Effects of early identification and intervention on language development in Japanese children with prelingual severe to profound hearing impairment.

Objectives: Early identification and intervention for prelingual bilateral severe to profound hearing loss is supposed to reduce the delay in language development. Many countries have implemented early detection and hearing intervention and conducted regional universal newborn hearing screening (UNHS). However, the benefits of UNHS in later childhood have not yet been confirmed, although language development at school age has a lifelong impact on children's future. Our Research on Sensory and Communicative Disorders project attempted to reveal the effects of UNHS and those of early intervention on the development of verbal communication in Japanese children.

Methods: In this study, 319 children with prelingual bilateral severe to profound hearing loss, 4 to 10 years of age, were evaluated with the Test of Question-Answer Interaction Development used as an objective variable. Participation in UNHS and early intervention were used as explanatory variables. The adjusted odds ratio (AOR) was calculated after adjusting several confounding factors with use of logistic regression analysis. In addition, caregivers' answers were obtained by a questionnaire, and the process of diagnosis with and without UNHS was analyzed retrospectively.

Results: Early intervention was significantly associated with better language development (AOR, 3.23; p < 0.01). Participation in UNHS may contribute to better language development to some extent (AOR, 1.32), but not one that was statistically significant (p = 0.37). However, UNHS was significantly associated with early intervention (AOR, 20.21; p < 0.001). The questionnaire results indicated a lag in treatment after UNHS in more than 40% of screened cases.

Conclusions: Early intervention strongly influenced language development. It is necessary to ensure that early identification leads directly to early intervention.