supplemental materials: prevalence of dsm-iv adhd 1...

Supplemental Materials: Prevalence of DSM-IV ADHD 1

PREVALENCE OF DSM-IV ATTENTION–DEFICIT/HYPERACTIVITY DISORDER

SUPPLEMENTAL MATERIALS

To conserve space in the print version of the journal, the technical details of the meta-analysis are provided in

these supplemental materials. The first section of the materials describes the methodology for the literature search and

meta-analysis. Supplement Table 1 then provides a summary of each of the studies that was included in the

meta-analysis, and Supplement Tables 2 - 11 list all individual studies and prevalence estimates that were used to

estimate the corresponding summary prevalence estimates included in Table 1 in the main paper. The final section of the

supplemental materials includes full citations for all studies that were included in the meta-analysis or cited in these

supplemental materials.

Methodology for the Literature search

Inclusion criteria

The literature search was completed as part of a larger meta-analysis of the validity of DSM-IV ADHD symptom

dimensions and subtypes [87]. Because DSM-IV was published in 1994, computer searches of were performed for the

years 1994-2010 in the Pubmed, PsycINFO, Educational Resources Information Center (ERIC), and Social Sciences

Citation Index databases. All studies with keyword ADHD were selected, and the terms ADHD, ADD, and attention deficit

disorder were also cross-referenced separately with DSM-IV, reliability, internal consistency, prevalence, validity,

impairment, comorbidity, factor, subtypes and (combined or inattentive or inattention or hyperactive-impulsive or

hyperactivity-impulsivity).

Tables of contents of journals that commonly publish articles on ADHD were reviewed for the same time period.

These were American Journal of Medical Genetics (Neuropsychiatric Genetics), American Journal of Psychiatry, Archives

of Clinical Neuropsychology, Archives of General Psychiatry, Behavioral and Brain Functions, Biological Psychiatry, Child

Neuropsychology, Child Psychiatry and Human Development, Development and Psychopathology, Developmental

Neuropsychology, European Child and Adolescent Psychiatry, Journal of Abnormal Child Psychology, Journal of

Abnormal Psychology, Journal of the American Academy of Child and Adolescent Psychiatry, Journal of Attention

Disorders, Journal of Child Neurology, Journal of Child Psychology and Psychiatry, Journal of Clinical Child and

Adolescent Psychology, Journal of Consulting and Clinical Psychology, Journal of Developmental and Behavioral

Pediatrics, Journal of Learning Disabilities, Journal of Psychopathology and Behavioral Assessment, Journal of the

American Academy of Child and Adolescent Psychiatry, Journal of the International Neuropsychological Society,

Molecular Psychiatry, Psychiatric Genetics, and Psychological Medicine.


Finally, the reference list of each paper was reviewed for additional studies, and several additional researchers in

the field screened the final list of studies. Studies known to the author that were in press at the time of the literature

search were included in the review, but other unpublished studies were excluded due to the expansive published literature

on the prevalence of DSM-IV ADHD.

Exclusion criteria

As described in more detailed previously [87], the search procedures yielded 15,736 articles after removal of

duplicates as of the end of 2010. A multi-stage review procedure yielded 86 studies that estimated the prevalence of

DSM-IV ADHD in children and adolescents, and 11 studies that estimated the prevalence of DSM-IV ADHD in adults. To

assess the reliability of the search procedures, a random sample of approximately 20% of the studies were also coded for

inclusion or exclusion by a second rater. The raters agreed on over 99.5% of the studies, and all disagreements were

resolved by consensus after additional discussion (disagreements primarily occurred when studies defined subtypes

based on criteria that were ambiguous and not fully consistent with DSM-IV criteria).

Extraction and coding of prevalence estimates from individual studies

A coding system was developed to classify each diagnostic algorithm and record each prevalence estimate, and

studies were coded separately by two independent raters to assess the reliability of the coding system. Interrater agreement

was high (over 99%), with the only disagreements occurring when the methodology of the study was not described in

sufficient detail to be certain how the diagnosis was made. In nearly all of these cases the inconsistency between raters was

resolved after reviewing previous papers that described the sample in question in more detail. Analyses were also repeated

with and without effect sizes from these studies, and the overall pattern of results did not change in any of these cases.

As in other statistical approaches, the effect sizes in a meta-analysis are assumed to be independent, so each study

must contribute only one effect size to a specific analysis [88-90]. Consistent with this assumption, most papers reported

prevalence estimates based on a single diagnostic algorithm that was used to define ADHD for the study. However, a subset

of studies compared prevalence rates based on different diagnostic algorithms. If a single study reported prevalence based

on different algorithms, the data from the study were included in the meta-analysis of each of the algorithms, but a study

was never included twice in the same analysis. To test the sensitivity of this decision, analyses were conducted with and

without studies that reported prevalence based on different diagnostic algorithms, and there were no significant changes in the

overall pattern of results.


Calculation of overall effect sizes

Summary prevalence estimates were calculated using the Comprehensive Meta-analysis statistical package [91]. For

each analysis the overall weighted estimate and corresponding 95% confidence interval is reported in Table 1 in the main

paper. Supplement Tables 2 - 11 list all effects that were included in each overall effect size estimate, and also provide a

summary of analyses used to test for publication bias and heterogeneity among the effects.

Heterogeneity of effects

When the individual effect sizes in a specific meta-analysis are homogeneous, an overall effect size can be estimated

with a fixed effects model that simply weights the effect size from each study by the corresponding sample size [92].

However, fixed effects models make the strong assumption that any differences in effect sizes among the studies are due

entirely to sampling error. If there is significant heterogeneity among studies due to systematic differences in study

populations, experimental design, measures, or other study procedures, the prevalence estimate and corresponding

confidence interval obtained from the fixed effects model may be biased, and a random effects model is more appropriate [93].

Two methods were used to test for heterogeneity among the effects in each analysis. Cochran’s Q statistic is an

estimate of the variability of individual effect sizes around the overall estimated effect size that takes a Χ2 distribution with one

less degree of freedom than the total number of effects in the analysis [94]. We also calculated I2, a more intuitive measure

that quantifies the percentage of the overall effect size that is attributable to heterogeneity among the effects [95]. Significant

heterogeneity among the effects was observed in the majority of the analyses. Due to this pervasive heterogeneity, the more

conservative random effects model was used for all analyses [93]. The random effects model adjusts for heterogeneity by

weighting each effect size by both the inverse variance of the sample and an additional weight based on Q. For analyses with

low heterogeneity Q is also low and the additional weight goes to zero, in which case the fixed effects and random effects

models yield identical results.

In addition to the use of random effects models, several approaches were used to identify the source and impact

of any significant heterogeneity that was detected among the effects. First, the distribution of effects was examined to test

whether heterogeneity was attributable to a small number of outlying values at either end of the distribution of effect sizes.

Effects with a significant standardized residual (P < .05) were identified as potential outliers, and analyses were

conducted again without these effects to examine the sensitivity of the overall results to these outlying values. In most

cases significant heterogeneity was explained by a single or small number of outlier effect sizes, and in nearly all of these


cases the point estimate of the overall effect size changed minimally when these outlier effects were excluded. Specific

results of heterogeneity analyses are summarized in the supplemental tables.

Prevalence estimates based on a small number of effects

Although many prevalence estimates in the meta-analysis were based on 15 or more effect sizes, for several specific

diagnostic algorithms only a handful of estimates were available. A recent paper provided a cogent summary of the strengths

and weaknesses of different approaches for the synthesis of results when only a small number of studies are available [96].

The authors first assert that the primary conclusion when a meta-analysis is underpowered is that more evidence is required.

Indeed, the current results suggest that additional research is needed regarding the prevalence of ADHD based on several

widely-used diagnostic algorithms, including the or-rule used in the DSM-IV field trials.

After underscoring this key point, the authors argue that even when the number of studies is small, a meta-analysis is

still a better approach than other methods that are often used to synthesize the results of a small number of studies [96].

Alternative approaches include qualitative statements regarding the similarity of effects across studies or broad summary

statements about the overall conclusions that should be drawn from studies that were deemed too heterogeneous to combine

for meta-analysis. These approaches involve subjective judgments based on internal rules that may be prone to bias and are

unlikely to be transparent to the reader.

While the utility of meta-analysis is also constrained by a small number of available studies, several considerations

support its use even in these scenarios. Perhaps most importantly, the meta-analytic approach is more transparent and less

susceptible to bias than alternative descriptive approaches. The greater degree of uncertainty in meta-analyses of a small

number of studies is explicitly reflected in a large standard error and wider confidence interval around the point estimate of the

effect size. The formal synthesis of results from a small number of studies may also provide important preliminary information

about issues that have received relatively little research attention, and the list of available effect sizes helps to underscore

explicitly the paucity of relevant data that are available.

Therefore, to provide a comprehensive summary of the literature, the supplemental tables include effect sizes from all

individual studies that estimated prevalence of DSM-IV ADHD, and meta-analytic procedures were used to estimate

prevalence rates if at least two studies used a diagnostic approach that was sufficiently similar to allow pooled analyses.

Nonetheless, it is also critical to emphasize that prevalence estimates derived from meta-analyses of a small number of

studies should be considered preliminary results that must be interpreted with caution.


Publication and other selection biases

In the context of meta-analysis, bias occurs if the studies included in the review are systematically

nonrepresentative of the total population of studies relevant to the question of interest (see [97] for a comprehensive

summary of different aspects of bias in meta-analyses). The type of bias discussed most frequently is publication bias,

which typically occurs if studies that report significant results are more likely to be published than studies that report

nonsignificant results. A related issue arises if published studies only report results of analyses that were significant, and

do not report analyses of other measures that yielded nonsignificant results. Other forms of reporting bias may occur if the

same result is published more than once or if results are published in journals that are not widely cited and are not

captured by typical search procedures. The remainder of this section briefly summarizes the specific methods that were

used to test for bias and estimate its impact on the results of the meta-analysis.

Egger's multiple regression test. This method tests whether there is evidence of significant publication bias that

may change the overall point estimate of the effect size [100]. A regression model is fitted to the association between the

magnitude and precision of the observed effect sizes included in the analysis. If there is no publication bias (i.e., if all

completed studies are included in the analysis) these two variables should be unrelated, whereas a significant value for

the regression intercept indicates the possibility of publication bias.

Trim and fill. The trim-and-fill procedure is a two-step procedure

that first evaluates the extent of any bias, then estimates the true effect

size and standard error that would be obtained if the missing studies had

been included in the analysis [101]. The first step of the trim-and-fill

procedure is based on the same idea that underlies the funnel plot, a

graphical approach that has often been used to screen qualitatively for

evidence of bias in meta-analyses. An example of a funnel plot from the

current meta-analysis is provided in Figure 1. Each unfilled circle in the

figure represents the point estimate of the prevalence of ADHD-H from a

single study. The x-axis of the plot indicates the effect size (for statistical

reasons prevalence rates are converted to logit event rates prior to meta-

analysis), and the vertical axis indicates the corresponding standard error

for each effect (a direct function of sample size). In the absence of bias, the scatterplot of effects should be distributed

symmetrically around the overall effect size, and the distribution should be shaped like an inverted funnel due to the less

precise estimates obtained in the smaller samples at the bottom of the chart.


In contrast, an asymmetric distribution of effects suggests that some effects are missing. The trim-and-fill

procedure first estimates the number of studies that are missing from one side of the distribution (in the example in Figure

1 three effects were missing from the higher tail of the distribution). The same number of studies are then removed

(trimmed) from the other side of the distribution to compensate for the hypothetical missing effects, and the overall point

estimate is recalculated. In the example the prevalence estimate was slightly higher after this procedure was completed

(3.7% vs. 3.2%). An imputation procedure is then used to estimate the effect size for each of the hypothetical missing

studies in the distribution, and these new effects are added to the original distribution (the filled circles in Figure 1). The

resulting distribution is then used to calculate the adjusted standard error of the overall effect size if the hypothetical

missing effects were included.

Summary of the impact of publication / selection bias. For each prevalence estimate that is based on three or

more samples, the Supplement Table provides a summary of analyses of heterogeneity and publication bias, including

Egger's regression and Trim and Fill procedures. All publication bias analyses were conducted after accounting for

heterogeneity among the effects [99].

Trim and fill procedures suggested that at least one effect size was missing from the distribution of effects in 29%

of the analyses. However, a relatively small number of distributions were missing more than three effect sizes (11%), and

Egger's regression analyses indicated significant bias in only 8% of analyses. Most importantly, when the hypothetical

missing effects were added to the distribution as part of the trim-and-fill procedure, the mean change in the point estimate

of the prevalence of ADHD was small (0.2%), and no point estimate changed by more than 0.5%. Overall, these results

suggest that the substantive conclusions of the review are unlikely to be attributable to publication bias or other sampling

biases in the literature search.


Supplement Table 1 Studies of the prevalence of DSM-IV ADHD included in the meta-analysis Cite

# Author / Year Location Age

Range Total

N Resp. Ratea

Exclusion Criteriab Sampling procedures and definition of ADHD

[1] Adewuya 2007 Nigeria 6 - 12 1,112 92% 1, 2, 5 A random sample was drawn from 192 classrooms in 16 schools in Osun state. If a teacher

endorsed three or more ADHD symptoms with impairment on the VADTRS, the child’s parent was asked to complete the VADPRS. Items rated as occurring "often" or "very often" were coded as positive symptoms. The operational definition of ADHD required the child to meet full DSM-IV criteria based on parent or teacher ratings and to exhibit at least 3 symptoms of inattention or hyperactivity-impulsivity on the rating by the other reporter.

[2] Alloway 2010 UK 10 964 NR None Classroom teachers in 12 schools rated DSM-IV ADHD symptoms on the ADHDRS-IV. Items endorsed as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on DSM-IV symptom criteria only.

[3] Alqahtani 2010 S. Arabia 7 - 9 708 72% None Parent and teachers completed the VADTRS and VADPRS on a random sample of ten children from each classroom in a randomly selected sample of 33 schools in the Assir region. Items rated as occurring "often" or "very often" were coded as positive symptoms, and the prevalence of ADHD was estimated based on DSM-IV symptom criteria only

[4] Alyahri 2008 Yemen 7 - 10 1,210 89% None Prevalence was estimated based on a one-stage random sample of 203 children in grades 1 - 4 in a rural district of Lahj province and a two-stage random sample of 1,007 children in the city of Mukalla. In the urban sample all children who screened positive on the SDQ received a full assessment using the DAWBA interview, along with a random sample of 17% of the children who screened negative. In the rural sample the SDQ and DAWBA were completed for all children. Best estimate ADHD diagnoses were made by experienced clinicians based on full DSM-IV criteria.

[5] Amador-Campos 2006

Spain 4 - 12 653 54%c None Parents and teachers completed DSM-IV ADHD checklists for a random sample of children attending six schools in Barcelona. Items rated as occurring "often" or "very often" were coded as positive symptoms, and the prevalence of ADHD was estimated based on DSM-IV symptom criteria only.

[6] Amiri 2010 Iran 7 - 15 1,658 NR 1 - 3, 13, 14 Random proportional cluster sampling was used to draw a random sample of 60 classes in 30 schools in Tabriz. Teachers completed the CTRS-R. Structured diagnostic interviews were then completed with parents and teachers of children with T scores 65 or higher on the CTRS-R, and prevalence was estimated using best estimate diagnoses based on full DSM-IV criteria.




Range Total

N Resp. Ratea


[7] Angold 2002 USA 9 - 17 920 65% None A random sample was drawn from all children in public school in four counties in North

Carolina. ADHD symptoms endorsed on parent- and self-report structured interviews (CAPA) were combined using the or-rule algorithm, and the prevalence of ADHD was estimated based on full DSM-IV criteria.

[8] Anselmi 2010 Brazil 11 - 12 4,452 81% None Prevalence in a Brazilian birth cohort was estimated using a two-stage sampling procedure. In the screening phase the mothers of 4,452 children completed the SDQ. Individuals with a positive screen (N = 122) and a random sample of those with a negative screen (N = 158) then completed the DAWBA interview. In the rural sample the SDQ and DAWBA were completed for all children. Best estimate ADHD diagnoses were then made by experienced clinicians based on full DSM-IV criteria.

[9] Bauermeister 2007

P. Rico 4 - 17 1,897 90% None Parent-report and self-report diagnostic interviews were completed with the DISC-IV for one child living in a random sample of households weighted to be representative of the population of children in Puerto Rico in 2000. The study compared the prevalence of ADHD subtypes based on different DSM-IV diagnostic criteria.

[10] Baumgaertel 1995 Germany 5 - 12 1,077 100% 6 A convenience sample of 44 teachers in 10 schools in Bavaria voluntarily completing anonymous ratings of all students in their class on the VADTRS. Items rated as occurring "often" or "very often" were coded as positive symptoms, and the prevalence of ADHD was estimated based on DSM-IV symptom criteria only.

[11] Benjasuw. 2002 Thailand 6 - 12 433 NR None Parents of children from a single school completed the CPRS, and follow-up interviews were completed with a DSM-IV interview. Prevalence was estimated based on full DSM-IV criteria.

[12] Bird 2006 P. Rico 5 - 13 1,353 89% 1, 2 A multistage probability sampling procedure was used to identify a representative sample of children from Puerto Rico. Parents were interviewed with the DISC-IV, and ADHD diagnoses were made based on full diagnostic criteria, with the exception that impairment was only required in one domain.

[12] Bird 2006 USA 5 - 13 1,138 81% 1, 2 A multistage probability sampling procedure was used to identify a representative sample of Puerto Rican children in South Bronx, New York. Parents were interviewed with the DISC-IV, and ADHD diagnoses were made based on full diagnostic criteria, with the exception that impairment was only required in one domain.

[13] Bohlin 2004 Sweden 5 - 13 834 56% None A random sample of children was drawn from the Swedish Population Register. Parents completed the FTF, and the prevalence of ADHD was estimated based on DSM-IV symptom criteria only.




Range Total

N Resp. Ratea


[14] Campbell 2009 USA 1st

grade 1,082 79% None Data were drawn from the NICHD Study of Early Child Care and Youth Development, a

longitudinal study of a birth cohort drawn from 10 sites around the country. Symptoms rated as "pretty much" or "very much" a problem were coded as positive symptoms, and prevalence was estimated based on DSM-IV symptom criteria only, with the exceptions that the prevalence of ADHD-H was not reported, and children who exhibited six or more symptoms of inattention and five symptoms of hyperactivity-impulsivity were not included in any subtype group.

[15] Canino 2004 P. Rico See description of [9].

[16] Carlson 1997 USA 5 - 12 2,984 93% None Teachers completed anonymous ADHD ratings on the SNAP-IV for all children in nine elementary schools in Texas selected due to low socioeconomic status. Items rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on DSM-IV symptom criteria only.

[17] Cho 2009 S. Korea 6 - 12 1,651 66% None One elementary school was selected randomly from each of six sections of Seoul, and ten classrooms were randomly selected from each school. Parents of all children in each class were interviewed using the DISC-IV, and prevalence was estimated based on full DSM-IV criteria.

[18] Costello 2003 USA 9 - 16 1,420 79% None A random sample was drawn to be representative of the population of children in 11 counties in western North Carolina. A parent-report structured interview (CAPA) was used to estimate the prevalence of ADHD based on full DSM-IV criteria.

[19] Döpfner 2008 Germany 7 - 17 2,452 68% None A random sample was selected from a larger nationally representative sample of 17,641 children. A DSM-IV ADHD rating scale was completed by parents, and items rated as "predominantly true" or "especially true" were coded as positive symptoms. Prevalence estimates based on different diagnostic algorithms were compared.

[20] DuPaul 1998 USA 4 - 19 2,000 85% None Teachers in 31 school districts completed anonymous ratings of one girl and one boy on the ADHDRS (N = 4,009). Items rated as occurring "often" or "very often" were coded as positive symptoms, and the prevalence of ADHD was estimated based on symptom criteria only in a random sample of 2,000 children selected from the total screening sample.

[21] DuPaul 2001 USA 17 - 49 799 NR None Students in undergraduate psychology courses at three universities completed self-report ratings of current DSM-IV ADHD symptoms on the YARS. Items rated as present "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on DSM-IV symptom criteria only.




Range Total

N Resp. Ratea


[21] DuPaul 2001 N. Zealand 17 - 51 213 NR None Volunteers from undergraduate psychology courses at the University of Otago completed

self-report ratings of current DSM-IV ADHD symptoms on the YARS. Items rated as present "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on DSM-IV symptom criteria only.

[21] DuPaul 2001 Italy 17 - 49 197 NR None Students in undergraduate psychology courses at Universita di Padova completed self-report ratings of current DSM-IV ADHD symptoms on the YARS. Items rated as present "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on DSM-IV symptom criteria only.

[22] Eapen 2003 UAE 6 - 18 329 86% None A random sample of households was selected from all households in Al Ain, a medium size city in which one-third of the population are UAE citizens. Parent-report and self-report interviews (K-SADS) were completed for children from a random sample of the families with UAE citizenship, and a best estimate diagnosis of ADHD was made based on full DSM-IV criteria.

[23] Egger 2006 USA 2 - 5 1,073 70% 1, 2, 12 A two-stage sampling procedure was used to estimate the prevalence of ADHD among children served by a single pediatric Primary Care clinic in North Carolina. In the screening stage all parents completed the CBCL. Parents of all children with scores in the top 30% of the population on the CBCL Total Problems scale completed a structured diagnostic interview (PAPA), along with the parents of a random sample of 20% of children with scores below the top 30% on the CBCL. Responses on the PAPA were used to estimate the prevalence of ADHD based on full DSM-IV diagnostic criteria.

[24] Ersan 2004 Turkey 6 - 15 1,415 71% None The sampling frame included all children attending a random sample of 8 elementary schools in Sivas, a city with lower mean socioeconomic status than the overall mean for Turkey. One reporter completed an unspecified measure of ADHD symptoms regarding each child (890 parents, 261 teachers, 73 other immediate family members, and 201 unidentified individuals), and the prevalence of ADHD was estimated based on DSM-IV symptom criteria only.

[25] Faraone 2005 USA > 18 966 19% None Random digit dialing was used to identify a random sample of adults, and DSM-IV ADHD symptoms were assessed via self-report interview. Items that were reported to occur "often" were coded as positive symptoms, and the prevalence of ADHD was estimated based on DSM-IV symptom criteria only.




Range Total

N Resp. Ratea


[26] Ford 2003 UK 5 - 15 10,440 78% None A stratified random sample was selected from a child benefits register which represents 90%

of children in Great Britain. Parents, teachers, and children each completed the DAWBA interview. A team of expert clinicians then reviewed all information and assigned a best estimate diagnosis of ADHD based on full DSM-IV criteria.

[27] Froehlich 2007 USA 8 - 15 3,082 79% None A multistage probability sampling procedure was used to select a representative sample of the noninstitutionalized US population. A DISC-IV interview was administered to all parents to estimate the prevalence of ADHD based on full DSM-IV diagnostic criteria.

[28] Gadow 1997 USA 3 - 5 531 NRd 2, 5 - 7, 9 Parents completed anonymous ratings of ADHD symptoms on the ECI for children attending a convenience sample of 11 private preschool and day care centers and 4 Head Start programs in New York. Items rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on DSM-IV symptom criteria only.

[29] Gadow 1998 USA 13 - 18 761 31% 6 Parents completed anonymous ratings of ADHD symptoms on the Adolescent Symptom Inventory (ASI) for a sample of adolescents attending a middle school and a high school in New York. Items rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[30] Gadow 1999 USA 6 - 12 552 NR 6 Parents of a subset of the sample completed anonymous ratings of ADHD symptoms on the CSI during their child’s regular visit to the pediatrician (N = 263), and the remainder were mailed the rating scale by one of a convenience sample of three schools in New York. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[31] Gau 2005 Taiwan 13 - 15 1,070 24% None A two-stage sampling procedure was used to estimate the prevalence of ADHD in a convenience sample of 2 schools in South Taiwan. All participants completed a screening version of the K-SADS-E. All participants who screened positive completed the full self-report interview, along with 10% of the students who screened negative. A team of three clinicians then assigned a consensus ADHD diagnosis based on the full K-SADS-E interview and collateral information from the TRF.

[32] Gaub 1997 USA See description of [16]. In this report only symptoms rated as occurring "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[33] Ghanizadeh 2008 Iran 7 - 12 1,600 80% 1, 2, 5, 11 Parents of all children in a stratified random sample of schools and classrooms were asked to complete the CSI. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.




Range Total

N Resp. Ratea


[34] Gimpel 2000 USA 2-6 253 NA None Parents completed the ADHDRS regarding children attending a convenience sample of 44

day care centers in a city and small town. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[35] Gomez 1999 Australia 5-11 1,275 66%e None The sample included all children attending a random sample of 16 schools in Melbourne and Ballarat. Parents and teachers completed the ADHDRS for all consenting participants in each school. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[36] Gomez 2008 Malaysia 6 - 12 845 93% None Parents of children from 14 randomly selected schools completed the DBRS. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[37] Graetz 2001 Australia 6 - 17 3,566 70% None A multistage probability sample was obtained that is representative of the population of Australia. Parents of all individuals in the sample completed the DISC-IV interview, and the prevalence of ADHD was estimated based on full DSM-IV diagnostic criteria.

[38] Gul 2010 Turkey 6 - 12 1,126 75% None A multistage stratified random sample of six schools was drawn from all schools in Trabzon. Parents and teachers completed a rating scale that included the DSM-IV symptoms of ADHD. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[39] Heiligenstein 1998

USA 17 - 46 448 NA None College students were recruited through a variety of procedures, then completed a DSM-IV ADHD rating scale regarding current symptoms. Items endorsed as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[40] Jané 2006 Spain 3 - 6 1,104 77%f None The sample included all children in public and private preschools in an urban and a rural area of Catalonia. Parents and teachers rated each child on the ECI. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[41] Kadesjo 2004 Sweden 6 - 15 854 63% None A stratified sample of children was selected to be representative of the population of Sweden in 2001. Parents of all children completed the FTF Questionnaire, and the prevalence of ADHD was estimated based on symptom criteria only.




Range Total

N Resp. Ratea


[42] Kashala 2005 Congo 7 - 9 1,187 50%g 3, 5, 13 Teacher ratings on the DBD were obtained for children in 10 schools selected randomly from

all consenting schools in Kinshasa, the largest city in the country. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[43] Katusic 2005 USA M = 18 5,718 67% 1 - 3 The sample is a birth cohort of children who remained in Rochester, MN after age 5. A best estimate diagnosis was determined for each child in the cohort after an extensive review of school and medical records. ADHD diagnoses were based on all DSM-IV criteria except age of onset, because this was not reliably available in the records.

[44] Kessler 2006 USA 18 - 44 3,199 71% None A screen for adult ADHD was included in a probability subsample of respondents in the National Comorbidity Survey Replication. Follow-up interviews were conducted with 154 respondents, and multiple imputation procedures were used to estimate prevalence based on full DSM-IV diagnostic criteria.

[45] Kroes 2001 Netherl. 6 - 8 1,317 51% None A two-stage sampling procedure was used to identify a sample of children in second grade in Limburg. All children scoring above the 95th percentile on CBCL Attention Problems were invited to complete the full study, and a child who scored below the 95th percentile cutoff was matched to each child above the cutoff on sex, age, and school. The prevalence of ADHD was estimated based on full DSM-IV diagnostic criteria as assessed by a parent-report interview (ADIKA).

[46] LaVigne 2009 USA 4 796 46% 1, 2 Families were approached through 13 public schools and 23 primary care pediatric practices in Chicago and invited to participate. Parents completed the DISC-IV, and the effect of different diagnostic algorithms on prevalence were examined.

[47] Leung 2008 China 11 - 16 541 NA None The sample included students in 7th - 9th grade in a random sample of 28 mainstream high schools in Hong Kong. ADHD symptoms endorsed in parent-report and self-report structured interviews (DISC-IV) were combined using the or-rule, and ADHD prevalence was estimated based on full DSM-IV diagnostic criteria.

[48] Levy 2005 Australia 4 - 18 4,356 48%h 1 - 3, 7, 9 An unselected sample of twins was recruited through the Australian Twin Registry, and parents rated each child on the ATBRS. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms. Prevalence was estimated based on symptom criteria only in this paper, and Rasmussen et al. [64] reported prevalence based on full DSM-IV criteria.




Range Total

N Resp. Ratea


[49] Magnússon 1999 Iceland 6 - 8 479 54%i None A random sample of children was drawn from first and third grade classrooms in five schools

in Reykjavik, and parents and teachers rated each child on the ADHDRS. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[50] McKee 2008 USA 16 - 22 1,077 NR None Entering first-year students in three private colleges completed self-report ratings of DSM-IV ADHD symptoms as part of their orientation. Items were rated on a three-point scale with anchors "disagree", "undecided", and "agree". The number of DSM-IV symptoms endorsed as "agree" were summed, and prevalence was estimated based on symptom criteria only.

[51] Merrell 2001 UK 5 - 7 4,148 NR None A sample was drawn at the beginning of formal education that was representative of children in England (schools paid a fee to participate). Teachers completed a rating scale that included the DSM-IV symptoms of ADHD, and were asked to indicate for each child which symptoms were considerably more frequent than that of children the same gender and developmental level. ADHD was then defined by symptom criteria only.

[52] Meyer 2004 S. Africa 6 - 15 6,094 95% None Participants were recruited from a convenience sample of 20 primary schools in Limpopo Province. Schools were required to have electricity and to be accessible by road. Teachers rated each child on the DBD, symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[53] Montiel 2008 Venezuela 4 - 12 1,535 81% 1, 3 A two-stage sampling procedure was used to estimate the prevalence of ADHD in a random sample of children attending schools in Maracaibo. All children in a randomly selected subset of schools were screened using the Conners Parent and Teacher Rating Scales. Parents of children with T scores greater than 70 on the CPRS or CTRS completed the DISC-IV interview, along with the parents of a random sample of children with T scores below 65. The prevalence of ADHD was estimated using full DSM-IV criteria assessed by the structured interview and C-GAS.

[54] Mugnaini 2006 Italy 6 - 7 1,891 78% 1, 2, 5 Teachers completed the VADTRS on a random sample of children selected from 49 public schools in Florence. . Items rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on full DSM-IV diagnostic criteria.

[55] Murphy 1996 USA 17 - 84 720 NR None A sample of 720 adults applying for or renewing their driver's licenses completed self-report rating scales for current symptoms of ADHD and retrospective recall of childhood symptoms. Items rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.




Range Total

N Resp. Ratea


[56] Neumann 2005 USA 7 - 17 1,472 49% 2, 8 Twin pairs in Missouri were identified through birth records, and a 2-stage screening

procedure was used to assess pairs who were not already participating in the separate study described below (72). Initial screening interviews were completed by telephone for the entire sample (N = 5,007), followed by structured diagnostic interviews of parents and twins in 564 families who met screening criteria and a comparison group of 183 families who did not meet the screening criteria. The structured interviews were used to estimate the prevalence of ADHD based on full DSM-IV criteria.

[57] Nolan 2001 USA 3 - 5 413 NR 6, 10j Teachers completed anonymous ECI ratings for children attending a convenience sample of 11 private preschool and day care centers and 4 Head Start programs. Items rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[57] Nolan 2001 USA 6 - 12 1,520 NR 6, 10k Teachers from regular education classrooms in 16 schools in Missouri, Wisconsin, and New York voluntarily completed anonymous CSI [30, 102] ratings for up to 10 children per classroom. Items rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[57] Nolan 2001 USA 13 - 18 1,072 NR 10 Teachers completed anonymous ratings on the ASI [29] for a sample of adolescents attending a convenience sample of regular education classrooms in 6 public schools from districts in Missouri, Wisconsin, and New York. Items rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[58] Owens 2003 USA 9 - 12 440 38% none Parents and teachers completed DBD ratings for all children in fourth through sixth grade in a convenience sample of 9 schools in Indiana. The or-rule algorithm was used to combine parent and teacher ratings of ADHD symptoms with items rated as occurring "very often" considered a positive symptom, and the prevalence of ADHD was estimated based on symptom criteria only.

[59] Petersen 2006 Denmark 7 - 8 5,563 42% 10 A two-stage sampling procedure was used to estimate the prevalence of ADHD in a random sample of children attending 34 schools in the county of Funen. All children with significantly elevated scores on the CBCL and a random sample of children without elevated scores completed parent-report and self-report structured diagnostic interviews (K-SADS; N = 373). Final ADHD diagnoses were based on full DSM-IV diagnostic criteria.




Range Total

N Resp. Ratea


[60] Pineda 1999 Colombia 4 - 18 540 88% 1, 2, 6, 11 A clustered random sample (based on SES, gender, and age) was selected from all children

attending schools in Manizales City. Parents rated each child on a DSM-IV ADHD rating scale, items rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[61] Pineda 2003l Colombia 4 - 18 330 77% 1 - 6, 9, 13 - 17

A clustered random sample of children (clusters based on SES, gender, and age) was selected from a random sample of 5 private and 15 public schools in Manizales City. The parent and teacher of each child completed a DSM-IV ADHD rating scale and the short-forms of the CPRS and CTRS, and the parents of children with six or more symptoms of inattention or hyp-imp on the rating scale completed a semi-structured diagnostic interview. A best estimate ADHD diagnosis was made for each child based on full DSM-IV criteria.

[62] Ramtekkar 2010 USA 18 - 29 3,193 2, 7, 11 Expansion of sample described by [56] to include young adults.

[63] Rasmussen 2002 USA Subsample of overall sample described by [72].

[64] Rasmussen 2004 USA See description of [72] and [48].

[65] Rohde 1999 Brazil 12 - 14 1,013 99% none A random sample of students was drawn from a clustered random sample of 64 schools in Porto Alegre. All students with 5 or more symptoms of inattention or hyp-imp on a screening assessment completed the full assessment, along with a random sample of those without elevations of inattention or hyp-imp. The second stage included self-report and parent-report interviews, and a best estimate diagnosis of ADHD was made by an experienced clinician based on full DSM-IV diagnostic criteria.

[66] Servera 2010 Spain 6 - 11 1,749 80-97% 1, 2, 13, 15 Teachers and parents completed the ADHDRS for students in a random sample of classrooms that were randomly selected from a random sample of 16 schools on the island of Majorca. Items rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[67] Skounti 2006 Greece 7 1,285 75% 1, 2, 6 Parents and teachers completed DSM-IV ratings of children in first grade in 55 mainstream public schools in a large city in Crete. Items rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on full DSM-IV criteria.




Range Total

N Resp. Ratea


[68] Smalley 2007 Finland 16 - 18 6,622 41% 2, 7 As part of a follow-up study of a birth cohort in northern Finland, parents completed the

SWAN. Individuals scoring above the 95th percentile on the SWAN inattention or hyperactivity-impulsivity scales were selected for more detailed assessment using the K-SADS-L, along with a control sample with scores below the 90th percentile. Prevalence was estimated for a best estimate diagnosis of ADHD. Participants between the 90th and 95th percentile were not included in additional testing or prevalence estimates.

[69] Sprafkin 2007 USA 18 - 75 900 NR None Participants were recruited through social, service, and religious groups in Suffolk County, New York. Anonymous self-report ratings of symptoms during the past six months were completed on the ASRI-4, and the prevalence of ADHD was estimated based on DSM-IV symptom criteria only.

[70] Talaei 2010 Iran 7 - 9 714 95% None A random sample of 24 classrooms were selected from 12 schools. Parents and teachers completed the Conners Rating Scales, and a clinical interview based on DSM-IV criteria was administered to participants who scored above a screening threshold. Prevalence estimates used a best estimate diagnosis of ADHD based on full DSM-IV criteria.

[71] Thabet 2010 Gaza / West Bank

6 - 15 349 NR None A random sample of 16 children was selected from a random sample of 15 schools in the Gaza Strip and 8 schools in Bethlehem and East Jerusalem. Parents and teachers completed a checklist keyed to DSM-IV symptoms, and ADHD was defined based on a best estimate diagnosis.

[72] Todd 2001 USA 13 - 23 4,036 77% None As part of the Missouri Adolescent Female Twin Study, female twins were identified from state birth records. Parents of each twin completed a structured diagnostic interview (DICA-IV), and full DSM-IV criteria were used to estimate the prevalence of ADHD.

[73] Tuvblad 2009 USA 9 - 10 1,219 NR 12 Participants were a representative sample of twins from Los Angeles. Parents completed the DSM-IV DISC-IV, and ADHD was defined based on full diagnostic criteria.

[74] Volk 2009 USA See description of [72]. This paper reported prevalence based on symptom criteria only.

[75] Waschbusch 2007

Canada 5 - 12 835 53% None The sample included all students attending a convenience sample of seven elementary schools in Ontario. Mother and father ratings on the ADS-IV were combined using the or-rule, and ADHD status was defined based on full DSM-IV diagnostic criteria with the exception of age-of-onset (the study tested the validity of this criterion).




Range Total

N Resp. Ratea


[76] Weiler 1999 USA 7 - 11 225 26% None Children in 2nd - 5th grade were recruited from a public school system in Massachusetts,

and parents and teachers rated each child on the DRS. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[77] West 2003 Scotland 15 1,860 67% 6 The study used a representative sample of adolescents in mainstream education in western Scotland. Each student completed a self-report diagnostic interview (Voice-DISC-IV), and full DSM-IV criteria were applied to define ADHD status.

[78] Willcutt 2007 USA 4 - 6 966 86% 1 - 5, 8 An unselected sample of twin pairs was recruited through a twin birth registry in Colorado. Parents completed ratings of each twin on the DBRS, and prevalence was estimated based on symptom criteria only.

[78] Willcutt 2007 Australia 4 - 6 512 60% 1 - 5, 8, 12 Parent ratings were obtained with the DBRS on an unselected sample of twin pairs recruited through twins clubs in New South Wales. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[78] Willcutt 2007 Sweden 4 - 6 345 60% 1 - 5, 8 Parent ratings were obtained with the DBRS on an unselected sample of twin pairs in a registry in Sweden. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[78] Willcutt 2007 Norway 4 - 6 193 60% 1 - 5, 8 Parent ratings were obtained with the DBRS on an unselected sample of twin pairs in a registry in Norway. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[79] Willcutt 2011a USA 18 - 25 2,400 67% 1, 2, 4 Students in Introductory Psychology courses completed the Current and Childhood Symptom Inventories, and prevalence was estimated based on full diagnostic criteria.

[80] Willcutt 2011b USA 6 - 13 7,874m 65% 1 - 3, 8, 10 A random sample of schools were selected from five school districts in Colorado, and parents and teachers completed the DBRS for all consenting participants in each school. The study compared the prevalence based on different algorithms for the combination of parent and teacher ratings of ADHD symptoms and functional impairment.

[81] Willoughby 2000 USA See description of [18]




Range Total

N Resp. Ratea


[82] Wolraich 1996 USA 5 - 11 8,258 NRn None During the 1993-1994 school year, all children in kindergarten through fifth grade in a middle

Tennessee county were rated anonymously by teachers on the VADTRS. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[83] Wolraich 1998 USA 5 - 11 4,323 63%o None During the 1994-1995 school year, all children in kindergarten through fifth grade in a middle Tennessee county were rated anonymously by teachers on the VADTRS. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[84] Wolraich 2003 USA 5 - 10 6,171 33% None During the 1998-1999 school year, all children in kindergarten through fifth grade in a middle Tennessee county were rated anonymously by teachers on the VADTRS. Symptoms rated as occurring "often" or "very often" were coded as positive symptoms, and prevalence was estimated based on symptom criteria only.

[85] Zuddas 2006 Italy 6 - 12 1,575 NR None Parents and teachers completed ratings on a disruptive behavior disorders ratings scale regarding a sample of children drawn from 21 primary schools in Bergamo, Venice, Padua, Florence, and Cagliari. Scores of 2 or 3 on the 0 - 3 scale were considered positive symptoms, and the prevalence of ADHD was estimated based on symptom criteria only.

[86] Zwirs 2007 Netherl. 6 - 10 2,041 67% None A two-stage procedure was used to assess a sample of children attending mainstream schools in low socioeconomic inner-city neighborhoods in Amsterdam and Utrecht. In the screening stage of the study parents of all children completed the SDQ. The full assessment was then completed by all children with scores above the 90th percentile on the SDQ and a randomly selected subsample of children who scores below the 90th percentile. A best estimate diagnosis of ADHD based on full DSM-IV diagnostic criteria was derived from parent-report, teacher-report, and self-report measures.


Supplement Table 1 continued Studies of the prevalence of DSM-IV ADHD included in the meta-analysis

Note. ADHDRS = ADHD Rating Scale [20], ADIKA = Amsterdam Diagnostic Interview for Children and Adolescents (translation of DICA), ADS-IV = Assessment of Disruptive Symptoms DSM-IV [103], ASI = Adolescent Symptom Inventory [29], ASRI-4 = Adult Self-Report Inventory-4 [104], ATBRS = Australia Twin Behavior Rating Scale [105], CAPA = Child and Adolescent Psychiatric Assessment [106], CBCL = Child Behavior Checklist [107], Current and Child Symptom Inventories [108], CSI = Child Symptom Inventory [30, 102], CTRS-R = Conners Teacher Rating Scale, Revised [109], DAWBA = Development and Well-being Assessment [110], DBD = Disruptive Behavior Disorders Rating Scale [111], DBRS = Disruptive Behavior Rating Scale [108], DICA-IV = Diagnostic Interview for Children and Adolescents [112], DISC-IV = DSM-IV Diagnostic Interview Schedule for Children [113], DRS = Diagnostic Rating Scale [76], ECI = Early Childhood Inventory [28], FTF = Five to Fifteen Questionnaire [41], K-SADS = Schedule for Affective Disorders and Schizophrenia for School-age Children [114], MAGIC = Missouri Assessment of Genetics Interview for Children [115], PAPA = Preschool Age Psychiatric Assessment [23], SDQ = Strengths and Difficulties Questionnaire [116], SNAP-IV = DSM-IV Swanson, Nolan, and Pelham Checklist (unpublished), VADTRS = Vanderbilt ADHD Teacher Rating Scale [82], VADPRS = Vanderbilt ADHD Parent Rating Scale [82], YARS = Young Adult Rating Scale [21]. aNR = response rate not reported or not available. bExclusion criteria: 1 = Autism / pervasive developmental disorder, 2 = Mental retardation, 3 = Psychosis, 4 = Traumatic Brain Injury, 5 = Neurological Disorder, 6 = Special Education, 7 = Physical Disorder, 8 = English as a second language, 9 = Seizure Disorder, 10 = home-school. 11 = Sensory Disorder, 12 = Parent did not speak the native language sufficiently to complete the study, 13 = Bipolar Disorder, 14 = Tourettes Disorder, 15. Developmental Coordination Disorder, 16 = Language Disorder, 17 = major depressive disorder. c54% of children were rated by both parent and teacher. dTotal participation rate not provided. 68 children in special education were excluded from the prevalence estimate. e76% of parents agreed to participate, and 90% of the teachers of these children completed ratings. fAn unreported number of parents provided initial consent for teachers to rate their children. 77% of the parents who provided initial consent completed the parent questionnaire. g10 of 20 schools agreed to participate. h73% of families completed an initial assessment based on DSM-III-R symptoms. 12% were excluded due to medical problems, and 48% of the initial population completed a second questionnaire that included the measure of DSM-IV ADHD. iTeachers in 3 of 5 schools agreed to participate. In schools that participated teacher ratings were obtained for 89% of the children. j143 children in special education were excluded. kchildren were included if they were in a regular classroom for part of the day..lre-analysis of data described by Pineda et al., 2001 [117]. Special education classes were excluded, and 15 - 30% of the population was estimated to have dropped out of school for economic reasons. mExpansion of the sample described in the initial paper. nAll teachers participated. Parents were provided with a number to call if they did not wish for their child to be rated. The number of parents who elected not to participate was not available due to procedures used to preserve confidentiality for the families. oAll teachers in 10 out of 16 schools agreed to participate.


Supplement Table 2 Estimated prevalence of DSM-IV ADHD in studies of parent ratings

DSM-IV Criteria / Age Sample Estimated Prevalence of ADHD (%) Study Range Size Total ADHD ADHD-C ADHD-H ADHD-I

Symptom criteria only Amador-C. 2006 4 - 12 653 15.6 1.2 10.4 4.0 Bauermeister 2007 4 - 17 1,897 10.5 2.6 5.2 2.5 Bohlin 2004 5 - 13 802 5.0 0.9 2.0 2.1 Döpfner 2008 7 - 17 2,452 5.0 0.8 0.6 3.6 DuPaul 1998 5 - 17 2,000 7.5 2.2 2.1 3.2 Ersan 2004 6 - 15 890 9.6 2.1 4.4 3.0 Gadow 1997 3 - 5 531 5.8 1.5 3.6 0.9 Gadow 1998 13 - 18 761 5.4 0.4 0.4 4.6 Gadow 1999 6 - 12 552 7.2 1.6 2.0 3.6 Ghanizadeh 2008 7 - 12 1,600 10.1 1.5 5.0 3.6 Gimpel 2000 2 - 6 253 9.5 4.0 3.6 2.0 Gomez 1999 5 - 11 1,275 9.9 2.9 2.7 4.2 Graetz 2001 6 - 17 3,566 7.5 1.9 1.9 3.7 Jané 2006 3 - 6 850 12.6 2.0 9.3 1.3 Kadesjo 2004 6 - 14 854 5.3 1.2 1.4 2.7 LaVigne 2009 4 796 12.8 4.1 6.9 1.8 Levy 2004 4 - 18 4,356 13.4 3.9 2.4 7.1 Magnusson 1999 6 - 8 427 4.4 2.6 1.4 0.5 Pineda 1999 4 - 11 540 16.1 3.3 8.5 4.3 Servera 2010 6 - 11 1,422 12.4 3.2 4.8 4.5 Thabet 2010 6 - 15 349 14.7 -- -- -- Volk 2009 13 - 23 4,170 12.7 2.8 3.0 7.0 Weiler 1999 6 - 12 225 12.0 5.3 0.9 5.8 Willcutt 2007a 4 - 6 966 8.7 2.3 4.5 2.1 Willcutt 2007b 4 - 6 512 9.4 0.8 7.2 1.4 Willcutt 2007c 4 - 6 345 5.5 1.2 3.5 0.9 Willcutt 2007d 4 - 6 193 6.7 1.0 4.1 1.6 Willcutt 2011b 6 - 13 7,874 9.0 2.9 2.0 4.5 Zuddas 2006 6 - 12 1,575 3.5 -- -- -- Overall prevalence (95% CI): 8.8 (7.7, 9.9) 2.1 (1.8, 2.5) 3.2 (2.5, 4.1) 3.1 (2.6, 3.7) Total sample size: 42,687 40,673 40,673 40,673 Heterogeneity and publication bias

Cochrane's Q (I2): 445 (94%) 142 (82%) 478 (95%) 279 (90%) Egger's regression (P value): ns .001 ns .001 Trim and fill missing studies: 2 (higher) 5 (higher) 3 (higher) 3 (higher) Trim and fill adjusted prevalence: 9.2 2.6 3.7 3.5

Full DSM-IV Criteria Anselmi 2010 11 - 12 4,448 4.1 -- -- -- Bauermeister 2007 4 - 17 1,897 7.5 -- -- -- Benjasuwantep 2002 6 - 13 353 6.5 -- -- -- Bird 2006e 5 - 13 1,138 7.1 -- -- -- Bird 2006f 5 - 13 1,353 6.4 -- -- -- Cho 2009 6 - 12 1,651 5.9 1.0 0.7 4.1 Costello 2003 9 - 16 1,420 4.1 -- -- -- Döpfner 2008 7 - 17 2,452 2.2 -- -- -- Egger 2006 2 - 5 1,073 3.9 -- -- -- Froehlich 2007 8 - 15 3,082 8.7 2.2 2.0 4.4 Graetz 2001g 6 - 17 3,566 7.0 1.9 1.6 3.5 Kroes 2001 6 - 8 1,317 3.7 -- -- -- Neuman 2005 7 - 18 1,472 6.0 2.4 0.9 2.9 Rasmussen 2004 4 - 18 3,861 5.0 2.3 0.7 2.0 Skounti 2006 7 1,285 7.4 -- -- --


Supplement Table 2 continued Estimated prevalence of DSM-IV ADHD in studies of parent ratings


Full DSM-IV Criteria continued Smalley 2007 16 - 18 6,622 8.5 2.4 0.7 5.4 Todd 2001 12 - 23 4,036 5.9 1.5 0.7 3.7 Tuvblad 2009 9 - 10 1,208 11.3 2.8 3.6 5.0 Waschbusch 2007 5 - 12 835 11.3 3.6 2.5 5.1 Willcutt 2011b 6 - 13 7,874 6.3 2.3 1.0 2.7 Willoughby 2000 9 - 13 1,419 7.2 2.8 1.7 2.7 Overall prevalence (95% CI): 6.1 (5.3, 7.1) 2.2 (1.9, 2.5) 1.3 (0.9, 1.8) 3.6 (3.0, 4.4) Total sample size: 57,616 35,626 35,626 35,626 Heterogeneity and publication bias

Cochrane's Q (I2): 370 (95%) 34 (71%) 116 (91%) 115 (91%) Egger's regression (P value): ns ns ns ns Trim and fill missing studies: 2 (lower) 0 0 0 Trim and fill adjusted prevalence: 5.9 2.2 1.3 3.6

Note: Summary statistics for the meta-analysis are described in detail in the first section of these supplemental materials. Q = Cochrane's Q. aColorado, bAustralia, cSweden, dNorway, eBronx, fPuerto Rico, gone severe or two moderate areas of impairment.


Supplement Table 3 Estimated prevalence of DSM-IV ADHD in males and females based on parent ratings

Estimated Prevalence of ADHD (%) DSM-IV Criteria / Sample Size Total ADHD ADHD-C ADHD-H ADHD-I

Study Male Fem Male Fem Male Fem Male Fem Male Fem Symptom criteria only

Bauermeister 2007 982 915 13.3 7.4 3.7 1.5 6.0 4.4 3.6 1.3 DuPaul 1998 930 1,043 11.0 4.5 3.5 1.0 3.4 1.0 4.0 2.6 Gadow 1997 271 260 8.1 3.8 2.2 0.8 4.8 2.3 1.1 0.8 Gadow 1998 375 386 7.7 3.1 0.8 0.0 0.5 0.3 6.4 2.8 Gadow 1999 272 280 9.9 4.6 2.6 0.7 2.2 1.8 5.1 2.1 Ghanizadeh 2008 800 800 13.6 6.5 2.5 0.5 6.1 3.9 5.0 2.1 Gimpel 2000 137 116 11.7 6.9 7.3 0.0 2.9 4.3 1.5 2.6 Gomez 1999 608 668 14.5 5.7 4.1 1.8 3.6 1.9 6.7 1.9 Graetz 2001 1,775 1,791 10.6 4.4 3.1 0.7 2.4 1.4 5.1 2.3 Kadesjo 2004 453 401 6.6 3.7 1.5 0.7 1.8 1.0 3.3 2.0 Levy 2004 2,167 2,189 18.8 8.0 5.8 2.0 3.0 1.7 10.0 4.2 Magnusson 1999 211 216 6.6 2.3 4.3 0.9 1.9 0.9 0.5 0.5 Pineda 1999 272 268 19.9 12.3 4.8 1.9 9.9 7.1 5.1 3.4 Volk 2009 -- 4,170 -- 12.7 -- 2.8 -- 3.0 -- 7.0 Weiler 1999 110 115 12.7 11.3 6.3 4.3 1.8 0.0 4.5 7.0 Willcutt 2007a 480 490 10.0 7.6 2.5 2.1 5.4 3.5 2.1 2.1 Willcutt 2007b 266 246 13.2 5.3 1.1 0.4 10.5 3.7 1.5 1.2 Willcutt 2007c 178 486 7.3 3.6 1.7 0.6 4.5 2.4 1.1 0.6 Willcutt 2007d 87 106 11.5 2.8 2.3 0.5 8.0 0.9 1.1 1.9 Willcutt 2011b 3,975 3,855 12.7 6.0 3.9 1.9 2.8 1.4 6.0 2.9

Overall prevalence: 11.5 5.9 3.4 1.4 3.9 2.3 4.1 2.4 (95% CI): (9.9, 13.2) (4.7, 7.3) (2.8, 4.1) (1.0, 1.8) (3.0, 5.1) (1.7, 2.9) (3.2, 5.2) (1.8, 3.3)

Total sample size: 14,349 18,801 14,349 18,801 14,349 18,801 14,349 18,801 Q (I2): 136, 87% 248, 92% 62, 71% 62, 69% 122, 85% 98, 81% 134, 85% 183, 90%

Full DSM-IV criteria

Bauermeister 2007 982 915 10.2 4.7 -- -- -- -- -- -- Bird 2006e 589 549 8.8 4.9 -- -- -- -- -- -- Bird 2006f 695 658 9.9 4.3 -- -- -- -- -- -- Costello 2003 3,669 3,005 7.0 1.1 -- -- -- -- -- -- Froehlich 2007 1,515 1,567 11.8 5.4 3.3 1.0 2.8 1.2 5.7 3.1 Kroes 2001 699 618 4.9 2.4 -- -- -- -- -- -- Neuman 2005 923 549 7.4 3.9 2.3 2.1 0.5 1.2 4.5 0.6 Rasmussen 2004 1,915 1,946 7.7 2.4 3.7 0.9 0.9 0.5 3.1 0.9 Skounti 2006 659 626 10.2 4.5 -- -- -- -- -- -- Smalley 2007 3,314 3,308 12.3 4.7 3.6 1.1 0.9 0.5 7.8 3.0 Todd 2001 -- 4,036 -- 5.9 -- 1.5 -- 0.7 -- 3.7 Waschbusch 2007 328 407 18.6 8.1 6.1 2.5 4.0 2.0 8.5 3.7 Willcutt 2011b 3,975 3,855 8.3 4.0 3.0 1.6 1.4 0.6 3.9 1.6 Willoughby 2000 794 625 10.1 3.5 4.3 1.0 2.4 0.8 3.4 1.8


Total sample size: 18,773 22,664 12,764 16,293 12,764 16,293 12,764 16,293 Q (I2): 132, 90% 132, 90% 14, 57% 14, 50% 49, 88% 18, 61% 80, 92% 60, 88%

Note: Summary statistics for the meta-analysis are described in detail in the first section of these supplemental materials. Q = Cochrane's Q. aColorado, bAustralia, cSweden, dNorway, eBronx, fPuerto Rico


Supplement Table 4 Estimated prevalence of DSM-IV ADHD based on teacher ratings


Symptom Criteria only Alloway 2010 10 964 8.0 1.6 5.0 1.5 Amador-C. 2006 4 - 12 653 31.2 5.8 11.2 14.2 Baumgaertel 1995 5 - 12 1,077 17.8 4.8 4.0 9.0 Carlson 1997 5 - 12 2,984 18.9 5.4 2.1 11.4 DuPaul 1998 4 - 19 2,000 21.6 8.4 3.2 10.0 Ersan 2004 6 - 15 261 7.3 3.4 1.5 2.3 Gomez 1999 5 - 11 1,276 8.8 2.1 0.9 5.8 Jané 2006 3 - 6 1,104 8.5 1.7 2.5 4.3 Kashala 2005 7 - 9 1,187 5.9 5.1 0.4 0.4 Magnusson 1999 6 - 8 353 5.1 1.4 0.8 2.8 Merrell 2001 5 - 6 4,148 11.2 2.5 2.9 5.8 Meyer 2004 6 - 15 6,032 19.7 6.1 3.7 9.9 Mugnaini 2006 6 - 7 1,891 12.3 -- -- -- Nolan 2001 3 - 5 413 17.7 7.7 6.5 3.9 Nolan 2001 6 - 12 1,520 15.9 3.3 2.3 10.3 Nolan 2001 13 - 18 1,073 14.8 2.5 0.8 11.5 Servera 2010 6 - 11 1,749 14.8 5.1 2.9 6.8 Thabet 2010 6 - 15 349 18.8 -- -- -- Weiler 1999 6 - 12 225 14.7 4.0 0.4 10.2 Willcutt 2011b 6 - 13 7,874 11.2 3.5 2.0 5.7 Wolraich 1996 5 - 12 8,258 11.4 3.6 2.4 5.4 Wolraich 1998 5 - 12 4,323 16.1 4.7 2.6 8.8 Wolraich 2003 5 - 12 6,171 19.8 7.5 3.1 9.2 Zuddas 2006 6 - 12 1,085 9.2 -- -- -- Overall prevalence (95% CI): 13.3 (11.6, 15.2) 4.0 (3.4, 4.8) 2.6 (2.1, 3.2) 6.6 (5.6, 7.8) Total sample size: 56,970 53,645 53,645 53,645 Heterogeneity and publication bias

Cochrane's Q (I2): 999 (97%) 356 (94%) 264 (93%) 453 (96%) Egger's regression (P value): ns ns ns ns Trim and fill missing studies: 0 0 4 (higher) 0 Trim and fill adjusted prevalence: 13.3 4.0 3.1 6.6

Full DSM-IV Criteria

Mugnaini 2006 6 - 7 1,891 7.1 1.3 2.3 3.5 Skounti 2006 7 1,285 7.9 -- -- -- Willcutt 2011b 6 - 12 7,874 7.2 2.7 1.0 3.5 Wolraich 1998 5 - 12 4,323 6.7 2.9 0.6 3.2 Overall prevalence (95% CI): 7.1 (6.6, 7.5) 2.3 (1.7, 3.2) 1.1 (0.5, 2.3) 3.4 (3.1, 3.7) Total sample size: 15,373 14,088 14,088 14,088 Heterogeneity and publication bias

Cochrane's Q (I2): 2 (0%) 13 (85%) 32 (93%) 1 (0%) Egger's regression (P value): ns ns ns ns Trim and fill missing studies: 1 (lower) 0 0 0 Trim and fill adjusted prevalence: 7.0 2.3 1.1 3.4

Note: Summary statistics for the meta-analysis are described in detail in the first section of these supplemental materials. Q = Cochrane's Q.


Supplement Table 5 Estimated prevalence of DSM-IV ADHD based on teacher ratings in males and females

Estimated Prevalence (%)

DSM-IV Criteria / Sample Size Total ADHD ADHD-C ADHD-H ADHD-I Study Male Fem Male Female Male Fem Male Fem Male Fem

Symptom criteria only Alloway 2010 528 436 8.0 8.0 1.7 1.4 4.4 5.7 1.9 0.9 Carlson 1997 1,562 1,422 25.5 11.6 7.8 2.7 3.1 1.1 14.6 7.9 DuPaul 1998 1,040 948 29.3 13.3 11.6 4.9 4.6 1.6 13.0 6.9 Gomez 1999 608 668 13.8 4.2 3.5 0.9 1.5 0.3 8.9 3.0 Kashala 2005 534 653 7.3 4.7 -- -- -- -- -- -- Magnusson 1999 175 178 9.1 1.1 2.9 0.0 1.7 0.0 4.6 1.1 Merrell 2001 2,168 1,980 15.0 7.1 3.8 1.0 3.9 1.9 7.3 4.2 Meyer 2004 3,154 2,878 22.6 16.5 7.6 4.5 4.2 3.1 10.8 8.9 Mugnaini 2006 952 939 18.7 5.8 -- -- -- -- -- -- Nolan 2001 237 176 21.5 12.5 10.1 4.5 7.6 5.1 3.8 4.0 Nolan 2001 788 939 23.1 8.2 5.3 1.1 3.4 1.1 14.3 6.0 Nolan 2001 573 500 20.1 8.8 4.0 0.8 1.6 0.1 14.5 8.0 Weiler 1999 110 115 20.0 9.6 6.4 1.7 0.9 0.0 12.7 7.8 Willcutt 2011b 3,975 3,855 15.4 7.0 5.3 1.8 2.6 1.4 7.5 3.8 Wolraich 1996 4,102 3,836 16.2 6.1 5.3 1.6 3.8 0.9 7.2 3.5 Wolraich 1998 2,179 2,064 22.8 9.2 7.4 2.1 3.9 1.3 11.5 5.8


Total sample size: 22,865 21,587 21,199 19,995 21,199 19,995 21,199 19,995 Q (I2): 331 (95%) 329 (95%) 139 (91%) 125 (90%) 45* (71%) 108 (88%) 200 (94%) 161 (92%)


Mugnaini 2006 954 937 10.4 3.8 1.9 0.7 4.1 0.4 4.4 2.7 Skounti 2006 659 626 10.3 5.4 -- -- -- -- -- -- Willcutt 2011b 3,975 3,855 10.2 4.0 4.2 1.2 1.4 0.5 4.6 2.3


Total sample size: 5,588 5,418 4,929 4,792 4,929 4,792 4,929 4,792 Q (I2): 0 (0%) 3 (31%) N/A N/A N/A N/A N/A N/A


Supplement Table 6 Estimated prevalence of DSM-IV ADHD based on self-report ratings


Symptom Criteria only

Rasmussen 2002a 13 - 19 497 18.7 4.2 3.2 11.3 Rasmussen 2002b 12 - 14 483 4.6 0.8 3.1 0.6 Willcutt 2011b 13 - 14 723 6.5 1.4 1.9 3.2 Overall prevalence (95% CI): 8.5 (3.3, 19.9) 1.8 (0.7, 4.8) 2.7 (1.9, 3.7) 3.2 (0.9, 11.2) Total sample size: 1,703 1,703 1,703 1,703 Heterogeneity and publication bias

Cochrane's Q (I2): 63 (97%) 14 (86%) 3 (22%) 47 (96%) Egger's regression (P value): ns ns ns ns Trim and fill missing studies: 0 0 0 0 Trim and fill adjusted prevalence: 8.5 1.8 2.7 3.2


Benjet 2009 12 - 17 3,005 1.6 -- -- -- West 2003 15 1,860 1.0 0.1 0.3 0.6 Willcutt 2011b 13 - 14 723 4.3 1.2 0.7 2.4 Overall prevalence (95% CI): 2.0 (0.9, 4.4) 0.5 (0.0, 4.6) 0.5 (0.2, 1.1) 1.3 (0.3, 4.8) Total sample size: 5,589 2,583 2,583 2,583 Heterogeneity and publication bias

Cochrane's Q (I2): 25 (92%) [not computed for fewer than 3 effect sizes] Egger's regression (P value): ns Trim and fill missing studies: 0 Trim and fill adjusted prevalence: 2.0

Note: Summary statistics for the meta-analysis are described in detail in the first section of these supplemental materials. Q = Cochrane's Q. amissouri bBrazil Supplement Table 7 Estimated prevalence of DSM-IV ADHD based on self-report ratings in males and females



Full DSM-IV Criteria West 2003 867 867 1.3 0.7 0.1 0.3 0.3 0.4 1.0 0.2 Willcutt 2011b 370 353 5.7 2.9 1.8 0.6 1.0 0.4 3.0 1.8


Total sample size: 1,237 1,220 1,237 1,220 1,237 1,220 1,237 1,220

Note: Summary statistics for the meta-analysis are described in detail in the first section of these supplemental materials. Heterogeneity calculations not computed for fewer than 3 effect sizes.


Supplement Table 8 Estimated prevalence of DSM-IV ADHD based on different algorithms to combine multiple sources of information


Best Estimate Adewuya 2006 6 - 12 1,112 8.7 2.6 1.2 4.9 Alyahri 2008 6 - 12 1,210 1.3 1.0 0.1 0.2 Amiri 2010 7 - 15 1,658 9.7 7.0 0.9 1.7 Angold 2002 9 - 17 920 2.7 1.3 0.7 0.8 Canino 2004 4 - 17 1,897 3.8 -- -- -- Eapen 2003 6 - 18 329 0.9 -- -- -- Ford 2003 5 - 15 10,438 2.2 1.4 0.2 0.7 Gau 2005 13 - 15 1,070 7.6 -- -- -- Katusic 2005 M = 18.3 5,718 5.9 4.0 0.4 1.5 Leung 2008 10-16 541 3.9 -- -- -- Montiel 2008 4 - 12 1,535 10.0 6.3 2.9 0.8 Petersen 2006 7 - 8 5,563 6.4 -- -- -- Pineda 2001/2003 4 - 17 330 16.7 9.4 0.6 6.7 Rohde 1999 12 - 14 1,022 5.8 2.9 0.8 2.0 Talaei 2010 7 - 9 714 15.3 5.3 4.6 5.3 Willcutt 2011b 6 - 13 7,874 8.0 4.4 0.6 3.0 Zwirs 2007a 6 - 10 662 6.0 -- -- -- Zwirs 2007b 6 - 10 349 5.0 -- -- -- Zwirs 2007c 6 - 10 415 6.0 -- -- -- Zwirs 2007d 6 - 10 615 11.0 -- -- -- Overall prevalence (95% CI): 5.9 (4.7, 7.5) 3.4 (2.4, 4.9) 0.8 (0.4, 1.5) 1.8 (1.1, 2.9) Total sample size: 43,972 32,531 32,531 32,531 Heterogeneity and publication bias

Cochrane's Q (I2): 634 (97%) 299 (97%) 217 (95%) 259 (96%) Egger's regression (P value): ns ns ns ns Trim and fill missing studies: 0 0 3 (higher) 0 Trim and fill adjusted prevalence: 5.9 3.4 1.1 1.8

Or-rule Campbell 2009 1st gr 1,082 N/Ae 5.3 --e 7.6 Owens 2003 9 - 12 440 10.2 3.2 2.0 5.0 Willcutt 2011b 6 - 13 7,874 15.6 5.7 3.3 6.6 Overall prevalence (95% CI): 12.9 (8.5, 19.2) 5.1 (4.1, 6.4) 2.9 (1.9, 4.4) 6.7 (5.8, 7.7) Total sample size: 8,314 9,396 8,314 9,396 Heterogeneity and publication bias

Cochrane's Q (I2): [Not computed 5 (60%) [Not computed 3 (42%) Egger's regression (P value): for fewer than ns for fewer than ns Trim and fill missing studies: three effects] 0 three effects] 0 Trim and fill adjusted prevalence: 5.1 6.7

And-rule Gul 2010 6 - 12 1,126 8.6 0.9 6.1 1.6 Willcutt 2011b 6 - 13 7,874 3.7 0.8 0.6 2.4

Overall prevalence: 5.7 0.8 1.9 2.1 (95% CI): (2.4, 12.6) (0.6, 1.0) (0.2, 17.0) (1.4, 3.0)

Total sample size: 9,000 9,000 9,000 9,000 Q (I2): [Not computed for fewer than three effects]


Supplement Table 8 continued Estimated prevalence of DSM-IV ADHD based on different algorithms to combine multiple sources of information


Parent / Teacher Agreementf Alqahtani 2010 7 - 9 708 4.1 0.7 1.4 2.0 Gomez 1999 5 - 11 1,276 2.4 0.5 0.2 1.6 Gomez 2008 6 - 12 855 2.2 0.4 0.4 1.5 Gul 2010 6 - 12 1,126 8.6 0.9 6.1 1.6 Servera 2010 6 - 11 1,422 3.9 -- -- -- Skounti 2006 7 1,285 6.5 -- -- -- Thabet 2010 6 - 15 349 4.3 -- -- -- Weiler 1999 6 - 12 225 5.8 1.3 0.0 4.4 Willcutt 2011 6 - 13 7,874 4.7 1.0 0.2 1.5 Zuddas 2006 6 - 12 1,085 1.5 -- -- -- Overall prevalence (95% CI): 4.0 (3.0, 5.3) 0.9 (0.7, 1.1) 0.6 (0.1, 3.0) 1.8 (1.4, 2.4) Total sample size: 16,205 12,064 12,064 12,064 Heterogeneity and publication bias

Cochrane's Q (I2): 98 (91%) 6 (12%) 192 (97%) 12 (57%) Egger's regression (P value): ns ns ns ns Trim and fill missing studies: 0 0 0 0 Trim and fill adjusted prevalence: 4.0 0.9 0.6 1.8

Note: Summary statistics for the meta-analysis are described in detail in the first section of these supplemental materials. Q = Cochrane's Q. aMorroccan ethnicity. bSurinamese ethnicity. cTurkish ethnicity. dDutch ethnicity. ePrevalence not reported for overall ADHD or ADHD-H. fFor total ADHD the prevalence indicates agreement between parent and teacher ratings regarding the overall ADHD diagnosis without regard to the specific subtype endorsed by each rater. Prevalence estimates for the subtypes indicate parent and teacher agreement on subtype classification.


Supplement Table 9 Estimated prevalence of DSM-IV ADHD based on different algorithms to combine multiple sources of information



Best Estimate Adewuya 2006 682 430 11.0 5.1 3.2 1.6 1.6 0.5 6.2 3.0 Alyahri 2008 608 602 2.1 0.5 -- -- -- -- -- -- Amiri 2010 877 781 10.8 8.3 8.4 5.4 1.3 0.5 1.1 2.4 Angold 2002 482 438 4.1 1.1 2.1 0.5 1.0 0.2 1.0 0.5 Ford 2003 5,212 5,226 3.6 0.8 2.3 0.5 0.3 0.0 1.0 0.3 Gau 2005 532 538 12.2 3.0 -- -- -- -- -- -- Leung 2008 261 280 5.4 2.5 -- -- -- -- -- -- Montiel 2008 859 676 13.6 5.5 8.4 3.6 4.2 1.3 1.2 0.4 Petersen 2006 2,781 2,782 9.2 3.6 -- -- -- -- -- -- Pineda 2001 184 157 22.8 10.8 13.6 4.5 1.1 0.0 7.1 6.4 Talaei 2010 714 -- 15.3 -- 5.3 -- 4.6 -- 5.3 -- Willcutt 2011b 3,975 3,855 11.3 4.5 6.6 2.2 1.0 1.0 3.7 2.0 Zwirs 2007a 352 310 10.0 2.0 -- -- -- -- -- -- Zwirs 2007b 158 191 8.0 1.0 -- -- -- -- -- -- Zwirs 2007c 202 213 7.0 6.0 -- -- -- -- -- -- Zwirs 2007d 313 312 22.0 1.0 -- -- -- -- -- --

Overall prevalence: 9.3% 2.9% 5.3% 2.0% 1.4% 0.4% 2.5% 1.4% (95% CI): (7.1, 12.1) (2.0, 4.3) (3.5, 8.1) (1.0, 4.0) (0.7, 2.9) (0.2, 1.0) (1.4, 4.5) (0.7, 3.0)

Total sample size: 18,192 16,791 12,985 11,963 12,985 11,963 12,985 11,963 Q (I2): 393 (96%) 205 (93%) 165 (96%) 107 (94%) 119 (94%) 25* (76%) 138 (95%) 82* (93%)

Or-rule Campbell 2009 541 541 N/Ae N/Ae 8.8 4.6 --e --e 9.4 3.8 Willcutt 2011b 3,975 3,855 22.2 10.8 7.4 3.1 4.1 2.4 9.4 5.7



Q (I2): [Not computed for fewer than three studies]

And-rule Gul 2010 611 515 12.8 3.7 1.5 0.2 9.3 2.3 2.0 1.2 Willcutt 2011b 3,975 3,855 5.5 1.9 1.2 0.3 0.9 0.3 3.5 1.2



Q (I2): [Not computed for fewer than three studies]

Agreementf Alqahtani 2010 318 390 6.0 2.6 0.9 0.5 2.2 0.8 2.8 1.3 Gomez 1999 608 668 4.1 0.7 1.0 0.1 0.2 0.1 3.0 0.4 Gul 2010 611 515 12.8 3.7 1.5 0.2 9.3 2.3 2.0 1.2 Skounti 2006 659 626 8.8 4.2 -- -- -- -- -- -- Weiler 1999 110 115 7.3 4.3 2.7 0.4 0.5 0.4 4.5 4.3 Willcutt 2011b 3,975 3,855 6.8 2.5 1.5 0.5 0.3 0.1 2.1 0.8


Total sample size: 6,281 6,169 5,622 5,543 5,622 5,543 5,622 5,543 Q (I2): 37, 87% 16, 69% 3 (0%) 2 (0%) 105 (96%) 26 (85%) 5 (13%) 14 (72%)

Note: Summary statistics for the meta-analysis are described in detail in the first section of these supplemental materials. Q = Cochrane's Q. aMorroccan ethnicity. bSurinamese ethnicity. cTurkish ethnicity. dDutch ethnicity. eCampbell note: Prevalence not reported for overall ADHD or ADHD H. fFor total ADHD the prevalence indicates agreement between parent and teacher ratings regarding the overall ADHD diagnosis without regard to the specific subtype endorsed by each rater. Prevalence estimates for the subtypes indicate parent and teacher agreement on subtype classification.


Supplement Table 10 Estimated prevalence of DSM-IV ADHD in adults Age Sample Estimated Prevalence of ADHD (%) Study Range Size Total ADHD ADHD-C ADHD-H ADHD-I

DuPaul 2001a 18 - 35 197 1.0 0.3 0.5 0.5 DuPaul 2001b 17 - 51 182 2.7 0.3 2.2 0.5 DuPaul 2001c 17 - 49 799 3.4 0.5 2.1 0.8 Faraone 2005 > 18 966 2.6 1.1 1.1 0.7 Heiligenstein 1998 17 - 46 448 4.0 2.2 0.9 0.9 Kessler 2006 18 - 44 3,199 4.4 -- -- -- McKee 2008 16 - 22 1,077 7.5 0.5 2.9 4.1 Murphy 1996d 17 - 84 720 7.4 1.5 3.5 2.4 Ramtekkar 2010 18 - 29 3,193 6.4 1.3 0.7 4.4 Sprafkin 2007 18 - 75 900 6.7 1.6 2.0 3.1 Willcutt 2011ad 18 - 25 2,400 6.9 1.2 1.4 4.3 Overall prevalence (95% CI): 5.0 (4.1, 6.2) 1.1 (0.9, 1.4) 1.6 (1.1, 2.4) 2.4 (1.7, 3.3) Total sample size: 14,081 10,882 10,882 10,882 Heterogeneity and publication bias

Cochrane's Q (I2): 66 (84%) 12 (27%) 48 (81%) 56 (84%) Egger's regression (P value): ns .01 ns ns Trim and fill missing studies: 3 (higher) 2 (higher) 0 2 (higher) Trim and fill adjusted prevalence: 5.7 1.2 1.6 2.6

Note: Summary statistics for the meta-analysis are described in detail in the first section of these supplemental materials. Q = Cochrane's Q. aItaly, bNew Zealand, cUnited States. destimate based on current symptoms were used to match other prevalence studies


Supplement Table 11 Estimated prevalence of DSM-IV ADHD in male and female adults

Estimated Prevalence (%) DSM-IV Criteria / Sample Size Total ADHD ADHD-C ADHD-H ADHD-I

Study Male Fem Male Fem Male Fem Male Fem Male Fem DuPaul 2001a 27 170 7.4 0.3 1.8 0.0 3.7 0.3 3.7 0.0 DuPaul 2001b 37 175 8.1 1.1 1.3 0.0 5.4 1.1 2.7 0.0 DuPaul 2001c 407 391 2.9 3.8 0.2 0.8 2.0 2.3 0.7 0.8 McKee 2008 509 568 9.1 6.1 0.4 0.5 2.9 2.9 5.8 2.6 Ramtekkar 2010 1,811 1,672 7.7 3.8 1.7 0.7 0.8 0.5 5.2 2.6 Sprafkin 2007 450 450 6.9 6.4 1.8 1.3 1.8 2.2 3.3 2.9 Willcutt 2011b 812 1,588 8.8 5.9 2.5 0.8 1.6 1.2 4.7 3.9


Total sample size: 4,053 5,014 4,053 5,014 4,053 5,014 4,053 5,014 Q (I2): 15 (60%) 21 (72%) 11 (46%) 4 (0%) 16 (64%) 23 (74%) 15 (61%) 16 (64%)

Note: Summary statistics for the meta-analysis are described in detail in the first section of these supplemental materials. Q = Cochrane's Q. aItaly, bNew Zealand, cUnited States


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