Estimated cumulative incidence of intervention by children's social care services to age 18: a whole-of-England administrative data cohort study using the child in need census.

Introduction: Each year, children's social care (CSC) recognises around 3% of all children as children in need (CiN) of intervention, including those who receive a child protection plan due to risks of substantial harm and those who become looked after in state care. A previous cumulative estimate of the incidence of becoming CiN of 14% to age 5 indicates that the childhood lifetime incidence is likely very high.

Objectives: We aimed to estimate the cumulative incidence of referrals, social work assessments, being recognised as a CiN or made subject to a child protection plan (CPP) before age 18 in England.

Methods: The annual CiN census contains all-of-England longitudinal records of CSC referrals. Data collection began in 2008, meaning there is no cohort that can be followed up from birth to age 17 (i.e., before 18^th birthday). Analyses revealed data quality issues before 2011/12. We estimated the above cumulative incidences in three cohorts and combined them, adjusting numerators to account for left-censoring. The three cohorts were children born in: (a) 2012/13, followed to age 5; (b) 2005/06, followed from age 6 age to 12; and (c) 2000/01, followed from age 13 to 17. We carried out sensitivity analyses to address possible bias induced by linkage error using one of two encrypted identifiers in the dataset.

Results: Of all children living in England, before turning 18, 35.4% were referred, 32.3% were assessed, 25.3% were recorded as CiN and 6.9% were subject to a CPP (37.5%, 34.6%, 26.0% and 7.1%, respectively, in sensitivity analyses).

Conclusions: By age 18, an estimated 1 in 4 children are identified by CSC as needing support at some point. Government should monitor the cumulative incidence of ever receiving CSC support with a view to addressing upstream health and social determinants.