Development and validation of the Dermatology Social Comparison (DSC) Scale

Social comparison, the process of evaluating one's characteristics in relation to others, influences individuals' self-perception and behavior. However, instruments are scarce for assessing social comparison in the medical setting.

Our aim was to develop and validate a new scale for assessing social comparison.

Seven statements were developed, encompassing the perceived normality of having rashes, the tendency to compare their situation with others, and the emotional response when seeing someone better or worse off than themselves. The instrument was piloted in 15 patients for readability and face validity, then prospectively validated using modern psychometric methods in 1,053 adult patients with eczema or psoriasis from three tertiary dermatological centers in Singapore.

Of 1,053 adult patients, 802 (76.2%) had eczema, and 251 (23.8%) had psoriasis. Exploratory factor analysis (using a 70% sample split) showed a single factor model comprising three questions (Eigenvalue: 1.4). Confirmatory factor analysis with the remaining 30% of the sample confirmed an excellent model fit. Cronbach's alpha was 0.7, and inter-item correlations ranged from 0.42 to 0.46. In the Rasch analysis, item fit statistics and item characteristic curves showed appropriate discrimination between response options, although reliability was suboptimal with a person separation reliability of 0.63.

Comprising 3 questions, the newly derived social comparison scale showed acceptable psychometrics as a measure of social comparison for clinical and research purposes in dermatology. Its brief nature likely results from its brevity and applicability to conditions beyond eczema and psoriasis, which warrants further investigation.