TUESDAY, Oct. 2 (HealthDay News) -- Parents should not worry that proposed changes to the criteria for diagnosing autism might leave their child ineligible for care, a new study indicates.

Researchers assessed the impact of the proposed changes, which were developed by an expert panel appointed by the American Psychiatric Association and are expected to take effect in May 2013.

Previous research had suggested that 45 percent or more of children who currently qualify for a diagnosis of autism would not under the new criteria. Those findings caused widespread concern among parents who depend on state-financed health services for their children, The New York Times reported.

However, this latest study concluded that only 10 percent of these children would be excluded under the new criteria.

"I know that parents worry, but I don't believe there is any substantial reason to fear that children who need to be diagnosed with autism spectrum disorders, and provided with vital services, will not be included in the new criteria in this updated manual," said study senior investigator Dr. Catherine Lord, director of the Center for Autism and the Developing Brain at New York-Presbyterian Hospital's Westchester campus, along with its affiliated medical schools Weill Cornell Medical College and Columbia University College of Physicians and Surgeons.

The study is the largest to date to try to determine the effects of the new diagnostic criteria for autism. It was published in the Oct. 1 issue of the American Journal of Psychiatry.

Lord and her colleagues looked at 4,453 children currently diagnosed with autism and found that 91 percent of them would still qualify for the diagnosis under the proposed new criteria. Many of the remaining 9 percent would likely qualify with additional input from their doctors, the study added.

The proposed changes are designed to better identify autism and to distinguish it from other conditions, the researchers said.

The overall issue with the current criteria is "not that a lot of people are diagnosed with autism who shouldn't be, but that there is a lot of confusion because the criteria were not very accurate," Lord, who was a member of the panel that proposed the new criteria, said in a hospital news release.

She explained that in developing the new criteria, the panel "deliberately added and organized things to try to bring in and better address the needs of people with autism spectrum disorders (ASD) of all developmental levels and ages -- including girls, who were not represented as well as they should be in" the current criteria.

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New Autism Criteria Will Have Minor Impact: Study