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

Participation was voluntary, so parents who noticed disfluencies may have been more likely to respond, while stigma may have made some parents avoid reporting. Some children were confirmed only by parent report or questionnaire, not direct observation, so classification could be incomplete. Past stuttering history relied partly on retrospective parent memory, although the recall period was short. The model's predictive power was low, and the stuttering group was moderate size, so risk-factor findings should be read cautiously. The study did not include children older than the 3-year checkup age, so it cannot capture all early-onset stuttering cases. The Kawasaki disease association may be a false positive, and the paper says it cannot definitively claim an association. Family history may have been underreported because of stigma.

The authors declared no conflict of interest. The work was funded by Japan Agency for Medical Research and Development and partially by JSPS KAKENHI.

Do not read the prevalence and incidence figures as evidence that most 3-year-old stuttering needs immediate treatment. The study found that some children had already recovered by the checkup, and it did not follow children prospectively to identify persistent cases.