Studies were eligible for inclusion if they evaluated either a behavioural or psychological, or a pharmacological intervention for skin picking, defined as self-inflicted tissue damage by pulling, scratching, lancing, digging, gouging, or picking, causing significant distress or impairment. Studies were excluded if there was insufficient data to estimate an effect size; the primary diagnosis was a developmental disorder, eating disorder or body dysmorphic disorder; skin picking was better understood as deliberate self-harm; or interventions were primarily dermatological and not focused on improving skin-picking behaviour.
In the included pharmacological studies, the mean age of participants ranged from 32 to 46 years, and the mean duration of the disorder, where reported, ranged from 18 to 20 years. The drugs used were citalopram (20mg/day for four weeks), fluvoxamine (up to 300mg/day for 12 weeks), lamotrigine (up to 300mg/day for 12 weeks), escitalopram (up to 30mg/day for 18 weeks), or fluoxetine (60mg/day for 10 weeks). Treatment completion rates ranged from 21% to 86.96%.
In the included psychological studies, the mean age of participants ranged from 22 to 45 years, and the mean duration of the disorder, where reported, ranged from 15 to 19 years. The treatments were cognitive-behavioural therapy (four to seven sessions), habit reversal (three sessions in one study), and acceptance and commitment therapy (eight sessions). Completion rates ranged from 15.86% to 100%.
Studies were published between 1981 and 2011. Two reviewers independently selected studies for inclusion, with any disagreements resolved through discussion.