Multiple-Community-Based Epidemiological Study of Stuttering among 3-Year-Old Children in Japan.

Introduction: Many epidemiological studies of the disorder of stuttering have been conducted during the 20th century, continuing during the current one. Unfortunately, only a few were carried out in Japan. This study aimed at assessing (1) the incidence and prevalence of stuttering in 3-year-old children in multiple Japanese communities and (2) factors associated with the onset of stuttering among these children.

Methods: A questionnaire aimed at screening for the presence of stuttering was employed for 2,055 children aged 3 years, who underwent a standard nationwide health checkup. Positive responses were confirmed in several ways: (1) direct interviews and assessment of the child's speech, (2) confirmatory questionnaire, or (3) telephone interviews by licensed Speech Language Hearing Therapists.

Results: Approximately 6.5% of the children were found to exhibit stuttering at the time of their health checkup. This figure rose to 8.9% after including individuals who previously, but not currently, were reported to have exhibited stuttering. Among the putative risk factors, higher stuttering odds (odds ratio, OR = 3.27) were detected in those with a family history of stuttering, those whose guardians had concerns about their child's development (OR = 1.75), and those with diagnosed diseases or disabilities (OR = 2.13).

Discussion/conclusions: It was concluded that, in Japan, both the risk of stuttering incidence (8.9%) in children up to, and including, the age of 3 years, as well as its prevalence (6.5%) in this population, was similar to those reported by recent studies in other countries. Additionally, our findings also confirmed that an increased risk for stuttering at age 3 is associated with a family history of stuttering.