Longitudinal effects of residential treatment for eating disorders: symptom trajectories and predictors of functional outcomes

Objective: Residential treatment for eating disorders addresses the gap between inpatient and outpatient care, but evidence for longer-term and functional outcomes remains limited. The current study examined both clinical and functional outcomes from admission to a 6-month follow-up from Australia's first residential service for eating disorders. Method: Measures of eating disorder symptoms, body mass index (BMI), anxiety, depression, general and eating disorder-specific health-related quality of life (HRQoL), and functional disability were completed at pretreatment, posttreatment, and 3- and 6-month follow-ups by 81 individuals with eating disorders (M_age = 25.78 years). Results: Linear mixed effects modeling found that change in outcomes over time was best modeled by a cubic growth curve, such that participants showed a steep improvement from pretreatment to posttreatment followed by a worsening of symptoms by 3 months post-discharge, which tapered off by 6 months post-discharge. Pairwise comparisons indicated significant improvement between pretreatment and posttreatment for all outcomes, and between pretreatment and 6 months post-discharge for all outcomes except mental HRQoL. Treatment gains were maintained after discharge for shape and weight concerns, anxiety, general and eating disorder-specific HRQoL, and functional disability. Greater in-treatment improvement in eating disorder symptoms predicted steeper in-treatment improvement and posttreatment deterioration in eating disorder-specific HRQoL, mental HRQoL, and functional disability. Greater post-discharge mental health support predicted steeper improvement in functional disability. Discussion: Results support the longitudinal effectiveness of residential treatment for clinical and functional outcomes. However, not all outcomes may maintain the degree of improvement seen at discharge, highlighting the importance of appropriate step-down care. Trial Registration: Registration number: ACTRN12621001651875.