Abstract
OBJECTIVE: Outcomes for low-weight restrictive eating disorders, including anorexia nervosa, restricting type (AN-R) and avoidant/restrictive food intake disorder (ARFID), are sub-optimal. Reducing dietary restriction is a key treatment target. Understanding heterogeneity in patterns of change in dietary restriction may aid in improving outcomes. We examined latent trajectories of change in dietary restriction during treatment and follow-up in AN-R and ARFID. METHODS: Adolescents and adults with R-EDs (N = 276, 18% ARFID, 90% female, M (age) = 18) receiving intensive ED treatment completed assessments at five timepoints. Latent growth mixture modeling examined trajectories of change in dietary restriction, measured using the Eating Pathology Symptoms Inventory Restricting subscale. Classes were compared on clinical features at admission to determine characteristics prospectively associated with trajectory. RESULTS: A 3-class solution emerged: Class 1 comprising individuals with "good response" (n = 138; 33% of those with ARFID in the sample); Class 2 with "good response, rebounding" (n = 81; 41% of ARFID); and Class 3 with "gradual response, low symptoms" (n = 57; 26% of ARFID). Class 3 had lower anxiety and R-ED symptoms than Classes 1 and 2. Class 2 presented with older age than Class 1. DISCUSSION: No ARFID-specific classes emerged, underscoring similarities in response to intensive treatment between AN-R and ARFID.