Psychometric properties of the Reflective Function Questionnaire for Youth Five-Item version in adolescents with restrictive eating disorders

Objective: Mentalizing difficulties are an established correlate of eating disorders, but there is a need to establish the validity and reliability of easy-to-administer instruments to measure the construct in adolescents. This study evaluated the psychometric properties of a five-item version of the Reflective Function Questionnaire for Youth (RFQY-5) in a sample of adolescents with restrictive eating disorders recruited for a prospective observational study. Method: Adolescents completed the 46-item version of the RFQY at the start of treatment (T1) (n= 171) and nine months later (n=51). The factor structure, internal reliability and convergent validity of the RFQY-5 were assessed for T1. Sensitivity to change was assessed in a subsample of n=51 who completed the RFQY nine months after the start of treatment (T2). Results: At T1, the RFQY-5 demonstrated inadequate internal reliability (McDonald’s Omega = .655) and poor model fit for the unidimensional structure (Χ2(5) = 27.64; p < .001; CFI = .815; TLI = .630; RMSEA = .162; SRMR = .07). Convergent validity was partially supported. The RFQY-5 was not sensitive to change. Discussion: The RFQY5 was found to have inadequate psychometric properties in adolescents with restrictive eating disorders. Psychometric studies are needed to further develop valid and reliable measures of mentalizing for this population.