ADHD prevalence climbs 4% annually among U.S. teens.

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