Table 4

Recent studies on the prevalence of autism spectrum disorders in children estimated at approximately 1% or higher

Study and locationAge groupsMethodNumber of clinically verified casesTarget populationPrevalence %Male/female ratio
Baird (2006)3 UK9–10Records/Survey15856 9461.16*3.3
Kawamura (2008)4 Japan1–7Clinical22812 5891.81†2.8
ADDM (2009)25 USA8RecordsNA307 7900.90‡3.2–7.6
Baron-Cohen (2009)5 UK5–9Records/SurveyNA88241.57*Not reported
Posserud (2010)24 Norway7–9Survey1466090.87*Not reported
Kim (2011)6 South-Korea7–12Records/Survey20155 2662.64*2.5
Present study Iceland11–15Clinical26722 2291.20†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.