The Spanish version of the Excoriation (Skin-Picking Disorder) Dimensional Scale (SPD-D): An assessment of its psychometric properties

Background: In 2013, the DSM-5 obsessive-compulsive spectrum disorders sub-workgroup developed the Excoriation (skin-picking disorder) Dimensional Scale (SPD-D) as a dimensional assessment that enquires about excoriation disorder symptoms that have occurred over the past week. This study aimed to assess the psychometric properties of the Spanish version of the SPD-D in a population sample from Paraguay. Method: Participants were recruited through an Internet-based survey. Subjects included were individuals ≥ 18 years old, who self-reported a diagnosis meeting the criteria for excoriation disorder. 531 individuals were rated for the validation analysis. SPD-D was back-translated and validated into Spanish. Exploratory and confirmatory factorial analysis were performed. Participants were also assessed with the Skin Picking Scale-Revised (SPS-R). Results: Exploratory factorial analysis reported that only one factor had a raw eigenvalue greater than 1, and explained 57.4% of total variance. Thus, the scale is considered one-dimensional, as confirmed by confirmatory analysis. Fit indices suggest a good adjustment and Cronbach's alpha showed good internal consistency (α=0.816). Good convergence was found between the scores of the SPD-D and the SPS-R (r=0.822, p<0.0001). Conclusion: The Spanish version of SPD-D shows good psychometric properties and adequately reproduces the one-dimensional model of the original English version.