Commentary: Are complex parenting interventions less than the sum of their parts? A reflection on Leijten et al. (2022).

Parenting interventions provide the backbone of professional support for children with behavioural problems and their families (Maughan et al., 2005). The overwhelming evidence for their value, at least in the short term, has prompted the field to move away from simply testing their efficacy to focus on issues of implementation. More and more studies are therefore addressing the interrelated goals of optimising outcomes, increasing scalability and affordability, improving access and removing barriers for hard-to-reach and treat families (e.g., Barnett et al., 2019; Day et al., 2012; Kazdin, 2015). Because parenting interventions are often complex and integrate multiple discrete therapeutic elements, achieving cost-effective interventions that can be implemented efficiently at scale will depend on identifying which elements work best and which are redundant and can be cut. This can help streamline interventions to make them less burdensome by cutting the time, effort and resources needed for families to take part and making the interventions themselves easier to train and deliver. It can also help focus energies on areas where improvements of existing interventions are most needed and/or likely to yield the most value. Leijten and colleagues (2022) addressed these issues in their excellent review.