Parent training for 842 families experiencing disruptive child behavior across 19 Danish community sites: A benchmark effectiveness study.

Interactional processes between child and parents, in particular harsh and coercive parenting practices, have been established as important factors maintaining and shaping the developmental trajectory of disruptive child behavior. The Incredible Years Parent Training (IYPT) is a well-established evidence-based program targeting negative parent-child interactions in families with children exhibiting high levels of disruptive behaviors. There are, however, few studies investigating the effectiveness of the IYPT when implemented in established practice settings independently from research environments. Also, very little evidence exists for the program's effectiveness for school-aged children. The IYPT was administered to consecutive groups of parents (N = 842) across 19 Danish community sites during the period from 2012 to 2019. Pre and post data were collected using the Eyberg Child Behavior Inventory (ECBI). By means of a benchmark approach, the effectiveness of the intervention was compared with that of two European effectiveness randomized controlled trials. Large effect sizes were seen from pre to post for both parent-reported number of problematic disruptive child behaviors (ECBI Problem subscale; d = 1.51, p = 0.000, 95% CI [9.06-10.01]) and frequency of these behaviors (ECBI Intensity subscale; d = 1.15, p = 0.000, 95% CI [29.33-32.73]). Treatment effects found in this study are comparable to or larger than those found in previous effectiveness studies and show the IYPT to be an effective intervention when implemented across a range of different community settings in a large community sample of children across an age span of 2 to 12 years.