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WannapaschaiyongP, etal. BMJ Paediatrics Open 2025;9:e003282. doi:10.1136/bmjpo-2024-003282
Open access
Predictors of successful Picture
Exchange Communication System
training in children with
communication impairments: insights
from a real- world intervention in a
resource- limited setting
Prakasit Wannapaschaiyong , Thitaporn Vivattanasinchai,
Awassada Wongkwanmuang
To cite: WannapaschaiyongP,
VivattanasinchaiT,
WongkwanmuangA. Predictors
of successful Picture Exchange
Communication System training
in children with communication
impairments: insights from
a real- world intervention in
a resource- limited setting.
BMJ Paediatrics Open
2025;9:e003282. doi:10.1136/
bmjpo-2024-003282
Received 18 December 2024
Accepted 28 February 2025
Department of Pediatrics,
Faculty of Medicine Siriraj
Hospital, Mahidol University,
Bangkok, Thailand
Correspondence to
Dr Prakasit Wannapaschaiyong;
prakasit. wan@ mahidol. ac. th
Original research
© Author(s) (or their
employer(s)) 2025. Re- use
permitted under CC BY- NC. No
commercial re- use. See rights
and permissions. Published by
BMJ Group.
ABSTRACT
Background Children with communication
impairments—such as autism spectrum disorder or
global developmental delay—face signicant challenges
affecting their emotional and behavioural development.
The Picture Exchange Communication System (PECS)
is an augmentative communication tool designed to
enhance their skills. However, its effectiveness can vary
in resource- limited settings. This study aimed to identify
predictors of successful PECS training among children with
communication impairments in such environments.
Methods This retrospective study analysed records of 61
children with communication impairments who underwent
PECS training at Siriraj Hospital in Bangkok, Thailand, from
2020 to 2023. Success was dened as achieving PECS
phase 3 prociency and a Clinical Global Impression–
Improvement score of 1–3 after 1 year. Logistic regression
identied predictors of successful outcomes based on
demographic, clinical, family and training- related factors.
Results After 1 year, 46% (28 out of 61) of the children
achieved successful PECS outcomes. Signicant predictors
of success were lower severity of communication
impairment (Clinical Global Impression–Severity ≤4;
adjusted OR= 15.24, p = 0.002), higher frequency of
PECS sessions (>6 times per year; OR = 9.11, p = 0.010),
higher family income (≥20,000 baht per month; OR = 9.83,
p = 0.024) and frequent home practice (≥3 times per
week; OR = 7.02, p = 0.066).
Conclusions In resource- limited settings, factors
such as severity of impairment, intensity of intervention,
socioeconomic status and caregiver involvement
signicantly inuence the success of PECS training.
Tailored interventions and strategic resource allocation
are crucial to optimise communication outcomes for these
children.
INTRODUCTION
Communication is a fundamental skill for
human development and learning. However,
certain paediatric populations experience
communication impairments that hinder
their ability to express themselves and
comprehend their environment. One such
group is children with autism spectrum
disorder (ASD), which has a prevalence
as high as 1 in 36 children.1 Other groups
WHAT IS ALREADY KNOWN ON THIS TOPIC
⇒The Picture Exchange Communication System
(PECS) is a widely used augmentative and alterna-
tive communication method for children with autism
spectrum disorder or other developmental disorders,
but evidence of its effectiveness in resource- limited
settings is scarce.
⇒Previous research has suggested that baseline lan-
guage abilities, communication severity and therapy
intensity can inuence PECS outcomes.
WHAT THIS STUDY ADDS
⇒Unlike previous studies that focused primarily on
PECS phase progression, this study uniquely denes
‘success’ using both mastery of PECS phase 3 and
measurable improvements in social communication.
⇒In a real- world, resource- limited context, lower
severity of impairment (Clinical Global Impression–
Severity; CGI- S), more frequent PECS training ses-
sions, higher family income and consistent home
practice emerged as strong predictors of successful
outcomes.
HOW THIS STUDY MIGHT AFFECT RESEARCH,
PRACTICE OR POLICY
⇒Clinicians can use communication severity (CGI- S≤4)
to prioritise referrals and personalise intervention
intensity.
⇒Emphasising frequent in- hospital sessions and ro-
bust caregiver support for home practice can im-
prove communication gains even in settings with
limited resources.
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affected by communication impairments include those
with global developmental delay (GDD) or intellectual
disabilities (IDs).
Language deficits in children can precipitate emotional
and behavioural problems. A meta- analysis by Yew and
O’Kearney demonstrated that children with communica-
tion challenges have a 2.26- fold increased risk of exter-
nalising behaviours compared with peers with typical
communication skills.2 These behaviours include aggres-
sion, defiance, self- harm and property destruction. This
may be attributed to their inability to communicate needs
effectively, leading to misaligned caregiver responses and
triggering frustration and aggressive emotions.3 Concur-
rently, communication impairments hinder participation
in social activities and peer interactions, contributing to
internalising behavioural issues such as depression and
anxiety.4 Yew and O’Kearney’s study also indicates a 1.84-
fold higher risk of internalising behavioural problems in
these children compared with those with normal commu-
nication abilities.2
Speech therapy is essential for children with commu-
nication impairments to promote language develop-
ment and mitigate associated emotional and behavioural
issues. However, its efficacy depends on multiple factors,
including the age at intervention, intensity and frequency
of therapy, family involvement, utilisation of advanced
technologies, and the severity of the child’s communica-
tion deficits.5 6 In some instances, speech therapy alone
may be insufficient to fully develop communication skills
or address the accompanying behavioural and emotional
challenges.
To address these challenges, augmentative and alter-
native communication (AAC) systems are employed.
AAC provides tools and methods to assist individuals
with severe communication difficulties in expressing
themselves effectively.7 Among the various AAC methods,
the Picture Exchange Communication System (PECS) is
widely used.
PECS was developed by Andy Bondy and Lori Frost
in 1985 to help individuals with communication impair-
ments, particularly children with ASD or other devel-
opmental disorders, communicate more effectively. It
involves using picture cards to express needs or thoughts,
reinforced by principles of positive reinforcement and a
supportive learning environment.7–10 Numerous studies
have demonstrated that PECS enhances requesting and
initiating communication skills in children with autism8 9
and reduces inappropriate behaviours such as repetitive
actions and negative expressions.10
Previous research has identified various factors influ-
encing PECS training outcomes. Koudys et al examined
predictors such as initial language abilities and found
that children with higher baseline skills progressed
further in PECS phases.11 However, studies focusing on
resource- limited countries are scarce, highlighting a gap
in understanding how resource limitations impact PECS
effectiveness.
Since 2020, the Division of Child Development and
Behavior at the Department of Pediatrics, Faculty of
Medicine Siriraj Hospital, has implemented PECS
training for children with communication impair-
ments. This programme includes children with autism,
GDD or hearing impairments who face challenges with
speech therapy. Despite the growing number of patients
needing PECS training, the hospital has only one trained
instructor responsible for both PECS training and
other developmental stimulation programmes, leading
to prolonged waiting times. Moreover, not all children
benefit from PECS, and some fail to achieve the targeted
communication goals.
This study aimed to identify specific predictors associ-
ated with successful PECS training outcomes in children
with communication impairments. By understanding
these predictors, we can inform strategies to optimise
intervention programmes in resource- limited settings.
The findings may help develop criteria for patient refer-
rals, reduce waiting times and improve overall training
outcomes.
MATERIALS AND METHODS
Study design and population
This retrospective chart review aimed to identify predic-
tive factors associated with the success of PECS training
among children with communication impairments.
We included paediatric patients who underwent PECS
training at the Department of Pediatrics, Siriraj Hospital,
between 2020 and 2023. Eligible participants were chil-
dren who had completed at least 1 year of PECS training
during this period and had complete medical records.
The required sample size was calculated using
G*Power software, assuming an OR of 2.62 based on
prior research,11 a type I error rate of 0.05 and a power of
80%. This calculation resulted in a minimum of 55 partic-
ipants. To account for potential data loss, we added 10%,
bringing the total to 61 participants.
PECS training procedure
PECS training follows a structured progression designed
to develop communication skills step by step. It consists
of six phases, each focusing on different aspects of func-
tional communication:9
Phase 1: Basic exchange—The child learns to exchange
a single picture for a desired item.
Phase 2: Increasing spontaneity—The child learns to
travel to a communication partner to exchange pictures
independently.
Phase 3: Picture discrimination—The child learns
to select from two or more pictures to request desired
items, demonstrating the ability to distinguish between
different symbols.
Phase 4: Sentence structure—The child learns to
construct simple sentences using a picture- based commu-
nication strip (eg, “I want+item”).
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WannapaschaiyongP, etal. BMJ Paediatrics Open 2025;9:e003282. doi:10.1136/bmjpo-2024-003282
Open access
Phase 5: Responding to questions—The child learns to
answer “What do you want?” using their picture exchange
system.
Phase 6: Commenting—The child expands communi-
cation skills by using pictures to describe things, answer
questions or make observations.
Among these phases, phase 3 is a critical milestone,
as it marks the transition from basic picture exchange
to intentional communication through picture discrim-
ination. Mastery of this phase is essential for developing
functional communication skills beyond simple requests.
Therefore, achieving proficiency in phase 3 is often used
as a key criterion for defining successful PECS training in
previous studies.8 11
Since PECS is a structured programme, all children
begin at phase 1 and progress sequentially through the
phases based on their individual learning pace. Training
is conducted systematically to support children in
mastering phase 3 and beyond.
To facilitate this progression, structured PECS training
sessions are implemented in a clinical setting.
In routine practice, PECS training sessions were
conducted at the hospital every 4 weeks, though sched-
uling varied depending on parental compliance. Each
session lasted 45–60 min, adjusted to the child’s engage-
ment and progress. During these sessions, therapists
focused on reinforcing PECS use, assessing progress and
introducing higher- level skills when appropriate.
Given the crucial role of home- based reinforcement in
PECS training, parental involvement was an integral part
of the intervention. During each hospital session, parents
received individual coaching from therapists, focusing
on PECS implementation strategies, reinforcement tech-
niques and ways to generalise PECS use in daily routines.
Caregivers were encouraged to practise PECS daily as part
of the child’s routine communication, with each session
typically lasting 15–30 min, depending on the child’s
engagement and response. To track adherence, parents
were asked to maintain a logbook, recording how many
days per week PECS was practised and in which daily situ-
ations it was implemented. These records were reviewed
during follow- up visits to provide guidance and address
challenges in home implementation.
Data collection
After obtaining ethical approval, data were meticulously
extracted from medical records using a standardised data
collection form to ensure consistency and accuracy. The
information collected comprised the following:
►Demographic details: The children’s sex and their
age at the initiation of PECS training.
►Clinical characteristics: Developmental and behav-
ioural diagnoses, severity of impairments, comorbidi-
ties and concurrent treatments.
►PECS training details: Frequency of PECS training
sessions at the hospital and frequency of PECS prac-
tice at home.
Pretraining and post- training language develop-
ment was evaluated using the Denver II Developmental
Screening Test. The developmental quotient (DQ) was
calculated as the developmental age divided by the
chronological age, multiplied by 100.12 Social commu-
nication outcomes and the severity of communication
impairments were assessed using the Clinical Global
Impression–Severity (CGI- S) and the CGI–improvement
(CGI- I) scales.13 To ensure reliability and minimise varia-
bility, the same developmental- behavioural paediatrician
performed both assessments.
In routine clinical practice, patients are scheduled for
follow- up every 4–6 months, and at each clinical visit,
these assessments are conducted to monitor progress.
However, for this study, only preassessment data (before
initiating PECS training) and postassessment data (1 year
after training began) were analysed to ensure consistency
in evaluation time points.
The CGI- S scale was used to assess the baseline severity
of each child’s communication and social impairments.
This scale rates severity on a 7- point rating:
►Normal (1): The child frequently uses spontaneous
communication behaviours for diverse purposes,
including initiating and maintaining interactive
exchanges across various contexts.
►Borderline (2): The child uses expressive language
for interactive social communication but occasionally
demonstrates one- sided or awkward interactions.
►Mild (3): The child can request, initiate and take
turns fluently in familiar contexts.
►Moderate (4): The child occasionally initiates
requests or expresses opinions with support but lacks
social intent for sharing information.
►Marked (5): The child predominantly communi-
cates through simple requests or labelling, often
only in response to prompts and initiates commu-
nication primarily in highly motivated or repetitive
contexts.
►Severe (6): The child seldom attempts communica-
tion, and when attempts are made, they often involve
unusual vocalisations or echolalia without commu-
nicative intent.
►Most severe (7): The child exhibits minimal to no
observable communication behaviours.
The CGI- I scale was used to assess changes in commu-
nication and social skills postintervention. This scale also
employs a 7- point rating:
►Very much improved (1): Significant and consistent
progress in social communication, accompanied by a
noticeable reduction in CGI- S.
►Much improved (2): Clear and consistent progress in
social communication, potentially with a reduction in
CGI- S.
►Minimally improved (3): Some observable improve-
ment in communication, though CGI- S may remain
unchanged.
►No change (4): No discernible improvement in social
communication.
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►Minimally worse (5): Minor regression or loss of previ-
ously acquired communication skills, insufficient to
increase CGI- S.
►Much worse (6): Clear regression in natural commu-
nication skills, potentially corresponding to an
increase in CGI- S.
►Very much worse (7): Significant and substantial
regression in communication skills, leading to a
notable increase in CGI- S.
Both scales have demonstrated moderate to strong
inter- rater reliability, with weighted kappa values of 0.517
for the CGI- S and 0.650 for the CGI- I.13 Their inclusion
allowed for a comprehensive evaluation of the severity
of communication impairments at baseline and enabled
tracking of meaningful changes following PECS training.
The criteria for success in PECS training were
defined as achieving proficiency in PECS phase 3 and
obtaining a CGI- I score between 1 and 3. While PECS
phase 3 measures a child’s ability to differentiate and
select symbols to request items, it does not fully capture
broader social communication improvements.9 14 Many
children may learn to exchange pictures correctly but
struggle with spontaneous communication, turn- taking
or social interaction beyond requesting. The CGI- I scale
addresses this limitation by providing a clinician- rated
measure of overall social communication progress.
By integrating both measures, this study ensures that
success is not solely defined by reaching a technical
milestone in PECS but also by demonstrating real-
world communication gains that reflect meaningful
behavioural change.
Statistical analyses
Data were analysed using IBM SPSS Statistics, V.26 (IBM).
Descriptive statistics summarised demographic and clin-
ical characteristics. Categorical variables were presented
as frequencies and percentages, while continuous varia-
bles were expressed as means with SD or medians with
IQRs. Differences between the successful and unsuc-
cessful groups were evaluated using χ2 or Fisher’s exact
tests for categorical variables and independent t- tests for
continuous variables.
Variables with p values ≤0.1 from univariate analyses
were included in a multivariate logistic regression model
using the backward stepwise method to identify indepen-
dent predictors of successful PECS training. Adjusted ORs
with 95% CIs quantified associations. Receiver operating
characteristic curve analyses were performed for signifi-
cant continuous variables—specifically, the CGI- S score,
receptive language DQ, and expressive language DQ—
to determine optimal cut- off points and assess predictive
accuracy using the area under the curve (AUC).
Patient and public involvement
Patients or the public were not involved in the design,
conduct, reporting or dissemination plans of this
research.
RESULTS
Participant demographics and clinical characteristics
From 2020 to 2023, 110 children with communication
impairments participated in PECS training at Siriraj
Hospital. Among these, 61 children met the eligibility
criteria for inclusion in this study, which required
completing at least 1 year of PECS training and having
complete medical records (table 1). All 61 eligible partic-
ipants were analysed, with no missing data throughout
the study process. The median age at the initiation of
PECS training was 5.92 years (IQR: 4.59–7.71 years).
Among these children, 35 (57.4%) were male, and 26
(42.6%) were female. The vast majority, 59 children
(96.7%), had IDs or GDDs. Additionally, 34 children
(55.7%) were diagnosed with ASD, and 10 (16.4%) had
hearing impairments. Prior to PECS training, the median
receptive language DQ was 24.00 (IQR: 16.67–34.52),
and the median expressive language DQ was 18.75 (IQR:
11.57–29.13).
PECS training outcomes
1 year after initiating PECS training, 35 children (57.4%)
achieved proficiency in phase 3 or higher of the system
(table 2). According to the CGI- I scale, 29 children
(47.5%) demonstrated significant improvement in social
communication, indicated by CGI- I scores between 1 and
3. Post- training assessments revealed minimal changes in
language abilities. The median receptive language DQ
increased to 27.27 (IQR: 16.34–41.40), while the median
expressive language DQ increased to 19.05 (IQR: 11.66–
30.00). The median differences for receptive and expres-
sive language DQs were 0.00 (IQR: 0.00, 4.89) and 0.00
(IQR: –3.60, 3.80), respectively.
Relationship between PECS phase and CGI-I scores
A cross- tabulation was conducted to examine the rela-
tionship between PECS Phase three proficiency and
social communication improvements, as measured by
CGI- I scores (table 3). Among the 61 participants, 35
(57.4%) achieved PECS phase 3 or higher, while 29
(47.5%) demonstrated significant improvement in social
communication (CGI- I scores 1–3).
Of the 35 children who attained PECS phase 3 or higher,
28 (80.0%) had CGI- I scores between 1 and 3, while 7
(20.0%) had CGI- I scores between 4 and 7. Among the 26
children who did not reach phase 3, 1 (3.8%) had CGI- I
scores between 1 and 3, whereas 25 (96.2%) had CGI- I
scores between 4 and 7.
Predictive accuracy of key variables
Receiver operating characteristic curve analyses were
conducted to evaluate the predictive accuracy of key
pretraining factors. The CGI- S score, receptive language
DQ and expressive language DQ demonstrated signifi-
cant predictive value for training success.
The CGI- S score yielded an AUC of 0.781 (95% CI:
0.661 to 0.900, p<0.001), indicating good predictive accu-
racy. At a cut- off of ≤4, the CGI- S score had a sensitivity
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WannapaschaiyongP, etal. BMJ Paediatrics Open 2025;9:e003282. doi:10.1136/bmjpo-2024-003282
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of 70% and a specificity of 82% for predicting successful
PECS training (figure 1). The receptive language DQ had
an AUC of 0.672 (95% CI: 0.535 to 0.809, p=0.014); a cut-
off of ≥21 provided a sensitivity of 71.4% and a specificity
of 52% (figure 2). The expressive language DQ showed
an AUC of 0.686 (95% CI: 0.551 to 0.820, p=0.007); at
a cut- off of ≥17, it achieved a sensitivity of 71.4% and a
specificity of 61% (figure 3).
Comparison between successful and unsuccessful groups
Participants were categorised into ‘successful’ and
‘unsuccessful’ groups based on achieving PECS phase
3 proficiency and obtaining a CGI- I improvement score
between 1 and 3 (table 4). Of the 61 participants, 46%
(28 children) were classified as successful, while 54%
(33 children) were classified as unsuccessful. Significant
differences were observed between the two groups.
Success rates differed by sex. Female participants were
more likely to succeed compared with males (57.1% vs
30.3%, p=0.035). Regarding diagnoses, children with
ASD were less likely to achieve success than those without
ASD (39.3% vs 69.7%, p=0.017). Conversely, children
with hearing impairments showed a higher success rate
than those without hearing impairments (28.6% vs 6.1%,
p=0.034).
Higher pretraining expressive language DQ scores
(≥17) were associated with success (71.4% vs 39.4%,
p=0.012). Similarly, receptive language DQ scores (≥21)
were also significantly associated with success (75.0% vs
Table 1 Baseline demographic and clinical characteristics
of participants before Picture Exchange Communication
System training
Demographic characteristics
Descriptive results
(N=61)
Child- related factors
Sex
Male 35 (57.4)
Female 26 (42.6)
Age (years)
<6 31 (50.8)
≥6 30 (49.2)
Communicable disease
ASD 34 (55.7)
ID/GDD 59 (96.7)
Hearing impairment 10 (16.4)
Coexisting conditions
ADHD 22 (36.1)
Cerebral palsy 4 (6.6)
Genetic disease 13 (21.3)
Receptive language (DQ)* 24.00 (16.67, 34.52)
Expressive language (DQ)* 18.75 (11.57, 29.13)
CGI- S
1 0
2 0
3 1 (1.6)
4 25 (41.0)
5 20 (32.8)
6 13 (21.3)
7 2 (3.3)
Treatment- related factors
Received speech therapy 57 (93.4)
Received occupational therapy 39 (63.9)
Received physical therapy 8 (13.1)
Frequency of PECS training at the hospital (times per year)
1–3 5 (8.2)
4–6 22 (36.1)
7–9 23 (37.7)
≥ 10 11 (18.0)
Frequency of PECS practice at
home (times per week)
0 2 (3.3)
<1 1 (1.6)
1–2 14 (23)
3–5 4 (6.6)
6–7 40 (65.6)
Caregiver- related factors
Continued
Demographic characteristics
Descriptive results
(N=61)
Caregiver sex
Male 6 (9.8)
Female 55 (90.2)
Caregiver age (years)† 44.26±7.67
Caregiver educational level
Below bachelor’s degree 23 (37.7)
Bachelor’s degree and above 38 (62.3)
Family monthly income
<20,000 baht 13 (21.3)
≥20,000 baht 48 (78.8)
Number of children in the house
1 40 (65.6)
2–3 21 (34.4)
Data are presented as numbers (percentages).
*Data are presented as medians (IQRs).
†Data are presented as means±SDs.
ADHD, attention decit/hyperactivity disorder; ASD, autism
spectrum disorder; CGI- S, Clinical Global Impression–Severity;
CP, cerebral palsy; DQ, developmental quotient; GDD, global
developmental delay; ID, intellectual disability; PECS, Picture
Exchange Communication System.
Table 1 Continued
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51.5%, p=0.059). Additionally, lower CGI- S scores (≤4)
were strongly associated with success (71.4% vs 18.2%;
p<0.001; table 4).
In terms of treatment factors (table 4), children who
did not receive occupational therapy exhibited a higher
success rate compared with those who received it (75.8%
vs 50.0%, p=0.037). A higher frequency of PECS training
sessions at the hospital (>6 times per year) was signifi-
cantly associated with increased success rates (82.1%
vs 33.3%, p<0.001). Similarly, regular PECS practice at
home (≥3 times per week) was strongly correlated with
success (92.9% vs 54.5%, p=0.001).
Among caregiver- related factors, children whose care-
givers had a bachelor’s degree or higher were more
likely to achieve successful outcomes (75.0% vs 51.5%,
p=0.059). Moreover, higher family income (≥20,000 baht
per month) was significantly associated with success
(92.9% vs 66.7%, p=0.013).
Multivariate predictors of PECS training success
Multivariate logistic regression analysis using a back-
ward stepwise approach identified four key predictors of
successful PECS training (table 5). First, lower severity of
communication impairment, indicated by CGI- S scores
≤4, significantly predicted success (adjusted OR=15.24,
95% CI: 2.75 to 84.49, p=0.002). Second, a higher
frequency of PECS training sessions—more than six
times per year—was also a significant predictor (adjusted
OR=9.11, 95% CI: 1.71 to 48.56, p=0.010). Third, higher
family income (≥20,000 baht per month) was associated
with greater odds of success (adjusted OR=9.83, 95% CI:
1.35 to 71.78, p=0.024). Lastly, frequent home practice of
PECS, defined as three or more times per week, showed
a trend towards significance (adjusted OR=7.02, 95% CI:
0.88 to 56.13, p=0.066).
DISCUSSION
In this study, approximately 46% (28 out of 61) of the
children achieved success in PECS training after 1 year.
Success was defined as reaching proficiency in PECS
phase 3 and demonstrating significant improvement in
social communication, indicated by CGI- I scores between
1 and 3.
The cross- tabulation analysis revealed that 80.0% of
children who attained PECS phase 3 or higher showed
significant social communication improvements (CGI- I
scores 1–3), reinforcing the importance of progressing
to this phase. However, 20.0% of these children did not
demonstrate notable CGI- I improvements, indicating
that achieving PECS milestones alone does not guarantee
broader social communication gains. Conversely, nearly
all children (96.2%) who did not reach phase 3 remained
in the CGI- I 4–7 category, with only 3.8% showing measur-
able improvement. These findings highlight the need for
a multidimensional approach in assessing PECS effective-
ness, considering both functional picture exchange profi-
ciency and overall social communication development.
Compared with previous studies, our success rate is
somewhat lower. For instance, Koudys et al11 reported
that 57.1% (12 out of 21) of participants mastered PECS
skills after the intervention. It is important to note that
the criteria for success in their study differed from ours,
which may contribute to the disparity in success rates.
In Koudys et al’s study,11 success was primarily defined by
the highest PECS phase attained by participants, without
considering improvements in social communication or
other functional outcomes. Specifically, they focused on
Table 2 PECS training outcomes after 1 year
Demographic characteristics Descriptive results
The nal phase of the PECS training procedure after 1 year
1 17 (27.9)
2 9 (14.8)
3 21 (34.4)
4 12 (19.7)
5 2 (3.3)
6 0 (0)
CGI- I
1 1 (1.6)
2 16 (26.2)
3 12 (19.7)
4 32 (52.5)
5 0 (0)
6 0 (0)
7 0 (0)
Receptive language (DQ)* 27.27 (16.34, 41.40)
Expressive language (DQ)* 19.05 (11.66, 30.00)
Median difference in receptive
language DQ*
0 (0.00, 4.89)
Median difference in expressive
language DQ*
0 (−3.60, 3.80)
Data are presented as numbers (percentage).
*Data are presented as medians (IQRs).
CGI- I, Clinical Global Impression–Improvement; DQ,
developmental quotient; PECS, Picture Exchange Communication
System.
Table 3 Cross- tabulation of the nal PECS phase and
CGI- I scores after 1 year of PECS training procedure
The nal phase of the
PECS training procedure
after 1 year
CGI- I scores 1–3
(improved)
CGI- I scores 4–7
(not improved)
Phase 1–2 (n=26) 1 (3.8) 25 (96.2)
Phase 3–6 (n=35) 28 (80.0) 7 (20.0)
Total (n=61) 29 (47.5) 32 (52.5)
Data presented as numbers (percentage).
CGI- I, Clinical Global Impression–Improvement; PECS, Picture
Exchange Communication System.
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progression through the PECS phases as the sole indi-
cator of success. In contrast, our study employed a dual
criterion for success: participants were required not only
to achieve proficiency in PECS phase 3 but also to demon-
strate significant improvement in social communication
skills, as measured by the CGI- I scale.
By incorporating the CGI- I score into our success
criteria, we set a higher threshold for successful PECS
training. The CGI- I scale assesses the degree of improve-
ment in a patient’s condition throughout treatment,
providing a broader evaluation of functional gains
beyond mere progression through PECS phases.13 There-
fore, our stricter definition of success likely contributed
to a lower overall success rate compared with Koudys et
al’s findings.
Variations in success rates may also be influenced by
differences in participant characteristics. Our study
included a high proportion of children with severe
communication impairments and coexisting conditions
such as IDs and GDDs. These factors can make PECS
training more challenging and may affect the rate at
which children progress through the PECS phases and
improve in social communication.11
Our findings indicate that lower severity of communi-
cation impairment, higher frequency of PECS training at
the hospital, higher family income and frequent home
practice are significant predictors of successful PECS
training outcomes.
The severity of communication impairment, assessed
using the CGI- S scale, emerged as a strong predictor of
success. Children with less severe impairments (CGI-
S≤4) were significantly more likely to achieve proficiency
in PECS phase 3 and demonstrate substantial improve-
ments in social communication. This finding aligns with
previous research suggesting that initial impairment
severity influences the effectiveness of communication
interventions. For instance, Koudys et al11 found that chil-
dren with milder communication deficits were signifi-
cantly more likely to attain higher levels of proficiency in
PECS training. Similarly, Romski and Sevcik15 emphasised
that children with less severe impairments may acquire
communication skills more rapidly through augmenta-
tive interventions. They noted that early introduction of
AAC systems like PECS can lead to quicker communica-
tion gains in children who possess foundational levels of
language comprehension and cognitive skills.
Figure 1 Receiver operating characteristic (ROC) curve for predictive accuracy of Clinical Global Impression–Severity (CGI- S)
scores in determining Picture Exchange Communication System training success.
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8WannapaschaiyongP, etal. BMJ Paediatrics Open 2025;9:e003282. doi:10.1136/bmjpo-2024-003282
Open access
The frequency of PECS training sessions at the hospital
also emerged as a significant predictor of success. Chil-
dren attending more than six sessions per year were more
likely to achieve positive outcomes. This underscores the
importance of intervention intensity in AAC outcomes.
Previous studies have highlighted that increased therapy
intensity is associated with better communication
outcomes in children with developmental disabilities.5 16
Roberts and Kaiser5 demonstrated that children receiving
more frequent language intervention sessions showed
greater improvements in language skills. Similarly, Yoder
and Stone16 reported that higher treatment intensity led
to more significant language gains in children with ASD.
However, these earlier studies focused on intensive
interventions delivered within a short time frame,5 11 16
which differs from the real- world context of our study.
In resource- limited settings like ours, where there is
a shortage of qualified personnel to provide PECS
training, the maximum feasible frequency was often just
one session per month per patient. Additionally, our
early implementation phase of PECS training coincided
with the COVID- 19 pandemic, further disrupting sched-
uled sessions for many patients. Despite these challenges,
our findings emphasise that even in constrained circum-
stances, maintaining consistent training sessions with
specialists remains crucial for optimising PECS outcomes.
Family income emerged as a significant predictor of
successful PECS training, with children from higher-
income families (≥20,000 baht per month) demon-
strating greater odds of achieving favourable outcomes.
Socioeconomic status influences access to resources,
consistency in therapy attendance and the capacity to
implement intervention strategies at home. Families with
higher incomes may have greater flexibility to attend
more frequent sessions and invest in supplementary
materials or additional support services. Weisleder and
Fernald17 found that children from higher socioeco-
nomic backgrounds are exposed to increased amounts
Figure 2 Receiver operating characteristic (ROC) curve for predictive accuracy of receptive language developmental
quotients (RL- DQ) in determining Picture Exchange Communication System training success.
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9
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of child- directed speech, which enhances language
processing efficiency and vocabulary development.
Similarly, Hoff18 noted that the quality and quantity of
parental speech, influenced by socioeconomic factors,
play crucial roles in early language development.
Frequent home practice of PECS (≥3 times per week)
demonstrated a trend towards significance as a predictor of
successful outcomes. Although not statistically significant
in our multivariate analysis, the importance of caregiver
involvement and home practice is well documented.2 19 20
Active caregiver participation in AAC interventions can
reinforce skills acquired during therapy sessions and facil-
itate the generalisation of communication abilities across
settings. Kent- Walsh and Mcnaughton19 emphasised that
communication partner instruction, including training
caregivers, enhances the effectiveness of AAC interven-
tions. Similarly, Tamis- LeMonda et al20 highlighted that
maternal responsiveness and active engagement are crit-
ical for children’s language development, suggesting that
caregiver involvement can significantly impact interven-
tion outcomes.
Our study also found that children with ASD were less
likely to achieve success in PECS training compared with
those without ASD. This finding may be attributed to
the core social communication challenges inherent in
ASD, which can hinder the acquisition and generalisa-
tion of PECS skills. Kasari et al21 highlighted that children
with ASD might require more specialised interventions
tailored to their unique social communication deficits.
In contrast, children with hearing impairments demon-
strated a higher success rate, suggesting that PECS may
be particularly beneficial for this population. Notably,
all participants with hearing impairments in this study
used hearing aids, which likely facilitated their ability
to process auditory cues and engage more effectively in
PECS training. Previous studies have supported the role
of hearing aids in augmenting communication skills,
highlighting their contribution to improving speech
Figure 3 Receiver operating characteristic (ROC) curve for predictive accuracy of expressive language developmental
quotients (EL- DQ) in determining Picture Exchange Communication System training success.
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Open access
Table 4 Comparison of demographic and clinical characteristics between successful and unsuccessful PECS training groups
Demographic characteristics
Unsuccessful group
(N=33)
Successful group
(N=28) P value
Child- related factors
Sex 0.035*
Male 23 (69.7) 12 (42.9)
Female 10 (30.3) 16 (57.1)
Age 0.531
<6 years 18 (54.5) 13 (46.4)
≥6 years 15 (45.5) 15 (53.6)
Communicable disease
ASD 23 (69.7) 11 (39.3) 0.017*
ID/GDD 33 (100.0) 26 (92.9) 0.207
Hearing impairment 2 (6.1) 8 (28.6) 0.034*
Coexisting conditions
ADHD 13 (39.4) 9 (32.1) 0.557
Genetic disease 7 (21.2) 6 (21.4) 0.984
CP 4 (12.1) 0 (0) 0.118
Receptive language (DQ) 0.059*
<21 16 (48.5) 7 (25.0)
≥21 17 (51.5) 21 (75.0)
Expressive language (DQ) 0.012*
<17 20 (60.6) 8 (28.6)
≥17 13 (39.4) 20 (71.4)
CGI- S <0.001*
≤4 6 (18.2) 20 (71.4)
>4 27 (81.8) 8 (28.6)
Treatment- related factors
Received other treatment
Speech therapy 30 (90.9) 27 (96.4) 0.618
Occupational therapy 25 (75.8) 14 (50) 0.037*
Physical therapy 7 (21.2) 1 (3.6) 0.060*
Frequency of PECS training at the
hospital (time per year)
<0.001*
≤6 22 (66.7) 5 (17.9)
>6 11 (33.3) 23 (82.1)
Frequency of PECS practising at home
(time per week)
0.001*
<3 15 (45.5) 2 (7.1)
≥3 18 (54.5) 26 (92.9)
Caregiver- related factors
Caregiver sex 1.000
Male 3 (9.1) 3 (10.7)
Female 30 (90.9) 25 (89.3)
Caregiver age (years)† 44.88±7.99 43.54±7.34 0.500
Caregiver educational level 0.059*
Below bachelor’s degree 16 (48.5) 7 (25.0)
Bachelor’s degree and above 17 (51.5) 21 (75.0)
Continued
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perception and social interactions in children with
hearing loss.22 23 While research specifically on PECS for
children with hearing impairments is limited, the broader
body of evidence supports the utility of AAC interven-
tions in enhancing communication skills across various
developmental disabilities.24 These findings emphasise
the importance of addressing sensory deficits alongside
communication training to optimise outcomes.
Furthermore, the observation that female participants
were more likely to succeed in PECS training is intriguing.
Some studies have reported sex differences in language
development, with females often exhibiting advanced
language skills compared with males.25 Eriksson et al25
found that girls tend to develop language skills earlier
and have larger vocabularies than boys across different
languages and cultures, which might contribute to better
outcomes in communication interventions. However, the
impact of sex on AAC intervention outcomes is less clear
and warrants further investigation.
Although prior studies suggest that younger chil-
dren often benefit more from early intervention due to
greater neuroplasticity,26 27 our study did not find a signif-
icant association between age at initiation and PECS
training success. This finding aligns with the current
understanding that there are no established guidelines
on the ideal age for initiating PECS. Previous research
has demonstrated that PECS can be effective across a
wide age range, provided that interventions are tailored
to the individual’s developmental level and communica-
tion needs.10 28 These findings highlight that age alone
may not be a determining factor. Instead, factors such
as intervention intensity, caregiver involvement and the
individual’s baseline communication abilities may play
more critical roles.
Interestingly, the median difference in receptive
and expressive language DQs was zero, with wide IQRs
observed. These results suggest that while some chil-
dren achieved substantial improvements, others showed
minimal or no progress after 1 year of PECS training.
This variability might be influenced by individual factors
such as baseline language abilities, severity of impair-
ments or training intensity, as previously discussed.11
From a clinical perspective, these findings underscore
the importance of personalised interventions and poten-
tially increased training intensity, particularly for chil-
dren demonstrating limited progress.
It is also important to note that almost all participants
in this study were concurrently receiving speech therapy.
Therefore, the lack of improvement observed in some
children may be attributed to underlying factors. These
factors include the severity of their primary condition,
comorbidities or insufficient frequency of PECS practice
Demographic characteristics
Unsuccessful group
(N=33)
Successful group
(N=28) P value
Family monthly income 0.013*
<20,000 baht 11 (33.3) 2 (7.1)
≥20,000 baht 22 (66.7) 26 (92.9)
Number of children in the house 0.845
1 22 (66.7) 18 (64.3)
2–3 11 (33.3) 10 (35.7)
Data are presented as numbers (percentage), with percentages calculated by column unless otherwise specied.
*Statistically signicant with p≤0.1.
†Data are presented as means±SD.
ADHD, attention decit/hyperactivity disorder; ASD, autism spectrum disorder; CGI- S, Clinical Global Impression–Severity; CP, cerebral
palsy; DQ, developmental quotient; GDD, global developmental delay; ID, intellectual disability; PECS, Picture Exchange Communication
System.
Table 4 Continued
Table 5 Multivariable logistic regression analysis of predictors for successful PECS training outcomes
Potential variables Adjusted OR 95% CI P value
Frequency of PECS practice at home
≥3 times/week
7.023 0.879 to 56.131 0.066
Frequency of PECS training at the
hospital >6 times/year
9.106 1.707 to 48.562 0.010*
CGI- S≤4 15.241 2.750 to 84.485 0.002*
Family monthly income ≥20,000 baht 9.830 1.346 to 71.783 0.024*
*Statistically signicant with p≤0.05.
CGI- S, Clinical Global Impression–Severity; PECS, Picture Exchange Communication System.
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both at the hospital and at home. These considerations
highlight the need for tailored strategies to address indi-
vidual barriers and optimise the effectiveness of PECS
training.
Limitations
Several limitations of this study warrant acknowledge-
ment. The retrospective design restricts our ability to
establish causal relationships between the identified
predictors and PECS training outcomes. Although the
sample size was calculated to be sufficient, it was relatively
small and drawn from a single institution, which may
affect the generalisability of the findings. Reliance on
medical records for data collection may have introduced
information bias due to incomplete or inconsistent docu-
mentation.
A key methodological consideration in this study is the
use of the Denver II Developmental Screening Test for
language assessment. While Denver II is typically designed
for children under 6 years old, its use was justified in this
study as all participants had a language developmental
level below 6 years. However, we acknowledge that Denver
II has limitations. As a screening tool, it may lack sensi-
tivity in detecting minor changes in receptive language
skills, potentially leading to an underestimation of subtle
improvements in communication abilities, particularly in
older children with communication impairments. This
limitation may affect the precision of language outcome
measurements. Future research should consider inte-
grating more comprehensive and standardised language
assessment tools to improve measurement accuracy and
capture nuanced changes in receptive and expressive
language development more effectively.
Differences in success criteria across studies can signifi-
cantly impact reported success rates. Our definition of
success required both proficiency in PECS phase 3 and
significant improvement in social communication, indi-
cated by CGI- I scores between 1 and 3. This dual focus
on functional skills and overall social communication
outcomes diverges from studies such as Koudys et al11
which evaluated success primarily based on PECS phase
progression. This discrepancy may explain the lower
success rate observed in our study. By incorporating the
CGI- I as a complementary measure, we aimed to provide
a more holistic evaluation of the training’s impact, consid-
ering both functional milestones and clinical improve-
ments in social adaptability. Although the CGI- I scale is
not a standard outcome measure in PECS research, it was
chosen to align with clinical priorities and enhance the
applicability of our findings to real- world settings. This
dual criterion offers a nuanced understanding of inter-
vention success, emphasising the importance of assessing
both skill acquisition and meaningful behavioural
changes.
Our findings indicate that higher training frequency
(>6 sessions/year) and more frequent home practice
(≥3 times/week) were significant predictors of PECS
training success. However, we did not account for all
potential confounding factors, such as the quality of
PECS implementation, therapist experience or aspects of
the home environment beyond practice frequency, which
may have also influenced outcomes. Additionally, while
some participants continued training beyond 1 year, our
study focused on a standardised 1 year period, limiting
the ability to assess the impact of longer intervention
durations.
Another limitation is that while our study included a
substantial number of participants diagnosed with GDD/
ID without ASD, we did not conduct a separate analysis
to compare their outcomes with those of children with
ASD. Our findings suggest that overall communication
severity (CGI- S) and training frequency were stronger
predictors of PECS success than diagnostic category
alone. However, differences in cognitive and adaptive
functioning between these groups may influence the rate
and nature of progress in PECS training. Future studies
should explore subgroup- specific outcomes to better
understand the differential impact of PECS training on
children with varying neurodevelopmental profiles.
We also did not account for all potential confounding
variables, such as the quality of PECS implementation,
therapist experience or aspects of the home environment
beyond practice frequency. Additionally, while family
income was analysed as a predictor of PECS success, we
did not examine whether higher income was associated
with more frequent PECS training sessions or greater
home practice time. Socioeconomic status may influence
access to intervention services and caregiver involve-
ment, potentially impacting PECS outcomes. Future
studies should explore the role of income as a mediator
in PECS success, particularly in resource- limited settings.
The CGI- S and CGI- I scales, while useful, are subjective
measures and may be influenced by clinician bias. Future
research should employ prospective designs with larger,
more diverse samples and incorporate objective measures
of communication outcomes.
Implications for practice
Our findings have practical implications for clinicians
working in resource- limited settings. Given that the
severity of communication impairment, as measured
by the CGI- S, is a significant predictor of PECS training
success, clinicians can use the CGI- S as a screening tool
to identify children more likely to benefit from PECS
training. By prioritising referrals for children with lower
CGI- S scores (≤4), limited resources can be allocated
more effectively to those most likely to achieve successful
outcomes.
Conversely, factors such as the frequency of PECS
training sessions at the hospital and the family’s monthly
income, while significant, are often beyond the direct
control of healthcare providers. These factors are influ-
enced by systemic issues such as staffing constraints,
healthcare infrastructure and socioeconomic dispari-
ties. Therefore, in resource- limited settings, focusing on
modifiable child- related factors like the CGI- S score may
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WannapaschaiyongP, etal. BMJ Paediatrics Open 2025;9:e003282. doi:10.1136/bmjpo-2024-003282
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be a more feasible strategy for optimising intervention
outcomes within existing constraints.
CONCLUSIONS
Our study highlights key predictors of successful PECS
training in children with communication impairments,
emphasising the roles of impairment severity, inter-
vention intensity, socioeconomic status and caregiver
involvement. These findings contribute to a better
understanding of how to optimise PECS interventions
and support children in developing effective communi-
cation skills.
Acknowledgements The authors would like to express their gratitude to the
Division of Developmental and Behavioral Pediatrics, Department of Pediatrics,
Siriraj Hospital, for supporting this study. Special thanks to the children and
families who participated in the training programme and shared their experiences.
Contributors PW was responsible for the overall content as guarantor. PW:
conceptualisation, statistical analysis, data interpretation, writing–original draft
preparation, reviewing and editing. TV: literature review, data collection, statistical
analysis, writing–original draft preparation. AW: data collection, data acquisition. All
authors reviewed and approved the nal version of the manuscript.
Funding The authors have not declared a specic grant for this research from any
funding agency in the public, commercial or not- for- prot sectors.
Competing interests No, there are no competing interests.
Patient and public involvement Patients and/or the public were not involved in
the design, or conduct, or reporting, or dissemination plans of this research.
Patient consent for publication Not applicable.
Ethics approval The study was approved by the Siriraj Institutional Review Board
(approval number: Si- 723/2024 (IRB2)), which waived the requirement for informed
consent due to the retrospective nature of the study and anonymisation of patient
data. All data were deidentied and stored securely in password- protected les
accessible only to the research team, ensuring condentiality and compliance with
data protection regulations.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on reasonable request. The
datasets generated and/or analysed during the current study are available from the
corresponding author on reasonable request.
Open access This is an open access article distributed in accordance with the
Creative Commons Attribution Non Commercial (CC BY- NC 4.0) license, which
permits others to distribute, remix, adapt, build upon this work non- commercially,
and license their derivative works on different terms, provided the original work is
properly cited, appropriate credit is given, any changes made indicated, and the
use is non- commercial. See:http://creativecommons.org/licenses/by-nc/4.0/.
ORCID iD
PrakasitWannapaschaiyong http://orcid.org/0000-0001-7099-0183
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BMJ Paediatrics Open: first published as 10.1136/bmjpo-2024-003282 on 13 March 2025. Downloaded from https://bmjpaedsopen.bmj.com on 15 March 2025 by guest.
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