Childhood diagnosis of ADHD increased dramatically over 9-year period

The study examined the electronic health records of nearly 850,000 ethnically diverse children, aged 5 to 11 years, who received care at Kaiser Permanente Southern California between 2001 and 2010. It found that among these children, 4.9 percent, or 39,200, had a diagnosis of ADHD, with white and black children more likely to be diagnosed with the neurobehavioral disorder than Hispanics and Asian/Pacific Islander children. For instance, in 2010, 5.6 percent of white children in the study had an ADHD diagnosis; 4.1 percent of blacks; 2.5 percent of Hispanics; and 1.2 percent of Asian/Pacific Islanders.

The study also examined increases in the rates of first-time ADHD diagnosis. Researchers found that the incidence of newly diagnosed ADHD cases rose from 2.5 percent in 2001 to 3.1 percent in 2010 -- a relative increase of 24 percent. Black children showed the greatest increase in ADHD incidence, from 2.6 percent of all black children 5 to 11 years of age in 2001 to 4.1 percent in 2010, a 70 percent relative increase. Rates among Hispanic children showed a 60 percent relative increase, from 1.7 percent in 2001 to 2.5 percent in 2010. White children showed a 30 percent relative increase, from 4.7 percent in 2001 to 5.6 percent in 2010, while rates for Asian/Pacific Islander children and other racial groups remained unchanged over time.

"Our study findings suggest that there may be a large number of factors that affect ADHD diagnosis rates, including cultural factors that may influence the treatment-seeking behavior of some groups," said study lead author Darios Getahun, MD, PhD, from Kaiser Permanente Southern California's Department of Research & Evaluation. "These findings are particularly solid given that our study relied on clinical diagnoses of ADHD based on the criteria specified within the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders and that it represents a large and ethnically diverse population that can be generalized to other populations."

In addition, the study found that boys were three times more likely to be diagnosed with ADHD than girls. Higher family incomes also were associated with the likelihood of ADHD diagnosis; children from families with a household income of more than $30,000 a year were nearly 20 percent more likely to be diagnosed with ADHD than children from families making less $30,000.

According to the Centers for Disease Control and Prevention, ADHD is one of the most common neurobehavioral disorders of childhood. The CDC estimates that between 4 percent and 12 percent of school-aged children have the disorder, which generates health care costs of between $36 billion and $52 billion per year. Children with ADHD are more likely to experience learning problems, miss school, become injured and experience troublesome relationships with family members and peers, according to the researchers.

"While the reasons for increasing ADHD rates are not well understood, contributing factors may include heightened awareness of ADHD among parents and physicians, which could have led to increased screening and treatment," said Dr. Getahun. "This variability may indicate the need for different allocation of resources for ADHD prevention programs, and may point to new risk factors or inequalities in care."

This study is part of Kaiser Permanente's broader efforts to deliver transformational health research regarding the impacts of ADHD. One recent Kaiser Permanente study found an association between conditions in which the prenatal brain is deprived of oxygen and the risk of ADHD in children and adults.

And last December, a Kaiser Permanente study found little evidence of increased risk of heart attack, sudden cardiac death or stroke associated with use of medications used primarily to treat ADHD. The population-based study included more than 150,000 adults aged 25 to 64 years who used ADHD medications.

These studies are made possible in part by Kaiser Permanente's extensive electronic health record system, one of the largest private systems in the world. The organization's integrated model and electronic health record system securely connects 9 million people, 611 medical offices, and 37 hospitals, linking patients with their health care teams, their personal health information and the latest medical knowledge. The system coordinates patient care between the physician's office, the hospital, radiology, the laboratory and the pharmacy, and helps eliminate the pitfalls of incomplete, missing, or unreadable charts. It also connects Kaiser Permanente's researchers to one of the most extensive collections of longitudinal and de-identified medical data available, facilitating studies and important medical discoveries that shape the future of health and care delivery for patients and the medical community.

In addition to lead author Dr. Getahun, study authors included Steven J. Jacobsen, MD, PhD, and Wansu Chen of the Kaiser Permanente Southern California Department of Research & Evaluation; Michael J. Fassett, MD, of the Department of Maternal-Fetal Medicine, West Los Angeles Medical Center; and Kitaw Demissie, MD, PhD, and George G. Rhoads, MD, MPH, of the Department of Epidemiology, University of Medicine and Denistry, New Jersey-School of Public Health.