Overall prognosis of preschool autism spectrum disorder diagnoses

What proportion of preschool aged children diagnosed with autism spectrum disorder retain their diagnosis one or more years later?

Key messages

  • Nine out of 10 preschool aged children diagnosed with autism in a research setting may continue to meet diagnostic criteria one or more years later.
  • Due to lack of robust evidence, this finding may not be able to be generalised to children outside a research setting, and we were not able to identify any child or research study factors that influenced if a child retained their diagnosis.
  • Future research should focus on designing a robust study exploring whether a child retains their autism diagnosis over time in clinical practice and what other factors, if any, may change how likely a child is to retain their diagnosis.

What is autism?

Autism (autism spectrum disorder) is a common neurodevelopmental condition that is generally considered to be lifelong. It is characterised by difficulties in social communication, and restricted interests and repetitive behaviours. How much of a challenge these areas present for each individual is highly variable.

How is autism diagnosed?

Autism is diagnosed by assessing whether an individual meets a set of standardised diagnostic criteria.

In children, an autism diagnostic assessment may involve a paediatrician, child psychiatrist, speech pathologist, occupational therapist and psychologist. One or more of these health professionals may observe and ask questions about a child’s social and communication skills, any difficulties in restricted interests and repetitive behaviours, and how they process and respond to sensory information from the world around them. There are diagnostic assessment tools that these professionals can use, alone or in combination, to help make the diagnosis.

What is diagnostic stability, and why is it important?

Diagnostic stability refers to whether an individual retains their diagnosis over time. The diagnostic stability of autism is important to help health professionals, autistic individuals and their families understand how likely it is for a diagnosis of autism spectrum disorder to be lifelong. Additionally, it helps government and community groups to plan what health, education and employment resources are required to support autistic children and their families. Diagnostic stability also helps us to understand whether the characteristics of autistic children and the way that autism spectrum disorder is currently diagnosed influences whether a child continues to meet the criteria for an autism diagnosis over time.

What did we want to find out?

We wanted to find out whether a preschool child who was given a diagnosis of autism spectrum disorder before the age of six years retained their diagnosis at repeat diagnostic assessment one or more years later.

We also wanted to learn more about whether any factors relating to the individual child, the way the child was diagnosed with autism, or the research methods used in the studies, made it more or less likely for the child to continue to meet diagnostic criteria for autism spectrum disorder over time. The factors relating to the individual child included the children's age at the initial and follow‐up diagnostic assessments, their intelligence quotient (IQ) score, their ability to complete daily living tasks for a child of their age (adaptive behaviour score), and their ability to communicate with those around them (language score). Factors relating to the way children were diagnosed included the type of tool or criteria used to make the diagnosis, the length of time between diagnostic assessments, and whether the diagnosis was made by a multidisciplinary team. The factors related to the research methods included the year the study was published and the robustness of the evidence.

What did we do?

We searched for studies looking at preschool aged children diagnosed with autism. We then summarised the results, evaluated the evidence and rated our confidence in the evidence based on factors such as study methods and participation.

What did we find?

In total, 49 studies met our inclusion criteria and 42 of these (11,740 children) had data that could be used. The biggest study had 8564 children and the smallest had 11. These studies were from 13 countries, with 16 from the USA. The average age of the children was three years at their first diagnosis and six years at follow‐up. The average length of follow‐up was 2.86 years.

We found that, in a research setting, nine out of 10 of preschool children diagnosed with autism spectrum disorder may keep their diagnosis one or more years later.

What are the limitations of the evidence?

We have little confidence in the evidence because not all the studies provided data about everything that we were interested in, and the studies were done with different types of people and diagnostic assessments.

For the one in 10 children who no longer met diagnostic criteria for an autism diagnosis at follow‐up, we were not able to tell whether they had 'grown out' of their autism because they became more mature over time, or because they had received intervention, or whether the original diagnosis was inaccurate.

How up to date is this evidence?

The evidence is up to date to July 2021.

Read the full review here on the Cochrane Library.