomes between intervention groups versus control on parent-reported measures [70, 72] of child internalizing 13 BPT and STEPP combined > waitlist DBD oppositional defiant disorder (P) (p < 0.01, d = 0.44)** BPT and STEPP combined = waitlist DBD inattentive (P) (ns, d = 0) DBD hyperactive/impulsive (P) (ns, d = 0.11) STEPP > traditional BPT DBD oppositional defiant disorder (P) (p < 0.01, d = 0.75)** STEPP = traditional BPT DBD inattentive (P) (ns, d = −0.16) DBD hyperactive/impulsive (P) (ns, d = −0.16) Standard program > WL CBCL externalizing behavior (P) (p < 0.001, d = 0.80)*** Enhanced program > WL CBCL externalizing behavior (P) (p < 0.001, d = 0.76)*** Outcome not measured 3. Chacko et al. [49]b N = 120 6. Duncombe et al. [47]c N = 320 5. de Groot et al. [54] N = 29 4. David et al. [53] N = 130 TIK or PPP > WL ECBI behavior intensity (P) 6-month FU (p = 0.000, d (TIK) = 0.40, d (PPP) = 0.40)*** PT > WL ECBI behavior intensity (P) (p = 0.001, d = 1.17)** ECBI behavior problems (P) (p = 0.003, d = 1.26)** PMT = WL CBCL total problem behavior (P) (ns, d = 0.66) CBCL externalizing behavior (P) (ns, d = 0.91) CBCL aggressive behavior (P) (ns, d = 0.81) CBCL delinquent behavior (P) (ns, d = 0.63) 1. Axberg and Broberg [51] N = 61 2. Braet et al. [52] N = 64 Child externalizing o­ utcomesa Study Table 2 Summary of child outcomes and quality of evidence High (outcome assessment partially blinded; not all of the study’s pre-specified outcome measures were reported; reported loss to follow up imbalanced across groups: PMT −4/34 (12%) loss and WL −11/30 (37%) loss; study did not specify reasons for attritions or exclusions; randomization claimed but not described and unclear if allocation was concealed) Unclear (outcome assessment partially blinded; unclear randomization method and allocation concealment unclear; study did not specify reasons for attritions) Unclear (outcome assessment partially blinded; unclear randomization method and allocation concealment unclear; adequate attrition analysis) PMT = WL CBCL internalizing behavior (P) (ns, d = 0.23) Outcome not measured GCBT = ICBT ADIS-IV-C/P clinical severity of anxiety (CL) (ns) SDQ emotional symptoms (P) (ns) Outcome not measured High (outcome assessment partially blinded; unclear randomization method; allocation not concealed as parents aware of allocation when received pre-measures via post) Unclear (outcome assessment not blinded; randomization method described but unclear if allocation concealed) Unclear (outcome assessment partially blinded; unclear randomization method and allocation concealment unclear; unequal sample sizes) PT = WL SDQ emotional symptoms (P) (p = 0.993, d = 0.004) Outcome not measured Quality of evidence—bias risk Child internalizing o­ utcomesa Child Psychiatry Hum Dev (2018) 49:244–267 255 13 13 PPCP > CG SDQ total difficulties (P) (p < 0.01, d = 0.32)** SDQ hyperactivity problems (P) (p < 0.01, d = 0.31)** SDQ conduct problems (P) (p > 0.05, d = 0.41) PPCP = CG SDQ peer problems (P) (p > 0.05) TIK > WL ECBI oppositional defiant disorder (P) 6-month FU (p = 0.011, d = 0.37)* ECBI conduct disorder (P) 6-month FU (p = 0.012, d = 0.37)* TIK = WL ECBI hyperactivity disorder (P) 6-month FU (p = 0.066, d = 0.29) TIK > WL (treatment as usual) ECBI behavior intensity (P) (p = 0.009, d = 1.20)** TIK = WL (treatment as usual) ECBI behavior problems (P) (ns, d = 1.05) Outcome not measured 8. Hand et al. [56] N = 75 12. Holmes et al. [59] N = 42 11. Herman et al. [58]d N = 159 10. Havighurst et al. [57] N = 54 Outcome not measured ACT > CG CBCL aggressive behavior (P) (p < 0.01)** 7. Fung & Tsang [55] N = 18 9. Havighurst et al. [48] N = 204 Child externalizing o­ utcomesa Study Table 2 (continued) Unclear (outcome assessment partially blinded; randomization technique adequate but unclear if allocation concealed) High (outcome assessment partially blinded; unclear randomization method and unconcealed allocation; results of two experimental groups collapsed into one overall group (n = 12) and compared with control group (n = 6), leading to potential source of bias in results) High (outcome assessment not blinded; randomization claimed but method unclear; at 6-month follow-up, there was approximately 55% missing data for participating families from the intervention group - nil reasons provided regarding attrition at post-intervention or follow-up for either group; nil intention-to-treat analysis performed) Unclear (outcome assessment not blinded; randomization technique adequate but unclear if allocation concealed) Quality of evidence—bias risk Unclear (outcome assessment not blinded; ranTwo-Group ANCOVA analysis domization technique adequate but unclear if PT + TT + CT > control allocation concealed) CBCL internalizing behavior (P) (p = 0.006, d = 0.64)* PT = control CBCL internalizing behavior (P) (p = 0.06, d = 0.42) PT + TT = control CBCL internalizing behavior (P) (p = 0.08, d = 0.44) Treatment program > WLC group Low (outcome assessment partially blinded; ADIS-IV-C/P severity of anxiety (CL) (p < 0.001, adequate description of randomization method; partial η2 = 0.43)*** attrition analyses adequate and attrition balanced across groups) Treatment program = WLC group SCAS-P total anxiety score (P) (ns) SCAS-P GAD subscale score (P) (p = 0.053) CBCL internalizing behavior (P) (ns) Outcome not measured Outcome not measured PPCP = CG SDQ emotional symptoms (P) (p > 0.05) Outcome not measured Child internalizing o­ utcomesa 256 Child Psychiatry Hum Dev (2018) 49:244–267 PT > WL condition ECBI behavior intensity (P) (p = 0.003, d = 0.65)** CBCL attention problems (P) (p = 0.012, d = 0.53)* CBCL aggressive behavior (P) (p = 0.007, d = 0.58)** PT = WL condition ECBI behavior problems (P) (ns, d = 0.47) PT + CT > WL condition CBCL aggressive behavior (P) (p = 0.004, d = 0.75)** PT + CT = WL condition ECBI behavior intensity (P) (ns, d = 0.42) ECBI behavior problems (P) (ns, d = 0.55) CBCL attention problems (P) (ns, d = 0.59) IY parenting program > delayed treatment CBCL externalizing behavior (P) (p < 0.05, d = −0.40)* Triple P = waitlist (receiving services as usual) SDQ conduct problems (P) (p = 0.65) SDQ hyperactivity (P) (p = 0.54) SDQ total difficulties (P) (p = 0.83) ECBI behavior intensity (P) (p = 0.40) ECBI behavior problems (P) (p = 0.10) STEPP > traditional BPT (sum of families who met criteria for reliably improved but not recovered, reliably improved but came in functional, and reliably improved and recovered) ECBI behavior intensity (P) (p = 0.004)** ECBI behavior problems (P) (p = 0.036)* STEPP = traditional BPT: (reliable change and recovery) ECBI behavior intensity (P) (ns) ECBI behavior problems (P) (ns) 13. Larsson et al. [60]d N = 136 15. Little et al. [62] N = 146 16. Rajwan et al. [50] N = 120 14. Lau et al. [61] N = 54 Child externalizing o­ utcomesa Study Table 2 (continued) Outcome not measured Unclear (outcome assessment partially blinded; unclear randomization method and allocation concealment unclear; study did not specify reasons for attritions) High (outcome assessment not blinded; adequate randomization method described; investigators enrolling participants could possibly foresee assignments and thus introduce selection bias) High [unclear if outcome assessment blinded; randomization method adequately described but unclear if allocation concealed; poor fidelity of implementation; poor attendance rate of parents (average of 40% across groups)] IY parenting program > delayed treatment CBCL internalizing behavior (P) (p < 0.05, d = −0.51)* Triple P = Waitlist (receiving services as usual) SDQ emotional symptoms (P) (p = 0.83) Unclear (outcome assessment partially blinded; randomization stated but insufficiently described; unclear if allocation concealed) Quality of evidence—bias risk PT > WL condition CBCL internalizing behavior (P) (p = 0.012, d = 0.57)* PT + CT = WL condition CBCL internalizing behavior (P) (ns, d = 0.60) Child internalizing o­ utcomesa Child Psychiatry Hum Dev (2018) 49:244–267 257 13 Child externalizing o­ utcomesa Parent + teacher arm > control arm CPRS-R hyperactivity (P) (p = 0.05)* Parent + teacher arm = control arm CPRS-R oppositional (P) (p = 0.78) CPRS-R inattention (P) (p = 0.64) CPRS-R ADHD symptoms (P) (p = 0.31) Parent-only arm = control arm CPRS-R hyperactivity (P) (p = 0.24) CPRS-R oppositional (P) (p = 0.17) CPRS-R inattention (P) (p = 0.27) CPRS-R ADHD symptoms (P) (p = 0.57) 18. Scott, O’Connor et al. [64] IY parenting program = CG N = 174 PACS conduct problems (CL) 12-month FU (ns) SDQ conduct problems (P) 12-month FU (ns) 19. Scott, Sylva et al. [65] IY parenting program > CG N = 112 PACS ADHD symptoms (CL) 12-month FU (p = 0.002, d = 0.44)** PACS antisocial behavior (CL) 12-month FU (p < 0.001, d = 0.52)*** ECBI oppositional defiant disorder (P) 12-month FU (p = 0.011)* 20. Van den Hoofdakker et al. [66] BPT + RCC > RCC alone N = 94 CBCL externalizing behavior (P) (p = 0.021, d (BPT + RCC) = 0.56)* BPT + RCC = RCC alone CPRS-R: ADHD symptoms (P) (p = 0.161, d (BPT + RCC) = 0.51) P + C = PO 21. Waters et al. [67] N = 60 CBCL externalizing behavior (P) (ns) 17. Sayal et al. [63]e N = 199 Study Table 2 (continued) High (outcome assessment not blinded; adequate randomization method described, baseline and 6-month outcome data collected for less than 50% of parents) Low (outcome assessment partially blinded; adequate randomization method described and allocation appears to have been concealed) Low (outcome assessment partially blinded; randomization method adequately described; allocation appears to have been concealed) Unclear (outcome assessment not blinded; randomization stated but insufficient information about method; unclear if allocation concealed) High (outcome assessment partially blinded; randomization stated but not described; allocation not concealed) Outcome not measured IY Parenting Program = Control PACS emotional symptoms (CL) 12-month FU (p = 0.60, d = 0.10) BPT + RCC > RCC alone CBCL internalizing behavior (P) (p = 0.042, d (BPT + RCC) = 0.33)* P + C or PO > WL ADIS-IV-C/P severity of anxiety (CL) (p < 0.05, partial η2 = 0.08)* P + C = PO CBCL internalizing behavior (P) (ns) SCAS-P total anxiety score (P) (ns) Quality of evidence—bias risk Outcome not measured Child internalizing o­ utcomesa 258 Child Psychiatry Hum Dev (2018) 49:244–267 13 Intervention > WL CBCL externalizing behavior (P) (p ≤ 0.05, partial η2 = 0.06)* CBCL aggressive behavior (P) (p ≤ 0.05, partial η2 = 0.04)* CBCL attention problems (P) (p ≤ 0.05, partial η2 = 0.04)* CPRS-R oppositional (P) (p ≤ 0.001, partial η2 = 0.11)*** CPRS-R inattention (P) (p ≤ 0.01, partial η2 = 0.07)** CPRS-R hyperactivity (P) (p ≤ 0.01, partial η2 = 0.13)** ECBI behavior intensity (P) (p ≤ 0.001, partial η2 = 0.22)*** ECBI behavior problems (P) (p ≤ 0.001, partial η2 = 0.24)*** PTP > WL CBCL externalizing behavior (P) (p = 0.005, partial η2 = 0.128)* 22. Webster-Stratton et al. [68]d N = 99 PTP > WL CBCL internalizing behavior (P) (p = 0.025, partial η2 = 0.084)* Intervention = WL CBCL internalizing behavior (P) (ns, partial η2 = 0.02) Child internalizing o­ utcomesa High (outcome assessment not blinded; investigator enrolling participants could possibly foresee assignments and thus introduce selection bias; insufficient reporting of attrition/exclusions) Unclear (outcome assessment partially blinded; randomization stated but not described; unclear if allocation concealed) Quality of evidence—bias risk Data from Chacko et al. [49] and Rajwan et al. [50] based on the same trial Parent data based on maternal report Outcomes reported in this paper were based on treatment effect on mean from baseline. Outcome here is based on p value for change difference between active treatments versus control arm. e d Data from Duncombe et al. [47] and Havighurst et al. [48] based on the same trial c b = Denotes non statistically significant difference in outcome between intervention versus control. Effect sizes reported using Cohen’s d with the exception of Holmes et al. [59], Waters et al. [67], Webster-Stratton et al. [68] and Wiggins et al. [69] that reported partial eta squared (partial η2). According to Cohen [44], guidelines for magnitude of partial eta squared are that 0.02, 0.13 and 0.26 indicate small, medium and large effect sizes respectively, whereas guidelines for magnitude of Cohen’s d are that 0.2, 0.5 and 0.8 indicate small, medium and large effect sizes respectively > Denotes statistically significant difference in outcome between intervention versus control, where *p < 0.05 **p < 0.01 ***p ≤ 0.001 and ns not significant Child externalizing and internalizing outcomes are reported as follows: a ACT anger coping training, ADHD attention deficit hyperactivity disorder, ADIS-IV-C/P anxiety disorders interview schedule for the fourth edition of the diagnostic and statistical manual of mental disorders (DSM-IV): child/parent versions, BPT behavior parent training, CBCL child behavior checklist, CG control group, CL clinician report; CPRS-R Conners’ parent rating scalerevised, CT child therapy, DBD disruptive behavior disorders, ECBI Eyberg child behavior inventory, FU follow-up, mo months, GAD generalized anxiety disorder, IY incredible years, (P) parent report, PACS parent account of child symptoms, partial η2 partial eta squared, P + C parent + child, PMT parent management training, PO parent only, PPCP parents plus children’s program, PPP Triple P-Positive Parenting Program, PT Parent Training, PTP pathways triple P, RCC routine clinical care, SCAS-P Spence Children’s Anxiety Scale-Parent Version, SDQ strengths and difficulties questionnaire, TIK tuning in to kids, TT teacher training, WL waitlist control 23. Wiggins et al. [69] N = 60 Child externalizing o­ utcomesa Study Table 2 (continued) Child Psychiatry Hum Dev (2018) 49:244–267 259 13 260 Child Psychiatry Hum Dev (2018) 49:244–267 problems ranged from small practical significance to medium treatment effect (d = 0.004–0.64). Effect size values reported with partial eta squared for difference in outcomes between intervention groups versus control on parent-reported measures [70] of child internalizing problems ranged from small to medium (partial η2 = 0.02–0.084). The effect size value reported with Cohen’s d for difference in outcomes between intervention groups versus control on a clinician-reported measure [75] of child internalizing problems showed low practical significance (d = 0.10). Effect size values reported with partial eta squared for difference in outcomes between intervention groups versus control on a clinician-reported measure [76] of child internalizing problems were medium to large (partial η2 = 0.08–0.43). Study Quality A summary risk assessment of each included study is located in Table 2 and the overall quality of the included studies is summarized in Fig. 2. Many studies were unclear about important quality criteria, including allocation concealment, random sequence generation and blinding. Other aspects of studies which contributed to bias risk and therefore possibly on study outcomes and interpretation, included not reporting results of all pre-specified outcome measures, reported loss to follow-up imbalanced across groups, failure to specify reasons for attrition or exclusions, and poor fidelity of implementation of treatment. We also examined the included studies for conflict of interest, which was implicated in the following ways: three studies where the study author also delivered the intervention [54, 63, 67]; six studies where the program developer was involved in the evaluation [47, 48, 57, 58, 68, 69], in particular Fig. 2 Assessment of risk of bias within studies using The Cochrane Collaboration’s tool for assessing risk of bias [41] for randomized trials studies involving the incredible years, Triple P and tuning into kids; and, three studies where the program developer was involved in a supervisory or consultative role [58, 60, 62]. Based on our earlier described approach to determining summary risk assessment for each study, the majority (20/23 or 87.0%) of studies included in the current systematic review were deemed to have ‘unclear’ [12/23 or 52.2%] or ‘high risk’ [9/23 or 39.1%] of bias. The two studies [59, 64] that were deemed to have overall ‘low risk’ of bias involved an RCT of a behavioral parent training program (the incredible years programme) designed to address child behavior combined with a literacy programme [64] and an RCT [59] comparing a group-based cognitively-focussed treatment program for parents of children with generalised anxiety disorder (GAD). Refer to Table 2 for specific outcomes of these trials. Meta‑analysis Of the 23 studies meeting inclusion criteria, 20 reported externalizing outcomes and 14 reported internalizing outcomes with 11 studies reporting both internalizing and externalizing outcomes. De Groot et al. [54] was a comparison of two active treatments without a control arm and was excluded from the meta-analysis. Sayal et al. [63] included change data however the authors could not be contacted for the post data and therefore this study was excluded from the meta-analysis. Chacko et al. [49] and Rajwan et al. [50] reported different outcome measures on the same treatment cohort. As such, Rajwan et al. [50] was excluded from the meta-analysis as it reported on child outcome variables using reliable change data and reported fewer child externalizing outcome data. Havinghurst et al. [48] and Assessment of risk of bias within studies Random sequence generation (selection bias) Allocation concealment (selection bias) Blinding of participants (performance bias) Blinding of personnel (performance bias) Blinding of outcome assessment (detection bias) Incomplete outcome data (attrition bias) Selective reporting (reporting bias) Other bias High Risk 13 Unclear Risk Low Risk Child Psychiatry Hum Dev (2018) 49:244–267 Duncombe et al. [47] also used the same treatment cohort reporting different outcome measures. Havighurst et al. [48] was excluded from the meta-analysis due to having a smaller sample size. Waters et al. [67] was included in the meta-analyses involving internalizing data, but could not be included in the meta-analysis of externalizing outcomes as no post intervention of follow-up data was reported for the waitlist-control group. Sixteen studies [47, 49, 51–53, 55–57, 60–62, 64–66, 68, 69] were included in the meta-analysis of the effect of parent group treatment on externalizing symptoms. Five of these studies [47, 49, 53, 55, 60] utilised more than one intervention group. The active interventions in these studies were combined on the advice of a biostatistician to create a single pair-wise comparison with the control group. Externalizing outcome measures included parent rated child behavior checklist (CBCL) [70] broadband externalizing scale, Eyberg child behavior inventory (ECBI) [71], strengths and difficulties questionnaire (SDQ) [72] conduct problems scale, and the disruptive behavior disorders (DBD) rating scale [73]. A random-effects metaanalysis (see Fig. 3) revealed a statistically significant and small treatment effect for parent group treatment over control for child externalizing problems (g = −0.38, 95% CI −0.56, −0.19, z = 3.97, p < 0.001). Visual inspection of the funnel plot (see Fig. 4) suggested no evidence for publication bias. However, the level of study heterogeneity (I2 = 61.80%, p = 0.001) was substantial. Independent variables of (1) study quality, (2) hours of planned parent 261 group treatment and (3) treatment recipient were separately entered into a meta-regression for the child externalizing problems. Neither hours of planned parent group treatment (I2 residual = 63.67%, p = 0.53) nor treatment recipient (I2 residual = 59.32%, p = 0.28) were a significant moderator of treatment response. However, study quality was a significant moderator in studies with a summary risk assessment of ‘Low risk’ compared to studies with a summary risk assessment of ‘unclear risk’ or ‘high risk’ of bias (coefficient = 0.72, p = 0.02). This would suggest that the average standardized mean difference for studies with a summary risk assessment of ‘low risk’ of bias compared with studies with a summary risk assessment of ‘unclear risk’ or ‘high risk’ of bias is 0.72 larger. Thirteen studies [51, 52, 56, 58–62, 65–69] were included in the meta-analysis of the effect of parent group treatment on internalizing symptoms. Three of these studies [58, 60, 67] utilised more than one intervention group. The active interventions in these studies were combined on the advice of a biostatistician to create a single pair-wise comparison with the control group. Internalizing outcome measures included the CBCL broadband internalizing scale [70], SDQ emotional symptoms scale [72], parent account of child symptoms (PACS) [75], and anxiety disorders interview schedule for the fourth edition of the diagnostic and statistical manual of mental disorders (DSM-IV): child/parent versions (ADIS-IV-C/P) [76]. A random-effects meta-analysis (see Fig. 5) revealed a statistically significant albeit Fig. 3 Forest plot of studies included in the meta-analysis for effect of parent group intervention on child externalizing problems 13 262 Child Psychiatry Hum Dev (2018) 49:244–267 Fig. 4 Funnel plot of included studies in the meta-analysis for effect of parent group intervention on child externalizing problems (N = 16) Fig. 5 Forest plot of studies included in the meta-analysis for effect of parent group intervention on child internalizing problems small treatment effect for parent group treatment over control for child internalizing problems (g = −0.18, 95% CI −0.36, −0.01, z = 2.03, p = 0.04). The level of study heterogeneity (I2 = 41.9%, p = 0.056) was moderate. Visual inspection of the funnel plot (see Fig. 6) suggested no evidence for publication bias. Independent variables of (1) study quality, (2) hours of planned parent group treatment and (3) treatment recipient were separately entered into a meta-regression for the child externalizing problems. Neither hours of planned parent group treatment 13 (I2 residual = 46.72%, p = 0.97), treatment recipient (I2 residual = 39.53%, p = 0.28), nor study quality (I2 residual = 46.85%, p = 0.68) were significant moderators of treatment response. A meta-analysis of the two studies which compared an active parent group treatment for child anxiety with control [59, 67] was not significant (g = −0.40, 95% CI −1.50, 0.71, z = 0.71, p = 0.48). Finally, a meta-analysis of the 11 studies [51, 52, 56, 58, 60–62, 65, 66, 68, 69] that evaluated parent group interventions with samples of children Child Psychiatry Hum Dev (2018) 49:244–267 263 Fig. 6 Funnel plot of included studies in the meta-analysis for effect of parent group intervention on child internalizing problems (N = 13) with externalizing problems found no change in internalizing problems (g = −0.16, 95% CI −0.34, 0.01, z = 1.87, p = 0.06). Discussion This systematic review and meta-analysis examined parent group training interventions aimed at the treatment of externalizing and internalizing problems for children aged 4–12 years. Whereas previous reviews have focused on one child outcome variable, such as conduct problems [21] or disruptive behaviors [19], the current review included samples with externalizing and/or internalizing problems commonly seen in clinical practice (e.g., conduct problems, oppositional behavior, inattention and hyperactivity, depression, anxiety). The majority of studies included in the review consisted of samples of children with diagnoses of or subthreshold symptoms of externalizing (i.e., ADHD, ODD, CD) or internalizing (i.e., anxiety) disorders. The review revealed fewer studies of indicated prevention for children with externalizing and/or internalizing problems at risk of developing severe behavior disorders. Of the included studies that reported on child externalizing problems, 80.0% studies reported significant findings that favored the parent group intervention over control (or alternative treatment). Of the included studies that reported on child internalizing problems, 35.7% studies reported significant findings that favored the parent group intervention over control (or alternative treatment). Results from the current meta-analysis demonstrated that parent group intervention programs are effective for the amelioration of child externalizing problems, with a significant and small treatment effect size but with substantial heterogeneity. This heterogeneity was evidenced by the broad range (i.e., negligible to large) of effect size values reported for difference in outcomes between intervention groups versus control on parent- and/or clinician-reported measures of child externalizing problems. Study quality moderated the treatment effect sizes for child externalizing problems, but hours of planned parent group treatment and treatment recipient did not. Findings from the moderator analysis may inform mental health service providers and clinicians who are seeking cost effective parent group interventions. That is, the addition of teacher or child intervention components to parent group interventions or increase in treatment hours may not necessarily translate to greater improvements in child externalizing behavior problems. However, further research is needed to determine the optimal treatment recipients and dose for this population. The second meta-analysis conducted in this review showed a statistically significant reduction in child internalizing problems, however the effect size was more modest and the level of study heterogeneity was moderate. None of the intervention-based variables explored explained the variability in treatment effect size for child internalizing problems. Although a meta-analysis conducted to explore the efficacy of parent group interventions aimed at reducing child anxiety was non-significant, this analysis only relied upon two studies. The meta-analysis of 11 studies that evaluated parent group interventions with samples of children with externalizing behavior problems resulted in non-statistically significant improvement in internalizing problems. Given that the majority of studies included in the 13 264 review were parent group interventions focused on reduction of child externalizing or disruptive behavior problems, this finding is not necessarily unexpected. However, this demonstration of the absence of a cross-impact treatment effect suggests the need for specific targeting of internalizing symptoms within programs for externalizing disorders, if this comorbid symptom cluster is to be prioritized. Results of the current review are broadly consistent with findings of earlier reviews that included studies published prior to 2005 [19–21, 24, 29], providing further evidence of the efficacy of parent training interventions for treatment of child externalizing behavior problems. The current review’s effect size for child externalizing problems is in line with findings by Kaminski et al. [20] but smaller than the medium effect sizes found in some earlier reviews [19, 21, 24, 29], perhaps accounted for by differences in review design. For instance, in contrast to the current review, other reviews [19–21, 24] included both group and individually delivered parent training, while Dretzke et al. [21] only reviewed studies of interventions aimed at treatment of children with conduct problems. In regards to child internalizing problems, the current review’s effect size is concordant with the effect size for emotional problems reported by Furlong et al. [29] but smaller than the effect size for internalizing problems reported by Kaminski et al. [20]. However, Kaminski et al. [20] included both group and individual treatments and samples of children aged 0–7 years whereas the current review included samples of children aged 4–12 years. The current review’s finding that the addition of child and/or teacher intervention components failed to moderate treatment outcomes for child externalizing problems is consistent with Lundahl et al. [19]. Finally, treatment effect on child externalizing outcomes was not moderated by treatment hours in the current review, consistent with previous research [26, 77]. While this review specifically set out to review the published literature pertaining to parent group interventions, current results should take into account the broader psychosocial treatment literature, inclusive of individual parent training programs. For instance, current review results for parent group treatment effect on child externalizing problems are smaller than some previously reported treatment effect outcomes for individual parent training programs to modify child externalizing behaviors [19] and child social, emotional and behavioral outcomes [24]. The current review’s effect size for internalizing problems is also smaller than results of some individual parent training programs aimed at modifying child anxiety disorders [78, 79]. However, there is mixed evidence regarding the relative efficacy of individual parent training versus group parent training for children with externalizing problems. Some studies have reported superior outcomes for individual 13 Child Psychiatry Hum Dev (2018) 49:244–267 parent training [19, 24], other studies have reported superior outcomes for group parent training [80], and others have reported no difference [38, 81, 82]. There are advantages of both individual and group-based parent interventions. For example, individual parent training programs include the ability to tailor treatment to fit the needs of the individual child, the opportunity to adjust to each parent’s mastery level, and the possibility that a parent might be more willing to disclose sensitive information in an individual session [83]. However, group approaches can also provide parents with social support, normalize individual parent’s experiences, and offer extra solutions as individual members suggest specific techniques [84]. Conducting parent training in groups rather than individually can also be more cost-effective [80]. Selection of treatment modality should also take into account parent preferences [85]. This systematic review and meta-analysis should be interpreted in the context of its limitations. As documented in Fig. 1, four studies were excluded from the current review on the basis that review authors were unable to locate full-text english-language translations. In each of these instances, although the abstracts for these studies were written in english, inadequate information was provided in the abstracts to determine whether the studies met selection criteria, thus introducing the possibility of a language bias [86, 87]. As this review only included published studies, there is also a risk that a bias towards trials with positive outcomes occurred [88]. Due to the limited number of studies included in the meta-analyses, moderator analyses should be interpreted with caution and require replication, while other potential moderating variables should also be explored. Future reviews would benefit from reporting on data from all available informants, including teacher-rated measures and child self-report measures. Summary This review provides an important update for the field on contemporary research outcomes on the efficacy of parent group interventions and provides support for their ability to reduce externalizing behaviors in children. While study methodology may have contributed to the variability in treatment effect sizes for child externalizing problems, further research is needed to determine the optimal treatment recipients and dose and explore other potential moderators of treatment response. Whilst statistically significant, the effect of parent group treatment on child internalizing problems was modest, however the majority of studies evaluated interventions focused on treatment of child externalizing problems. There was no evidence to support treatment effect on anxiety symptomatology or on cross-impact Child Psychiatry Hum Dev (2018) 49:244–267 treatment effect on internalizing behaviors for treatments that aimed to address child externalizing problems. Metaanalysis results thus highlight the need for more specific targeting of internalizing symptoms within programs for externalizing disorders, if this comorbid symptom cluster is to be prioritized. Given the high prevalence of internalizing disorders in childhood and adolescence [89, 90], review results suggest the need for more research focused on parent group interventions for treatment of child internalizing disorders, regardless of whether such problems are targeted in isolation or in conjunction with externalizing problems. Funding The authors received no financial support for the research, authorship, and/or publication of this article. References 1. Kieling C, Baker-Henningham H, Belfer M, Conti G, Ertem I, Omigbodun O et al (2011) Child and adolescent mental health worldwide: evidence for action. Lancet 378:1515–1525 2. Lawrence D, Johnson S, Hafekost J, Boterhoven de Haan, K, Sawyer M, Ainley J et al (2015) The mental health of children and adolescents. 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