A new study found that approximately 60 percent of the reported cases of Autism Spectrum Disorder (ASD) in Denmark were brought by changes in reporting practices.
There has been a dramatic increase of ASD diagnoses for the past three decades in Denmark, which currently affects one percent of the children population. In the United States, 1 in 68 children has been diagnosed with the disorder. Disabilities observed include speech and language impairments to serious mental and developmental disabilities.
In Denmark, researchers from Aarhus University, led by Stefan N. Hansen looked at the national health registries dated 1980 to 1991 that includes 677,915 children from Denmark.
Analysis of the data showed that 3,956 children were diagnosed with ASD after 1995. About 33 percent of the cases were linked to the changes in how hospitals diagnose autism while 42 percent were from outpatient data or self-diagnoses. The researchers concluded that 60 percent (2,373 cases) could be attributed to both factors.
"This study supports the argument that the apparent increase in ASD prevalence in Denmark in recent years is in large part attributable to changes in reporting practices over time. However, a considerable part of the increase in ASD prevalence is not explained by the two changes in reporting practices. Thus, the search for etiologic factors that may explain part of the remaining increase remains important," the study concludes," the study wrote.
Other experts explained that the changes were necessary as the definition of autism is more specific than 30 years ago.
"The definition of autism is more precise today compared to the 1980's," said Hjordis Osk Atladottir, who also works in the department of public health at Aarhus University but was not involved in the new study, to Reuters Health. "We got the ICD-10 in 1994 in Denmark and before that we had ICD-8, but autism was very poorly defined in the ICD-8, resulting in almost no autism diagnoses prior to 1994."
Further details of the study were published in the Nov. 3 issue of JAMA Pediatrics.
