(PS7-B46) Evaluation of the Psychometric Properties of Trichotillomania Severity Measures

Introduction

Trichotillomania (TTM), or hair pulling disorder, is a psychiatric condition that results in hair loss, distress, and functional impairment. There are few existing measures to assess TTM, and research on the psychometric properties of these tools is sparse (Diefenbach et al., 2005). This lack of information on TTM measures may be a barrier to advancing both the research and treatment of the disorder. The present study aimed to evaluate the psychometric properties of commonly used TTM severity measures and extend prior research by including hair loss severity ratings and patient self-monitoring data in our analyses.

Methods

Data for this study were collected as part of a randomized clinical trial (RCT) examining psychotherapy for TTM (Woods et al., 2022). Participants included 91 adults with TTM (92.3% Female; M age = 35.0; 82% Caucasian, 13% African American, 3.5% did not identify race) who completed baseline assessments for the RCT. TTM measures included self-report Massachusetts General Hospital Hairpulling Scale (MGH-HS) and clinician-administered National Institute of Mental Health Trichotillomania Severity Scale (NIMH-TSS). Independent raters used a one-item hair loss severity scale to rate each participant’s most severely affected pulling site. A subset of participants (N=38) completed self-monitoring records of time spent pulling over the course of a week.

Results

The MGH-HS showed acceptable internal consistency (α = 0.83) but low test-retest reliability (r = .56, p < .001). The NIMH-TSS demonstrated low internal consistency (α = 0.52) and low test-retest stability (r = .61, p < .001). Interrater reliability for the hair loss severity measure was acceptable (ICC = 0.76, p < .001). The MGH-HS and NIMH-TSS were moderately correlated with one another (r = .61, p < .001). Hair loss severity was not significantly correlated with MGH-HS, NIMH-TSS, or self-monitoring reports (ps > .05). Self-monitoring reports of time spent pulling were moderately associated with the MGH-HS (r = .40, p = .014) and the NIMH-TSS (r = .68, p < .001). CGI-S scores were moderately correlated with NIMH-TSS (r=.33, p = .002) and self-monitoring reports of time spent pulling (r = .50, p = .002).

Discussion

Our results show mixed psychometric properties for existing TTM measures. The MGH-HS and NIMH-TSS showed low to moderate internal consistency and low test-retest reliability. Low stability is of concern; this could bring into question conclusions drawn from outcome data based on these measures. Additionally, the nonsignificant correlations between hair loss and scores on the MGH-HS and NIMH-TSS may indicate that hair loss in TTM occurs independently of factors assessed by these scales. Overall, these findings underscore the need for future research aimed at developing new, psychometrically sound TTM rating scales. These results also emphasize the importance of a multi-method approach to TTM assessment. Hair loss severity ratings and patient self-monitoring records may offer useful supplemental data in evaluating TTM severity.