皮膚掻痒症（皮膚掻痒症）治療のためのセルフガイド型デジタル介入であるStopPickingの効果とユーザーエンゲージメントの評価

Excoriation, or skin picking disorder (SPD), is a common and impairing condition, yet many individuals face barriers to accessing evidence-based care. Digital interventions offer a scalable option, but few have been evaluated in real-world settings. This study examined naturalistic outcomes among 2063 adult users of StopPicking, a self-guided online intervention for SPD. The program includes three modules: Module 1 focuses on self-monitoring and assessment, Module 2 delivers personalized behavioral strategies, and Module 3 supports maintenance and relapse prevention. Symptom severity was assessed at baseline, post-Module 1, and at final program use. Using an intent-to-treat approach, multilevel modeling showed a medium-sized reduction in symptom severity over time (Hedges' g = 0.71). Greater engagement, measured by self-monitoring frequency and number of weeks active in the program, was associated with lower final severity scores. Baseline severity, age of SPD onset, and age group were linked to usage patterns: users with higher severity or earlier onset tended to self-monitor more consistently, while older adults had higher rates of early discontinuation. Findings support StopPicking as a viable self-help option and highlight the importance of promoting meaningful engagement. Results also suggest that self-monitoring may function both as an indicator of engagement and a potential mechanism of change.