Infant mental health services for birth and foster families of maltreated pre-school children in foster care (BeST?): a cluster-randomized phase 3 clinical effectiveness trial

Children entering foster care are at high risk of poor mental health. In this single-blind, cluster-randomized phase 3 trial, 382 families with 488 0–5-year-old children, entering foster care, were randomized to the New Orleans Intervention Model (NIM) or social work services as usual (SAU). NIM offers infant mental health assessment (~3 months) and treatment (6–9 months) to children and to their birth and foster families, aiming to improve child mental health and recommend return home or adoption. The principal outcome was child mental health, as measured by the Strengths and Difficulties Questionnaire Total Difficulties (SDQ-TD) scale at 2.5 years after study entry. In total, 286 families (149 NIM and 137 SAU, 367 children) were followed-up (79.4%). Intention-to-treat analysis found no intervention effect of NIM: mean (s.d.) SDQ-TD NIM, 11.5 (7.6); SAU, 11.1 (7.2); adjusted mean difference (NIM − SAU), 1.4; 95% confidence interval (−0.63, 3.53); P = 0.17. No within-trial effects for primary or secondary outcomes were observed. Despite its components being delivered to a high standard, the UK legal context surrounding NIM led to it being impossible to deliver to all eligible families, and less than 70% of families received the intervention to which they were randomized. Future research will be required to evaluate NIM in more favorable social and legal contexts. ClinicalTrials.gov registration: NCT02653716.