Epidemiological investigation of expressive language delay at age two

Abstract

Two studies are presented investigating the feasibility of using the Language Development Survey (LDS), a vocabulary checklist completed by parents, for the epidemiological investigation of the prevalence of expressive language delay in 2-year-olds. Two samples of upper-middle class toddlers were studied (Study 1: N = 108; Study 2: N = 92). Mean vocabulary reported was 195 words in Study 1 and 184 words in Study 2, with 13% and 15% of the respective samples reported to have fewer than 50 words of vocabulary. The correlation between reported LDS vocabulary and total number of Bayley objects and Stanford-Binet pictures named by the child was 0.78 in Study 1 and 0.82 in Study 2. In both studies, the LDS exhibited excellent sensitivity and specificity for the identification of language delay at 2 years old. Results of the two studies suggest that the LDS can be a useful and practical tool for the epidemiological identification of expressive language delay in 2-year-olds in the general population.