3 - (SYM 102) the General Appearance Concerns Scale: Development of a Model-based Transdiagnostic Measure Using Item-response Theory

Physical appearance concerns are a prominent feature of several psychiatric conditions including body dysmorphic disorder, eating disorders, and social anxiety disorder, and a growing body of research suggests that appearance concerns may have important utility as a transdiagnostic construct. However, self-report measures of this individual difference characteristic have been developed primarily within disorder-specific frameworks, in contrast with emerging dimensional models which seek to identify and investigate shared factors impacting systematic comorbidity. The lack of a psychometrically sound, transdiagnostic measure of appearance concerns constitutes a major limitation of ongoing work in this area that hinders the ability of researchers to integrate results across studies and samples. Thus, the aim of the current work was to develop and validate an efficient scale measure of physical appearance concerns for use in future studies investigating its role in different psychiatric conditions and their systematic comorbidity. Building on prior work from our lab which found that three widely used questionnaires developed to assess appearance concerns in relation to specific psychiatric disorders are in fact indicators of a common latent construct, we utilized model-based multidimensional item response theory to identify a subset of items from those measures with optimal measurement properties for indexing variations in the general appearance concerns factor identified in the original model. These efforts resulted in the brief, nine-item General Appearance Concerns Scale (GACS). This new scale showed effective coverage of the general appearance concerns trait continuum, a unidimensional structure and excellent internal consistency, and evidence of criterion-related validity. Results support the GACS as an effective instrument for assessing symptoms within the domain of appearance concerns and a vehicle for pursuing systematic research on physical appearance concerns as a transdiagnostic construct. The current findings and broader utility of the quantitative methods will be discussed in relation to dimensional approaches to psychopathology, such as the Hierarchical Taxonomy Of Psychopathology (HiTOP) model.