Integrated Behavior Therapy for Exclusively Anxious Selective Mutism: A Nonconcurrent Multiple-Baseline Design across Five Participants.

Selective mutism (SM) is a rare childhood anxiety disorder which may be markedly detrimental to a child's academic and social functioning if left untreated. Cognitive-behavioral treatments for social anxiety disorders have been found to be effective for SM, yet a paucity of published studies have explored manualized treatment approaches carried out by novice clinicians. The purpose of the present study was to examine the adherence, effectiveness, and acceptability of a condensed, 16-session version of Integrated Behavior Therapy for Selective Mutism (IBTSM; Bergman, 2013), the first manualized treatment for SM. A nonconcurrent multiple-baseline single-case design was used across five children diagnosed with SM, exclusively anxious subtype. IBTSM was implemented with excellent adherence (M = 98%) over an average of 19 weeks (range = 16-22 weeks). Visual analyses of weekly caregiver ratings of social anxiety and speaking behaviors did not demonstrate a replicated intervention effect; however, Tau-U effect sizes and Reliable Change Index (RCI) calculations demonstrated significant individual improvements in social anxiety and speaking behaviors over time on several measures. Three children (60%) no longer met diagnostic criteria for SM following treatment. All caregivers rated IBTSM as acceptable, with specific endorsements of acceptability in the areas of time required and treatment quality.