REVIEW ARTICLESA Systematic Review of Early Intensive Intervention
for Autism Spectrum Disorders
AUTHORS: Zachary Warren, PhD,a,b Melissa L.
McPheeters, PhD, MPH,c,d Nila Sathe, MA, MLIS,cJennifer H. Foss-Feig, MA,e Allison Glasser, BA,c andJeremy Veenstra-VanderWeele, MDb,f,g
a

Departments of Psychiatry and Pediatrics, bVanderbilt Kennedy
Center/Treatment and Research Institute for Autism Spectrum
Disorders, cVanderbilt Evidence-Based Practice Center, Institutefor Medicine and Public Health, and dDepartment of Obstetrics
and Gynecology, Vanderbilt Medical Center, eDepartment of
Psychology and Human Development, and fDepartments of
Psychiatry, Pediatrics, and Pharmacology, gCenter for Molecular
Neuroscience, Vanderbilt University, Nashville, Tennessee
KEY WORDS
autism spectrum disorders, early intervention, behavioral
intervention
ABBREVIATIONSASD—autism spectrum disorder
AHRQ—Agency for Healthcare Research and Quality
ADOS—Autism Diagnostic Observation Schedule
UCLA—University of California Los Angeles
EIBI—early intensive behavioral intervention
SOE—strength of the available evidence
RCT—randomized controlled trial
ESDM—Early Start Denver Model
We acknowledge that all authors of this article meet authorshipcriteria and have made substantial contributions to conception
and design, acquisition of data, or analysis and interpretation of
data; have participated in drafting the article or revising it
critically for important intellectual content; and have given final
approval of the version to be published.
The authors of this article are responsible for its content.
Statements in the report should not be construed asendorsement by the Agency for Healthcare Research and Qualityor the US Department of Health and Human Services.
www.pediatrics.org/cgi/doi/10.1542/peds.2011-0426
doi:10.1542/peds.2011-0426
Accepted for publication Mar 1, 2011
Address correspondence to Zachary Warren, PhD, Vanderbilt
University, 230 Appleton Place/PMB 74, Nashville, TN 37203-5721.
E-mail: zachary.warren@vanderbilt.edu

abstract
CONTEXT: Early intensive behavioral and developmental interventions
for young children with autism spectrum disorders (ASDs) may enhance developmental outcomes.
OBJECTIVE: To systematically review evidence regarding such interventions for children aged 12 and younger with ASDs.
METHODS: We searched Medline, PsycINFO, and ERIC (Education Resources Information Center) from 2000 to May 2010. Two reviewers
independently assessed studies against predetermined inclusion/
exclusion criteria. Two reviewers independently extracted data regarding participant and intervention characteristics, assessment techniques, and outcomes and assigned overall quality and strength-ofevidence ratings using predetermined criteria.
RESULTS: Thirty-four unique studies met inclusion criteria. Seventeen
studies were case series; 2 were randomized controlled trials. We
rated 1 study as good quality, 10 as fair quality, and 23 as poor quality.
The strength of the evidence overall ranged from insufficient to low.
Studies of University of California Los Angeles/Lovaas– based interventions and variants reported clinically significant gains in language andcognitive skills in some children, as did 1 randomized controlled trial ofan early intensive developmental intervention approach (the Early
Start Denver Model). Specific parent-training approaches yielded
gains in short-term language function and some challenging behaviors. Data suggest that subgroups of children displayed more prominent gains across studies, but participant characteristics associated with greater gains are not well understood.
CONCLUSIONS: Studies of Lovaas-based approaches and early intensive behavioral intervention variants and the Early Start Denver Model
resulted in some improvements in cognitive performance, language
skills, and adaptive behavior skills in some young children with ASDs,
although the literature is limited by methodologic concerns. Pediatrics
2011;127:e1303–e1311

PEDIATRICS (ISSN Numbers: Print, 0031-4005; Online, 1098-4275).
Copyright © 2011 by the American Academy of Pediatrics
FINANCIAL DISCLOSURE: Dr Warren has received researchsupport from the Marino Autism Research Institute, Autism Speaks,
and the Simons Foundation; and Dr Veenstra-VanderWeele hasreceived research support from Autism Speaks, the American
Academy of Child and Adolescent Psychiatry, NARSAD, Seaside
Therapeutics, Roche Pharmaceuticals, and Novartis. The otherauthors have indicated they have no financial relationships
relevant to this article to disclose.
COMPANION PAPERS: Companions to this article can be found on
pages e1312 and e1322 and online at www.pediatrics.org/cgi/
doi/10.1542/peds.2011-0427 and www.pediatrics.org/cgi/doi/
10.1542/peds.2011-0428.

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Autism spectrum disorders (ASDs) arecharacterized by impairments in social interaction, behavior, and communication. Although once considereduntreatable, findings published by
Lovaas1 in 1987 suggested that with intensive intervention using applied behavioral analysis, some children may
experience a degree of improvement.
That report, in which “recovery” of justless than 50% of a subgroup of young
children who were receiving intensive
intervention was described, initiated a
growing body of research. Results ofindividual studies have suggested thatsome children who enter into intensive
autism-specialized intervention services at young ages may show larger
gains in terms of cognitive and adaptive functioning and early educational
attainment than children who do notreceive such services.2–6 This research
led to a reconceptualization of ASDs as
a group of disorders marked by plasticity and heterogeneity and for which
there was hope for better outcomesfor some children who receive appropriate intervention. Subsequent research has focused on social communication and behavioral impairments
and used highly structured approaches, developmental approaches
that deliver intervention within naturalcontexts, and integrative approaches.
There continues to be no global consensus on what treatment strategies
are most effective for patients with
ASDs, although it is clear that chronic
management is often necessary to
maximize independence and quality oflife. Children frequently receive combinations of interventions that may include behavioral, educational, andmedical therapies as well as allied
health and complementary approaches. For many children, behavioral interventions form the cornerstone of their treatment. As results ofstudies on behavioral interventions
that present a range of outcomes fore1304

potentially different subgroups of children continue to be published, it is imperative to summarize the evidence sothat parents and care providers canmake informed decisions for specificchildren.
In this systematic review we examined
the available published evidence regarding the effectiveness of early intensive
behavioral and developmental interventions for children with ASDs. This review
is a component of an Agency for Healthcare Research and Quality (AHRQ)–
commissioned comparative-effectiveness
review of therapies for children with
ASDs that was conducted by the Vanderbilt Evidence-Based Practice Center. The
full comparative-effectiveness review7 isavailable at www.effectivehealthcare.
ahrq.gov.

METHODS
Search Strategy
We searched Medline via the PubMedinterface, PsycINFO (psychology/psychiatry literature), and ERIC (Education Resources Information Center)(educational literature) from 2000 to
May 2010 using controlled vocabularyterms and key words related to ASDs
and therapy-related terms. We also
hand-searched the reference lists of
all included articles to identify additional studies and reviewed clinical trials related to therapies for ASDs.
Study Selection
We developed study inclusion and exclusion criteria in consultation with anexpert panel of clinicians, researchers, and educators involved in the careof children with ASDs. We included all
study designs except single case reports and required that studies include at least 10 participants younger
than 13 years of age with a diagnosis of
ASD. Given concerns about diagnostic
certainty in very young children, we
also included studies with children

younger than 2 years if they included
children who were at risk for an ASD.
Studies had to be published after or in
the year 2000, coincident with the revision of the Diagnostic and Statistical
Manual of Mental Diseases, Fourth Edition8 and widespread implementationof gold-standard assessment tools including the Autism Diagnostic Observation Schedule (ADOS)9 and the Autism Diagnostic Interview-Revised10
over the same time frame.
Characterization of Studies
We considered interventions to beearly intensive behavioral and developmental if their approach was primarily behavioral and if they werecomprehensive (ie, targeted multiple
areas of functioning). Studies of intensive interventions that were focusedon single target areas (ie, joint attention,
imitation) or delivered primarily in educational settings were addressed elsewhere in the full review7 (see www.
effectivehealthcare.ahrq.gov).
We further classified studies into 1 of 3
categories: (1) University of California
Los Angeles (UCLA)/Lovaas– based interventions and approaches that areoften termed early intensive behavioral intervention (EIBI) in the literature; (2) comprehensive interventions
for children younger than 2 years; and(3) parent-training protocols. We notethat the studies in the first category
used a range of specific methodologies, but they all emphasized core tenets of intensive (ie, many hours perweek) approaches and often through1-on-1 instruction.
Data Extraction
Using standardized forms, 2 investigators independently extracted data regarding study design; descriptions of
the study populations, comparisongroups, and intervention; and baselineand outcome data. We also extracted
data about harms or adverse effects of

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therapies. We captured data on the
conduct of assessments to inform theevaluation of quality. Principal outcomes of interest included effects oncore symptoms of ASDs and othersymptoms commonly associated with
ASDs, including cognitive functioning
and behavioral challenges.
Study-Quality Assessment● study design (eg, randomized con-trolled trial [RCT], group design);● diagnostic approach (eg, ADOS, Au-

tism Diagnostic Interview-Revised,clinical diagnosis, combination);● participant

ascertainment andcharacterization (eg, baseline characteristics assessed);● intervention description (eg, manu-

Two investigators independently assessed each study by using a prespecified quality-assessment form developed and tested by the review teamwith input from experts in the field. We
evaluated the following elements witha series of yes/no questions related toeach of them:
TABLE 1 Domains Used to Assess Strength of
Evidence
Risk of bias: Reflects issues in study design andconduct that could result in biased estimatesof effect
Consistency: Reflects similarity of effect sizes
seen across studies; consistency cannot be
assessed when only 1 study is available
Directness: Reflects the relationship between theintervention and the ultimate health outcomeof interest
Precision: Reflects the level of certainty aroundthe effect observed

alized intervention, treatment description, fidelity measurement);● outcomes measurement (eg, stan-

dardized measures, blinded assessment, multiple informants); and● statistical analysis (eg, appropriate

statistical methodology).
Disagreements between assessors
were resolved through discussion toreach consensus, and studies could
receive an overall score of good, fair,or poor. The full quality tool and approach to assessment are available in
the full report7 (see www.effective
healthcare.ahrq.gov), as are assessments for each individual study.
We also assessed the strength of theavailable evidence (SOE), which is ourdegree of confidence that the observed
effect of an intervention is unlikely tochange with further research. The SOE
can be regarded as insufficient, low,
moderate, or high. SOE assessments
were based on consideration of 4 domains (Table 1). Our full methodology
and algorithm for structuring the SOE
are presented in the full AHRQ report7(see www.effectivehealthcare.ahrq.gov).
Role of the Funding Source
The topic of therapies for children with
ASDs was nominated by the Centers
for Medicare and Medicaid Services
and Autism Speaks and selected by the
AHRQ for a comparative-effectiveness
review by the Vanderbilt EvidenceBased Practice Center. A task-order officer from the AHRQ provided technicalassistance during the conduct of theevidence report and commented on report drafts.
Data Synthesis
Considerable heterogeneity in the interventions and outcome measuresused in studies that met our inclusion
criteria precluded a meta-analysis. We

TABLE 2 Summary of Results
Study Design/Quality

Study Results and Overall Strength of Evidence

UCLA/Lovaas–based
interventions and EIBI
variants

Intervention

1 RCT/fair quality3; 3 nRCTs/fair quality12,19,34;
5 prospective cohorts/3 of fairquality4,33,37; 2 retrospective cohorts/poor
quality14,38; 6 prospective caseseries5,11,13,16,21,26; 6 retrospective caseseries20,22,25,28,29,35,39

Comprehensive approaches
for children ⬍2 y old

1 RCT/good quality2; 1 nRCT/fair quality15;
2 prospective case series32,39

Parent training

3 RCTs/fair quality17,18,43; 1 nRCT/fairquality15; 3 prospective case series23,24,36

Young children who received high-intensity interventions (⬎30 h/wk for 1–3 y
by well-trained therapists) displayed improvements in areas of cognitive,
language, and adaptive functioning; subgroups of children displayed apositive response to this intervention, although this subgroup has not yet
been clearly described; there have been few randomized studies; few haveused approaches as outlined in treatment manuals; there have been
variations in interventions delivered and participant characteristics withinstudies; strength of evidence for UCLA/Lovaas–based intervention and EIBI
variants in affecting language, cognitive, educational, and adaptive
outcomes and ASD symptom severity is low
Improvements in cognitive, language, and adaptive behavior skills have been
seen over 2 y of ESDM intervention; ESDM findings have not yet been
replicated, and it is unclear how core ASD symptoms change in responseto treatment; strength of evidence for comprehensive interventions forchildren ⬍2 y of age is currently insufficient
There is some indication of short-term improvements in language, social, andadaptive skills for children whose parents receive training in these areas;
there has been a lack of standardized measures and baseline differencesamong participants in some studies; data have not yet demonstrated longterm functional improvements across domains for any specific form of
training; strength of evidence for changing core ASD deficit areas is
insufficientnRCT indicates non-randomized controlled trial.

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Nonduplicate articles
identified in searches

Articles excluded
n = 3406

n = 4120● Literature search: n = 3779
● Hand search/grey literaturesearch: n = 341
Full-text articles excludedan = 531• Participants not within age range
n = 293• Not original research

Full-text articles
reviewedn = 714n = 135• Ineligible study sizen = 406• Not relevant to key questionsn = 285• Unable to abstract datan = 16

Unique full-text
articles included inreviewn = 183 (comprising
159 unique studies)

Unique full-text articles included in theearly intensive behavioral anddevelopmental literaturen = 34

FIGURE 1
Location of studies of early intensive behavioral and developmental intervention. a The total number ofarticles in the exclusion categories exceeds the number of articles excluded because most of thearticles fit into multiple exclusion categories.

summarized characteristics of study
populations and interventions andused descriptive statistics to reportstudy outcomes.

RESULTS
Search Results
Among 4120 articles located for thefull review, 382–6,11–43 (comprising 34
unique studies) met study inclusion
criteria and addressed early intensive
behavioral and developmental interventions (Fig 1).
UCLA/Lovaas–Based Interventions
and EIBI Variants
Among the 23 unique studies fromwhich UCLA/Lovaas– based interventions and EIBI variants were reported,
8 were rated as being of fair quality*and 15 were of poor quality (Table 2).†
The 1 RCT on the UCLA/Lovaas– based
treatment that met inclusion criteria*Refs 3, 4, 12, 16, 33, 34, 37, 41, 42, and 44.
†Refs 5, 6, 11, 13, 20, 21, 25, 26, 28–31, 35, 38, and 40.

e1306

was considered to be of fair quality.3 This
study, the first attempted replication of
Lovaas’ manualized intervention to use
random assignment, a standardized assessment battery, and explicit accounting of intervention hours, compared aclinic-based method to a parent program. The study randomly assigned 28
children with a mean IQ of 51 to either an
intensive treatment group (UCLA/Lovaas
model with an average of 25 hours/weekof individual treatment per year with reduced intervention over the next 1–2
years) or a parent-training group (3–9months of parent training). Gains in IQ
were much more tempered than those in
Lovaas’ original noncontrolled study.1
Children in the treatment group gained amean of 15 IQ points in comparison withthe relatively stable cognitive functioning of the control group, although average IQ in the treatment group remainedin the impaired range. Most of the children who demonstrated large IQ gains
were within the subgroup diagnosed

with pervasive development disordernot otherwise specified, whereas children with classically defined autistic
disorderdemonstratedmodestimprovements. Although the study replicatedcognitive improvements for some children as seen in Lovaas’ studies, it revealed a less dramatic effect for the population of children for whom thisapproach is often recommended (ie,children with classically defined autistic
disorder) compared with what was reported previously. An additional study
that attempted to approximate an RCTformat45 did not meet methodologic inclusion criteria in this capacity and, assuch, was addressed in the moderatorsof-treatment-effect portion of the full
review.
Seven prospective cohort studies andnonrandomized trials were available
on UCLA/Lovaas– based or EIBI methodologies, but none made the same
comparisons in terms of either interventions or populations. Hayward etal34,41 examined the progress of children who received either intensive
clinic-directed UCLA/Lovaas– based intervention or an intensive parentmanaged model over the course of 1
year. At follow-up, children in bothgroups had improved significantly in
IQ, nonverbal IQ, language use/understanding, and most areas of adaptivefunctioning with the exception of dailyliving skills, but there were no differences between the groups.
Two studies compared intensive
center-based treatment to communitycare. Howard et al37 studied preschoolaged children who received intensive
behavior analytic treatment, intensive“eclectic” intervention, and general intervention in public early-intervention
programs. Groups were assigned via
educational placement teams that specifically included parent input. Controlling for age at diagnosis and combinedparental education, children in the intensive behavior analytic group dem-

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onstrated significant improvements inall areas assessed at follow-up, including an average IQ of 89 (41-point improvement over baseline) and a 24point difference from the combinedmean of the other intervention groups.
Significant differences between theeclectic and general-intervention
groups were not present at follow-up.
Findings suggest substantial improvement via an intensive approach foryoung children with autism; however,important differences in group assignment at baseline, difficulties with systematic measurement overtime, thelack of reported treatment fidelity or
adherence characteristics, and thesmall number of children in the comparison group limit interpretation ofthese findings.
These results were echoed in anotherstudy4 of 42 children in which those
who received the Lovaas intervention
had significantly higher IQs and adaptive behavior skills at follow-up compared with children in undefinedcommunity care. Receptive language
improvements were not significant,and expressive language skills and socialization scores were not different
for the 2 groups at year 3. Twelve of the
21 children in the Lovaas group had IQs
higher than 85 compared with 7 of 21
in the eclectic treatment group at outcome. Likewise, more children in the
Lovaas group were in typical schools
subsequent to intervention (17 vs 1),
although this specific outcome may
have been attributable to factors, including differences in socioeconomic
status and family constellation, thatwere evident between the groups.
One study33 of 2 centers compared aneclectic approach to EIBI-based intervention alone. Children received 8hours of intervention per day and wereassessed over 1 year. Significant
group differences were noted in language/communication and reciprocalsocial interaction measures; bothgroups showed decreases in symptom
tallies, but there were more substantial decreases in the UCLA/Lovaas–
based group. No significant differences in IQ change were reported. In a
subsequent study on diagnostic stability31 with unclear sample overlap, mostchildren who received the intervention
continued to display scores in the ASD
range on the ADOS (n ⫽ 53).
Finally, 1 study tried to assess the roleof intensity of the intervention on outcomes. Reed et al12 studied the effectiveness of varying-intensity homebased and Lovaas– based programs
that offered primarily 1-to-1 teaching.
Assignment to high-intensity or lowintensity interventions (30 vs 13 hours/
week on average) was based on geographic location. Children in the highintensity group had higher ability andcognitive scores and lower autism severity scores at baseline. At thefollow-up assessment 9 to 10 months
after beginning the intervention, children who received the high-intensity
intervention demonstrated statistically significant improvements in intellectual and educational functioning.
Children who received the lowintensity intervention demonstrated
statistically significant changes in educational functioning and nonsignificant improvement in cognitive functioning. The only significant difference
between the groups was improved educational functioning associated withhigh-intensity intervention.
Three additional cohort studies6,14,38 provided inconsistent data on the benefit of
behavioral approaches, but all 3 of themhad substantial risk of bias. Case seriesof early-intervention approaches13,22,25,26,40
had mixed results, likely in part becauseof the substantial heterogeneity of interventions examined even within individual
studies, little or no control of concomitant interventions, and poor fidelity to
any given approach. Outcomes in thesestudies were more likely to be parent-

reported and not based on validated
tools.
Several chart reviews and other retrospective analyses have been used to understand treatment patterns and effects.5,20,21,28–30 Interpretation of findings
is most appropriately confined to noting that some children who receive intervention have displayed improvements during intervention in cognitive,
adaptive, and autism-specific impairments, that characteristics of starting
treatment and baseline abilities arecorrelated with improvement in someinstances, and heterogeneity in termsof improvement is quite common. One
chart review of 322 children served ina large catchment area,29 however,provided some evidence for the feasibility of providing intensive behavioral
interventions on a larger scale. Given
the methodologic limits, including lackof clearly defined intervention characteristics, lack of a comparison group,
retrospective collection, and lack of
key measures for certain children atcertain times, the intervention results
were limited.
Comprehensive Intervention
Approaches for Children Younger
Than 2 Years
We identified 4 articles2,15,32,39 withunique study populations that addressed treatment approaches forchildren younger than 2 years: 2 of thestudies were prospective case series32,39; 1 was a nonrandomized controlled trial of fair quality15; and 1 wasan RCT of good quality (Table 2).2
The Dawson et al2 trial evaluated theeffectiveness of the Early Start Denver
Model (ESDM), an intervention approach in which applied behavior analysis techniques are blended within afunctional developmental framework,for young children (mean age: 23
months) with ASDs. After 2 years of intensive intervention, children who received the ESDM displayed signifi-

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cantly larger IQ gains compared withthose in a community sample of children who received less-intensive intervention. Children in the experimentalgroup also demonstrated significantly
larger gains in adaptive behavior than
did controls. Although the authors also
reported diagnostic shifts within the
spectrum in the sample (ie, autism topervasive development disorder-not
otherwise specified), these shifts were
not matched with clinically significant
improvements in terms of ADOS severity scores or measurements of repetitive behaviors.
The ESDM has also been studied in an
early effectiveness trial39 wherein the research team compared distance learning and live instruction for communitybased therapists implementing
intervention and training parents. Results suggest that both modalities
were effective in teaching therapists toimplement and train parents. There
were significant child gains over timeand across modalities; however, theresults also suggested that implementation with fidelity required specificand explicit supervision. Thus, although promising in terms of treatment efficacy and extension to ayounger population of children with
ASDs, training demands for broad implementation seem substantial. In addition, the average age for enrollment wasclose to 2 years of age. As such, questions
remain about how this model would apply
to children younger than 2 years.
In another evaluation of an earlyintervention approach, parents of 51
preschool-aged children suspected ofhaving an ASD participated in the
Hanen More Than Words program either immediately or after a delay.15 Investigators’ operationalization of “suspected ASD” included identification of
language delay and concerns about social behavior by a pediatrician and/or
a speech and language therapist,
which resulted in inclusion of children
e1308

without ASDs within the intervention andcontrol groups. Investigators grouped
pervasive development disorder-not
otherwise specified and other developmental concerns under a category of“non– core autism.” After the intervention period, reported language use
was substantially higher for children
in the intervention group, and bothchildren with core autism and non–core autism demonstrated improvements. No group differences were
found for ADOS scores or behavior issues. It is notable that more children in
the intervention group had ASDs, andchildren in the intervention group had
also received more “substantial intervention” outside of the treatment context. Thus, although potential benefit
from parent training in social communication for young children with ASDs
was demonstrated, the unique impactof this program for specific children
remains unclear.
A prospective case series by Wetherby
and Woods32 served as a preliminary
study for the Early Social Interaction
Project, which emphasizes a parentimplemented individualized curriculum in a natural environment. The authors found significant within-groupdifferences from before to after thetest on social-communication measures in the early-social-interactiongroup. The number of children considered verbal also increased in the treatment group. These findings suggestthat the Early Social Interaction Project has a positive effect on ASD symptoms, but findings have been limited bya lack of baseline comparisons andlack of documentation of parental
implementation.
Parent Training
Of the 7 studies17,18,23,24,27,36,43 on parent training, 417,18,28,43 included comparison groups; 3 of these studies17,18,43 were of fair quality (Table 2).

Three case series addressed parenttraining approaches.23,24,36
Three RCTs in this category17,18,43 compared parent training to eclectic approaches or pivotal response training.
Drew et al18 compared the effects of ahome-based, parent-delivered intervention aimed at improving social
communication and managing challenging behavior for 12 children with
ASDs with a community-based control
intervention group of 12 children. One
year after treatment initiation, parents
in the parent-training group reported
that their children used more words
than those in the community group.
There were no group differences on nonverbal IQ, autism symptom severity,
or words/gestures observed duringfollow-up assessment. Children in thetreatment group unexpectedly lost IQ
points during the study, whereas thosein the control group demonstrated relatively stable cognitive abilities, althoughchildren in the treatment group had ahigher IQ at study initiation.
Aldred et al17 compared a social communication parent-based intervention
with treatment as usual. Parents participated in initial workshops, monthly
intervention sessions for which videotaped interactions were reviewed, and6 months of maintenance visits. Twelve
months after baseline, blinded evaluations revealed improvements on ADOS
scores, and there was substantial improvement within the social domain,increased expressive vocabulary, andimproved communication-related behaviors coded during interactions.
Language gains were most prominent
in younger, lower-functioning children.
A lack of standardized measures of developmental performance, including
baseline cognitive skills, and challenges in understanding and defining“treatment as usual” limit interpretation of the findings.
In a later report of this model, 152 children were randomly assigned to treat-

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ment as usual or treatment as usualplus parent training.43 Time intreatment-as-usual interventions was
similar across groups, as were thetypes of interventions used. Similar
numbers of children in both groups experienced diagnostic shifts from core
autism to other diagnoses on the ASD
spectrum. Teacher ratings of language
and communication after intervention
were not significantly different between groups, although ratings ofparent-child interactions by independent assessors were positive for children in the social-communicationgroup. Parent ratings of language andsocial communication were also morepositive in the parent-training group.
Finally, Stahmer and Gist27 examinedthe effects of a parent education support group with a parent education
program that focused on pivotal response training, a treatment program
designed to enhance core skill areas in
autism by using naturalistic interactions. Involvement in the intervention
was successful in changing parenting
techniques and perceived language
gain. However, the small sample size,lack of randomization, wide variationin children served, and the lack of objectively assessed changes in child behavior limit the reported results.

DISCUSSION
The evidence related to early intensive
behavioral and developmental interventions comes primarily from 2 overlapping, but quite different, approaches: (1)UCLA/Lovaas– based intervention and
EIBI variants; and (2) a developmentally
focused comprehensive approach thatuses the principles of applied behavior
analysis (ie, the ESDM) geared toward
very young children.2,3 Individual studies
of both approaches revealed greater improvements in cognitive performance, language skills, and adaptive behavior whencompared with broadly defined eclectic
treatments in subgroups of children.

In general, however, there have been
too few studies of either approach toassert that observed estimates of effect for either approach are unlikely tochange with future research. With arelatively larger (albeit still inadequate) body of literature, UCLA/
Lovaas– based intervention and EIBI
variant studies have revealed positive
shifts in language, adaptive, cognitive,and educational outcomes, but ourconfidence (strength of evidence) inthat effect is low because of the needfor additional, confirmatory research,a lack of high-quality RCTs, and nostudies that have directly compared effects of promising manualized treatment approaches. The evidence basefor interventions for very young children, including the ESDM, is insufficient; there has been only 1 RCT, although results of this study werepositive and the study warrants replication. On balance, however, the combined research on UCLA/Lovaas–
based interventions and the ESDM
suggests a benefit of early intensive
approaches for some children thatshould continue to be studied.
Less-intensive interventions that provide parent training also may be usefulfor younger children with ASDs, particularly for improving social communication, language use, and, potentially,
symptom severity and family functioning, but the current evidence base forsuch treatment remains insufficient.17,18,27 Although parent-training
programs can modify parenting behaviors during interactions, data arelimited about their contribution to
specific improvements in the shortterm and long-term beyond simple
language gains for some children.
The few available studies used interventions that varied from study to
study. Furthermore, outcomes assessed in these studies were frequently short-term, indirect (intermediate) measures.

One powerfully replicated finding
across the available literature is thatmany children who receive early intensive intervention, across methodologies, will not demonstrate dramatic
gains in social, cognitive, adaptive, andeducational functioning. In addition,
many children who do show robust
gains in certain domains (ie, cognitive
functioning or educational attainment) also continue to display otherprominent areas of impairment. At thesame time, although dramatic improvements in standardized scores
have been observed in only a subset ofchildren to date, it is important to notethat even small improvements in standardized outcomes may translate intolarge, meaningful improvements inquality of life for children and theirfamilies. As such, early intensive behavioral and developmental approaches have significant potential
but require further research. Specifically, research to better characterize
subgroups of children who responddifferently to individual approaches ismuch needed to make informed
choices about which intervention ismost likely to be beneficial for specificchildren.
We note that this review did not incorporate a selection of studies with fewer
than 10 participants, many of which used
the single-subject design methods thatare common in the behavioral literature.
Summary information on these studies
is available in other reviews.46 Furthermore, a particular challenge of conducting a systematic review of therapies for
ASDs is the heterogeneity of the children
within this spectrum disorder and thematching heterogeneity of populations
across studies. Further complicating
our assessment was the variety of intervention techniques and outcome measurements applied in this population.
The field of autism research is relatively young and growing, and as the
body of literature develops further it is

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likely that research methods and studies will coalesce in a way that will provide substantially more confidence inthe evidence. At present, a paucity of
research leaves us with individual
studies that suggest promising outcomes but a critical need for replication, extension, and controlled studies of the factors that moderate
treatment outcome. Thus, the low
and insufficient strength of evidence
reported in this review should not beinterpreted as evidence that the interventions are not effective but,rather, as encouragement for additional research before effectivenesscan be established.

CONCLUSIONS
There is not yet adequate evidence to pinpoint specific behavioral intervention approaches that are the most effective forindividual children with ASDs. Authors ofindividual studies have reported positive
outcomes from early and intensive behavioral and developmental intervention
in cognitive performance, language
skills, and adaptive behavior when delivered over substantial intervals of time(ie, 1–2 years) compared with broadly
defined eclectic treatments. Variability
in terms of response to such approaches seems great with subgroupsof children who demonstrate more moderated response. To date, our ability todescribe and predict these subgroups islimited.

ACKNOWLEDGMENTS
This project was supported by the
AHRQ (contract number HHSA 290 2007
10065 I). Dr Warren has received research support from the National Institute of Mental Health, the Eunice Kennedy Shriver National Institute of Child

Health and Human Development, theMaternal and Child Health Bureau,
the National Science Foundation, and
the AHRQ; and Dr VeenstraVanderWeele has received researchsupport from the National Institute of
Mental Health, the Eunice Kennedy
Shriver National Institute of Child
Health and Human Development, and
the AHRQ.
We are grateful for the contributions of
Wendy Stone, PhD, who provided guidance and mentorship including insight
into the development of key questions
and interpretation of the data. Allison Nahmias, MEd, was a tireless andpositive part of the team, extracting
data and providing input into the review process. We also appreciate thecontributions of the parents who
participated as we formulated ourapproach.

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PEDIATRICS Volume 127, Number 5, May 2011
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e1311

A Systematic Review of Early Intensive Intervention for Autism Spectrum
Disorders
Zachary Warren, Melissa L. McPheeters, Nila Sathe, Jennifer H. Foss-Feig, Allison
Glasser and Jeremy Veenstra-VanderWeele
Pediatrics 2011;127;e1303
DOI: 10.1542/peds.2011-0426 originally published online April 4, 2011;

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A Systematic Review of Early Intensive Intervention for Autism Spectrum
Disorders
Zachary Warren, Melissa L. McPheeters, Nila Sathe, Jennifer H. Foss-Feig, Allison
Glasser and Jeremy Veenstra-VanderWeele
Pediatrics 2011;127;e1303
DOI: 10.1542/peds.2011-0426 originally published online April 4, 2011;

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Pediatrics is the official journal of the American Academy of Pediatrics. A monthly publication, it
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