Intervention Effectiveness of The Incredible Years: New Insights Into Sociodemographic and Intervention-Based Moderators

Abstract

We tested the effectiveness of the preventive behavioral parent training (BPT) program, The Incredible Years (IY), and the independent effects of previously suggested sociodemographic and intervention-based moderator variables (i.e., initial severity of externalizing problem behavior, child gender, social economic status, family composition, and number of sessions parents attended), in a large-scale randomized controlled trial. Questionnaire and observation data from 387 parents and children ages 4-8 years (M= 6.21, SD = 1.33, 55.30% boys) across pretest, posttest, and 4-month follow-up were analyzed, using full intention-to-treat analyses and correcting for multiple testing. IY was successful in decreasing parent-reported child externalizing behavior (Cohen's d = 0.20 at posttest, d = 0.08 at follow-up), increasing parent-reported (d = 0.49, d = 0.45) and observed (d = 0.06, d = 0.02) positive parenting behavior, and decreasing parent-reported negative parenting behavior (d = 0.29, d = 0.25). No intervention effects were found for reported and observed child prosocial behavior, observed child externalizing behavior, and observed negative parenting behavior. Out of 40 tested moderation effects (i.e., 8 Outcomes × 5 Moderators), only three significant moderation effects appeared. Thus, no systematic evidence emerged for moderation of IY effects. The present multi-informant trial demonstrated that many previously suggested moderators might not be as potent in differentiating BPT effects as once thought.

Genetic Moderation of Intervention Efficacy: Dopaminergic Genes, The Incredible Years, and Externalizing Behavior in Children

“…It is also notable that evidence of genetic moderation of intervention efficacy only emerged in child behavior reported by parents and not in case of observed externalizing behavior. This is consistent with the overall intervention effect for this sample (see Weeland, Chhangur et al., ). It seems plausible that the null G × I findings reported here for observed behavior could be due to the limited sampling period (i.e., 20 min) and highly structured observation context.…”

“…Although the overall effects of the IY parent program (on boys and girls together) were more pronounced at the immediate posttest relative to the delayed follow‐up (see Weeland, Chhangur et al., ), inspection of Figures and makes clear that, in the case of the more genetically susceptible boys, treatment effects were not especially evident immediately after the intervention but became so by about 4 months later. This observation suggests that it may take time, in the case of more genetically susceptible boys, for increases in positive parenting induced by the IY intervention to become consolidated and thus influence child behavior.…”

“…Data were collected in two cohorts from November 2012–2013 through November 2013–2014. Detailed information about the sample and sampling appears elsewhere (Chhangur, Weeland, Overbeek, Matthys, & Orobio de Castro, ; Weeland, Chhangur et al., in press). Using a randomized control design, the ORCHIDS study addresses the differential effectiveness—across children with varying temperamental and genetic characteristics—of the IY program in reducing externalizing behavior in 4‐ to 8‐year‐old children showing moderate to high levels of such problems by enhancing a warm parent–child relationship through child‐directed play; coaching of social, emotional, and academic skills; praise and rewards; effective limit setting; and handling (e.g., ignore and time‐out techniques).…”

“…All leaders received 2‐hr supervision sessions at least three times across the 14‐week period. Besides these, regular intersession meetings between group leaders took place (see also Weeland, Chhangur et al., in press).…”

“…IY parent training (Webster‐Stratton, ) is one such program designed to prevent the development of child externalizing behavior problems or to ameliorate early emerging problems and is therefore the specific focus of this report. IY has been evaluated in over 50 studies and proven effective in both clinical and community samples (Menting, Orobio de Castro, & Matthys, ; Webster‐Stratton & Hammond, ; Weeland, Chhangur et al., in press). IY intervention effects have been replicated independently (e.g., Scott, Spender, Doolan, Jacobs, & Aspland, ), and results include reductions in externalizing behavior that endure several years after exposure to the program (e.g., Jones, Daley, Hutchings, Bywater, & Eames, ; Posthumus, Raaijmakers, Maassen, Van Engeland, & Matthys, ).…”