The conclusions reached by Wilson et al. cast doubt over the entire Triple P evidence-base. However, their conclusions hinge on a restrictive and narrow evaluation framework, primarily resulting in an inappropriate pooling across differing types of intervention studies, and exclusive focus on child-only outcome data. These limitations restrict the conclusions that can reasonably be drawn on the basis of their analysis.
Triple P is a blended model that incorporates both universal and indicated interventions for vulnerable families . It is based on social learning theory and cognitive-behavioral principles, and is not a single intervention program. It is a tiered multilevel system of parenting support that has both preventive and treatment components and incorporates five levels of intensity and several delivery formats (for example, large group, small group, individual, self-directed, media and online interventions), with different variants and applications targeting different types of clinical problems, age groups and populations [2–4]. The evaluation of such a system of intervention is inevitably complex. By simply pooling studies, Wilson et al. fail to take into account differences in type and intensity of the interventions employed. The studies pooled included interventions of greatly varying intensity, modes of delivery and contact hours from self-help workbooks, and watching a brief television series, to intensive face-to-face behavioral family intervention. The random effects model employed was not sufficient to control for the differences across studies in terms of the type of intervention (for example, Stepping Stones, Indigenous, Workplace) and intervention intensity (for example, Level 1-5, Group, Individual, Self-Directed). An alternative approach would be to conduct subgroup analyses or moderator analyses examining these intervention differences. This approach would have provided a more accurate representation of the effects of the Triple P System of interventions.
A significant limitation of the Wilson et al. review is that it only reports on a narrow range of child outcomes. Importantly, there was no examination of any parent- or family-level outcomes, which are the primary targets of parenting interventions. Wilson et al.'s rationale for only focusing on child-based outcomes ignores the importance of parent- and family-level outcomes. The analysis ultimately reports a narrow index of child outcome data, using an inadequate pooled model of effects, which is insufficient to derive clear conclusions about the overall effectiveness of the Triple P system.