Table 1.
Prevalence estimates of language disorder of unknown origin using SCALES (DSM‐5) criteria, Tomblin et al. (1997) criteria and ICD‐10 criteria. Estimates for language impairment associated with known medical diagnosis/intellectual disability, and intellectual disability alone are provided for reference. NVIQ bands include ‘average’ (−1SD or greater), ‘low‐average’ (−2SD to −1SD) and ‘intellectual impairment (<−2SD)
| Raw number of children meeting criteria (denominator = 529) | Estimated numbers of children meeting criteria (denominator = 6,442) | Population prevalence in SCALES sample (% of population) (95% CIs) | Functional impact: % achieve ‘good level of development’ on EYFSPg | Functional impact: % abnormal behaviour on SDQ | |
|---|---|---|---|---|---|
| Language disorder of unknown origina (total) | 91 | 488 | 7.58 (5.33, 10.66) | 11.8 (3.71, 31.71) | 9.68 (5.43, 16.66) |
| ‘average’ NVIQ | 54 | 309 | 4.80 (3.06, 7.44) | 9.00 (1.92, 33.37) | 9.85 (4.66, 19.62) |
| ‘low‐average’ NVIQ | 37 | 179 | 2.78 (1.57, 4.86) | 16.62 (2.96, 56.57) | 9.38 (3.76, 21.54) |
| ‘Specific Language Impairment’ Tomblin et al. (1997) criteriab | 78 | 499 | 7.74 (5.38, 11.02) | 27.60 (13.19, 48.88) | 9.10 (4.96, 16.13) |
| ‘Developmental Language Disorder’ ICD10 criteriac | 14 | 69.2 | 1.07 (0.41, 2.82) | 0 | 11.79 (2.57, 40.42) |
| Language impairment and known medical diagnosis/intellectual disabilityd | 45 | 151 | 2.34 (1.40, 3.91) | 14.73 (2.18, 57.24) | 51.36 (27.55, 74.57) |
| Intellectual disability (NVIQ scores <−2SD)e | 30 | 119 | 1.84 (0.97, 3.46) | 18.9 (2.86, 64.81) | 38.97 (13.49, 72.34) |
| Total language disorderf | 136 | 639 | 9.92 (7.38, 13.20) | 12.49 (4.70, 29.23) | 19.55 (11.57, 31.08) |
DSM‐5 criteria: Language scores −1.5SD or more below normative mean on 2/5 language composite scores. NVIQ > 70, breakdown of average (above 85) and low‐average (between 70 and 85) in italic font. No known medical diagnosis.
Tomblin et al. (1997): Language scores −1.25SD or more below normative mean on 2/5 language composite scores. NVIQ > 85. No known medical diagnosis. Note: inclusion of children with NVIQ > 70 increases prevalence estimate to 11.11%.
ICD10 criteria: Language scores −2SD or more below normative mean on 2/5 language composite scores; NVIQ > 85, and no known medical diagnosis. Note this creates a significant (1SD) discrepancy between verbal and nonverbal ability.
Breakdown of diagnoses given in Table S2.
Includes both children meeting criteria for language impairment and those that did not.
Total language disorder combines prevalence estimates from the SCALES DSM‐5 criteria and those with language impairments associated with a known medical diagnosis and/or intellectual disability. It does not include children with English as an additional language or children who started school in a specialist provision for children with severe and complex learning disabilities. This figure thus represents the minimum overall need for language‐based clinical/educational support.
EYFSP: total achieving a ‘good level of development’ (GLD) in typically developing population is 69.59%.