To Fidelity and Beyond: Development of an Implementation Fidelity Tool for Early Intervention for Eating Disorders...

First Episode Rapid Early Intervention for Eating Disorders (FREED) is an early intervention service model for young people with recent-onset eating disorders. This manuscript describes the development and pilot testing of an implementation fidelity tool for FREED or similar early intervention models, exploring feasibility of the tool and changes in fidelity over time.

An iterative consultation process within the FREED national team reviewed the core aims, functions, principles, and key components of FREED services. A set of items and a scoring rubric were drafted and pilot-tested via two assessments in a London-based FREED service with routine data and interviews with team members. Items were scored independently by two raters. Inter-rater reliability was assessed.

The fidelity tool comprised 35 items across two components: (1) rapid access to the service and (2) adherence to the FREED care package (e.g., family involvement, attention to transitions). Overall fidelity scores were 63% at time 1% and 60% at time 2, indicating 'lower' fidelity. Component scores ranged from 'not satisfactory' for rapid access, to 'medium fidelity' for care package components. Weighted Cohen's kappa indicated almost perfect agreement across assessments.

This is the first fidelity measurement tool for early intervention eating disorders services. It demonstrated feasibility, simple administration, and time efficiency. Pilot testing suggested fidelity to some aspects of FREED, but further support is required to improve fidelity. Future work should focus on refining the tool (e.g., further psychometric evaluation) and testing it in more services to investigate whether ongoing assessments support fidelity.