Factor analysis of the Massachusetts General Hospital Hairpulling Scale.

OBJECTIVE We explored the factor structure of the Massachusetts General Hospital Hairpulling Scale (MGH-HPS), a self-report measure for trichotillomania (TTM). METHODS Self-reported hairpullers who responded to an Internet-based survey (N=990) completed the MGH-HPS, demographic items, and other survey instruments. Principal axis exploratory factor analysis with Promax rotation of scores was conducted. RESULTS A two-factor solution was revealed, with "Severity" and "Resistance and Control" as separate factors. CONCLUSION The MGH-HPS consists of two separate factors. Factor scores can be utilized to track naturalistic TTM symptom changes, improve patient characterization and treatment matching, and clarify the timing and mechanism of action for different treatment modalities.