Research Review: No robust effects of Circle of Security-Parenting (COSP) on parenting, parents, or children - a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Circle of Security-Parenting (COSP) is one of the most popular attachment-based preventive support programs for parents and children. More than 50,000 participants from different (para)professional disciplines have been trained in the formal COSP™ protocol. METHODS: In a preregistered meta-analysis and synthesis of all eight randomized trials (N = 1,094 families), we examined COSP's efficacy on caregivers' parenting (sensitive parent-child interactions, reflective functioning, and parenting attitudes), on parent mental health outcomes (stress, depression, and anxiety), and on child attachment security and behavior problems. RESULTS: We found an overall nonsignificant effect size of Cohen's d = 0.142 (SE = 0.089; p = .154, 95% Confidence Interval -0.068, 0.353, 95% Prediction Interval -0.444, 0.729), in a homogeneous set of studies. The pooled effect sizes of the parenting, parent, and child domains did not differ from each other or from zero. Cluster-robust inference tests showed converging (nonsignificant) results. The majority of the randomized studies (82%) were identified with some concerns about risk of bias. CONCLUSIONS: We conclude that the evidence for COSP efficacy does not keep pace with the uptake of COSP in professional practice and policy.