Effectiveness of digitally-delivered interventions for trichotillomania and skin picking disorder: A systematic review and meta-analysis.

Trichotillomania (TTM) and excoriation disorder (skin picking) disorder (SPD) are common yet undertreated conditions. Although evidence-based cognitive behavioral treatments exist, therapy access is often limited by insufficient provider availability, cost, and stigma. Several technology-based interventions have emerged as a scalable and accessible alternative, but their overall effectiveness for TTM and SPD remains unclear. This systematic review and meta-analysis evaluated the efficacy of digitally-delivered interventions for TTM and SPD. The review protocol was pre-registered on PROSPERO. PsycINFO, MEDLINE, and Embase were searched for studies testing digital interventions for TTM/SPD grounded in cognitive and/or behavioral therapies, including both therapist-assisted and self-guided formats and both controlled and uncontrolled study designs. Random-effects meta-analyses estimated within-group effect sizes for all included studies and between-group effects for randomized controlled trials. Subgroup analyses examined study, sample, and intervention characteristics. Fourteen studies (N = 5468) met inclusion criteria. Large within-group effect sizes were found for symptom reduction from pre- to post-treatment (g = 1.01), with sustained follow-up effects (1-3 months: g = 1.22; 6 months: g = 1.15). Between-group analyses of randomized controlled trials showed a medium effect favoring digital interventions over control (g = 0.63). Subgroup analyses showed trends toward stronger effects in interventions that explicitly incorporated ACT-based therapeutic content and included accountability features (e.g., reminders, therapist messaging). Effects for secondary outcomes (quality of life, depression, anxiety) were minimal. Overall, digitally-delivered interventions are associated with meaningful reductions in TTM and SPD symptom severity. Although heterogeneity and variability in study design warrant cautious interpretation, these findings support digital interventions as a promising option for improving access to care.