Jan. 22, 2013— -- The rates of childhood attention deficit hyperactivity disorder (ADHD) diagnosis have increased by nearly 25% over the past decade, researchers found.
From 2001 to 2010, the rate of ADHD diagnosis increased from 2.5% to 3.1%, according to Darios Getahun, MD, PhD, of Kaiser Permanente Southern California Medical Group in Pasadena, and colleagues.
Increases were significant among whites, blacks, and Hispanics, but did not change significantly among Asians, Pacific Islanders, and other racial groups over the 10-year period, Getahun and colleagues reported online in JAMA Pediatrics.
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They noted that, over the previous decade, the prevalence of ADHD reached epidemic proportions in the U.S.
"It is one of the most common chronic childhood psychiatric disorders, affecting 4% to 12% of all school-age children and persisting into adolescence and adulthood in approximately 66% to 85% of children," they wrote. "This large cohort study with children from diverse racial/ethnic and socioeconomic backgrounds provides assurance on the generalizability of our findings."
The researchers examined trends in ADHD by race, age, sex, and household income among 842,830 children, ages 5 to 11, with an ADHD diagnosis in the Kaiser Permanente Southern California health plan.
The primary diagnosis of ADHD was made based on International Classification of Diseases, Ninth Revision, coding on child hospitalization, outpatient office visits, and emergency department visits across all Kaiser facilities.
They looked at increases in rates of ADHD prevalence among other races compared with white race and among children of higher socioeconomic status across all age groups. They also investigated whether the "sex gap in ADHD diagnosis has narrowed over time."
Prevalences were calculated in 2-year intervals from January 2001 to December 2010. Outcomes were stratified by age, race, sex, and household income.
There was an overall 4.9% prevalence of ADHD among children treated at Kaiser Permanente over the 10-year study period. From 2001 to 2010, prevalence of ADHD increased from 6,869 to 8,006.
Mean age of patients at diagnosis remained stable at 8.4 to 9.5 years over the course of the study.
Patients with ADHD were more likely to be white or black, come from families earning $70,000 or more annually, and were more likely to be male than female.
Over the 10 years, blacks had the highest relative increase in ADHD diagnosis rates followed by Hispanics, and whites. The authors noted that despite the higher increases in prevalence, "white children had substantially higher ADHD diagnosis rates than children of other races in every age group."
By race and gender, black girls had a significant increase in ADHD prevalence over the study period . The sex gap in ADHD prevalences remained stable among other races.
"The findings of this study suggest increasing trends in the clinical diagnosis of ADHD among children in the health plan," they concluded, adding that they "observed disproportionately high ADHD diagnosis rates among white children and notable increases in rates among black girls over time."
The study was limited by missing race data for some participants, they noted.
The study was supported by Kaiser Permanente Direct Community Benefit funds.
The authors declared no conflicts of interest.