A federal advisory panel is urging clinicians to be careful when applying new diagnostic criteria for autism in order to ensure that no one is denied needed services.

Dramatic changes to the definition of autism took effect last year with publication of the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders. Under the new definition, autistic disorder, Asperger’s syndrome, childhood disintegrative disorder and pervasive developmental disorder, not otherwise specified were folded under an umbrella classification of “autism spectrum disorder” with clinicians specifying a level of severity.

Now the Interagency Autism Coordinating Committee — a federal advisory panel comprised of government officials and members of the autism community — is highlighting a number of implications that may result from the shift.

Specifically, the committee said many unknowns remain regarding who will be flagged and how under the new DSM and what it will mean to be classified under the updated diagnosis.

“The new criteria reflect advances in our understanding of ASD. At the same time, many in the community have raised questions about how the changes will affect people in the community,” said Geraldine Dawson, a former chief science officer at Autism Speaks who now works as a professor at Duke University Medical Center and chaired the IACC’s DSM-5 planning group.

In practical terms, the IACC is cautioning clinicians, noting that the new diagnostic criteria have not yet been rigorously tested in young kids, adults and individuals from various ethnic populations.

The group is also citing concerns about the reliability of severity ratings used to denote where an individual falls on the autism spectrum and the applicability of the new criteria for children under age 3 who may not yet fully display symptoms despite a need for early intervention.

“Services should be based on need rather than diagnosis; it would not be appropriate for a child to be denied ASD-specific services because he or she does not meet full DSM-5 criteria if a qualified clinician or educator determines that the child could benefit from those services,” the panel said in its report, adding that the updated DSM requires that all those who previously had an autism diagnosis under the old diagnostic criteria retain that label going forward.

The IACC said further research is needed to determine how reliable and valid the DSM-5 definition is and to weigh the impact of the changes on diagnosis, prevalence and access to services.