Photo of an ethnically diverse group of 4-year-old girls and boys holding hands and smiling.

Findings from 2020 data

How many 4-year-old children were identified with ASD in Minnesota?

1.9% or 1 in 53 children were identified with ASD in Minnesota.

Using data from 2020, MN-ADDM researchers found 1 in 53 (1.9%) 4-year-old children were identified with ASD. This is lower than the overall ADDM Network prevalence of 4-year-old children identified with ASD (1 in 46 or 2.2%) in the United States where the CDC tracked ASD in 2020.

Which children were more likely to be identified with ASD in Minnesota?

Among 4-year-olds, boys were 3.3 times more likely to be identified with ASD than girls.

Prevalence of ASD in 4-year-old children in Minnesota by sex and U.S. Census race and ethnicity

Prevalence estimate

Prevalence per 1,000 children

95% confidence interval per 1,000

Overall

1 in 53, 1.9%

18.7

16.7-20.9

Males

1 in 34, 3.5%

29.7

26.3-33.6*

Females

1 in 37, 0.7%

7.3

5.7-9.4

All Asian/Pacific Islander, incl. Hmong

1 in 53, 1.9%

18.9

14.4-25.0*

All Black, Non-Hispanic, incl. Somali

1 in 43, 2.3%

23.4

19.0-28.7*

Hispanic

1 in 41, 2.4%

24.4

17.8-32.4*

White, Non-Hispanic

1 in 76, 1.3%

13.1

10.7-16.1

Two or more races

1 in 53, 1.9%

19.0

12.4-28.8

American Indian or Alaska Native children were included in the denominator but were not included in prevalence estimations due to low numbers of children with ASD

*Wilson score 95% CIs exclude 1.0, indicating significantly higher prevalence.

Males had a higher ASD prevalence than females.

Asian/Pacific Islander children had higher ASD prevalence than White children.

Black children had higher ASD prevalence than White children.

Hispanic children had higher ASD prevalence than White children.

Prevalence of ASD in Somali and Hmong 4-year-old children in Minnesota

Prevalence estimates for Somali and Hmong children were determined by including only the children enrolled in a participating school district. This is because Somali and Hmong children were identified using data from the Minnesota Department of Education.

Prevalence estimate

Prevalence per 1,000 children

95% confidence interval per 1,000

Hmong

1 in 45, 2.2%

22.2

14.5-32.3

Somali

1 in 16, 6.3%

61.7

43.8-84.1

Hmong 4-year-old children had a similar ASD prevalence as other 4-year-old children.

Somali 4-year-old children had a higher ASD prevalence than other 4-year-old children.

What do the sex and race/ethnicity differences in prevalence rates tell us?

Males aged 4 years had an ASD prevalence 4.1 times higher than females aged 4 years.

Using U.S. Census race/ethnicity categories, Asian/Pacific Islander (including Hmong), Black (including Somali), and Hispanic 4-year-old children had a higher ASD prevalence than White 4-year-old children.

Looking at Hmong and Somali students attending our participating school districts, Hmong 4-year-old children had a similar ASD prevalence as other 4-year-old children. Somali 4-year-old children had a higher ASD prevalence than other 4-year-old children.

What was the percentage of 4-year-old children with ID in Minnesota?

Percent of 4-year-old autistic children with intellectual disability

Estimates included Somali and Hmong children and were determined by including only the children enrolled in a participating school district. This is because Somali and Hmong children were identified using data from the Minnesota Department of Education.

Black non-Somali, Hmong, and Somali 4-year-olds had higher rates of intellectual disability than White 4-year-olds.

This information is based on the analysis of data collected from the health and educational records of children who were 4 years old in 2020. To compare the rate of co-occurring intellectual disability across race and ethnicity, including Hmong and Somali children, we included children attending one of our participating school districts. Black non-Somali, Hmong, and Somali 4-year-olds had higher rates of intellectual disability than White 4-year-olds.

When were 4-year-old children first diagnosed with ASD in Minnesota?

Cumulative incidence refers to the rate of identification over time. Compared with children aged 8 years, Minnesota 4-year-olds had a higher cumulative incidence than 8-year-olds, meaning ASD identification is happening at a faster pace in the younger age group than the older age group. Minnesota 4-year-olds were identified at 1.5 times the rate of 8-year-olds.

ASD identification of Minnesota 4-year-olds had an incidence of 1.5 times the rate of 8-year-olds, which is higher than the incidence rate of 1.6 times the rate of 8-year-olds of all ADDM sites.

Tracking Area

The tracking area included parts of three counties (Anoka, Hennepin, Ramsey) including the large metropolitan cities of Minneapolis and Saint Paul.

4-year-old children in the tracking area included 16,326 children of the following race and ethnicity

  • American Indian or Alaska Native - 1%
  • Asian or Pacific Islander (including Hmong) – 16%
  • Black, non-Hispanic (including Somali) – 23%
  • Hispanic –11%
  • White, non-Hispanic – 43%
  • Two or more races – 7%

4-year-old children attending one of our participating school districts included 13,524 children

  • Somali – 4%
  • Hmong – 9%

Implications

This is the fourth time Minnesota data has been included in findings from the ADDM Network and the second time we have included 4-year-old prevalence. Overall prevalence of ASD among 4-year-olds in 2020 (1 in 53) was 18% lower than prevalence among 4-year-olds in 2018 (1 in 44). The portions of Ramsey and Hennepin counties included in prevalence estimates differed in 2018 and 2020, which may have impacted prevalence estimates. Prevalence rates for Black and Hispanic children were similar from 2018 to 2020, while rates for White and Asian/Pacific Islander children were lower in 2020.

In Minnesota, there are differences between the proportions of 4-year-old males and females identified with ASD, with more males than females. This is consistent with previous estimates and with estimates across the ADDM network. (Note: the ADDM project only collects data on male and female sex as indicated in records and does not include gender identification information.)

We found varying prevalence rates across racial and ethnic groups in Minnesota. Somali children, with a rate of 1 in 16, had an ASD prevalence rate higher than other groups. The small number of children in some of these groups makes it difficult to determine whether the rates of children with ASD truly are different across groups. When differences are found, it is important to focus on general health disparities that may influence these differences.

In Minnesota, we identify ASD much later than when first concerns are reported. The median age of the first ASD diagnosis for 8-year-olds was 4 years and 11 months, which was the latest age across the ADDM Network. We found that 4-year-old children are being identified with ASD at 1.5 times the rate of 8-year-olds, which indicates that identification is happening more frequently at earlier ages, but the late age of identification remains concerning due to the critical importance of early identification and intervention. Many states, including MN, have invested in early intervention to help children and families gain access to early intervention services. For example, Minnesota’s Early Intensive Developmental and Behavioral Intervention (EIDBI) Benefit provides early intensive intervention for people with ASD and related conditions. To learn more about the EIDBI benefit follow this link:

https://mn.gov/dhs/partners-and-providers/news-initiatives-reports-workgroups/long-term-services-and-supports/eidbi/eidbi.jsp

We found that among 4-year-old children with IQ information, 62% had an intellectual disability, compared to 32% for 8-year-olds. The higher rate of intellectual disability in the younger group is not unexpected, as children with ASD with developmental delays are often identified earlier than children with ASD without developmental delays. We also found differences in co-occurring intellectual disability by race/ethnicity. Black non-Somali, Hmong, and Somali 4-year-olds had higher rates of intellectual disability than White 4-year-olds. Further research is needed to understand why these groups had higher rates of intellectual disability than White children. This would be helpful in identifying and addressing health disparities and increasing equitable access to ASD diagnosis and services in Minnesota.

Limitations

The findings in this report reflect a small number of children concentrated in a large metropolitan area and may not reflect prevalence across the entire state.

The numbers of 4-year-old children with ASD from some racial/ethnic groups are small, and their prevalence estimates will be less precise than estimates for larger-sized populations. Confidence intervals show the range in which we are 95% confident that true prevalence lies, and a larger confidence interval means less precision (e.g., 14.4–25.0 for All Asian/Pacific Islander children). This tells us we should use caution before drawing conclusions about differences between some groups.

MN-ADDM reviewed records from participating public school special education programs but did not review private school education records or all charter school education records in our geographic area. Similarly, if a child was identified with ASD in a clinic outside of those included in MN-ADDM’s geographic area, their health records may not have been captured. Incomplete information could lead to misclassifying children’s cognitive ability, overestimating the age when they were first evaluated or when ASD was identified, or failing to capture that the children were identified as having ASD.

Somali and Hmong children with ASD were identified based on language spoken in the home documented in health or educational records. Population denominators for Somali and Hmong children were determined from data from the Minnesota Department of Education on the percent of students in each district who spoke Hmong or Somali in the home. This method may miss Somali and Hmong children who speak English or other languages in their home.