Increasing Prevalence of Parent-reported Attention-deficit/Hyperactivity Disorder Among Children — United States, 2003 and 2007

SN Visser, MS; RH Bitsko, PhD; ML Danielson, MSPH; R Perou, PhD; SJ Blumberg, PhD

Disclosures

Morbidity and Mortality Weekly Report. 2010;59(44):1439-1443. 

In This Article

Abstract and Introduction

Introduction

Attention-deficit/hyperactivity disorder (ADHD) is a neurobehavioral disorder that typically begins in childhood and often persists into adulthood. ADHD is characterized by developmentally inappropriate levels of inattention and hyperactivity resulting in functional impairment in academic, family, and social settings.[1] ADHD is the most commonly diagnosed neurobehavioral disorder of childhood, with previous reports documenting increasing trends in prevalence during the past decade and increases in ADHD medication use.[2,3] National estimates of the number of children reported by their parents to have ever been diagnosed with ADHD and the percentage of children with ADHD currently taking ADHD medications were published in 2005 using data from the 2003 National Survey of Children's Health (NSCH).[4,5] This report describes results from the second administration of NSCH in 2007,[6] which indicated that the percentage of children aged 4–17 years with a parent-reported ADHD diagnosis (ever) increased from 7.8% to 9.5% during 2003–2007, representing a 21.8% increase in 4 years. The findings in this report help to further characterize the substantial impact of ADHD on families.

The 2003 and 2007 NSCH were national, cross-sectional, random-digit–dialed landline telephone surveys used to estimate the prevalence of health and well-being indicators among children aged <18 years in the United States.[5,6] * One child was selected randomly from each household to be the focus of the parent or guardian interview. Information about the design and response rates of the 2003 NSCH have been published.[5] The design of the 2003 and 2007 surveys were similar. During April 2007–July 2008, a total of 91,642 interviews were completed for the 2007 NSCH (overall response rate = 46.7%; cooperation rate = 66.0%). In 2007, data, including complete information on ADHD and sex, were obtained for 73,123 children aged 4–17 years. Data were weighted to account for unequal probabilities of selection of households and children, nonresponse, and households without landline telephones, and to reflect the demographic distribution of noninstitutionalized children in the United States.§

In both 2003 and 2007, parents were asked whether or not a doctor or other health-care provider had ever told them that their child had "attention deficit disorder or attention deficit hyperactive disorder, that is, ADD or ADHD." In 2007, parents who reported an ADHD diagnosis (ever) also were asked whether the child currently had ADHD and to describe its severity (mild, moderate, or severe). The question about medication use in the 2003 survey differed from that in the 2007 survey. Current medication treatment for ADHD was asked about children who ever had ADHD in 2003 and about children with current ADHD in 2007. Estimates of parent-reported ADHD (ever and current) among children aged 4–17 years, current medication use, and ADHD severity were calculated overall and by sociodemographic characteristics (Table 1) using 2007 data and NSCH survey weights. Rates of ADHD by sociodemographic characteristics using the 2003 survey data have been published[4] and were compared with 2007 data for the present analysis (Table 2). Estimated rates of children medicated for ADHD were calculated by dividing the weighted estimate of the number of children with current ADHD who were being medicated for the disorder by the total weighted estimate of the number of children aged 4–17 years. Prevalence ratios and 95% confidence intervals were calculated to compare ADHD prevalence (ever diagnosed, current ADHD diagnosis, and currently taking medications for ADHD) of sociodemographic subgroups to referent subgroups (Table 1), and across the two surveys (ever diagnosed; Tables 2 and 3).

Prevalence of ADHD diagnosis (ever) was compared between the two surveys using weighted logistic regression, predicting ADHD from survey year, while controlling for sociodemographics. Statistical interactions of survey year by sociodemographics were tested. The average annual percentage difference was calculated by dividing the 2003 to 2007 percentage difference by 4.

In 2007, the estimated prevalence of parent-reported ADHD (ever) among children aged 4–17 years was 9.5%, representing 5.4 million children (Table 1). Of those with a history of ADHD, 78% (4.1 million, or 7.2% of all children aged 4–17 years) were reported to currently have the condition. Of those with current ADHD, nearly half (46.7%) had mild ADHD, with the remainder having moderate (39.5%) or severe (13.8%) ADHD. ADHD (ever) was more than twice as common among boys as girls (13.2% versus 5.6%). High rates of ADHD (ever) were noted among multiracial children (14.2%) and children covered by Medicaid (13.6%).

Among children with current ADHD, 66.3% were taking medication for the disorder. In total, 4.8% of all children aged 4–17 years (2.7 million) were taking medication for ADHD. Among boys, the prevalence of medicated ADHD (current) was highest for boys 11–14 years. The rates of medicated ADHD (current) increased with age among girls. The proportion of children taking medication for ADHD increased with severity, from 56.4% among children with mild ADHD, to 71.6% among children with moderate ADHD and 85.9% among children with severe ADHD (p<0.0001). The national prevalence of ADHD (ever) increased significantly between the two surveys (from 7.8% to 9.5%; Table 2), even after adjustment for sociodemographics, equating to a 21.8% increase in 4 years, or an average annual increase of 5.5%. The national estimate of children aged 4–17 years with parent-reported ADHD (ever) increased from 4.4 million in 2003 to 5.4 million in 2007, an increase of approximately 1 million children. Compared with 2003, the 2007 rates were significantly higher for each subgroup, with three exceptions: among households with less than a high school education, "other" (not white or black) races, and those living in the western United States. The magnitude of increase was largest among older teens, multiracial and Hispanic children, and children with a primary language other than English. A significant interaction was identified for age and survey year, with the rate of ADHD diagnosis (ever) increasing more for those in the oldest age group (15–17 years). The national increase in ADHD (ever) was reflected in significant increases within 12 states (Table 3).

* The 2003 and 2007 NSCH were directed by the Health Resources and Services Administration's Maternal Child Health Bureau and conducted by CDC's National Center for Health Statistics through the State and Local Area Integrated Telephone Survey. Additional information about NSCH is available at https://www.cdc.gov/nchs/slaits/nsch.htm.
The response rate represents the percentage of households that completed interviews among all eligible households, including those that were not successfully contacted. The cooperation rate is the percentage of households that completed interviews among all eligible households that were contacted. NSCH attempts to minimize nonresponse bias by incorporating nonresponse adjustments in the development of the sampling weights.
§ Demographic distributions were based on the 2007 American Community Survey of the U.S. Census Bureau.
The time between the two surveys was calculated from the survey midpoints, which were September 2003 and August 2007.

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