Abstract: We identified 22 RCTs and two quasi-RCTs evaluating the effectiveness of group-based parenting programmes in improving the emotional and behavioural adjustment of children aged up to three years and 11 months (maximum mean age three years 11 months). The total number of participants in the studies were 3161 parents and their young children. Eight studies were conducted in the USA, five in the UK, four in Canada, five in Australia, one in Mexico, and one in Peru. All of the included studies were of behavioural, cognitive-behavioural or videotape modelling parenting programmes. We judged 50% (or more) of the included studies to be at low risk for selection bias, detection bias (observer-reported outcomes), attrition bias, selective reporting bias, and other bias. As it is not possible to blind participants and personnel to the type of intervention in these trials, we judged all studies to have high risk of performance bias. Also, there was a high risk of detection bias in the 20 studies that included parent-reported outcomes. The results provide evidence that group-based parenting programmes reduce overall emotional and behavioural problems (SMD -0.81, 95% CI -1.37 to -0.25; 5 studies, 280 participants, low quality evidence) based on total parent-reported data assessed at postintervention. This result was not, however, maintained when two quasi-RCTs were removed as part of a sensitivity analysis (SMD -0.67, 95% CI -1.43 to 0.09; 3 studies, 221 participants). The results of data from subscales show evidence of reduced total externalising problems (SMD -0.23, 95% CI -0.46 to -0.01; 8 studies, 989 participants, moderate quality evidence). Single study results show very low quality evidence of reductions in externalising problems hyperactivity-inattention subscale (SMD -1.34; 95% CI -2.37 to -0.31; 19 participants), low quality evidence of no effect on total internalising problems (SMD 0.34; 95% CI -0.12 to 0.81; 73 participants), and very low quality evidence of an increase in social skills (SMD 3.59; 95% CI 2.42 to 4.76; 32 participants), based on parent-reported data assessed at postintervention. Results for secondary outcomes, which were also measured using subscales, show an impact on parent-child interaction in terms of reduced negative behaviour (SMD -0.22, 95% CI -0.39 to -0.06; 7 studies, 941 participants, moderate quality evidence), and improved positive behaviour (SMD 0.48, 95% CI 0.17 to 0.79; 4 studies, 173 participants, moderate quality evidence) as rated by independent observers postintervention. No further meta-analyses were possible. Results of subgroup analyses show no evidence for treatment duration (seven weeks or less versus more than eight weeks) and inconclusive evidence for prevention versus treatment interventions. The findings of this review, which relate to the broad group of universal and at-risk (targeted) children and parents, provide tentative support for the use of group-based parenting programmes to improve the overall emotional and behavioural adjustment of children with a maximum mean age of three years and 11 months, in the short-term. There is, however, a need for more research regarding the role that these programmes might play in the primary prevention of both emotional and behavioural problems, and their long-term effectiveness.

Plain-language summary: We searched the scientific literature for all randomised controlled trials (RCTs) and quasi-RCTs published up to July 2015. RCTs are studies in which people are randomly allocated to treatment groups. Quasi-RCTs are studies in which people receive treatment based on methods that are not strictly random such as date of birth, or their hospital record number, and the results of quasi-RCTs are generally considered less trustworthy than those of RCTs. We found 24 trials (22 RCTs and two quasi-RCTs) to include in our review. These studies included, in total, information from 3161 parents and their young children. Eight studies had been carried out in the USA, five in the UK, four in Canada, five in Australia, one in Mexico, and one in Peru. All of the studies looked at behavioural, cognitive-behavioural or videotape modelling parenting programmes. Behavioural programmes are aimed at helping parents develop methods that will reduce bad behaviour, usually with the use of techniques such as praise or rewards. It also aims to help parents set limits that make sense. Cognitive-behavioral skills allow parents think about behaviour patterns and focus on solutions. Programmes can use a variety of techniques; for example, videotape modelling programmes enable parents to learn by watching videotaped films of other parents implementing some of the techniques described above. Some of the studies we found included people chosen specially because they were ‘at risk’ of behavioural problems, while others included parents and children without any specific risks. When we put all of the studies together, overall, we found that group-based parenting programmes can improve the emotional and behavioural development of young children, although the quality of the evidence was, on the whole, low. Furthermore, our findings were not convincing when we removed two studies that used quasi-randomised methods. Our findings also showed evidence of an improvement in externalising problems (these might include negative behaviours in children or young people that are directed towards the external environment such as anger, aggression or conflict with the law). However, the evidence for this, once again, came from studies that we rated as being of only moderate quality, and was only found for some parts of the outcome measure (known as a subscale). Results from single studies that could not be combined with other studies and that were of poor quality, on the whole, showed no impact on children’s internalising problems (e.g. depression and anxiety). However, there was some improvement on one subscale of a measure that focused on children’s hyperactivity-inattention and another subscale that focused on social skills. There was moderate-quality evidence that group-based parenting programmes also improve the way in which parents and children interact, as measured by fewer negative behaviours. Our reasons for rating the quality of the evidence as low or moderate included: inconsistency in the findings from different studies (different studies yielded different results); unclear risk of bias (where it was not possible for us to assess the ways in which the included studies might be biased due to inadequate information); and small numbers of parents in the included studies. We believe more research is needed to be able to reach a firm conclusion about whether the effects we have found are short term only or whether they continue over time and therefore may be able to prevent future behavioural problems.