Preventing violence against children through parenting interventions – Measurements, moderators, and effects over time
Keywords: parenting intervention
violence against children
child maltreatment

Background: Violence against children is a global phenomenon affecting over one billion children a year, with severe consequences for child well-being and development.
Parents are the primary perpetrators of violence against children. Violent behaviours of parents often occur in the context of physical and emotional disciplining, such as spanking, slapping, beating, threatening, insulting, or screaming. These violent acts by parents are assessed using a variety of instruments, but it is unclear whether these instruments measure the same or different violent parenting behaviours. Examining these instruments is crucial since the conclusions drawn from research findings and approaches to prevention rely on consistent definitions and operationalisations. This is particularly the case for systematic reviews and meta-analyses where various instruments are consolidated under an overarching outcome category. For instance, previous reviews on the effectiveness of interventions to reduce violence against children varied widely in the instruments included to measure violent parenting. While some reviews only included substantiated maltreatment cases or validated child maltreatment instruments, others included harsh parenting instruments or risk for maltreatment, producing different overall estimated effects of interventions (from d = 0.02 to d = –0.42).
Interventions that support parents have been emphasised by international organisations as one of seven global strategies to end violence against children. Parenting interventions encourage alternative non-violent behaviour management skills and promote activities to strengthen parent-child relationships. While various systematic reviews concluded that parenting interventions are an effective strategy to reduce violence perpetrated by parents, the findings were limited to short-term effects. Yet, the key interest of policymakers is whether these interventions reduce violence in the long-term. Moreover, parenting interventions are implemented across the globe, raising the question of whether families experiencing social disadvantage equally benefit from parenting interventions. This information becomes more urgent since parenting interventions are gradually taken to scale.
Objectives: The goals of this thesis are: i.) to understand similarities and differences between child maltreatment and harsh parenting instruments; ii.) to examine the effects over time of parenting interventions to reduce violence against children; and iii.) to identify whether families that live in conditions of social disadvantage benefit less (or more) from parenting interventions to reduce violence against children.
Methods: DPhil Paper 1 used a mixed-method approach for analysing the overlap of physical and emotional violent parenting behaviours between child maltreatment and harsh parenting instruments. For this, it used two systematic reviews to select child maltreatment and harsh parenting instruments, a thematic content analysis to identify which parenting behaviours were measured, and the Jaccard Index to quantify the homogeneity in content between instruments. DPhil Paper 2 used a systematic review that was conducted following best practice standards including GRADE assessments and PRISMA reporting guidelines. For this, 26 databases and trial registries were searched, and screening and data extraction were conducted by two review authors. Standardised effects sizes were pooled across studies using robust variance estimation meta-analysis, which allows the inclusion of all effect sizes assessing similar constructs, and consequently reduces bias associated with the selection of effect sizes. DPhil Paper 3 used individual participant level data of European parenting trials, and data from the systematic review of parenting interventions used in DPhil Paper 2. Uniquely, it utilised the strengths of these two approaches to meta-analysis to analyse differential effects based on social disadvantage factors. For this, an existing dataset of European Incredible Years randomised controlled trials was updated, and meta-regression analyses conducted on both datasets testing the same four social disadvantage moderators: low income, low education, joblessness, and ethnic minority status.
Results: DPhil Paper 1 found that 73% of content (i.e., parenting behaviours measured) of child maltreatment and harsh parenting instruments overlaps. All physical behaviours measured in harsh parenting instruments (e.g., spanking, beating up) were also measured in child maltreatment instruments. Unique physical behaviours measured in maltreatment instruments included, for example, twisting body parts and choking. All emotional behaviours in maltreatment instruments were included in harsh parenting instruments, and vice versa. DPhil Paper 2 found that parenting interventions based on social learning theory reduce physical and emotional violent parenting behaviours immediately after the intervention (d = −0.46; 95% CI: –0.59, –0.33, p <.001, I2 = 76.66), at 1–6 months follow up (d = −0.24; 95% CI: −0.37, −0.11), and at 7–24 months follow-up (d = −0.18; 95% CI: −0.34, −0.02), but effects were smaller over time. DPhil Paper 3 found that these parenting interventions are equally effective in reducing physical and emotional violent parenting behaviours. Both traditional aggregate-level and individual participant data meta-analysis found no evidence that families of social disadvantage benefited more or less from parenting interventions.
Discussion: The contribution of these findings is threefold. First, this thesis shows that operationalisations of child maltreatment and harsh parenting are relatively similar, but not identical. This can help to guide discussions on definitions, operationalisations, and their consequences for research on violence against children. Second, this thesis highlights that parenting interventions based on social learning theory remain effective up to 2 years post-intervention, but effects become smaller over time. Accordingly, it calls for further research on ways to provide parents with sustained support. Third, with global policy interest and scale-up of interventions, this thesis suggests that parenting interventions unlikely widen social inequalities. This finding is very timely given the recent recommendation from the World Health Organization to provide parents with access to these social learning theory-based parenting interventions.