The Prevalence of Autism Spectrum Disorder In An Israeli Population

Background:  

There is a dramatic rise in the prevalence of autism spectrum disorder (ASD) being reported around the world, and these figures are steadily increasing.  In the United States alone, the Center for Disease Control (CDC) reported an overall average prevalence of 9.0 per 1,000 individuals (0.90%) in 2006.  However, to-date, data on incidence and prevalence of ASD in Israeli populations has been limited.

Objectives:  

To calculate the prevalence and incidence of ASD in an Israeli population.

Methods:  

Data on ASD was available from the database of Israel’s second-largest of four healthcare organizations, Maccabi Healthcare Services, which provides services to 1.8 million people (approximately 25% of the population). A case of ASD was defined as any child in the target age group with at least one physician-recorded diagnosis.   ASD criteria included those diagnosed with autism disorder, PDD-NOS, and Asperger’s syndrome. Autism prevalence was calculated as the total number of children under twelve years of age who had ever received an autism diagnosis, divided by total membership in that group.  Data on prevalence was available for the 2009 calendar year.  Autism incidence was calculated as the total number of new cases in children under twelve years of age divided by the total membership in that group. Data on incidence was available for the 2002-2009 calendar years.

Results:  

In the 2009 calendar year, the prevalence of ASD for children under twelve years of age was 4.5 out of 1,000 (0.45%).  Out of this figure, 83% were males.  Since we found that most children (84%) were diagnosed with ASD through the age of six, we divided the resulting incidence figures into two groups: children up to the age of the six, and children between the ages of six and twelve.  For children up to the age of six, there was a slight increase in incidence between 2002 (0.34 for 1,000 individuals) and 2003 (0.41), but a dramatic increase between the year 2003 and 2004, when the figure jumped to 1.09 diagnoses per 1,000 individuals.  Thereafter, the incidence remained mostly steady with slight increases each year, peaking in 2009 at an incidence of 1.20.  For children between the ages of six and twelve, there was a marked increase in incidence between 2002 (0.18 per 1,000) and 2003 (0.46).  Thereafter, between the years of 2004-2009, the incidence fluctuated in the range of 0.40 and 0.60 per 1,000 individuals with no clear observable trend.

Conclusions:  

The incidence of ASD in Israel is on the rise, mirroring the larger global trend of a rise in cases of ASD. However, the prevalence of ASD in Israel (0.45%) remains significantly lower than in the United States (0.90%).  Since there is extensive screening for ASD in Israel, as well as widespread awareness and services, it is unlikely that this discrepancy is due to differences in these factors.  It is possible that there is a stricter interpretation of the ASD diagnosis in Israel, although differing genetic and environmental influences cannot be ruled out.