Abstract
This study explored participation- and impairment-based outcomes for 24 late-to-talk toddlers (M age = 20.46 months, SD = 3.09, 62.5% male) whose parents participated in Target Word™, The Hanen Program® for Parents of Children who are Late Talkers in community clinics across Ontario. Parents completed the MacArthur–Bates Communicative Development Inventories (MBCDI), The Focus on the Outcomes of Communication Under Six (FOCUS-34), and a speech sound checklist: (1) prior to starting the program, (2) at the end of direct intervention, and (3) after a consolidation period. Speech-language pathologists classified children’s communicative function using the Communication Function Classification System (CFCS) at all assessment points and provided FOCUS scores from an initial assessment. No change was recorded in CFCS levels between initial assessment and start of the program, but many children moved to a more advanced level by the end of the program (n = 12) or consolidation period (n = 19). Significant changes in children’s communicative participation skills (FOCUS) were found between initial assessment and the start of the program, and during the 12-week direct intervention (75% made clinically meaningful change). Significant growth in expressive vocabulary and consonant inventory occurred during direct intervention. Correlations between change on impairment- and participation-based measures were not significant. The Target Word program appears to improve communicative function for late-to-talk preschoolers. Children also made gains in communicative participation skills, expressive vocabulary, and consonant inventory during the program, but further research is needed to determine the effectiveness of Target Word in these areas.
I Introduction
Children between 18 and 30–35 months of age are considered ‘late-to-talk’ when they exhibit delayed expressive language skills in the presence of typically developing skills in other domains (e.g. play, motor, social) and in the absence of a causal condition (Rescorla, 2011). These children may have expressive language delay only, or they may also have mild receptive language delay (Rescorla, 2011). Although many children who are late-to-talk score within normal limits on standardized language assessments after school entry (e.g. Rescorla, 2009; Rice et al., 2008), it is important to note that these children may continue to score below their peers who were not late-to-talk and to have difficulty with higher-level language tasks (Girolametto et al., 2001; Paul et al., 1996; Rescorla, 2009; Rice et al., 2008). These negative outcomes can be mediated with early intervention (Armstrong et al., 2017; Scheffner Hammer et al., 2017).
Several language intervention models exist for toddlers who are late-to-talk including consultation, direct treatment with a speech-language pathologist (SLP), and parent-implemented intervention. While parents may be reluctant to take the lead role in their child’s therapy (Watts Pappas et al., 2016), parent-implemented interventions have resulted in greater language gains than interventions delivered by a SLP (Roberts and Kaiser, 2015). This may be because parents learn to implement language facilitation strategies throughout each day, creating a more language-rich learning environment than can be offered during weekly or bi-weekly intervention sessions with a SLP (Roberts and Kaiser, 2015). Parents can effectively learn to use language facilitation strategies to support their child’s language development (DeVeney et al., 2017; Girolametto et al., 1996), and use of these strategies can increase expressive vocabulary, mean length of utterance, and target word acquisition (Buschmann et al., 2010). Parent-implemented interventions may also support the development of receptive language, phonological skills, socialization, and speech intelligibility (Buschmann et al., 2015; DeVeney et al., 2017). While multiple studies have shown parent-implemented language interventions to be effective, it is important to note that a few have found no benefit for improving children’s expressive language and vocabulary skills (Kaiser et al., 1995; Wake et al., 2011). Although discrepancies have been noted, much of the evidence suggests that parent-implemented interventions improve children’s language comprehension and use (Roberts and Kaiser, 2011).
The positive impact of parent-implemented interventions on children’s impairments (i.e. development of specific language skills) is well documented, but little is known about how parent-implemented interventions impact children’s communicative participation, that is, how they use communication to participate in everyday situations (Eadie et al., 2006). The World Health Organization’s International Classification of Functioning, Disability and Health (ICF) framework provides a useful way of thinking about impairment versus participation-based outcomes (World Health Organization, 2001). Most research in the field has focused on growth within the Body Functions and Structures (e.g. consonant acquisition) and Activities (e.g. expressive vocabulary) components. Very little has reported on children’s outcomes within the Participation component. One study has been published on the development of children’s communicative participation skills (Cunningham et al., 2017). In this study, Cunningham and colleagues modeled growth in children’s communicative participation skills from 18-months to six years of age stratified by five levels of communicative function. In a separate study, Cunningham et al. (2018) found that predicted communicative participation skills were higher for children receiving intervention (versus those waiting for treatment), but as this was a population-level study using pre-existing datasets, they were unable to stratify by the types of interventions children received. A handful of studies have measured changes in children’s communicative participation skills following clinician-implemented interventions (Namasivayam et al., 2015; Pennington et al., 2013; Thomas-Stonell et al., 2013; Thomas-Stonell et al., 2016). This type of functional outcome provides the most complete picture of how interventions impact children and families and is most important and meaningful to them (Roulstone et al., 2013). It is also not yet well understood how the development of impairment-based skills is associated with the development of communicative participation skills. Knowing the relation between impairment and participation-based outcomes will provide insights into whether interventions that target impairment-based skills also impact a child’s communicative participation. A recently revised parent-implemented intervention for children who are late-to-talk provides an opportunity to explore these issues.
Target Word™ – The Hanen Program® for Parents of Children who are Late Talkers was specifically designed for parents and caregivers of children who are late-to-talk and incorporates evidence-based language facilitation strategies and theories of adult learning to teach parents to support their child’s language development. An important focus of the intervention is for parents to learn to use these language facilitation strategies in everyday activities (e.g. meal times, bath time, story time) in order to promote functional communication skills and communicative participation of children who are late-to-talk. The program is described in detail in the Method section. Parent-implemented language interventions like Target Word are known to support the development of impairment-based skills such as expressive/receptive vocabulary, syntax, and morphology (Roberts and Kaiser, 2011). This provides some evidence of treatment efficacy, but the ultimate goal of intervention should be to support children in using communication to independently participate in everyday environments. Our research team recently conducted a retrospective chart review of 76 preschoolers whose parents participated in the Target Word program and found that 75% of children made clinically meaningful changes in their communicative participation skills during the program (Kwok et al., 2019), but more research is needed to understand the effectiveness of this program in this regard.
The primary aim of this community-based effectiveness study was to explore children’s language and communicative participation outcomes during the Target Word program. A secondary aim was to explore the relation between communicative participation and impairment-based outcomes, and to explore the relation between those outcomes and levels of communicative function.
II Method
1 Ethics approval
The Hamilton Integrated Research Ethics Board at McMaster University approved this study. The first author was a postdoctoral fellow at McMaster when this study was conducted.
2 Participants
Five Hanen certified SLPs who were scheduled to run a Target Word program in the fall of 2017 enrolled parents of preschoolers who were late-to-talk to participate in this study. The SLPs worked at four different community preschool programs in Ontario, Canada.
Parents of 33 children were invited, and 31 agreed to participate in the study. Each SLP had 5 to 7 families enrolled in their program. Twelve children were female (39%) and 19 were male (61%). The mean age at initial assessment was 20.81 months (SD = 2.83, range 16–28 months). All children met criteria for enrollment in the Target Word program (described below). Complete data was collected for 24 children. Program goals for those children included imitation (n = 12), spontaneous single words (n = 7), and word combinations (n = 5). Demographic data was not available for the families who participated.
3 Outcome measurement tools
The SLPs who collected data for this study were employed by the Province of Ontario’s Preschool Speech and Language Program. This program requires its clinicians to use two participation-based measurement tools for all children accessing services: The Focus on the Outcomes of Communication Under Six (FOCUS) and the Communication Function Classification System (CFCS). The Hanen Centre recommends clinicians who deliver the Target Word program measure children’s progress at three assessment points (pre-program, end of direct intervention, and end of consolidation) using the MacArthur–Bates Communicative Development Inventories – Words and Gestures (MBCDI) and an informal speech sound checklist. These tools were used for this study because they measured constructs specific to our research questions, but also because they were part of standard care and would not be an additional burden to clinicians or families. The measures are described in detail below.
a FOCUS-34
The FOCUS-34 is a 34-item parent-report outcome measurement tool designed to measure changes in children’s communicative participation skills during a speech-language intervention (Thomas-Stonell et al., 2015). On the first 23 items parents rate their child on a 7-point scale that ranges from ‘Not at all like my child’ to ‘Exactly like my child’. Example items include: ‘My child can communicate independently’, ‘My child is understood the first time when s/he is talking with other children’, and ‘My child can talk to other children about what s/he is doing’. On the last 11 items ratings are made using a different 7-point scale with items ranging from ‘Cannot do at all’ to ‘Can always do without help’. Example items include: ‘My child can communicate effectively with other children’, ‘My child joins in conversations with her/his peers’, and ‘My child will try to carry on a conversation with adults who do not know my child well’ (Thomas-Stonell et al., 2010; 2015). Scores on the FOCUS-34 range from a minimum of 34 to a maximum of 238, however it is the FOCUS change scores that are used to determine whether children have made meaningful change during an intervention. Children who make 11 or more points of change on the FOCUS-34 during an intervention period have made clinically meaningful changes in their communicative participation skills (Thomas-Stonell et al., 2015). This number was derived statistically based on a clinical study done using the original FOCUS (Thomas-Stonell et al., 2013). The original 50-item FOCUS is a valid and reliable measure of change for preschool-aged children with a range of speech-language impairments (Thomas-Stonell et al., 2010).
b CFCS
The CFCS is a valid and reliable classification tool that allows clinicians and/or parents to classify children’s communication abilities into one of five meaningful levels of communicative function (Hidecker et al., 2011; Hidecker et al., 2017). Children in level I are ‘Effective senders and receivers with unfamiliar and familiar partners’, and function best in terms of their communication, while children in level V are ‘Seldom effective senders or receivers even with familiar partners’ and function least well in their communication (Hidecker et al., 2011). Clinically, a child in CFCS level I may have only a few speech sound or grammatical errors, while a child in CFCS level V may lack communicative intent. Most young children who are late-to-talk would be classified as Level IV: ‘inconsistent sender and/or receiver with familiar partners’ because they do not always understand messages spoken to them, and their messages are not consistently understood by all listeners.
c MBCDI – Words and Gestures
The MBCDI – Words and Gestures is a parent-report instrument designed to capture information about early communication development, including expressive and receptive vocabulary (Fenson et al., 2007). Using this tool, parents provide information about their child’s early communication skills, and then complete a vocabulary checklist where they indicate whether their child understands or both understands and says 396 words (Fenson et al., 2007). Vocabulary scores range from 0 to 396. The MBCDI – Words and Gestures was developed for use up until 18 months of age, but is used by clinicians running Target Word as a tool for counting children’s expressive vocabularies and to identify a receptive-expressive language gap.
d Informal Speech Sound Checklist
An Informal Speech Sound Checklist developed by the Hanen Centre was used to determine each child’s consonant inventory. Using the checklist, parents and clinicians indicate whether a child does/does not use 23 single consonant phonemes, so scores can range from 0 to 23. The checklist also collects binary data for whether a child has restricted use of vowel and/or diphthong sounds and syllable structures (Earle and Lowry, 2015). For the purposes of this study, the checklist was used only to identify the number of sounds in a child’s consonant inventory (see Appendix 1), as SLPs did not consistently indicate whether a child had restricted vowels or syllable structures.
4 The Target Word program
The Target Word program was developed for children under 30 months of age who have been identified as late-to-talk. To be eligible for the program, children must also have typically-developing comprehension or a mild receptive language delay; typically-developing play, social, motor, and cognitive skills; and two or more risk factors for developing a speech/language disorder listed on an informal child profile checklist. The program is run by a Hanen certified SLP and consists of a pre-program consultation, five group training sessions, and two individual video feedback sessions. This face-to-face portion of the program typically lasts for 10–12 weeks and is followed by a consolidation period of 6–12 weeks during which parents continue implementing the strategies learned during the program (Earle & Lowry, 2015).
During the pre-program consultation, the SLP provides an overview of the program and collaborates with parents to choose a communication goal for the child. Program goals include: (1) getting the child noisy; (2) spontaneous verbal imitation; (3) spontaneous use of single words; and (4) word combinations. During the first two group training sessions, parents learn strategies to support interactions through sessions that combine multiple video examples, and opportunities to interact with the material and practice strategies. Parents then participate in their first individual video feedback session where they use the newly learned interaction strategies, view videos of themselves using the strategies, and formulate plans for increasing use of these strategies in everyday activities with their child. At the end of the first individual video feedback session, parents also choose (with the SLP) 10 target words they will try to use multiple times during everyday interactions for the rest of the program. During the remaining group training sessions, parents learn to use focused stimulation and incorporate the 10 target words and other meaningful words at least 5 times during everyday activities. During the second individual video feedback session, parents demonstrate their ability to use specific language facilitation strategies to highlight target words, observe how their child responds, and dialogue about the impact with the SLP (Earle and Lowry, 2015).
5 Treatment fidelity
Speech-language pathologists completed informal fidelity checklists that were developed for Target Word at the pre-program consultation, following each group intervention, and after each individual appointment to ensure the format and content of the intervention was delivered consistently across clinicians (see example checklist in Appendix 2).
6 Procedures
SLPs who were scheduled to run the Target Word program in the fall of 2017 were approached by the third author (CE), the Program Director for Target Word, and asked to help recruit parents. All parents were invited to participate at their pre-consultation appointment. They were provided with an information letter, and if they agreed, parents signed the consent form. All forms were anonymized and uploaded to REDCap, a secure online data collection system hosted at McMaster University (Harris et al., 2009). In the community settings where Target Word was run, it was offered as the primary intervention, thus, children were not receiving direct intervention from a speech-language pathologist during the time in which their parents participated in the program. For most children in these community settings, Target Word was the point of first intervention, and children had not typically received other intervention services prior to their parents participating in Target Word.
First, SLPs were asked to go back into the child’s chart and provide the FOCUS score and CFCS level from the child’s initial assessment appointment as these tools were completed as part of routine outcome monitoring. Parents completed the MBCDI, FOCUS, and Speech Sound Checklist at three points in time: at the pre-program consultation; at the end of the 12-week program; and after the consolidation period. SLPs also classified and reported the child’s level of communicative function using the CFCS and completed the program’s intervention fidelity checklists at each assessment point (fidelity checklists were also completed following each group and individual session). Data were therefore available for four assessment points: (1) initial assessment (FOCUS and CFCS only), (2) pre-program consultation; (3) end of the program; and (4) end of the consolidation period (see Table 1).
Descriptive statistics and change across assessment points.
Note. p-values denote whether change from the average score/level at the previous assessment point was statistically significant.
7 Handling of missing data
Complete data were obtained for 24 of the 31 children enrolled in the study. One child dropped out of the program after the pre-program consultation appointment; parents for one child did not submit the MBCDI at session 5; parents of four children did not attend the last group training session for reasons including illness, medical complication, and family challenges; and one child did not attend the consolidation appointment. At initial assessment, there were no significant differences between children with complete versus incomplete data for mean age, CFCS level, or FOCUS score. At the pre-program consultation, there were no significant differences between the groups for mean age, CFCS level, expressive vocabulary (MBCDI), or consonant inventory. Children with complete data did, however, have significantly higher FOCUS scores (M = 90.92, SD = 22.33) than those with incomplete data (M = 60.86, SD = 24.65; t (29) = −3.07, p < 0.05). Only children with complete data were included in the analysis (9 female, 15 male).
8 Statistical analysis
Descriptive statistics were used to describe participants. Because the data did not meet the assumptions of normality or sphericity required for repeated measures ANOVA, the non-parametric Friedman Test was used to identify statistically significant changes in mean outcome scores across assessment points. Post-hoc pairwise comparisons were conducted using the Wilcoxon Signed Rank test. Spearman rank correlations with Sidak correction were used to explore the relation between change scores on the FOCUS and changes in expressive vocabulary and consonant inventory. Correlations between change scores and children’s CFCS classifications were also explored. Due to the number of comparisons made, we used the Benjamini–Hochberg correction to control for false discoveries (level of significance, q < 0.05).
III Results
Children’s mean age (months), FOCUS scores, MBCDI expressive vocabulary counts, and consonant inventories at each assessment point are presented in Table 1. On average, there were 3.3 months between Time 1 (initial assessment) and Time 2 (pre-program consultation), 2.5 months between Time 2 (pre-program consultation) and Time 3 (end of the program), and 2.2 months between Time 3 (end of the program) and Time 4 (the consolidation follow-up appointment). Our review of clinicians’ treatment fidelity checklists indicated that both the format and content of the intervention was delivered consistently across clinicians (see Table 2).
Percent fidelity across five clinicians at each fidelity check point.
1 Changes in communicative participation skills
A significant difference in Total FOCUS score was found across assessment points, X2 = 55.70, p < 0.01. Post-hoc pairwise comparisons showed significant differences in the mean Total FOCUS scores between Times 1 (initial assessment) and 2 (pre-program consultation), z = −3.32, p < 0.01, r = 0.34, and between Times 2 (pre-program consultation) and 3 (end of group treatment), z = −4.19, p < 0.01, r = 0.43, but not between Times 3 (end of group treatment) and 4 (end of consolidation), z = −1.96, p = 0.06, r = 0.2 (see Table 1). To further understand change in FOCUS scores across assessments, we calculated Spearman correlations between FOCUS change scores at Times 2, 3, and 4. The change between initial assessment and the start of the program was not correlated with change at the end of the program or at consolidation (rs < –0.15, p > 0.4). However, a significant negative correlation was found between FOCUS change scores at Time 3 and Time 4; rs = −0.54, p < 0.01).
The average change in Total FOCUS score was more than the 11 points required to be considered clinically meaningful between Times 1 (initial assessment) and 2 (pre-program consultation) (average change = 18.67) and between Times 2 (pre-program consultation) and 3 (end of group treatment) (average change = 30.66), but not between Times 3 (end of group treatment) and 4 (end of consolidation) (average change = 8.42). Most children showed clinically meaningful change on the FOCUS between Time 1 (initial assessment) and 2 (pre-program consultation) (n = 13, 54%), and between Time 2 (pre-program consultation) and 3 (end of group treatment) (n = 18, 75%), but not between Time 3 (end of group treatment) and 4 (end of consolidation) (n = 9, 38%) (see Table 3). Overall, the proportion of children showing clinically meaningful change in communicative participation differed significantly across the three assessment points, X2 = 6.86, p = 0.03. Post-hoc analysis revealed no difference in the proportion of children who changed during the pre-program period as compared to the end of the program, X2 = 2.28, p = 0.13, but significantly more children showed clinically meaningful change at the end of the program compared to the end of the consolidation period, X2 = 6.86, p = 0.009.
Distribution of FOCUS change scores across assessment points.
Previous research found that children who waited two months to begin intervention did not show clinically significant change on the FOCUS (Thomas-Stonell et al., 2013), therefore a Wilcoxon Rank Sum test was used to compare FOCUS change scores for children who waited two months or less (n = 10) and for those who waited more than two months (n = 14) between the initial assessment and the start of intervention. No significant difference was found, z = −1.87, p = 0.06.
2 Changes in communicative function
All 24 children were classified as CFCS Level IV at both initial assessment and the start of intervention. At the end of intervention, 12 were still classified as Level IV but 10 moved to Level III and two to Level II. At the consolidation follow-up appointment, only five children remained classified as Level IV (see Figure 1). Fisher’s Exact test revealed there was a significant change in the distribution of children across CFCS levels over the four assessment points (p < 0.01). Changes in CFCS level from Times 2 (pre-program consultation) to 3 (end of group treatment) and from Times 3 (end of group treatment) to 4 (end of consolidation) were significantly different (p < 0.01 and p = 0.04, respectively).
Children’s CFCS classifications at each assessment point.
3 Changes in expressive vocabulary
Table 1 presents the means and standard deviations for Total MBCDI scores at three assessment points. Total MBCDI scores differed across the three time points, X2 = 59.01, p < 0.01. Post-hoc pairwise comparisons showed significant differences in Total MBCDI scores between Time 2 (pre-program consultation) and 3 (end of group treatment), z = −3.66, p < 0.01, r = 0.75, and Times 3 (end of group treatment) and 4 (end of consolidation), z = −2.07, p = 0.04.
4 Changes in consonant inventory
Means and standard deviations for children’s consonant inventories at three assessment points are presented in Table 1. There was a significant difference in consonant inventory across the three time points, X2 = 51.26, p < 0.01. Post-hoc pairwise comparisons showed significant differences between Times 2 (pre-program consultation) and 3 (end of group treatment), z = −4.33, p < 0.01, r = 0.88, but not between Times 3 (end of group treatment) and 4 (end of consolidation), z = −0.14, p = 0.89.
5 Relationship between outcomes
Spearman correlation with Sidak correction was used to investigate the relationship between communicative participation and impairment-based outcomes. Change in communicative participation was not significantly correlated with vocabulary change or consonant inventory change during the program or during consolidation (see Table 4).
Correlations between change on the FOCUS and impairment-based measures during direct intervention and the consolidation period.
Because we found significant change on the FOCUS and MBCDI at both the end of the program and the end of consolidation, and significant change in consonant inventory at the end of the program, we examined whether change on these measures was related to level of communicative function (CFCS level). Spearman correlations of change scores with CFCS level revealed that most changes were not related to level of communicative function either during intervention or during consolidation. However, there was a significant negative correlation between CFCS level and expressive vocabulary change during the program (q = 0.01) (see Table 5).
Correlations between Communication Function Classification System (CFCS) level and outcome measures.
Note. * q < 0.05.
IV Discussion
The first aim of this study was to explore communicative participation outcomes for preschoolers identified as late-to-talk whose parents participated in Target Word™ – The Hanen Program® for Parents of Children who are Late Talkers. Overall, children were reported to have made clinically meaningful changes in their communicative participation skills between Times 1 (initial assessment) and 2 (pre-program consultation), and during the face-to-face portion of the program (between Times 2 and 3), but not during the consolidation period (between Times 3 and 4).
Because there was a significant change between the first two time points when no intervention was provided, we cannot directly attribute changes in communicative participation to parents’ participation in the Target Word program. We did not expect to find clinically significant changes on the FOCUS during the period between initial assessment and the start of the program. Thomas-Stonell et al. (2013) found that children on a two-month waiting list made, on average, much less change than the 18.67 change we observed here. A possible explanation could be that children in our study waited varying amounts of time to start the program, however our analysis revealed that children who waited two months or less did not differ from those waiting more than two months in their Total FOCUS scores or FOCUS change scores at any assessment point. From our own clinical experience working in the program where Target Word was delivered, it is likely that at the initial assessment appointment, parents were provided with some suggestions for supporting their child’s language development at home. Perhaps the parents who participated in this study successfully adopted these suggestions to facilitate this clinically meaningful change in their child’s communicative participation skills before the start of the program. Alternately, it is possible that this change was the result of natural development. However, in this case, we might also expect similar change during the consolidation period.
Although change during the direct intervention (between Times 2 and 3) cannot be directly attributed to parents’ participation in Target Word, it is interesting to note that the highest proportion of children made clinically meaningful change during this period. In fact, the proportion of children who made clinically meaningful change in communicative participation during direct intervention (75%) was the same as the proportion of children who made this change in our retrospective chart review of the same program (Kwok et al., 2019). Other studies have explored the development of preschoolers’ communicative participation skills broadly across all disorder types and levels of severity (Cunningham et al., 2017; 2018), and demonstrated clinically meaningful growth in communicative participation skills following clinician-directed interventions in specific populations including children with dysarthria, childhood apraxia of speech, and those requiring augmentative and alternative forms of communication (Namasivayam et al., 2015; Pennington et al., 2013; Thomas-Stonell et al., 2013; Thomas-Stonell et al., 2016). To our knowledge, this is the first published prospective study to measure changes in communicative participation skills for children who are late-to-talk. Findings are consistent with other studies of communicative participation outcomes following intervention, namely that a high proportion of children made clinically meaningful change during a period of direct intervention (Namasivayam et al., 2015; Pennington et al., 2013; Thomas-Stonell et al., 2013; Thomas-Stonell et al., 2016), but additional work is needed to attribute that change to the intervention.
On average, children did not make clinically significant changes in communicative participation during the consolidation period (between times 3 and 4), but skills were maintained. There were no significant differences in the amount of change observed during the consolidation period for children based on how long the consolidation period was (i.e. 1 vs. 2–3 months). While it may be ideal for children to show further clinically significant change during the consolidation period, this is not necessarily to be expected. Growth in communicative participation may not be linear, and a period of flat growth may be typical following a period of intensive intervention. Our finding of a significant negative correlation between FOCUS change scores during the direct intervention and change scores during the consolidation period lends some support to this hypothesis. Children who made clinically meaningful change during direct intervention may have entered a period of plateau during the consolidation period and vice versa. An alternate interpretation is that children’s needs changed during the consolidation period, but parents continued to apply strategies they had learned during Target Word that were no longer relevant to the child’s needs.
These are all areas of future research for our team. We are currently working to develop a randomized trial to learn more about how children who are late-to-talk develop when their parents do versus do not participate in Target Word. Future research will also explore parents’ experiences during the consolidation period, as well as the changes that take place between initial assessment and the start of this program, in greater detail.
Another aim of this study was to explore children’s functional communication outcomes using the CFCS. Children moved levels of communicative function over the course of the program (between Times 2 and 3), and again during the consolidation period (between Times 3 and 4). This means children became more effective and independent senders and receivers of information during these times. The lack of change in CFCS level prior to the start of the program (between Times 1 and 2) relative to the significant changes during the program and consolidation provides some preliminary support for treatment effectiveness, that is, that these changes can be attributed to the Target Word program. Some studies have used the CFCS to classify children’s communicative function at one point in time (e.g. Cunningham et al., 2018), but to our knowledge, this is the first study to show that children’s communicative function changes during intervention.
In addition to clinically significant changes on the CFCS and FOCUS, children made statistically significant changes in their impairment-based skills during Target Word. Significant changes in expressive vocabulary were observed during the face-to-face portion of the program (between Times 2 and 3) and during the consolidation period (between Times 3 and 4). Children’s consonant inventories also increased significantly during the face-to-face portion of the program. This finding is consistent with several previous studies evaluating vocabulary outcomes following parent-implemented intervention for children who are late to talk (Buschmann et al., 2010, 2015; DeVeney et al., 2017; Girolametto et al., 1996). The finding also contradicts results from other studies (Kaiser et al., 1995; Wake et al., 2011). Differences in family characteristics, and treatment format, intensity, and degree of individualized support have been hypothesized to influence the outcome of parent-training programs for children who are late-to-talk (Kaiser et al., 1995; Wake et al., 2011). It may be that our study included characteristics like those that have found a positive effect of programs like Target Word in the past. We believe the treatment format (group and individual sessions delivered by a SLP with time between each), and the degree of individualized support (individual home visits with feedback specific to each child) provided to parents in the Target Word program were important factors associated with the outcome of our study. In Wake et al. (2011) outcomes were evaluated after six weekly group training sessions for parents, with limited time between sessions for parents to practice and without individual visits from the SLP. In Kaiser et al. (1995), parents were trained by novice trainers, and not SLPs experienced in supporting parents of children who are late-to-talk.
At the start of the program, children’s consonant inventories were similar to those of children with expressive language delay, but by the end of the face-to-face portion of the program, children had an average of almost 16 consonant sounds, which was consistent with typically-developing children of the same age (Rescorla and Bernstein Ratner, 1996). There were no significant differences in the amount of change observed in impairment-based skills during the consolidation period for children based on how long the consolidation period was (i.e. 1 vs. 2–3 months). Significant changes in consonant inventory were not observed during the consolidation period. This may be because children’s skills had developed to within normal limits, and no further changes were expected until a later age, or it may be that parents were unable to facilitate growth in this skill without support of the SLP.
Because this study was completed in a community setting with an existing program and model of service delivery, we did not have data for expressive vocabulary or consonant inventory at initial assessment. This means that we cannot comment on whether children made more gains in these skills during their time in intervention than during the time between the initial assessment and start of the program. In other words, we cannot specifically attribute positive changes in vocabulary and speech production to the Target Word program. This is an area of future research for our group.
Secondary study aims were to explore the relation between communicative participation and impairment-based outcomes and the relation between all outcomes and levels of communicative function. We found no relationship between participation and impairment-based outcomes. Previous research has reported similar findings. For example, Pennington et al (2013) found that while communicative participation and speech intelligibility both increased significantly during an intervention for children with dysarthria, changes in communicative participation and speech intelligibility were not related. It may be that impairment- and participation-based skills develop in parallel, but are unrelated, but more evidence is needed to substantiate this claim.
When exploring the relationship between outcomes and levels of communicative function, we found a significant negative correlation between CFCS level and change on the MBCDI during the face-to-face portion of the program. This suggests that children who were classified in the higher levels of function (i.e. Levels II and III) at the end of the intervention made greater gains in their expressive vocabularies than children who remained in CFCS Level IV for the duration of the study. It is not surprising that children who expand their vocabularies become more functional communicators as it would likely allow children to use more word types (e.g. nouns, verbs, adjectives) and communicative functions (e.g. greet, request, protest). What is not yet clear is the direction of the relationship between vocabulary growth and communicative function. It may be that children who are less functional communicators gain fewer words during Target Word, or that children who gain fewer words are less likely to be rated highly in terms of their functional communication at the end of the intervention. It is unsurprising that change in communicative participation (FOCUS score) was not associated CFCS level because the FOCUS was designed to measure change in communicative participation equally regardless of a child’s level of function (Hidecker et al., 2017; Thomas-Stonell et al., 2013).
There are limitations to this study that must be acknowledged. First, because the study was conducted in publicly-funded community-based program, we did not have a control group. This means we could not compare outcomes for similar groups of children whose parents did not participate in a Target Word program. In future studies, we will work with community-based programs to identify methods for obtaining wait-list controls and to obtain more complete data at initial assessment to further establish the effectiveness of this program. We were also unable to collect information on factors like parents’ income and education that may have been associated with outcomes. As this was a parent-implemented intervention, it would have been beneficial to obtain direct observation of parents’ intervention fidelity and feedback about their experiences delivering the intervention. These are areas of future research for our team as we work to evaluate social and ecological validity of the program.
SLPs who run Target Word completed an informal Speech Sound checklist. For this study, we were able to obtain consonant inventory counts from this checklist, but information about restricted use of vowels and syllable/word shapes was not consistently completed by the SLPs. In future studies, we will provide training to ensure this information is provided consistently and reliably. The Target Word program was recently revised (2015) with the intention of supporting the discrimination of children who are late-to-talk from those who will continue to have speech sound delays and may go on to develop Childhood Apraxia of Speech (CAS), given that at this young age, it can be difficult to determine whether children who are late-to-talk have language difficulties or whether there may be an underlying motor-based speech disorder (Pukonen et al., 2017). More specifically, children who make gains in expressive vocabulary and consonant inventory during intervention are proposed to be most likely late-to-talk, while those who make few gains may be at risk for CAS. With better data related to children’s use of vowels and syllable shapes, and with studies that follow children over a longer term, we will be better positioned to investigate the program’s ability to discriminate between children with different impairments. Despite these limitations, we have evidence to suggest that the Target Word program effectively improves the communicative function of preschoolers who are late-to-talk, and that children make gains in their communicative participation skills, expressive vocabularies, and consonant inventories during the program.
