The percentage of adolescents being diagnosed with
attention-deficit/hyperactivity disorder is on the rise, but prevalence
rates remain constant among younger children, a new study shows.
Among children aged 12-17 years, the prevalence of
attention-deficit/hyper-activity disorder (ADHD) increased by an average
of 4% annually from 1997 to 2006. No significant increase was observed
among children aged 6-11 years.
Dr. James M. Perrin, cochair of the American Academy of Pediatrics
committee that developed practice guidelines for ADHD, suggested in an
interview that this increase in prevalence might stem from increased
awareness among clinicians that ADHD continues into adolescence and
adulthood.
"We have been trying to help parents and child health
providers realize that ADHD doesn't go away when you become a
teenager," Dr. Perrin said. "One of the reasons that
we're diagnosing it more commonly is that people recognize that
this is a phenomenon that very much does exist in adolescence."
The study was conducted by Patricia N. Pastor, Ph.D., and Cynthia
A. Reuben of the National Center for Health Statistics. Their results
are drawn from the National Health Interview Survey (NHIS), an ongoing,
annual household survey conducted by the NCHS (Vital Health Stat. 10
2008;237:1-22).
Between 1997 and 2006, NHIS researchers gathered interviews from
about 40,000 households per year. In each household with children,
interviewers randomly selected one child and asked an adult family
member whether that child had ever been diagnosed with ADHD, a learning
disability, or other chronic health conditions.
Average annual percentage changes in ADHD prevalence were modeled
using logistic regression. The researchers found that the percentage of
children diagnosed with ADHD grew slowly from 1997 to 2006, increasing
by an average of 3% per year.
To estimate the prevalence of ADHD, NHIS data from 2004, 2005, and
2006 were pooled to create a single sample of about 23,000 children.
About 5% of these children had ADHD without an accompanying learning
disability, 5% had a learning disability without ADHD, and 4% had both
conditions.
Children aged 12-17 years were more likely than children aged 6-11
years to have each of the three diagnoses.
Dr. Pastor and Ms. Reuben suggested that this apparent age-related
difference might result from improved access to health care services, as
well as from increased knowledge about ADHD.
"Although a number of factors may contribute to differences
between younger and older children, a higher 'lifetime'
prevalence rate among older children would be expected because of their
longer exposure to the possibility of evaluation and diagnosis,"
they wrote.
The researchers also reported that health insurance coverage might
play a role in whether a child is diagnosed with ADHD. "The
prevalence of diagnosed ADHD was similar among children with private
insurance coverage and Medicaid. Although many factors may contribute to
the differences between insured and uninsured children, access to health
care may make it more likely that a child will be diagnosed," they
said.
Dr. Pastor and Ms. Reuben ac knowledged the risks and limitations
of relying on parents and adult family members for information on a
child's medical history.
BY AUDREY KUBETIN
Editorial Intern
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