Prevalence of speech delay in 6-year-old children and comorbidity with language impairment

We estimate the prevalence of: speech delay(L. D. Shriberg, D. Austin, B. A . Lewis, J. L. McSweeny, & D. L. Wilson, 1997b) in the United States on the basis of findings From a demographically representative population subsamp le of 1,328 monolingual English-speaking 6-year-old children. All children' s speech and language had been previously assessed in the "Epidemiology of Specific Language Impairment" project (see J. B. Tomblin et al., 1997), whi ch screened 7,218 children in stratified cluster samples within 3 populatio n centers in the upper Midwest. To assess articulation, the Word Articulati on subtest of the Test of Language Development-2: Primary (Newcomer & Hammi ll, 1988) was administered to each of the 1,328 children, and conversationa l speech samples were obtained for a subsample of 303 (23%) children. The 6 primary findings are as follows: (a) The prevalence of speech delay in 6-y ear-old children was 3.8%; (b) speech delay was approximately 1.5 times mor e prevalent in boys (4.5%) than girls (3.1%); (c) cross-tabulations by sex, residential strata, and racial/cultural backgrounds yielded prevalence rat es for speech delay ranging from 0% to approximately 9%; (d) comorbidity of speech delay and language impairment was 1.3%, 0.51% with Specific Languag e Impairment (SLI); (e) approximately 11-15% of children with persisting sp eech delay had SLI; and (f) approximately 5-8% of children with persisting SLI had speech delay. Discussion includes implications of findings for spee ch-language phenotyping in genetics studies.