Psychometric evaluation of the Snaith-Hamilton pleasure scale in adult outpatients with major depressive disorder.

The inability to experience pleasure, anhedonia, is recognized as a hallmark symptom of depression. An instrument developed for the assessment of hedonic capacity is the 14-item, self-report, Snaith-Hamilton Pleasure Scale (SHAPS), but its psychometric properties have not been adequately evaluated. This study examined the reliability and validity of the SHAPS using a large sample of adult outpatients with major depressive disorder (MDD). Data for this study were obtained from 461 adult outpatients with a diagnosis of MDD who participated in Implementation of Algorithms using Computerized Treatment Systems Project. Internal consistency of the SHAPS was assessed using the Cronbach's coefficient α. A principal factor analysis was used to define the dimensionality of the SHAPS. Convergent and discriminant validity was assessed by evaluating the Pearson correlations between the SHAPS total score and the pleasure/enjoyment item of the 30-item Inventory of Depressive Symptomatology - Clinician-rating (IDS-C30); Quality of Life, Enjoyment, and Satisfaction Questionnaire; 17-item Hamilton Rating Scale for Depression; IDS-C30; 16-item Quick Inventory of Depressive Symptomatology; and 10-item clinician-rated Montgomery-Asberg Depression Rating Scale, respectively. The internal consistency of the SHAPS was 0.91. A one-factor solution emerged for the SHAPS (eigen-values of the first two initial factors were 5.95 and 0.43, respectively). Pearson correlations revealed a positive linear relationship between the SHAPS total score and the total scores on the 17-item Hamilton Rating Scale for Depression (r=0.49, P<0.0001), IDS-C30 (r=0.56, P<0.0001), 16-item Quick Inventory of Depressive Symptomatology (r=0.55, P<0.0001), and 10-item clinician-rated Montgomery-Asberg Depression Rating Scale (r=0.53, P<0.0001). The SHAPS total score was negatively correlated with the Quality of Life, Enjoyment, and Satisfaction Questionnaire (r=-0.65, P<0.0001). This study shows that the SHAPS is a reliable, valid, and unidimensional instrument used to assess the hedonic capacity in adult outpatients with MDD.