Psychometric properties of the Italian body shape questionnaire: an investigation of its reliability, factorial, concurrent, and criterion validity

Purpose This study was set up to investigate the reliability, factorial, concurrent, and criterion validity of the Italian version of the 34-item Body Shape Questionnaire (BSQ) and its shorter versions. Methods The study included 231 patients diagnosed with an eating disorder and 58 putatively healthy people (comparison sample). The Italian BSQ-34 was administered to participants together with the Hamilton Depression Rating Scale and the Hamilton Anxiety Rating Scale. Information on body mass index, caloric intake at baseline, and the number of episodes of self-vomiting per week was also acquired. Results Cronbach's alpha of BSQ-34 was 0.971 (95% confidence interval [CI] 0.965-0.976) in patients and 0.960 (0.944-0.974) in controls. Test-retest stability in patients (n = 69), measured with intraclass correlation coefficient, was 0.987 (0.983-0.991). Confirmatory factor analysis of the single-factor model yielded acceptable fit for all versions of the BSQ. On all BSQ versions, patients scored higher than controls with a large effect size when calculated as Cliff's delta. BMI and mean caloric intake at baseline had a stronger association with BSQ-34 than levels of anxiety and depression. The analysis with the receiver operating characteristics (ROC) curve showed that the BSQ-34 distinguished patients with an eating disorder from controls with good accuracy (Area Under the Curve = 86.5; 95% CI 82.2-90.7). Conclusion The Italian version of the BSQ possesses good psychometric properties, in both the long and the shortened versions, and it can be applied to measure body dissatisfaction for both clinical and research purposes.