Diagnostic Stability of Developmental Delay and Developmental Language Disorder in Infants and Toddlers

Numerous children are diagnosed with Developmental Delay (DD) and Developmental Language Disorder (DLD) each year in the US. There are inconsistent diagnostic definitions for these disorders because individual states determine diagnostic criteria, complicating prevalence and diagnostic stability estimation. In the current study, 37 children received a diagnosis of DD and 21 received a diagnosis of DLD at an initial evaluation as part of participation in a study investigating the early detection of Autism Spectrum Disorders (ASDs), and were seen for a follow-up evaluation. The DD group was significantly more likely to retain this diagnosis at follow-up than the DLD group. The DD and DLD group made significant gains on developmental measures between evaluations, and the DLD group made significantly greater gains in language skills than the DD group. Children in the DD group who were more delayed at their initial evaluation were more likely to retain their diagnosis at follow-up, approaching significance. Males from the DD group retained their diagnosis more often than males in the DLD group. Maternal education and family income did not have an effect on diagnostic stability in the DD and DLD groups. A small number of children from both the DD and DLD group received a diagnosis of an Autism Spectrum Disorder at follow-up, but this did not differ significantly between the groups or by gender. These findings emphasize the need for more clear and consistent diagnostic criteria for DD and DLD to allow for clearer measurement of prevalence and analysis of diagnostic stability.