Treating trichotillomania: A meta-analysis of treatment effects and moderators for behavior therapy and serotonin reuptake inhibitors

• Behavior therapy (BT) yields large treatment effects for trichotillomania (TTM).
• Therapeutic contact and mood-enhanced components moderated BT treatment effects.
• Serotonin reuptake inhibitors (SRIs) demonstrated modest treatment effects.
• No significant difference was found between clomipramine (CMI) and selective SRIs.
• Sensitivity analyses highlight the need for further evaluation of SRIs for TTM.

Few randomized controlled trials (RCTs) exist examining the efficacy of behavior therapy (BT) or serotonin reuptake inhibitors (SRIs) for the treatment of trichotillomania (TTM), with no examination of treatment moderators. The present meta-analysis synthesized the treatment effect sizes (ES) of BT and SRI relative to comparison conditions, and examined moderators of treatment. A comprehensive literature search identified 11 RCTs that met inclusion criteria. Clinical characteristics (e.g., age, comorbidity, therapeutic contact hours), outcome measures, treatment subtypes (e.g., SRI subtype, BT subtype), and ES data were extracted. The standardized mean difference of change in hair pulling severity was the outcome measure. A random effects meta-analysis found a large pooled ES for BT (ES = 1.41, p < 0.001). BT trials with greater therapeutic contact hours exhibited larger ES (p = 0.009). Additionally, BT trials that used mood enhanced therapeutic techniques exhibited greater ES relative to trials including only traditional BT components (p = 0.004). For SRI trials, a random effects meta-analysis identified a moderate pooled ES (ES = 0.41, p = 0.02). Although clomipramine exhibited larger ES relative to selective serotonin reuptake inhibitors, the difference was not statistically significant. Publication bias was not identified for either treatment. BT yields large treatment effects for TTM, with further examination needed to disentangle confounded treatment moderators. SRI trials exhibited a moderate pooled ES, with no treatment moderators identified. Sensitivity analyses highlighted the need for further RCTs of SRIs, especially among youth with TTM.