A Psychometric Evaluation of the Body Image Questionnaire Child and Adolescent Version.

Body dysmorphic disorder (BDD) typically develops during adolescence, but there has been little research evaluating assessment tools for BDD in youth. This study sought to provide a comprehensive psychometric evaluation of a brief self-report questionnaire of BDD symptoms, the Body Image Questionnaire Child and Adolescent version (BIQ-C), in both clinical and non-clinical adolescent samples. Properties of the BIQ-C were examined in 479 adolescents recruited through schools and 118 young people with BDD attending a specialist clinic. Sensitivity to change was additionally examined in a subgroup of the clinical sample who received treatment (n = 35). Exploratory factor analysis indicated that a two-factor structure provided the best fit for the data in the non-clinical sample. The two-factor solution was corroborated through confirmatory factor analysis as the best solution in the clinical sample, although it did not fulfil predefined fit thresholds The first factor encompassed preoccupation and repetitive behaviours, while the second included items assessing functional impairment. The BIQ-C showed good internal consistency across both samples, and convergent validity with other measures of BDD. Among those in the clinical sample who received treatment, BIQ-C scores decreased significantly, and BIQ-C change scores were highly correlated with change scores on the gold-standard clinician-rated measure of BDD symptom severity. These findings indicate that the BIQ-C is a suitable tool for assessing BDD symptoms in young people and measuring change during treatment.