Cognitive behavioral therapy (CBT) is generally considered the recommended approach for selective mutism (SM). Prospective follow-up studies of treated SM and predictors of outcome are scarce. We have developed a CBT home and school-based intervention for children with SM previously found to increase speech in a pilot efficacy study and in a randomized controlled treatment study. In the present report we provide outcome data 1 year after having completed the 6-month course of CBT for 24 children with SM, aged 3-9 years (mean age 6.5 years, 16 girls). Primary outcome measures were the teacher rated School Speech Questionnaire (SSQ) and diagnostic status. At follow-up, no significant decline was found on the SSQ scores. Age and severity of SM had a significant effect upon outcome, as measured by the SSQ. Eight children still fulfilled diagnostic criteria for SM, four were in remission, and 12 children were without diagnosis. Younger children improved more, as 78% of the children aged 3-5 years did not have SM, compared with 33% of children aged 6-9 years. Treatment gain was upheld at follow-up. Greater improvement in the younger children highlights the importance of an early intervention.
Trial registration: ClinicalTrials.gov NCT01002196.