A Pivotal Response Treatment Packagefor Children With Autism SpectrumDisorder: An RCTGrace W. Gengoux, PhD,a Daniel A. Abrams, PhD,a Rachel Schuck, MA,a Maria Estefania Millan, MA,a Robin Libove, BS,a

Christina M. Ardel, MA,a Jennifer M. Phillips, PhD,a Melanie Fox, MS,b Thomas W. Frazier, PhD,c Antonio Y. Hardan, MDa

abstractOBJECTIVES: Our aim was to conduct a randomized controlled trial to evaluate a pivotal responsetreatment package (PRT-P) consisting of parent training and clinician-delivered in-homeintervention on the communication skills of children with autism spectrum disorder.

METHODS: Forty-eight children with autism spectrum disorder and significant language delaybetween 2 and 5 years old were randomly assigned to PRT-P (n = 24) or the delayedtreatment group (n = 24) for 24 weeks. The effect of treatment on child communication skillswas assessed via behavioral coding of parent-child interactions, standardized parent-reportmeasures, and blinded clinician ratings.

RESULTS:Analysis of child utterances during the structured laboratory observation revealed that,compared with the delayed treatment group, children in PRT-P demonstrated greaterimprovement in frequency of functional utterances (F1,41 = 6.07; P = .026; d = 0.61). Themajority of parents in the PRT-P group (91%) were able to implement pivotal responsetreatment (PRT) with fidelity within 24 weeks. Children receiving PRT-P also demonstratedgreater improvement on the Brief Observation of Social Communication Change, on theClinical Global Impressions Improvement subscale, and in number of words used on a parent-report questionnaire.

CONCLUSIONS: This is the first 24-week randomized controlled trial in which communitytreatment is compared with the combination of parent training and clinician-delivered PRT.PRT-P was effective for improving child social communication skills and for teaching parentsto implement PRT. Additional research will be needed to understand the optimal combinationof treatment settings, intensity, and duration, and to identify child and parent characteristicsassociated with treatment response.

WHAT’S KNOWN ON THIS SUBJECT: There is growing support fornaturalistic developmental behavioral interventions for improvingsocial communication competence in young children with autismspectrum disorder. However, rigorous empirical testing of promisinginterventions is essential for allocating finite treatment resources andimproving patient outcomes.

WHAT THIS STUDY ADDS: This study reveals the efficacy of a pivotalresponse treatment package combining parent training and clinician-delivered intervention for young children with autism spectrumdisorder. The intervention resulted in significant improvements infunctional utterances, vocabulary, and social communicationbehaviors.

To cite: Gengoux GW, Abrams DA, Schuck R, et al. A PivotalResponse Treatment Package for Children With AutismSpectrum Disorder: An RCT. Pediatrics. 2019;144(3):e20190178

aDepartment of Psychiatry and Behavioral Sciences, School of Medicine, Stanford University, Stanford, California;bPGSP - Stanford Psy.D. Consortium, Palo Alto University, Palo Alto, California; and cAutism Speaks, New York, NewYork

Drs Gengoux and Hardan conceptualized and designed the study, supervised data collection andtreatment implementation, and drafted, reviewed, and revised the manuscript; Dr Abrams assistedin the analysis and interpretation of data, drafted the initial manuscript, and critically reviewed thefull manuscript for important intellectual content; Ms Schuck, Ms Millan, Ms Libove, and Ms Ardelcoordinated treatment implementation and data acquisition and reviewed and revised themanuscript; Dr Phillips contributed to study design, acquisition of data by supervising completion ofblinded assessment measures, and revision of the manuscript for important intellectual content;Ms Fox contributed to data acquisition and interpretation, completed analyses of the BriefObservation of Social Communication Change outcome measure, and revised the manuscript forimportant content; (continued)

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The high prevalence of autismspectrum disorder (ASD) in thepediatric population reveals a needfor effective treatment options. Thereis growing support for naturalisticdevelopmental behavioralinterventions (NDBIs), whichincorporate both applied behavioranalysis (ABA) and developmentalprinciples,1 for remediatingsymptoms in young children withASD. However, rigorous empiricaltesting of interventions remainsessential for allocating finitetreatment resources and improvingpatient outcomes. Pivotal responsetreatment (PRT)2 is an NDBI designedto increase child motivation tointeract by focusing on the child’sinterests and rewarding effort withnatural reinforcement.3 Thetreatment involves modelingappropriate language during play andwaiting for the child to attemptcommunication before providingaccess to the preferred activity. It alsotargets pivotal areas of a child’sdevelopment to promote moregeneralized behavioralimprovements. PRT involves trainingparents to perform the intervention,thereby increasing the child’sexposure to intervention across dailyroutines.

Although early behavioralinterventions are designed tocombine clinician-deliveredtreatment with parent training, incommunity practice, children oftenreceive primarily clinician-deliveredtreatment, and providers have limitedtraining in parent-mediatedapproaches.4 Importantly, empiricalevidence from randomized controlledtrials (RCTs) has emerged regardingthe efficacy of both clinician-deliveredPRT and parent training to effectivelyadminister PRT to the child. An RCTrevealed that children with ASDshowed greater improvement in themean length of utterance after3 months of clinician-delivered PRTcompared with a structured ABAapproach.5 Another recent RCT

revealed that, compared witha psychoeducation control group,children with ASD whose parentsparticipated in a 12-week PRTtraining group showed improvementsin frequency of utterances andadaptive communication skills.6

Finally, given evidence that parentfidelity of treatment implementationcan decline after training ends,7

a model to support maintenancebeyond an initial 12-week period iswarranted.

Here we report results from a 24-week RCT of PRT combining parenttraining and clinician-delivered in-home treatment compared witha delayed treatment group (DTG)receiving stable community-basedinterventions. The pivotal responsetreatment package (PRT-P) includeda 12-week intensive phase followedby an additional 12-weekmaintenance phase. In this pilotinvestigation, the effect of thetreatment on child communicationskills is assessed via behavioralcoding of parent-child interactions,standardized parent-report measures,and blinded clinician ratings. Thebenefits of a 24-week PRTintervention have not yet beencompared with those of communitytreatment in a controlled trial.

METHODS

Study Design

This investigation involved a 24-weekRCT in which we examined theefficacy of a PRT-P consisting ofparent training and clinician-delivered in-home intervention intargeting functional communicationdeficits in young children with ASD.This study was approved by StanfordUniversity’s Institutional ReviewBoard and was registered in theclinical trials database(clinicaltrials.gov; identifierNCT02037022). The full protocol isavailable on request. De-identifiedindividual participant data (includingdata dictionaries) will be made

available in addition to studyprotocols, the statistical analysis plan,and the informed consent form. Thedata will be made available afterpublication to investigators whoprovide a methodologically soundproposal for use in achieving thegoals of the approved proposal.Proposals should be submitted toggengoux@stanford.edu. Requests fordata will be available until 5 yearsafter the article publication.

Inclusion and Exclusion Criteria

Participants included children 2 to5 years old with ASD and significantlanguage delay. An ASD diagnosis wasbased on the Autism DiagnosticInterview–Revised,8 the AutismDiagnostic Observation Schedule,Second Edition,9 Diagnostic andStatistical Manual of Mental Disorders,Fifth Edition criteria, and expertclinical judgment. Consistent witha previous PRT trial,6 the expressivelanguage score on the PreschoolLanguage Scale, Fifth Edition (PLS-5)10 had to be at least 1 SD below themean for 2- and 3-year-old children, 2SDs below the mean for 4-year-oldchildren, and 3 SDs below the meanfor 5-year-old children. To limit theinfluence of concomitantcommunication interventions,children were excluded if they had.1 hour of weekly individual speechtherapy, .15 hours of weekly 1:1ABA treatment, or unstableinterventions 1 month beforebaseline or anticipated treatmentchanges during the trial. Additionalexclusion criteria included othersevere psychiatric disorders, geneticabnormality, an active medicalproblem, a primary language otherthan English, or living .50 milesaway. One parent was required toparticipate in parent training. Nochanges in inclusion and exclusioncriteria were applied duringthe study.

Participants

Participants were referred by localprofessionals or recruited through

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flyer distribution and word of mouthand were enrolled between December2013 and July 2016. One hundredforty-four potential subjects werescreened (see Fig 1); 93 familiesenrolled by signing a consent form.Thirty-nine did not meet eligibilitycriteria on the basis of baselinemeasures, and 6 families decided notto participate before randomassignment. Forty-eight subjectswere randomly assigned (PRT-P group:n = 24; DTG: n = 24), and 43 families

(PRT-P group: n = 23; DTG: n = 20)completed the 24-week trial. Oneparticipant in the PRT-P groupwithdrew when the family moved outof state; 4 participants in the DTGwere excluded from final analysesafter significant changes were madeto concomitant therapies during thetrial. The target sample size forending the trial (48) was determinedby power analysis on the basis ofa previous study of PRT parenttraining.6

Approximately 81% of participatingchildren were receiving ABAtreatment (mean hours per week =8.34; SD = 5.6). Ninety-five percentwere in school, primarily in specialeducation classes (79%), with16 hours of school per week onaverage (range: 0–37.5 hours).Language ability in the sample rangedfrom nonverbal to phrase speech, andalmost all of the children werereceiving speech therapy (98%), withan average of 45 minutes ofindividual therapy per week.Participating parents were primarilywomen (79%), and the majority werecollege graduates (84%). The samplewas ethnically diverse, with 28% ofparticipants white, 56% AsianAmerican, 7% Hispanic, 2% nativeHawaiian, and 7% biracial or otherrace. There were no significantdifferences between groups atbaseline on any child measures, withthe exception of the MacArthur-BatesCommunicative DevelopmentInventories (CDI) (Table 1).Differences in the CDI were found forthe CDI words out of 396 measure(PRT-P: 118.2 6 110.9; DTG: 59.0 673.6; t1,41 = 22.09; P = .044) but notfor the CDI words out of 680 measure(PRT-P: 141.9 6 129.9; DTG: 85.6 6105.6; t1,41 = 21.544; P = .130).

Procedures

After informed consent, familiesparticipated in a comprehensiveevaluation that includedpsychological assessments anda review of the medical history toconfirm eligibility. Eligible childrenwere stratified on the basis of sex andwere randomly assigned (1:1) to thetreatment (PRT-P) or control (DTG)group via electronic generation ofrandom numbers (www.randomizer.org) by a senior investigator notinvolved in the trial. All measureswere collected at baseline and atweek 24; the primary measure andsome secondary measures were alsoobtained at week 12. Data weremanaged by using ResearchElectronic Data Capture,11 hosted at

FIGURE 1Consolidated Standards of Reporting Trials form flowchart.

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Stanford University’s Center forClinical Informatics.

PRT-P

The PRT-P treatment consisted of anintensive phase from week 1 to week12, during which parents receivedweekly 60-minute parent trainingsessions and children received10 hours per week of clinician-delivered in-home treatment, anda maintenance phase from week 12 toweek 24, during which parentsreceived monthly 60-minute parenttraining sessions and childrenreceived 5 hours per week of in-hometreatment. The parent trainingcurriculum was based on a standardset of PRT teaching materials andvideo examples.6,7,12,13 Parenttraining was provided by master’s-level clinicians who were supervisedby the first author. In-home treatmentwas provided by bachelor’s-levelclinicians who had demonstratedfidelity of implementation of PRT andwho received weekly supervision (seeSupplemental Information fordetails).

DTG

Children assigned to the DTGcontinued with stable communitytreatments for the 24-week trial andreturned to the clinic at weeks 12 and24 for assessments. After completionof all study measures, families wereoffered PRT parent training and

in-home treatment, similar to thePRT-P intensive phase.

Measures

Diagnostic and Screening Instruments

The Autism DiagnosticInterview–Revised and the AutismDiagnostic Observation Schedulewere administered at baseline toconfirm ASD diagnosis for all studyparticipants. The PLS-5 was used toverify significant language delay atbaseline and as a secondary outcomemeasure at week 24.

Primary Outcome

Child frequency of functionalutterances was assessed during a 10-minute structured laboratoryobservation (SLO) at baseline, week12, and week 24, during whichparents were instructed to try to getthe child to communicate as much aspossible. Consistent with previousresearch,6,7 raters blind to groupassignment tallied the child’s totalfunctional verbal utterances and alsospecified utterance type (ie,unintelligible, imitative, verballyprompted, nonverbally prompted, orspontaneous). Multiple-wordutterances were scored as a singleinstance of communication (seeSupplemental Information fordetails). Two raters independentlyscored at least 30% of the videosrandomly selected from the total set.For functional utterances, intraclass

correlation coefficients (ICCs)indicated excellent (ICC2,1 = 0.94) toacceptable agreement (unintelligible= 0.83; imitative = 0.98; verballyprompted = 0.97; nonverballyprompted = 0.89; spontaneous =0.74).14

Secondary Outcomes

SLO videos were also scored by usingthe Brief Observation of SocialCommunication Change (BOSCC)coding guidelines,15 with high levelsof agreement between independentraters (ICC = 0.863). The BOSCCprovides a systematic method forblinded raters to code video-recordedinteractions and assess change across16 items in 2 domains (ie, socialcommunication symptoms andrepetitive behavior). The BOSCCyields a summary score and a socialcommunication subscore (items 1–8only). Higher scores indicate greaterimpairment; therefore, reduction overtime represents symptomimprovement.

Additional secondary measuresfocused on language andcommunication, as well associalization and global development,included the following: the CDI16

Words and Gestures, the CDI Wordsand Sentences, the Vineland AdaptiveBehavior Scales, Second Edition(Vineland-II)17 communicationsubscale, the PLS-5,10 the MullenScales of Early Learning (MSEL),18 theSocial Responsiveness Scale, SecondEdition (SRS-2),19 and the ClinicalGlobal Impressions20 Severity (CGI-S)and the Clinical Global ImpressionsImprovement (CGI-I) subscales. TheClinical Global Impressions (CGI)ratings were completed by a seniorinvestigator blind to groupassignment and were focused onsocial communication skills.6 SLOvideos were also scored for parentfidelity of PRT implementation,following published methods.6,21

Ratings of parent fidelity were madeon the basis of the same SLO videosused for assessment of utterances but

TABLE 1 Baseline Comparison of Participants With Autism in the PRT-P Group and DTG

PRT-P Group DTG

n 23 20Male/female sex, n 21/2 17/3Age, mean (SD), mo 49.5 (11.2) 47.2 (10.0)MSEL composite score, mean (SD) 49.9 (1.8) 50.9 (5.7)SRS-2 raw score, mean (SD) 95.8 (26.4) 98.3 (25.6)SLO total utterances, mean (SD) 49.9 (30.7) 52.8 (23.9)CGI-S score, mean (SD) 5.4 (0.5) 5.4 (0.6)CDI words out of 396, mean (SD)a 118.2 (110.9) 59.0 (73.6)CDI words out of 680, mean (SD) 141.9 (129.9) 85.6 (105.6)1-on-1 ABA treatment, mean (SD), h per wk 8.9 (5.2) 7.7 (6.1)

PRT-P group ethnicity: white: 6; Asian American: 12 (includes Southeast Asians); native Hawaiian: 1; Hispanic: 2; biracial: 1;and other: 1; DTG ethnicity: white: 6; Asian: 12 (includes Southeast Asians); Hispanic: 1; and other: 1.a No statistical differences between the PRT-P group and DTG on any of the baseline measures, with the exception of theCDI words out of 396; t1,41 = 22.09; P = .044.

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by a different set of raters trainedindependently. Ratings werecompleted by raters blind to groupassignment and time point.Agreement was 87%, and k22 wascalculated to correct for chanceagreement (k = 0.72). Parentscompleted a brief questionnaire toreport their children’s existing autisminterventions at baseline and at week24 along with a weekly concomitanttherapies log to document changes.

Statistical Analyses

Statistical analyses were completedby using IBM SPSS Statistics version24 (IBM SPSS Statistics, IBMCorporation, Armonk, NY). A mixed-effects regression model withtreatment group (PRT-P versus DTG),time (baseline and week 24), andtheir interaction as fixed-effectscovariates was used to examinedifferences between the 2 groups onprimary and secondary outcomemeasures. Mixed-effects regressionmodels were separately computed foreach specific type of utterance.

Additionally, a 3-level model for timewas also examined for the primaryoutcome measure (number ofutterances) and for the BOSCCbecause week 12 data were alsoavailable.

By using the same modelingapproach, secondary analyses werecomputed for the number of wordsproduced out of 396 on the CDIWords and Gestures form, thenumber of words produced out of680 on the CDI Words and Sentencesform, the CGI-S and CGI-I subscales,Vineland-II communication standardscores, the Vineland-II expressivev-scale score (mean of 15 andstandard deviation of 3), the PLS-5,the MSEL expressive language rawscore, the MSEL composite, and theSRS-2 social communication rawscore. These analyses were repeated,controlling for baseline differencesbetween groups when they existed(ie, CDI words produced out of 396).The association between severalbaseline characteristics, including sex,

age, and developmental level, and thekey outcome variables (total childutterances and BOSCC total score)were also investigated by examiningSpearman correlations between thesevariables.

The percentage of parents meeting80% fidelity of implementationcriteria was also computed for eachgroup. Because the sample size wasmodest and because the primarypurpose was to understand thenature of the treatment effects forplanning future studies, a type 1 errorrate of 0.05 was used for all analyses.

RESULTS

Outcome Measures

Children participating in the PRT-Pshowed significantly greater overallimprovement between baseline andweek 24 in total number ofutterances (F1,41 = 6.07; P = .026)compared with children in the DTG(Table 2). Similar treatment effectsare evident across the 3 time points

TABLE 2 Treatment Response of Participants in the PRT-P Group or DTG

Mean (SD) Group 3 TimeInteraction

Cohen’s d (Week 24)

Baseline Week 24 F P

PRT-P Group (n = 23) DTG (n = 20) PRT-P Group(n = 23)

DTG (n = 20)

SLOTotal utterances 49.9 (30.7) 52.8 (23.9) 71.3 (27.3) 53.4 (28.8) 5.808 .026 0.64

BOSCCTotal score 34.3 (7.5) 34.6 (4.2) 26.5 (6.2) 34.4 (4.9) 28.794 ,.001 1.41Social communication subscore 23.8 (4.3) 25.1 (4.0) 18.3 (4.8) 24.63 (3.9) 9.562 .004 1.45

CDIWords produced out of 396 118.2 (110.9) 54.2 (72.3) 194.9 (133.7) 84.4 (93.5) 5.663 .022 0.96Words produced out of 680 141.9 (129.9) 80.2 (105.7) 256.6 (200.1) 112.9 (148.1) 6.039 .018 0.82

Vineland-IIExpressive v-scale score 7.23 (1.9) 6.7 (1.3) 7.6 (2.4) 6.2 (1.6) 3.587 .066 0.58Communication standard score 63.8 (14.8) 62.5 (11.6) 64.9 (16.8) 62.6 (13.9) 0.230 .634 0.15

PLS-5Expressive standard score 58.4 (8.9) 57.9 (7.9) 58.7 (10.2) 56.9 (10.5) 0.384 .539 0.17

MSELMSEL expressive language raw score 18.2 (7.3) 14.9 (7.6) 21.0 (8.7) 17.3 (6.9) 0.082 .775 0.47MSEL composite score 49.9 (1.8) 50.9 (5.7) 51.1 (3.9) 53.8 (10.1) 0.425 .519 0.35

SRS-2Social communication raw score 95.8 (26.4) 98.3 (25.6) 91.9 (22.8) 93.1 (27.4) 0.061 .806 0.05

CGICGI-S 5.4 (0.5) 5.4 (0.6) 5.13 (0.7) 5.40 (0.5) 5.914 .019 0.44CGI-I — — 2.6 (0.8) 3.4 (0.7) 6.858 ,.001 1.06

CDI: df (1, 40), controlling for baseline difference; CDI 396: df (1, 39), F = 4.459, P = .041; CDI 680: df (1, 39), F = 4.134, P = .049; Vineland-II: df (1; 39); PLS-5: df (1, 41); MSEL: df (1, 41); CGI: df(1, 41), focused on social and communication symptoms. df, degrees of freedom; —, not applicable.

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(baseline, week 12, and week 24;F2,40 = 3.70; P = .034; Fig 2), withdifferences between the groupsbeginning at week 12 (F1,41 = 7.224;P = .010). Group differences weredriven primarily by the significantincrease in nonverbally promptedutterances in the PRT-P group (F1,41 =16.409; P , .001; see SupplementalTable 3).

Improvement in the PRT-P group wassimilarly observed on the BOSCCsocial communication subscale(Table 2) and in the BOSCC total score(Fig 3). Results remained unchangedfor the BOSCC total score whenanalyses were completed across the3 time points (baseline, week 12, andweek 24; F2,39 = 17.597; P , .001;Fig 3), with improvement beingobserved at week 12 (F1,40 = 4.345;P = .044). A significant treatmenteffect was also observed for the CDIwords produced out of 396 and CDIwords produced out of 680 measures,even when controlling for baselinedifferences. The treatment effect wasalso significant on the CGI-S subscalefor social communication symptoms(F1,41 = 5.91; P = .019). Significantgroup differences at week 24 were

also evident on the CGI-I subscale(F1,41 = 6.86; P # .001). There was notreatment effect for the PLS-5, theMSEL, the SRS-2, or the Vineland-IIcommunication subscale. Althoughnot statistically significant, effect-sizecalculations suggested a medium-sizetreatment effect for the Vineland-IIexpressive v-scale score. No adverseeffects were noted in either group.

No parent met fidelity of PRTimplementation at baseline. At week24, 21 of 23 parents (91%) in thePRT-P group met fidelity of PRTimplementation. Only 1 parent in theDTG met PRT fidelity at week 24;although this parent did not meetfidelity at baseline, she did showsome PRT skills at study entry.

Predictors of Response

Exploratory analyses were used toexamine whether demographic orclinical characteristics predictoutcome in the PRT-P group, asmeasured by changes in the totalnumber of utterances (SLO) and theBOSCC total score. There were noeffects of age, sex, or baselinedevelopmental characteristics (ie,MSEL composite or visual reception t

score) on treatment outcomes (P ..10 across all measures). A correlationwas observed between the baselinedevelopmental quotient (MSEL ageequivalent divided by chronologicalage) and changes on the BOSCC totalscore (N = 22; R = 0.483; P = .023).This association was likely related tothe contribution of the nonverbalsubscales (nonverbal developmentalquotient: N = 22; R = 0.685; P ,.001). Importantly, the positivecorrelation indicates that lower MSELscores at baseline were associatedwith greater improvement on theBOSCC.

DISCUSSION

The results of this RCT of PRT-Psupport the efficacy of combiningparent training with clinician-delivered in-home treatment forimproving functional communicationskills of young, minimally verbalchildren with ASD. The PRT-Presulted in greater improvement intotal frequency of child functionalutterances and social communicationbehaviors during SLO, greaterincrease in the number of wordsproduced on the basis of a parentchecklist, and greater improvement insocial communication function, asassessed by a blinded clinicianratings. The PRT-P retention rate(96% over 24 weeks) suggests strongacceptability of this treatment in ourdiverse sample. These positivefindings, on the basis of multiplemetrics, support PRT as an efficaciousearly-intervention approach, addingto the growing literature supportingPRT as an established interventionfor young children with ASD.23

Improvement in total functionalutterances in this controlled trialcorroborates the previous findingsthat PRT-group parent trainingimproves functional utterances.6

Significant results were drivenprimarily by improvement inintelligible nonverbally promptedutterances, and it is encouraging that

FIGURE 2Number of utterances by group during SLO at baseline (PRT-P group: mean 6 SE = 49.9 6 6.13; DTG:mean 6 SE = 52.7 6 5.08), week 12 (PRT-P group: mean 6 SE = 75.3 6 4.31; DTG: mean 6 SE =50.2 6 5.45), and week 24 (PRT-P group: mean 6 SE = 71.3 6 5.66; DTG: mean 6 SE = 53.4 6 5.96).F2,40 = 3.765; P = .032.

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PRT helped children generate novellanguage without verbal prompting.The current study was also 1 of thefirst efforts to employ the BOSCCcoding scheme as a measure oftreatment response in a clinical trial.Children receiving the PRT-Pdemonstrated a significant decreasein BOSCC scores (indicatingimprovement in socialcommunication behaviors) duringboth the intensive phase and themaintenance phase of the trial,whereas children in the DTG did notshow significant change despitecontinued involvement incommunity-based treatments.Evidence that overall socialcommunication skills improved, evenwhen parents were taught primarilyhow to elicit functional verbalcommunication, is consistent withprevious PRT research revealingbroad collateral improvements fromtargeting the pivotal area ofmotivation for communication.24

Although, in the current study, weapplied the BOSCC coding algorithmto existing videos of parent-childinteraction,15 our findings alsosupport the promise of the BOSCC

coding scheme as a sensitive measurefor capturing changes in socialcommunication behaviors as a resultof a behavioral treatment.

Additional evidence of improvementafter the PRT-P came from parentreport of greater change in thenumber of words produced and fromblinded clinician ratings of greatersocial communication improvement.Similar gains have been documentedin a previous PRT study for the CDI25

and for the CGI.6 The CDI isa quantitative communicationmeasure widely used in research onlanguage development, and evidenceof CDI improvement suggests that thelanguage gains made by children inthe study were recognizable andcommonly used words.26,27 This isparticularly important given thatchildren showed a high level ofunintelligible speech at baseline(∼70% of utterances on the basis ofthe SLO). Finally, the improvementobserved on the CDI, a standardizedlanguage measure, is consistent withthe changes observed during the SLOand supports the use of ratingsderived from laboratory observation

of adult-child interactions as anoutcome measure in interventionstudies used to target languagedeficits.

No benefits from the PRT-P comparedwith the DTG were observed on theVineland-II communication subscale,the MSEL, or the SRS-2. Theseobservations are not consistent withprevious studies of PRT in whichimprovement on the Vineland-IIcommunication subscale,6 the MSEL,7

and the SRS-228 were found.However, medium-size treatmenteffect was observed on the Vineland-II expressive subscale. Mixed findingshave been reported in previousstudies of parent-training andclinician-delivered intervention.29–31

Trials of greater treatment intensityor even longer duration may benecessary, especially in children whoare severely affected. Interestingly, inthis study, lower MSEL scores atbaseline, particularly in the nonverbaldomain, were found to predict greaterpositive response on the BOSCC. Thisfinding is different from previousreports of predictors of response toPRT6,32,33 but suggests optimism thatthe combined parent and clinician-delivered model may have promisefor children who have significantdevelopmental delays at baseline.

A high percentage of parents in thePRT-P group met PRT fidelity ofimplementation criteria aftertreatment. This finding is consistentwith previous research documentingthat parents can learn PRT ina relatively short amount of time.6,34

Although many existing early-intervention programs provideminimal parent training, the additionof this critical component may be keyto child progress and is cost-efficientrelative to intensive clinician-delivered programs. The hybridparent-training and clinician-delivered intervention isunderstudied despite having uniquepotential advantages, includingimmediate access to trainedclinicians, generalization across daily

FIGURE 3BOSCC total score from SLO by group at baseline (PRT-P group: mean 6 SE = 34.3 6 1.6; DTG:mean 6 SE = 34.6 6 0.93), week 12 (PRT-P group: mean 6 SE = 29.9 6 1.25; DTG: mean 6 SE =33.93 6 1.35), and week 24 (PRT-P group: mean 6 SE = 26.5 6 1.35; DTG: mean 6 SE = 34.4 6 1.13).F2,39 = 17.597; P , .001. Improvement was observed at week 12 (F1,40 = 4.345; P = .044).

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routines, and long-term cost savings,compared with clinician-deliveredservice models.

There were several limitations in thetrial. The combination of parent-training and clinician-delivered PRTmakes it impossible to determinewhich component had the greatesteffect on child progress. The samplesize was moderate, which limitedpower to evaluate complex patternsand predictors of treatment response.Children in the control group wereoffered PRT immediately after theconclusion of the 24-week trial;therefore, the long-term effects of thecontrol condition were not evaluated.Also, group differences in wordsproduced on the CDI at baselinenecessitated controlling for thisvariable in the analyses. Evaluation ofgeneralized changes in childutterances, social communicationskills (BOSCC), and parent fidelitywas limited by use of the same SLOvideo probe to evaluate each variable.Finally, in the current study, we usedPRT primarily to targetcommunication skills, althoughPRT may be effective in addressingother aspects of autismsymptomotology29,35,36 as well ascomorbid symptoms.37

CONCLUSIONS

The current study advances supportfor NDBIs by demonstrating

that children with ASD andsignificant language delaybenefit from the combination ofparent training and clinician-delivered PRT. Compared withstable community treatment,the PRT-P provided measurablebenefits for enhancing childsocial communication skillsacross a diverse set of objectiveoutcome measures. Furthermore,children who received PRTshowed greater overallimprovement in socialcommunication function onthe BOSCC, suggesting thatPRT that was focused onimproving functional verbalutterances produced generalizedeffects in a range ofsocial communication behaviors.Additional research will be neededto understand the optimalcombination of treatment providersand intensity as well as to identifywhich children and parents are mostlikely to benefit. Given promisingpreliminary data from uncontrolledtrials, future RCTs should also beused to examine the effects of PRT onother symptom areas28,35,37 and onpotential biomarkers of treatmentresponse.38–40

ACKNOWLEDGMENTS

We acknowledge the studyclinicians and participating

families for their contributions to theproject.

ABBREVIATIONS

ABA: applied behavior analysisASD: autism spectrum disorderBOSCC: Brief Observation of Social

Communication ChangeCDI: MacArthur-Bates

Communicative DevelopmentInventories

CGI: Clinical Global ImpressionsCGI-I: Clinical Global Impressions

ImprovementCGI-S: Clinical Global Impressions

SeverityDTG: delayed treatment groupICC: intraclass correlation

coefficientMSEL: Mullen Scales of Early

LearningNDBI: naturalistic developmental

behavior interventionPLS-5: Preschool Language Scale,

Fifth EditionPRT: pivotal response treatmentPRT-P: pivotal response treatment

packageRCT: randomized controlled trialSLO: structured laboratory

observationSRS-2: Social Responsiveness

Scale, Second EditionVineland-II: Vineland Adaptive

Behavior Scales,Second Edition

Dr Frazier provided statistical expertise to aid in the analysis and interpretation of data and critically reviewed the manuscript for important intellectual content;

and all authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

This trial has been registered at www.clinicaltrials.gov (identifier NCT02037022).

DOI: https://doi.org/10.1542/peds.2019-0178

Accepted for publication May 23, 2019

Address correspondence to Grace W. Gengoux, PhD, Division of Child and Adolescent Psychiatry, Department of Psychiatry and Behavioral Sciences, School of

Medicine, Stanford University, 401 Quarry Rd, Stanford, CA 94305-5719. E-mail: ggengoux@stanford.edu

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

Copyright © 2019 by the American Academy of Pediatrics

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

FUNDING: Supported by a grant from the National Institute on Deafness and Other Communication Disorders (DC01368902; principal investigator: Dr Hardan). Dr

Abrams received additional support from a National Institute of Mental Health K01 Mentored Research Scientist Development Award (MH102428). Data management

8 GENGOUX et al by guest on August 13, 2021www.aappublications.org/newsDownloaded from

was supported by the National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health through

grant UL1 TR001085. Funded by the National Institutes of Health (NIH).

POTENTIAL CONFLICT OF INTEREST: Dr Frazier is employed by Autism Speaks; the other authors have indicated they have no potential conflicts of interest to

disclose.

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DOI: 10.1542/peds.2019-0178 originally published online August 6, 2019; 2019;144;Pediatrics 

Frazier and Antonio Y. HardanRobin Libove, Christina M. Ardel, Jennifer M. Phillips, Melanie Fox, Thomas W. Grace W. Gengoux, Daniel A. Abrams, Rachel Schuck, Maria Estefania Millan,

Disorder: An RCTA Pivotal Response Treatment Package for Children With Autism Spectrum

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Disorder: An RCTA Pivotal Response Treatment Package for Children With Autism Spectrum

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