Recent studies on the prevalence of autism spectrum disorders in children estimated at approximately 1% or higher
| Study and location | Age groups | Method | Number of clinically verified cases | Target population | Prevalence % | Male/female ratio |
|---|---|---|---|---|---|---|
| Baird (2006)3 UK | 9–10 | Records/Survey | 158 | 56 946 | 1.16* | 3.3 |
| Kawamura (2008)4 Japan | 1–7 | Clinical | 228 | 12 589 | 1.81† | 2.8 |
| ADDM (2009)25 USA | 8 | Records | NA | 307 790 | 0.90‡ | 3.2–7.6 |
| Baron-Cohen (2009)5 UK | 5–9 | Records/Survey | NA | 8824 | 1.57* | Not reported |
| Posserud (2010)24 Norway | 7–9 | Survey | 14 | 6609 | 0.87* | Not reported |
| Kim (2011)6 South-Korea | 7–12 | Records/Survey | 201 | 55 266 | 2.64* | 2.5 |
| Present study Iceland | 11–15 | Clinical | 267 | 22 229 | 1.20† | 2.8 |
*Estimated prevalence taking non-responders into consideration.
†Calculated from raw numbers.
‡An overall average across 11 ADDM sites.
ADDM, Autism and Developmental Disabilities Monitoring Network, USA; NA, not applicable.