Validation of Dodd's Model for differential diagnosis of childhood speech sound disorders: A longitudinal community cohort study

Aim: Dodd's Model for Differential Diagnosis is one of the available clinical diagnostic classification systems of childhood speech sound disorders. Yet we do not understand the validity of this system beyond clinical samples, precluding its application in epidemiological or population‐based research. This study aimed to determine the prevalence of subgroups of speech sound disorders in a community sample, relative to past clinical samples, in children speaking standard Australian English. Method: We examined speech development in a community‐ascertained sample of children at 4 years (n=1607). Inclusion for speech sound disorder was a score of less than or equal to 1 standard deviation on a standardized speech test, and/or research assistant concern, and/or three or more speech errors on sounds typically acquired by 4 years. Dodd's model was then applied to 126 children. Results: Data revealed proportions of children across Dodd's diagnostic subgroups as follows: suspected atypical speech motor control (10%); inconsistent phonological disorder (15%); consistent atypical phonological disorder (20%); phonological delay (55%); and articulation disorder alone (0%). The findings are in line with known prevalence of these subgroups in clinical populations. Interpretation: Our findings provide additional support for speech‐language pathologists to use this system in clinical practice for differential diagnosis and targeted intervention of speech sound disorders in children.