Misdiagnosis, Statistical Flaws Not a Factor in Rise in State Autism Diagnoses, Study Finds
A "significant" increase in state autism cases that was first reported by researchers in 1999 cannot be attributed to statistical flaws, coincidence, relaxed diagnostic criteria or population shifts, according to a new study released yesterday, Bloomberg/Orange County Register reports. However, the study -- which was commissioned by Gov. Gray Davis (D) and conducted by researchers at the University of California-Davis -- does not determine why the number of autism diagnoses in the state is rising (Reed, Bloomberg/Orange County Register, 10/18). The earlier study found that from 1987 to 1998 the number of people with autism who received care through the state Department of Developmental Services increased 273%. Currently, about nine new cases of autism are diagnosed in the state every day, the Los Angles Times reports (Maugh, Los Angeles Times, 10/18). For the new study, researchers divided 684 children with autism who were treated by the state into two groups based on age. Children in one group were born between 1983 and 1985, while children in the other group were born between 1993 and 1995. Researchers examined parent surveys, medical charts and past autism assessment and concluded that the diagnosis for autism was accurate about 90% of the time in both groups of children. The study also found that 90% of children in both groups were born in California, discounting the theory that immigration played a significant role in the increase of diagnoses. In addition, researchers determined that the number of children who also met the diagnosis for mental retardation did not differ between the groups, bringing into question a theory that children with mental retardation are increasingly misdiagnosed as having autism (Griffith, Sacramento Bee, 10/18). Based on the findings, Dr. Robert Byrd, the lead author of the study, concluded, "Autism is on the rise in the state, and we still do not know why. The results are, without a doubt, sobering" (Blakeslee, New York Times, 10/18).
The study is "certain to shake up the neurodevelopmental research world," which has not reached a consensus on the causes for the increasing incidence of autism diagnoses in several states and the United Kingdom, the Sacramento Bee reports (Sacramento Bee, 10/18). According to the UC-Davis study, 33% of parents of children more recently diagnosed with autism said childhood vaccinations -- in particular the vaccine for measles, mumps and rubella -- are responsible for the rise of the disorder. While the study found that vaccine-related autism "may exist," Byrd said the data show immunizations are not the "driving force" behind the sudden increase, the San Francisco Chronicle reports (Seligman, San Francisco Chronicle, 10/18). Some researchers disagreed with the study's findings. Bryna Siegel, a child psychologist at the University of California-San Francisco, said, "I don't think there are more kids with autism. There are more labels of autism. There are a lot of problems with how autism is diagnosed in California." However, many advocacy groups praised the new findings. Michael Nanko, executive director of Los Angeles-based Cure Autism Now Foundation, said, "This study answers the skeptics and sends a message about the urgency for more funding for treatment and research" (Feder Ostrov, San Jose Mercury News, 10/18). Portia Iversen, vice president of the group, added, "My hope is this would be the beginning of serious federal investigation, at a funding level no private foundation can afford" (Sacramento Bee, 10/18).This is part of the California Healthline Daily Edition, a summary of health policy coverage from major news organizations. Sign up for an email subscription.