Article review

Trends in the Prevalence of Developmental Disabilities in US Children, 1997–2008

WHAT’S KNOWN ON THIS SUBJECT: US data on the changes in the prevalence of developmental disabilities are scarce. Although there are a few studies on individual disabilities, data examining the impact of the full range of developmental disabilities are unavailable.

WHAT THIS STUDY ADDS: Developmental disabilities make a significant contribution to overall childhood health. We show the health disparities that exist for specific populations and how selected conditions have increased over the past 10 years.

abstract OBJECTIVE: To fill gaps in crucial data needed for health and educa- tional planning, we determined the prevalence of developmental dis- abilities in US children and in selected populations for a recent 12-year period.

PARTICIPANTS AND METHODS: We used data on children aged 3 to 17 years from the 1997–2008 National Health Interview Surveys, which are ongoing nationally representative samples of US households. Parent- reported diagnoses of the following were included: attention deficit hyperactivity disorder; intellectual disability; cerebral palsy; autism; seizures; stuttering or stammering; moderate to profound hearing loss; blindness; learning disorders; and/or other developmental delays.

RESULTS: Boys had a higher prevalence overall and for a number of select disabilities compared with girls. Hispanic children had the low- est prevalence for a number of disabilities compared with non- Hispanic white and black children. Low income and public health insur- ance were associated with a higher prevalence of many disabilities. Prevalence of any developmental disability increased from 12.84% to 15.04% over 12 years. Autism, attention deficit hyperactivity disorder, and other developmental delays increased, whereas hearing loss showed a significant decline. These trends were found in all of the sociodemographic subgroups, except for autism in non-Hispanic black children.

CONCLUSIONS: Developmental disabilities are common and were re- ported in �1 in 6 children in the United States in 2006 –2008. The number of children with select developmental disabilities (autism, at- tention deficit hyperactivity disorder, and other developmental delays) has increased, requiring more health and education services. Additional study of the influence of risk-factor shifts, changes in acceptance, and benefits of early services is needed. Pediatrics 2011;127:1034–1042

AUTHORS: Coleen A. Boyle, PhD,a Sheree Boulet, PhD,a

Laura A. Schieve, PhD,a Robin A. Cohen, PhD,b Stephen J. Blumberg, PhD,b Marshalyn Yeargin-Allsopp, MD,a

Susanna Visser, MS,a and Michael D. Kogan, PhDc

aNational Center on Birth Defects and Developmental Disabilities and bNational Center for Health Statistics, Centers for Disease Control and Prevention, Atlanta, Georgia; and cMaternal and Child Health Bureau, Health Resources and Services Administration, Rockville, Maryland

KEY WORDS developmental disabilities, prevalence, autism, attention deficit hyperactivity disorder

ABBREVIATIONS NHIS—National Health Interview Survey ADHD—attention deficit hyperactivity disorder

All authors made substantial intellectual contributions to the study, including the conception and design, acquisition of data, analysis, and interpretation. All authors participated actively in the drafting and revising of the manuscript. Finally, all authors approved the final version that was submitted for publication. Dr Coleen A. Boyle had full access to all the data and takes responsibility for the integrity of the data and accuracy of the data analysis and contributed to the study design and concept, analysis and interpretation of the data, drafting of the manuscript, critical review of the manuscript, and statistical analysis. Dr Sheree Boulet contributed to the study design and concept, acquisition of the data, analysis and interpretation of the data, and critical review of the manuscript. Dr Laura Schieve contributed to the study design and concept, analysis and interpretation of the data, drafting of the manuscript, and critical review of the manuscript. Dr Robin A. Cohen contributed to the acquisition of the data and analysis and interpretation of the data. Dr Stephen J. Blumberg contributed to the analysis and interpretation of the data, drafting of the manuscript, and critical review of the manuscript. Dr Marshalyn Yeargin-Allsopp contributed to the analysis and interpretation of the data, drafting of the manuscript, and critical review of the manuscript. Dr Susanna Visser contributed to the analysis and interpretation of the data, drafting of the manuscript, and critical review of the manuscript. Dr Michael D. Kogan contributed to the analysis and interpretation of the data, drafting of the manuscript, and critical review of the manuscript.

The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention or the Health Resources and Services Administration.

www.pediatrics.org/cgi/doi/10.1542/peds.2010-2989

doi:10.1542/peds.2010-2989

Accepted for publication Feb 25, 2011

Address correspondence to Coleen A. Boyle, PhD, National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA 30333. E-mail: [email protected]

(Continued on last page)

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ARTICLES

Data on the prevalence of developmen- tal disabilities have been used to de- scribe the importance of these health problems and to assess the educa- tional, medical, and social support needs for children with developmental disabilities and their families. Esti- mates of the prevalence of develop- mental disabilities in US children on the basis of the 1988 National Health Interview Survey (NHIS) indicated that 16.8% of children younger than 18 years of age had lifelong conditions arising in early childhood as a result of cognitive or physical impairment or a combination of the 2.1 Findings from more recent surveys that used a more restrictive definition of developmental disabilities suggested that 13.2% of children had 1 or more developmental disabilities during 1997–2005 and 1.6% had 3 or more developmental disabili- ties.2 These studies also documented the considerable impact of the disorders as measured by higher rates of health and special-education service use for chil- dren with developmental disabilities compared with children without devel- opmental disabilities.

A number of factors may have influenced the prevalence of developmental disabil- ities over the past 10 to 15 years, includ- ing improved survival of the growing number of children born preterm or with birth defects or genetic disorders, such as spina bifida and Down syn- drome,3 whose improved survival may be offset by a disproportionate burden of neurologic and other impairments.4,5

Other trends and medical practice changes that might contribute to a re- duction of developmental disabilities in the population include increases in pre- natal diagnosis and therapeutic abor- tion, older maternal age, new infant vac- cines, and the expansion of newborn screening.6,7 Finally, increased aware- ness and improved diagnosis, particu- larly for conditions with a behavioral phenotype, such as autism or attention

deficit hyperactivity disorder (ADHD), may have contributed to changes over time.

Since 1997, the NHIS has routinely in- cluded questions on a broad array of developmental disabilities among chil- dren younger than 18 years of age. This survey, with population-based annual samples and consistent verbiage in in- dividual disability condition questions, is ideal for monitoring trends in prev- alence over time. We used data for a 12-year time period (1997–2008) to ex- amine (1) the national prevalence of developmental disabilities according to major demographic and socioeco- nomic characteristics and (2) changes in the prevalence of developmental disabilities over time.

PARTICIPANTS AND METHODS

We used the Family Core and Sample Child Components of the NHIS from 1997 to 2008. The NHIS is an ongoing annual survey, conducted by the Cen- ters for Disease Control and Preven- tion, National Center for Health Statis- tics, that uses a multistage probability sample to estimate the prevalence of a number of health conditions in the ci- vilian noninstitutionalized population of the United States.8,9 Demographic and health data on family members

are obtained through an in-person in- terview with a knowledgeable adult family member. For the Sample Child component, more detailed data are ob- tained for 1 randomly selected child younger than 18 years of age. For more than 90% of the children included in the NHIS Sample Child component, the knowledgeable adult interviewed was a parent or legal guardian.

The current analysis was limited to children aged 3 to 17 years (total 1997–2008 unweighted sample size: 119 367). Children younger than 3 years of age were excluded because many developmental disabilities are not recognized or diagnosed before that age. The average household re- sponse rate for the NHIS was 88.3% (range of annual rates: 84.9 –91.8%); the average conditional response rate for the sample child component was 91.2% (range: 85.6–93.7%).

The specific conditions assessed were as follows: ADHD; cerebral palsy; autism; seizures; stammering or stuttering; mental retardation; moderate to pro- found hearing loss; blindness; learning disorders; and other developmental de- lays (see Table 1 for the survey ques- tions). The same set of questions were asked over the 11 survey years; the ex-

TABLE 1 The NHIS Questions on Developmental Disabilities, 1997–2008

Condition Survey Question

ADHD/attention deficit disorder (ADD),a

autism, cerebral palsy, mental retardation,b and other developmental delay Seizures and stuttering or stammering

Moderate to profound hearing loss

Blindness Learning disability

“Has a doctor or health professional ever told you that [survey child] had any of the following conditions?”

“During the past 12 months, has [survey child] had any of the following conditions?” “Which statement best describes [survey child’s] hearing without a hearing aid: good, a little trouble, a lot of trouble, or deaf?”c

“Is [survey child] blind or unable to see at all?” “Has a representative from the school of a health professional ever told you that [survey child] has a learning disability?”

a NHIS shifted from asking about ADD in 1997–1999 to asking about ADD and ADHD in 2000 and later. b Referred to as intellectual disability in the text and tables. c Categories were revised in 2008 to the following: excellent; good; a little trouble; moderate trouble; a lot of trouble; and deaf. Moderate to profound hearing loss included the categories of deaf and a lot of trouble hearing for 1997–2007 and moderate trouble, a lot of trouble, and deaf for 2008.

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ception was an expansion of the hearing-loss categories in 2008 (see Table 1 for details). Although the NHIS questionnaire used the term “mental retardation,” to be more closely aligned to currently accepted termi- nology, we refer to this condition as “intellectual disability.”10 The time frame for the majority of the questions refers to whether the child was “ever” diagnosed with the condition; for sei- zures and stuttering or stammering the reference period was the “past 12 months,” and moderate to profound hearing loss and blindness referred to the current status of the child. A child was considered to currently have a condition if there was an affirmative response, regardless of the time frame of the questions. There was sub- stantial collinearity between learning disabilities and intellectual disabili- ties, and we therefore report learning disabilities as a consequence of the in- tellectual disability rather than a co- occurring condition. That is, children with reported intellectual disabili- ties and learning disabilities were only included in the intellectual dis- ability category.

We examined the prevalence of any parent-reported developmental dis- abilities and of each individual devel- opmental disability for the 12-year pe- riod combined and assessed how the estimates varied by a number of demo- graphic and socioeconomic character- istics, including the child’s age; gender and race/ethnicity; mother’s educa- tion; total family income level from all sources, including supplemental secu- rity income (with income defined rela- tive to the federal poverty level); and health insurance status (any public, private-only, no health insurance re- ported). Children covered by both pri- vate insurance and the state’s Medic- aid programs are included under “any public.” We also assessed secular trends for each disability over 4 3-year

time intervals (1997–1999; 2000–2002; 2003–2005; and 2006 –2008). For the disabilities with statistically signifi- cant temporal trends, we conducted additional analyses to determine whether trends were uniform within the demographic and socioeconomic subgroups. Income stratification in this report is based on both reported and imputed income.11

Prevalence estimates were weighted using NHIS weights to represent the US noninstitutionalized population of chil- dren. Variance estimates were pro- duced using Sudaan software to ac- count for the complex NHIS sample design. �2 Tests were used to deter- mine whether the prevalence esti- mates differed among the various groups being compared. Wald-F tests were used to assess linear trends over the 4-calendar-year time periods. All associations and differences de- scribed in the text were statistically significant at the P � .05 level. Human subject review was not required for this analysis of publicly available data.

RESULTS

Prevalence and Demographic Characteristics

The prevalence of any developmental disability in 1997–2008 was 13.87% and ranged from 0.13% for blindness to 6.69% for ADHD and 7.66% for learn- ing disabilities (Table 2). In general, there was higher prevalence in older children for conditions likely to be first recognized or confirmed in the school years, including ADHD and learning disabilities. Little change across age groups was noted for cerebral palsy, moderate to profound hearing loss, and other developmental delays. There was a lower prevalence in older chil- dren for stuttering or stammering. Hispanic children had a lower preva- lence of several disorders relative to non-Hispanic white and black chil- dren, including ADHD and learning

disabilities; the prevalence of other developmental delays was higher only in comparison to non-Hispanic white children. Stuttering or stammer- ing was reported more often in non- Hispanic black children than non- Hispanic white children. Boys had twice the prevalence of any developmental dis- ability and excess prevalence for ADHD, autism, learning disabilities, stuttering or stammering, and other developmen- tal delays, specifically.

There was a nearly twofold higher prevalence of any reported develop- mental disability among children in- sured by Medicaid relative to those in- sured by private insurance, and this pattern was statistically significant for ADHD, learning disabilities, intellec- tual disabilities, seizures, stuttering or stammering, and other develop- mental delays. Family incomes below the federal poverty level were associ- ated with a higher prevalence of parent-reported developmental dis- abilities overall and learning disabili- ties, intellectual disabilities, stuttering or stammering, and other develop- mental delays, specifically. Lower ma- ternal education (ie, any attainment less than a college degree) was associ- ated with a higher prevalence of any de- velopmental disabilities, learning dis- abilities, and stuttering or stammering.

Time Trends

For all developmental disabilities com- bined, there was a small, but statisti- cally significant, linear increase in the prevalence over the 4 time periods, from 12.84% in 1997–1999 to 15.04% in 2006–2008 (Table 3). Of the individual disorders, ADHD and autism showed significant and successive increases over time. Other developmental delays, a catch-all category, also showed sig- nificant increases over the time pe- riod, but the increase was observed only between the most recent 2 inter- vals (from 2003–2005 to 2006–2008).

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ADHD, because of its considerably higher prevalence, was chiefly respon- sible for the upward trend in the over- all prevalence of developmental dis- abilities, with a 33% increase in prevalence from 1997–1999 to 2006– 2008. Autism, however, showed, by far, the largest relative increase, with nearly a fourfold change from a prevalence of 0.19% in 1997–1999 to 0.74% in 2006– 2008. Moderate to profound hearing loss was the only disorder to decline in prev- alence, showing a 31% decrease from 1997–1999 to 2006–2008.

Although the magnitude of the change varied somewhat among the various descriptive factors (Table 4), in gen- eral, we observed upward trends in the parent-reported prevalence of ADHD and autism and a decrease for moderate to profound hearing loss. One exception was race/ethnicity and autism, with a lack of a significant in- crease in non-Hispanic black children.

DISCUSSION

Developmental disabilities affect a sig- nificant proportion of children in the United States. We found that 15% of children aged 3 to 17 years, or nearly 10 million children in 2006 –2008, had a developmental disability on the basis of parent report. The 17% increase in prevalence over the 12-year period represents �1.8 million more children with developmental disabilities in 2006–2008 than a decade earlier.

It is difficult to corroborate the overall prevalence reported in this study be- cause of the lack of comparable stud- ies using a similar grouping of condi- tions. In comparing the prevalence for individual disorders, however, we find good agreement for some of the prev- alence estimates. A comparable high prevalence of ADHD recently was re- ported from the 2003–2007 National Survey of Children’s Health, using a similar set of parent-reported survey questions.12 Prevalence rates for au- TA B LE

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TABLE 3 Trends in Prevalence of Specific Developmental Disabilities in Children Aged 3 to 17 Years, NHIS, 1997–2008

Disability n All Years, % 1997–1999, % 2000–2002, % 2003–2005, % 2006–2008, % Percent Change (Unweighted) 1997–1999

versus 2006–2008c

Any developmental disability 15956 13.87 12.84 13.70 13.88 15.04 17.1d

ADHD 7652 6.69 5.69 6.71 6.77 7.57 33.0d

Autism 537 0.47 0.19 0.35 0.59 0.74 289.5d

Blind/unable to see at all 160 0.13 0.11 0.15 0.12 0.13 18.2 Cerebral palsy 305 0.39 0.39 0.43 b b b

Moderate to profound hearing loss 533 0.45 0.55 0.44 0.42 0.38 30.9 Learning disability 8154 7.04 6.86 7.24 6.82 7.24 5.5 Intellectual disabilitya 868 0.71 0.68 0.73 0.75 0.67 �1.5 Seizures, past 12 months 792 0.67 0.66 0.65 0.66 0.72 9.1 Stuttered or stammered, past 12 months 1924 1.60 1.63 1.40 1.69 1.68 3.1 Other developmental delay 3978 3.65 3.40 3.28 3.67 4.24 24.7d

Source: Centers for Disease Control and Prevention, National Center for Health Statistics, NHIS. a Survey question asked about mental retardation, but we refer to the condition as intellectual disability. b We excluded cerebral palsy from the analysis for 2004–2007 because of the high likelihood of interviewer error arising from a questionnaire change in 2004. cPercent change between 1997–1999 and 2006–2008. d Test of linear trend over 4 time periods, P � .05.

tism, cerebral palsy, seizures, blindness, and stuttering or stammering are com- parable with those from several population-based prevalence studies us- ing varied study methods.13–18 This is particularly relevant for seizures, where the nomenclature, as en- dorsed by the International League Against Epilepsy, for recurrent sei- zures is epilepsy and not seizures or seizure disorder.18 The prevalence of moderate to profound hearing loss was considerably higher, whereas the prevalence of intellectual disabil- ities was �50% lower than findings from a population-based surveil- lance program that requires audi- tory test results for moderate to pro- found hearing loss and cognitive test results for intellectual disabilities.17

A number of factors may have influ- enced these discordant findings, in- cluding a more restrictive case defi- nition in the records-based surveillance program for moderate to profound hearing loss (ie, bilat- eral measured loss of 40 dB or greater) than that used in the NHIS analysis. In the case of intellectual disabilities, and particularly mild in- tellectual disabilities, because test- ing often is done in the context of educational placement, the parent or

guardian may never have been told that their child’s test results sug- gested functioning in the intellectual disabilities range. Also, since 1997, fed- eral law has allowed for state and local education agencies to extend the use of the less-specific “developmental de- lay” category up to 9 years of age, en- abling many children to not require a more specific education classifica- tion, such as intellectual disability.19

Some of these children may have been identified in the NHIS by the question “other developmental delay,” as sug- gested by the high and increasing prevalence for this category.20 Al- though it is not clear what specific functional problems children with other developmental delays have, Bou- let et al2 showed that 76% have a co- occurring developmental disability and that learning disabilities and ADHD were the most frequent co-occurring conditions.

The 17% increase in all developmental disabilities over the 12 years was caused in large part by shifts in the prevalence of ADHD and autism. In- creases in autism during the mid- 1990s to late 1990s and continuing through the late 2000s have been noted in a number of studies14,19,21–23

using varying definitions of autism and study designs, ranging from adminis- trative educational and service system data to retrospective studies of suc- cessive birth cohorts of children. Al- though data on trends in ADHD are less available, they support a similar in- crease.23,24 A Danish study23 reported that trends in the birth cohort prev- alence of several neuropsychiatric disorders, including autism and hy- perkinetic disorder (International Classification of Diseases 10 Revi- sion classification that is closely aligned with the hyperactivity com- ponent of ADHD) increased signifi- cantly for children born in 1990 through 1999. A US-based study24 re- ported significant increases in the prevalence of office-based visits for ADHD during 1991–1998. Finally, an upward trend in prevalence, using US education data, was found for the “other health impaired” education cat- egory, which, since 1991, is the educa- tion category used for children with ADHD.19,25 Decreases in the prevalence of moderate to profound hearing loss over the 12-year period have not been reported previously. Trend data from service records over a shorter time frame showed little to no change.17 Na- tionally, the number of infants identi-

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fied with congenital moderate to pro- found hearing loss from state newborn-screening programs has in- creased dramatically with the expan- sion of universal screening26; however, it is unlikely that this program would have impacted the prevalence for this survey. The lower prevalence of mod- erate to profound hearing loss from the NHIS was limited to 2006 –2008; in 2008, there was a modification in the moderate to profound hearing loss categories, which makes it difficult to determine whether this lower trend continues. More data are needed to better understand this finding.

Factors responsible for increases in autism and ADHD are numerous. Avail- ability of services and in how the ser- vice system classifies children with be- havioral disorders has progressed as we learn more about the advantages of earlier interventions. Improvements in clinical, parental, and societal recogni- tion of and screening for these disor- ders have occurred. For example, we have national campaigns to increase awareness of autism,27 and the American Academy of Pediatrics has incorporated ongoing monitoring of a child’s development as a practice recommendation for pediatricians in 2007.28 Another contributing factor may be the efficacy of medications and behavioral treatments for ADHD.29

There also has been an increase in the prevalence of known prenatal risk fac- tors for these conditions. Examples in- clude increases in the prevalence of preterm birth and the recognition of the full range of potential adverse developmental consequences of late preterm birth,4,5 shifts toward older parental age, and increases in the prevalence of assisted reproductive technologies and possibly other hor- monal infertility treatments and the consequent increase in multiple births, each of which is associated TA B LE

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with adverse developmental out- comes.30 Finally, given that the shift in developmental disability prevalence over time seems to be focused on con- ditions that are based on an emotional or behavioral phenotype, a societal shift in the acceptance and destigma- tization of such conditions in young children also may play a role.31

Several of our findings regarding the descriptive characteristics of children with developmental disabilities were noteworthy. Others studies have re- ported lower prevalence estimates for autism and ADHD in Hispanics,12,14,32,33

although findings from more recent studies suggest that the gaps may be closing.13 Rather than these patterns reflecting true differences, they are more likely the result of language bar- riers, lack of access to services, and health insurance coverage. The pre- dominance of boys with developmental disabilities also was remarkable. Al- though the increased gender ratio for selected developmental disabilities is well described, this study showed the pattern present for nearly all develop- mental disabilities. Some of this is cer- tainly biological, such as X-linked genetic disorders that result in intellectual dis- abilities and other functional limitations. Others have described a cultural fac- tor related to greater incentive for case finding in boys compared with girls.34 Alternatively, there may be gender-specific presentations of some of the disorders, particularly for condi- tions with an exclusively behavior pheno- type (ADHD and autism) that favor the identification of boys over girls. ADHD is a good example, in that girls tend to exhibit less of the impulsivity associated with the disorder and therefore maybe be less likely to come to clinical attention.35

Regarding socioeconomic inequities, public health insurance coverage

seemed to be associated with a higher prevalence of developmental disabili- ties; low family income and low maternal education had similar but less signifi- cant impacts. Larson and Halfon36

showed a similar inverse socioeconomic gradient with family income and the prevalence of ADHD, learning disabilities, and speech problems but not autism. Some of the impact with public insur- ance is likely reflecting eligibility for Medicaid for children with disabilities.

The strengths of the NHIS are impor- tant to highlight. The survey has a na- tionally representative sample that al- lows for generalizability to the US population of 3- to 17-year-old chil- dren. The same set of questions was asked of parents in each survey year. As a consequence, this is the only study able to examine, in detail, trends in these disorders. The response rate for the NHIS remained at exemplary high levels over the 11 years, despite the challenges of door-to-door sur- veys, limiting our concerns about the bias resulting from selectivity and nonresponse.

Limitations also are important to con- sider. Parent report of medical condi- tions is not without error. Inaccurate reporting can result from parental dis- tress and the stigma associated with some of the conditions; the questions may be misunderstood or there may be variations in professional terminol- ogy used for developmental disabili- ties; for example, autism can be re- ferred to by more broad or umbrella terms, such as autism spectrum disor- ders. Also, specific terms fall out of ac- cepted use (mental retardation versus intellectual disability and seizure dis- order versus epilepsy). A few stud- ies33,37,38 have examined the validity of parent report for selected develop- mental disabilities. Some, but not all,

of the conditions seem to have high va- lidity (see Boulet et al2 for more detail.) Ongoing survey research is needed to maintain the validity of the survey questions, while balancing the benefits of historical information to compare overtime. Finally, although we as- sumed that many of these conditions are chronic, in fact, a condition may resolve to the point where parents or health care providers may no longer consider the child as having the disor- der. Recent evidence13,39 of this was found for autism, and a longitudinal study showed considerable changes in diagnoses over time for children with physical and emotional or behavior di- agnoses. Finally, some children in- cluded in the stuttering or stammering or seizures categories may have had transient conditions, resulting in an overestimation of the prevalence of these conditions.

CONCLUSIONS

We found that the number of children with developmental disabilities has in- creased over the decade. These find- ings have a direct bearing on the need for health, education, and social ser- vices, including the need for more spe- cialized health services (mental health services, medical specialists, thera- pists, and allied health professionals). Also, the consequent burden on fami- lies and caregivers will need to be con- sidered. Finally, more detailed study of the influence of risk factor shifts, changes in acceptance, and benefits of early services is needed to better un- derstand why these shifts have occurred.

ACKNOWLEDGMENTS The National Health Interview Study is supported by the Centers for Disease Control and Prevention, Atlanta, Georgia.

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(Continued from first page)

PEDIATRICS (ISSN Numbers: Print, 0031-4005; Online, 1098-4275).

Copyright © 2011 by the American Academy of Pediatrics

FINANCIAL DISCLOSURE: The authors have indicated that they have no personal financial relationships relevant to this article to disclose.

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American Academy of Pediatrics DEDICATED TO THE HEALTH OF ALL CH I LDREN ™

Trends in the Prevalence of Developmental Disabilities in US Children, 1997− 2008

Coleen A. Boyle, Sheree Boulet, Laura A. Schieve, Robin A. Cohen, Stephen J. Blumberg, Marshalyn Yeargin-Allsopp, Susanna Visser and Michael D. Kogan

Pediatrics 2011;127;1034; originally published online May 23, 2011; DOI: 10.1542/peds.2010-2989

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American Academy of Pediatrics DEDI CATE D TO THE H EALT H OF ALL C H I LDREN ™

Trends in the Prevalence of Developmental Disabilities in US Children, 1997− 2008

Coleen A. Boyle, Sheree Boulet, Laura A. Schieve, Robin A. Cohen, Stephen J. Blumberg, Marshalyn Yeargin-Allsopp, Susanna Visser and Michael D. Kogan

Pediatrics 2011;127;1034; originally published online May 23, 2011; DOI: 10.1542/peds.2010-2989

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PEDIATRICS is the official journal of the American Academy of Pediatrics. A monthly publication, it has been published continuously since 1948. PEDIATRICS is owned, published, and trademarked by the American Academy of Pediatrics, 141 Northwest Point Boulevard, Elk Grove Village, Illinois, 60007. Copyright © 2011 by the American Academy of Pediatrics. All rights reserved. Print ISSN: 0031-4005. Online ISSN: 1098-4275.

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