Patient age plays a large role in changes over time to stimulant use for treatment of attention-deficit/hyperactivity disorder, according to a study of survey data from 1996 to 2008. Differences in ethnicity, insurance status, and geographic location also were associated with significant differences in use of these medications.
Reported stimulant use among children and adolescents in the United States grew significantly between 2.4% in 1996 and 3.5% in 2008. Researchers reported a 3.4% annual overall increase behind this slow and consistent increase in use of methylphenidate, dexmethylphenidate, pemoline, amphetamines, and/or dextroamphetamine.
An estimated 2.8 million children and teenagers reported use of one or more of these stimulant agents in 2008, according to an advance online report of the findings (Am. J. Psychiatry; Zuvekas and Vitiello. AiA:1-7).
Adolescents accounted for the greatest increase in use of stimulants for attention-deficit/hyperactivity disorder (ADHD), from 2.3% in 1996 to 5.0% in 2008, or an annual increase of 6.5%. "The continuous, steep increase in stimulant utilization in adolescents likely reflects the recent realization that ADHD tends to persist in puberty, causing significant functional impairment," wrote study authors Samuel H. Zuvekas, Ph.D., and Dr. Benedetto Vitiello.
They evaluated data from the annual, nationally representative MEPS (Medical Expenditure Panel Survey). The MEPS includes data on prescription drug use directly from household respondents and from pharmacies that they reported using during the survey.
Stimulant use remained the highest among children aged 6-12 years old, with no significant change during the study period. For example, 4.2% in this age group reported use in 1996 vs. 5.1% in 2008.
In contrast, stimulants were seldom used in children younger than 6 years during the duration of the study and dropped to very low rates in more recent years, the study reveals. Reported use toggled between 0.3% and 0.4% in the years from 1996 to 2003, and thereafter remained at 0.1% each year up until 2008.
Boys continue to use stimulants at a rate approximately three times greater than girls (5.3% vs. 1.6% in 2008, for example), a ratio that did not significantly change between 1996 and 2008.
Ethnicity, however, did account for some variation in ADHD treatment use. Although use overall increased among children from racial and ethnic minority groups, it remained lower than rates for non-Hispanic white children. For example, in 2008 4.4% of white children reported stimulant use, compared with 3.0% of black and 2.1% of Hispanic children. These differences could be explained, in part, because parents of black or Hispanic children are less likely to report ADHD, compared with parents of white children, the authors noted. Health and socioeconomic factors, including birth weight, income, and insurance coverage, did not account for these differences.
Insurance status made a difference on the overall sample, however. Children without health insurance had a much lower utilization rate, 1.3%, compared with 3.4% of those covered by private insurance and 4.3% of children with public insurance. Interestingly, the prevalence of stimulant use for ADHD did not vary significantly by family income level during the study period.
Geography also made a difference the researchers reported consistently and significantly lower use in the Western United States, compared with the Northeast, for example. In the West, utilization was 1.2% in 1996 and 1.6% in 2008. In contrast, the rates in the Northeast grew from 1.8% in 1996 to 4.6% in 2008. Rates elsewhere likewise increased, although not as significantly, from 2.6% to 3.9% in the Midwest and from 3.2% to 4.0% in the South, reported Dr. Zuvekas, an economist with the Agency for Healthcare Research and Quality, and Dr. Vitiello, a psychiatrist with the National Institute of Mental Health.
Overall, most children with ADHD are not treated with stimulants, the authors noted. They compared their findings with published estimates of ADHD diagnosis in community-based studies (J. Am. Acad. Child Adolesc. Psychiatry 2010;49:980-9; MMWR 2010;59:1439-43).
They explained that some children present with milder symptoms and stimulants tend to be prescribed for more severe forms of the condition. This was backed in their report by higher utilization among children reporting more significant impairment on the Columbia Impairment Scale. Treatment of ADHD with nonstimulant medication and psychosocial interventions also were likely contribute to lower use of stimulant medications.
Limitations of the study include a reliance on self-reported stimulant use, a lack of means to validate reported ADHD diagnoses, and a lack of statistical power in the MEPS database to assess nonstimulant medication use or use of combination treatment for ADHD.
Study authors Dr. Zuvekas and Dr. Vitiello reported they had no relevant financial disclosures.