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An investigation of language and phonological development and the responsiveness of preschool age children to the Lidcombe Program
Journal of Communication Disorders 40 (2007) 382–397
An investigation of language and phonological development and the responsiveness of preschool age children to the Lidcombe Program Isabelle Rousseau a, Ann Packman a,*, Mark Onslow a, Elisabeth Harrison b, Mark Jones c a
Australian Stuttering Research Centre, The University of Sydney, Australia b Department of Linguistics, Macquarie University, Australia c Queensland Clinical Trials Centre, University of Queensland, Australia
Received 6 February 2006; received in revised form 19 July 2006; accepted 5 October 2006
Abstract Knowledge of variables that predict treatment time is of benefit in deciding when to start treatment for early stuttering. To date, the only variable clearly related to treatment time with the Lidcombe Program is pre-treatment stuttering frequency. Previous studies have shown that children whose stuttering is more severe take longer to complete Stage 1 of the program. However, studies to date have not investigated phonology and language as predictors of treatment time. In the context of a Phase II clinical trial, the present prospective study showed that phonological development does not predict treatment time but that, together, stuttering severity, MLU and CELF Receptive Score predict 35–45% of the variance for time taken to complete Stage 1. Learning outcomes: The reader should be able to (1) understand guidelines developed for the timing of intervention with the Lidcombe Program based on previous retrospective studies, (2) determine whether pre-treatment language and phonological development play a role in treatmentled recovery with the Lidcombe Program and (3) understand recent empirical evidence on time taken by preschool children to complete Stage 1 of the Lidcombe Program. # 2006 Elsevier Inc. All rights reserved.
* Corresponding author at: Australian Stuttering Research Centre, The University of Sydney, P.O. Box 170, Lidcombe, NSW 1825, Australia. Tel.: +61 2 93519061; fax: +61 2 93519392. E-mail address: [email protected] (A. Packman). 0021-9924/$ – see front matter # 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.jcomdis.2006.10.002
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1. Introduction The Lidcombe Program of early stuttering intervention is a behavioral treatment developed for preschool age children who stutter. In this program, the parent presents verbal contingencies for stuttering and for stutter-free speech, at prescribed times in everyday speaking situations. During Stage 1 of the program, the parent and child visit the speech clinic once a week. At each visit, the speech–language pathologist (SLP) trains the parent in how to deliver the treatment at home. The parent demonstrates how treatment had been conducted during the previous week and the SLP gives feedback to ensure that treatment is appropriate. The SLP then demonstrates any adjustments that need to be made in the coming week taking into account, for example, the extent to which the child is responding to treatment. The SLP monitors the child’s stuttering by measuring the percentage of syllables that are unambiguously stuttered (%SS) at the start of the visit and collecting the daily ratings of stuttering severity made by the parent during the previous week. The parent uses a 10-point scale for these severity ratings, where 1 = no stuttering, 2 = extremely mild stuttering and 10 = extremely severe stuttering. Stage 2 commences when stuttering levels reach program criteria on both these measures for 3 consecutive weeks. These criteria reflect an absence – or a very low level – of stuttering both within and beyond the clinic. Parental verbal contingencies are withdrawn and frequency of clinic visits decreases during Stage 2. The aim of Stage 2 is to maintain program speech criteria. A treatment manual (Australian Stuttering Research Centre, 2004) and detailed clinician guide (Onslow, Packman, & Harrison, 2003) are available for the Lidcombe Program. The Lidcombe Program is supported by extensive evidence. A randomised controlled trial has shown that it is more effective than natural recovery (Jones et al., 2005). Safety and social validity have been demonstrated (Lincoln, Onslow, & Reed, 1997; Woods, Shearsby, Onslow, & Burnham, 2002) and Phase I and Phase II trials have shown that low levels of stuttering are maintained 2–7 years after treatment (Lincoln & Onslow, 1997; Onslow, Andrews, & Lincoln, 1994; Onslow, Costa, & Rue, 1990). Recovery plots are available from retrospective file audits of clinics in Australia and England (Jones, Onslow, Harrison, & Packman, 2000; Kingston, Huber, Onslow, Jones, & Packman, 2003), and research to date indicates that time taken to complete Stage 1 varies around a median of 11 clinic visits, with 90% of children completing Stage 1 in 22 visits. It should be noted, however, that when the children in those two studies were treated there was no stipulation that low within- and beyond-clinic stuttering criteria be maintained for three consecutive visits before concluding Stage 1. Guidelines have been developed for the timing of intervention with the Lidcombe Program (Packman, Onslow, & Attanasio, 2003). These have relied largely on regression studies that have investigated predictors of responsiveness to the program. The individual Jones et al. (2000) and Kingston et al. (2003) studies found that children with more severe stuttering took longer to complete Stage 1, but that neither gender, age, nor period elapsed since reported onset were related to this. However, meta-analysis of the two studies (see Kingston et al., 2003), employing large subject numbers, showed that children who had been stuttering for longer tended to take less time to complete Stage 1 than those who had been stuttering for a shorter period. In light of these findings, it is considered safe to wait for some period after stuttering onset, within the preschool years, before implementing the
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program, to see if natural recovery occurs. Around 75% of children who start to stutter recover naturally (Yairi & Ambrose, 1999), typically within 2 years of onset, although this figure is likely to be lower in clinical populations. It is considered prudent to intervene somewhat earlier with children whose stuttering is severe, as treatment times tend to be longer for these children. A striking feature of data from these regression studies is their inconsistency with case history variables known to be associated with natural recovery (Onslow & Packman, 2001). Time since reported onset and gender predict natural recovery, with stuttering severity apparently not salient (Bloodstein, 1995; Yairi & Ambrose, 1999). However, to date nothing is known about language and phonological development and responsiveness to the Lidcombe Program, although many studies have investigated language and phonological development and stuttering more generally (see Nippold, 1990, 2001, 2002, 2004 for reviews). Children who stutter frequently present with concomitant speech and language disorders, although the extent to which this occurs is still unclear (Nippold, 1990, 2001). Also, the onset of stuttering occurs at a time of rapid phonological and language development (Bernstein-Ratner, 1997; Yairi & Ambrose, 1992) and some have argued for a causal relationship between language and stuttering (Anderson & Conture, 2000; Homzie & Lindsay, 1984). The possible interaction between stuttering and phonology has also prompted the development of theoretical explanations of stuttering, such as the Covert Repair Hypothesis (Postma & Kolk, 1993). There has also been interest in the relationship between phonological and language development and natural recovery from stuttering. Children who recover naturally score somewhat higher on tests of phonological development than those who do not (Paden, Yairi, & Ambrose, 1999). However, persistent and recovered children score no differently on tests of language ability (Watkins, Yairi, & Ambrose, 1999). One study has investigated whether the reductions in stuttering that result from the Lidcombe Program come at the expense of curtailment of language use (Bonelli, Dixon, Ratner, & Onslow, 2000). No reductions were found in child and parental language functioning after treatment, although the data suggested that some children did not meet developmental expectancies at the end of Stage 1. Establishing whether language and phonological development predict treatment time with the Lidcombe Program has both clinical and theoretical significance. As with other known predictors, if there is a relationship between these variables and time taken to complete Stage 1, then the results of speech and language assessment could be incorporated into clinical decision-making about the timing of intervention. Theoretically, it would be interesting to determine whether phonological development has a role in treatment-led recovery, as appears to be the case in natural recovery. Further, while language development appears unrelated to natural recovery, children whose language is advanced may respond more quickly to the Lidcombe Program, given the known relationship between cognitive development and performance on certain language tests, such as the Peabody Picture Vocabulary Test (PPVT-R, PPVT-3) (Dunn & Dunn, 1997) and the Clinical Evaluation of Language Function (CELF-P, CELF-3) (Semel, Wiig, & Secord, 1995; Wiig, Secord, & Semel, 1992). On the other hand, it has been argued that advanced language development can contribute to stuttering (Starkweather, 1997), and so these children may take longer to respond to the Lidcombe Program.
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A clear strength of the Jones et al. and Kingston et al. studies is their large subject numbers that were able to sustain regression analyses and meta-analysis. However, their retrospective file audit methods involved some weaknesses. First, independent measures of treatment outcome were not obtained. Second, the variable onset-to-treatment interval was not established optimally using a standard protocol such as that used by Yairi and Ambrose (1992). Third, the children in those file audits were treated prior to the publication of the treatment manual in 1999 (Australian Stuttering Research Centre, 2004), which stipulates that children must maintain the low Stage 1 stuttering criteria for three consecutive visits before moving to Stage 2. Finally, in those studies it was not possible to investigate the effects of language and phonology on treatment times with the Lidcombe Program, because data pertaining to these variables were not collected in a standardised fashion. The present study, then, is a further investigation of predictors of treatment time for preschool age children treated with the Lidcombe Program. It is a replication and extension of the retrospective Jones et al. (2000) and Kingston et al. (2003) studies, conducted within the prospective context of a Phase II clinical trial involving objective measures of treatment outcome. The present study investigated whether there is a relationship between speech and language development at the start of treatment and time taken to complete Stage 1 of the program. It was not intended to specifically study children with identified concomitant speech and/or language disorders, which will be the topic of future research. A secondary aim of the study, using trial outcome data, was to generate new information on the mean and median times taken by preschoolers to complete Stage 1 of the program, given the relatively recent stipulation in the treatment manual that Stage 1 stuttering criteria be maintained for three consecutive visits before Stage 2 can commence.
2. Method 2.1. Participants Participants were 34 children recruited in order from the treatment waiting list of a public speech pathology clinic in Sydney. Treatment at this clinic is provided without direct cost to clients. The children had been brought to the clinic by parents who were concerned about their child’s stuttering. At the clinic intake assessment, children were referred to the study if they were identified as stuttering by the assessing SLP. When the children’s names reached the top of the waiting list, the treating SLP reassessed them and offered participation in the study if they met the following criteria: (1) age 3–6 years, (2) English the main language spoken at home, (3) onset of stuttering more than 3 months previously, (4) stuttering frequency above 1%SS in one of the pre-treatment samples (see measurement of treatment outcomes below) and (5) no treatment for stuttering in the previous 6 weeks. The mean time elapsed from clinic intake assessments to when children’s names reached the top of the waiting list was 6 months (range 1–10 months). Twenty-nine children completed Stage 1 and were included in the subsequent data analysis. Twenty-one (72%) of them were boys. Although English was the main language
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spoken by all children and parents, eight children were exposed to a second language at home. The reasons for children dropping out of the study are provided in detail below, in Clinical Progress. Three of the 29 children who completed Stage 1 had previously received treatment for their stuttering. Details of those treatments were obtained from the SLP who had treated them. The number of treatment sessions completed ranged from 3 to 13 and reported speech measures showed improvement in only one case (from a reported 4.2 to 2.9%SS). The time elapsed between the last treatment session completed and admission to the study ranged from 7 to 12 weeks. In the cases of recently discontinued treatment, parents were carefully instructed to stop implementing any procedures related to that treatment. 2.2. Assessment and treatment Before the start of treatment, children were assessed during two clinic visits, over a 2–4week period. At Assessment Visit 1, one or both parents were interviewed and relevant case history information was obtained. Testing of expressive and receptive language and phonological development (see Section 2.5 below) was conducted during Assessment Visits 1 and 2. Once the assessments were completed, all children were treated by the same SLP (the first author) with the Lidcombe Program, according to the treatment manual (Australian Stuttering Research Centre, 2004). The treating SLP had completed Lidcombe Program training. Treatment fidelity was ensured in two ways. First, the developers of the Lidcombe Program regularly observed clinic visits and provided feedback to the treating SLP. Second, as described above, at each clinic visit during the Lidcombe Program parents demonstrate how they had conducted home treatment during the previous week. This forms the basis of parent training. The parents in this study audio recorded at least one home treatment session to confirm that they were conducting treatment at home as they had been trained to do in the clinic. In this way, treatment fidelity was established for the 29 children. 2.3. Trial outcome measure Percent syllables stuttered was the trial outcome measure. This is measured in real-time with a button-press counter, with one button pressed for each syllable that is judged to be unambiguously stuttered and another button pressed for all other syllables. The measures were gathered from recordings made in naturalistic speaking situations before, during and after treatment. Parents made pre-treatment recordings at the time of Assessment Visits 1 and 2 and at the start of Stage 1. Post-Stage 1 measures of %SS were made from recordings made around the time of the last Stage 1 visit, and at 6, 12 and 24 months after starting Stage 2. At each of these seven measurement occasions, two beyond-clinic audio taped conversation samples were made by parents, one at home with a parent and another with a familiar adult away from home. Parents were supplied with an audiotape recorder if they did not have access to one. Additionally, at each measurement occasion a within-clinic recording was made of the children while conversing with the clinician and the parent.
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Most of these recordings were video recordings. All recorded conversations were approximately 10 min in duration. A total of 594 recordings were obtained in this fashion for the purposes of measuring outcome. In order to complete the study in a timely manner, %SS measures were obtained by two independent observers who were not associated with the study. Both were SLPs with extensive experience in measuring stuttering. A preliminary analysis was conducted to determine if data from the two observers could be pooled. Each observer rated the same 20 samples containing an equal number of pre- and post-Stage 1 recordings. A Pearson r of 0.90 showed high agreement between the two observers, and hence their %SS measures were pooled. All recordings were then randomised and presented blind to the independent observers who measured %SS using a Sony Professional Walkman WM-D6C tape recorder, Sennheiser HD 500 headphones and a button-press electronic counting device. Recordings that contained fewer than 200 syllables or were inaudible for the purpose of measuring %SS were deleted from the data set. On some measurement occasions, parents collected more than the required number of recordings. All recordings were rated for %SS and ratings of additional samples were pooled with another sample collected in the same speaking situation at the same data point. After these criteria and procedures were applied, a total of 509 speech measures remained for analysis. Reliability of %SS measures was assessed from 58 (10%) of the recordings. An even number of pre- and post-Stage 1 recordings were selected for each child who completed Stage 1. Thirty-eight of these recordings were beyond-clinic samples and 20 were withinclinic samples. Intrajudge agreement was assessed by having each independent observer re-measure %SS on the 58 recordings 6–8 weeks after the original measures were made. Interjudge agreement was assessed by presenting the 58 recordings to a third blinded independent observer, a SLP who was also experienced in measuring %SS. Intrajudge Pearson r was 0.95 and interjudge Pearson r was 0.82. Table 1 shows that in the case of intrajudge agreement 98% of the original and repeated ratings were within 2.0%SS, and in the case of interjudge agreement 79% of the original and independent ratings were within 2.0%SS. Intrajudge reliability was very high, and although interjudge reliability was lower, overall the data were deemed to be trustworthy, given the large treatment effect (see Section 3). Table 1 Intrajudge and interjudge agreement for %SS scores (n = 58) %SS scores Intrajudge agreement
Interjudge agreement
Difference (%SS)
No. of measures
% of total
Cumulative %
Difference (%SS)
No. of measures
% of total
Cumulative %
0 0–0.9 1–1.9 2–2.9
8 41 8 1
13.8 70.7 13.8 1.7
13.8 84.5 98.3 100.0
0 0–0.9 1–1.9 2–2.9 3–3.9 4–4.9
3 32 11 9 1 2
5.2 55.2 19.0 15.5 1.7 3.4
5.2 60.4 79.4 94.9 96.6 100.0
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2.4. Dependent variables The time taken to complete Stage 1 of the Lidcombe Program (treatment time) was number of Stage 1 visits and number of weeks in Stage 1. The former is of most relevance for SLPs, as it can help them plan the management of their caseload. However, children sometimes miss clinic visits, which is why the latter is included, as it is a more realistic guide for clinical time management. It comprises the total weeks elapsed between the first and last Stage 1 clinic visits. Stage 1 concludes when the child maintains criterion speech performance for 3 consecutive weeks, the criteria being beyond-clinic parent severity ratings of 1–2, and within-clinic %SS below 1.0. 2.5. Predictor variables 2.5.1. Case history variables Gender, age at first clinic visit and reported onset-to-treatment interval were the case history predictor variables. Reported onset-to-treatment interval was determined during the parent interview conducted at Assessment Visit 1. In order to establish this, Yairi and Ambrose’s (1992) protocol was used and cross-validated with information noted in the file at the clinic intake assessment and at the first contact of the family with the health service, when parents telephoned to request an assessment. When discrepancies were found between parents’ reports at Assessment Visit 1 and the file notes, parents were questioned again carefully. This procedure yielded onset-to-treatment interval data deemed to be accurate to the week, or at least the month, of onset. 2.5.2. Pre-treatment %SS At the three pre-treatment measurement occasions, when recordings were made of each child for the purpose of outcome assessment (see above), the treating SLP also made an online measure of %SS during conversation with the child and mother within the clinic. As in the two previous predictor studies (Jones et al., 2000; Kingston et al., 2003), the SLP-%SS measures generated within the clinic were used to calculate the predictor variable pretreatment %SS. The SLP measures were used because the criteria for completing Stage 1 and moving to Stage 2 (the dependent variables, see above) are based on %SS measures made in the clinic by the SLP, along with parental severity ratings. As will be seen in Section 3, the mean SLP within-clinic %SS and the mean outcome %SS differed by only 0.2. 2.5.3. Language Language development was assessed at Assessment Visit 2 with the Peabody Picture Vocabulary Test–Third Edition (PPVT-3) (Dunn & Dunn, 1997) and the Clinical Evaluation of Language Function–Preschool (CELF-P) (Wiig et al., 1992). For each child, one pre-treatment 10-min video speech sample was orthographically transcribed and analysed for MLU in morphemes (Brown, 1973) using the relevant module of Computerized Profiling Version 9.6.0 (Long, Fey, & Channel, 2000). Each sample consisted of a conversation between parent and child while playing with a standard set of toys within the clinic. Parents had been instructed to engage in play with their child as if
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they were at home and to attempt to limit their use of closed questions. Two trained research assistants transcribed the recordings and checked the other’s transcripts for transcription conventions and coding errors, utterance boundaries, intelligibility decisions and morpheme decisions. Interjudge agreement for transcriptions was assessed by measuring the pre-resolution percentage of agreement for utterance boundary decisions, intelligibility decisions and morpheme decisions, yielding overall levels of 97, 88 and 99%, respectively. All transcription disagreements were then resolved through consensus. Predictor variables for language were PPVT-3 Standard Score, CELF-P Total Standard Score, CELF-P Receptive Standard Score, CELF-P Expressive Standard Score and MLU in morphemes. 2.5.4. Phonology Phonological development was measured at Assessment Visit 1 using the Assessment of Phonological Processes–Revised (APP-R) (Hodson, 1986). The APP-R was scored according to the instruction manual. Level of phonological impairment was determined by counting the number of failures to produce each of the 10 phonological patterns. The percentage of error for each pattern was then calculated, followed by the Mean Percentage of Error for all 10 patterns. To account for decreases in errors with phonological development, the APP-R prescribes the addition of age-compensatory points to the Mean Percentage of Error for children aged 4 years and above (4 years, add 5 points; 5 years, add 10 points; 6 years, add 15 points; 7 years and above, add 20 points). The final score obtained, the Phonological Deviancy Score (PDS), indicates the severity of phonological impairment. A higher score indicates poorer phonological performance. Because the children were at the stage of rapid phonological development, it was deemed necessary to use a more precise compensation for age than that prescribed in the manual. The procedure used was that of Paden and colleagues (Paden, Ambrose, & Yairi, 2002; Paden & Yairi, 1996; Paden et al., 1999) for the APP-R with stuttering preschool children. That is, 0.417 was added to the Mean Percentage of Error for each month in age past 3 years. The predictor variable was APP-R Phonological Deviancy Score. Reliability of phonological productions on the APP-R was conducted for nine children (31%) chosen randomly. An independent SLP who had no knowledge of the participants but had considerable experience in the assessment of speech in young children listened to the children’s audio recorded productions on the APP-R and calculated the PDS scores following the same procedure. Agreement was deemed acceptable (r = 0.82). 2.6. Statistical methods The dependent variables, namely number of clinic sessions and number of weeks to complete Stage 1, were positively skewed. These variables were log transformed to remove skew and linear regression was used for analysis. As pre-treatment %SS has been shown to clearly predict treatment time in two previous studies (Jones et al., 2000; Kingston et al., 2003) this variable was included in all models tested. The remaining nine predictor variables were then added to the model individually to determine which, if any, were also potentially predictive. Finally, a forward selection technique was used to obtain the best multiple regression predictive model based on a cut-off p-value of <0.05 for acceptance of
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independent predictor variables in the final model. The adjusted r-square value for the best model is provided as a measure of how well the model fits the data. Estimates obtained from the best model were back transformed for the purpose of interpretation.
3. Results 3.1. Clinical progress Of the 34 children enrolled in the study, 29 completed Stage 1. The reasons for five children failing to complete Stage 1 are presented in Table 2. Table 2 shows that in only one case (Subject 3) could failure to complete Stage 1 be attributed to unsatisfactory clinical progress. This child also had a high stuttering frequency; however, this is not typically a barrier to completing the Lidcombe Program, as can be seen in Jones et al. (2000) and Kingston et al. (2003). Frequency of failure to complete Stage 1 in the present study was higher than reported by Jones et al. (2000) but similar to that reported by Kingston et al. (2003). The 29 children completed Stage 1 in a median of 16 clinic visits (mean 18), and in a median of 27 weeks (mean 24). Ninety percent of children had completed Stage 1 within 31 visits. 3.2. Trial outcomes The stuttering outcomes for the 29 children who completed Stage 1 are presented in Table 3. Of these 29 children, 24 had completed Stage 2 and two were still in Stage 2 at the time of data analysis. Of the remaining three children, one did not start Stage 2 and two discontinued Stage 2 for unremarkable reasons. As is usually the case in outcome studies of stuttering, a small amount of data is missing. Reasons include faulty equipment and recordings lost or not collected by parents. The majority of the missing data are at the 24-months measurement occasion because not all children had reached that point at the time of data analysis. Mean pre-Stage 1 stuttering frequency was 3.0%SS, which is lower than for previous trials of the Lidcombe Program, and mean post-Stage 1 stuttering frequencies were, with few exceptions, below 1.0%SS. A paired t-test for the difference between pre- and post-treatment %SS scores was significant (t = 7.195, d.f. = 28, p < 0.0001). The pooled mean number of syllables spoken was determined for all pre- and post-Stage 1 speech samples up to 24 months, for all children. The mean number of syllables spoken was 581 pre-Stage 1 and 715 post-Stage 1, indicating that treatment outcome was not associated with reduced speech output. 3.3. Prediction of treatment time Table 4 presents treatment times and continuous predictor variables for the 29 children who completed Stage 1. As was the case for the outcome %SS scores (see above), mean SLP pre-treatment stuttering frequency of 3.2%SS was lower than in previous regression
Gender
Previous treatment for stuttering (no. of sessions)
Age at start of Stage 1 (months)
Average pre-treatment within-clinic %SSa
No. of Stage 1 clinic visits
Reason treatment was not completed
%SS at last Stage 1 clinic visit attended a
1
M
Y (10)
37
10.9
11
2.4
2
F
N
38
7.4
12
3
M
Y (26)
51
21.3
32
4
M
N
58
3.0
5
5
M
N
61
1.8
8
Baby brother became very ill and mother could not continue weekly clinic visits. Wanted to resume Stage 1 after a 6-month break Mother had chronic depression and could not attend weekly clinic visits. Wanted to resume Stage 1 after 3 months Stage 1 was discontinued due to lack of progress. Child had a long history of unsuccessful treatment prior to entering study and was becoming adverse to any form of treatment Child had very challenging behavior and mother found it too difficult to attend weekly clinic visits with two younger siblings. She also reported not being overly concerned with the stuttering after the last clinic visit Family moved and travelling to clinic became impossible. Mother kept doing the treatment and at phone contacts 2 weeks and 3 months after last clinic visit, the child was not stuttering
a
As measured by the treating clinician.
2.2 3.4
1.8
0.2
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Table 2 Details of the five children who did not complete Stage 1
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Table 3 Mean, standard deviation, median, minimum and maximum pre- and post-treatment %SS outcome measures for 29 preschool age children who completed Stage 1 (At all data points, speech samples were collected (A) at home, (B) away from home with a familiar adult and (C) within the clinic) No. of measures
Mean
S.D.
Median
Min
Max
Pre-Stage 1 Assessment Visit 1 A 29 B 20 C 28
3.1 3.2 3.3
1.6 1.8 2.2
2.8 2.9 3.2
0.2 0.3 0.0
6.3 7.1 8.5
Assessment Visit 2 A 28 B 24 29 Ca
3.4 3.5 2.4
2.4 2.2 1.6
2.8 3.0 2.0
0.3 0.7 0.0
10.3 9.6 6.7
First Stage 1 visit A 28 B 22 C 27
2.6 2.5 2.6
1.7 1.8 2.0
2.3 2.3 2.4
0.0 0.3 0.2
6.9 8.1 8.6
Post-Stage 1 Last Stage 1 visit A 28 B 23 29 Ca
1.2 0.9 1.0
0.8 0.7 0.7
1.2 0.8 0.9
0.0 0.0 0.0
3.0 2.8 2.8
6 months post-Stage 1 A 25 B 23 26 Ca
1.1 1.0 0.8
0.8 0.7 0.7
1.1 1.0 0.6
0.0 0.0 0.0
2.7 2.8 2.7
12 months post-Stage 1 A 23 B 23 23 Ca
1.0 0.8 0.6
0.9 0.6 0.8
0.7 0.7 0.0
0.0 0.0 0.0
3.3 2.8 2.4
24 months post-Stage 1 A 15 B 13 16 Ca
0.3 0.3 0.1
0.4 0.3 0.1
0.2 0.2 0.0
0.0 0.0 0.0
1.6 1.1 0.4
a
These %SS scores were obtained from a video recording of the child in the clinic.
studies (Jones et al., 2000; Kingston et al., 2003). The reason for this is unknown but it may have partially been due to the fact that one of the dropouts had extremely severe stuttering. Most children scored within normal limits on the CELF-P. Only two children scored below the average range (<1S.D.) and six children scored above the average range (>1S.D.). Overall, children performed slightly better on receptive language tasks. Ten children scored above average in the receptive component whereas six children scored above average in the expressive component. Most children performed within normal limits on the PPVT-3; one child scored below the average range and eight scored above the average range. Most children (69%) were included in the ‘mild’ category as defined by the APP-R (PDS between 1 and 19 points). Twenty-eight percent had a PDS in the ‘moderate’ category
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Table 4 Treatment time and predictor variables (continuous) Variable
No. of measures
Mean
S.D.
Median
Min
Max
Treatment time variables Number of Stage 1 visits Number of weeks in Stage 1
29 29
17.9 27.2
9.7 16.2
16 24
6 9
40 80
Predictor variables Age at first Stage 1 clinic visit (months) Onset-to-treatment interval (months) Pre-treatment %SS PPVT-3 Standard Score CELF-P Total Standard Score CELF-P Receptive Standard Score CELF-P Expressive Standard Score MLU (in morphemes) APP-R
29 29 29 29 29 29 29 29 29
46.7 12.7 3.2 106.7 104.6 106.4 103.0 4.01 13.4
7.5 5.6 2.0 12.8 11.0 11.6 12.2 0.93 8.9
47 13 2.8 110 105 108 102 4.2 9.8
36 4 0.3 84 82 83 79 2.2 0
67 25 7.6 132 127 122 126 6.3 35.5
and no children were categorized as ‘severe’ or ‘profound.’ One child had no speech sound errors. The 29 conversations transcribed for MLU-m had an average length of 116 utterances (range: 68–240; S.D.: 39). Based on age at time of language sampling and on Miller and Chapman’s (1981) criteria, MLU in morphemes was 1S.D. below the predicted performance for seven children and 2S.D. below for one child; four children were 1S.D. above and one child was 2S.D. above the predicted performance. Although most children (55%) performed within normal age expectancies, the mean difference between the predicted MLU and the actual MLU for all children was 0.25. A paired t-test was not significant ( p = 0.21), suggesting that as a group the children had normally developing expressive language. Using multiple linear regressions and the forward selection technique it was found that pre-treatment %SS, CELF Receptive Score and MLU were all independent predictors of log(number of Stage 1 visits). The best predictor model is presented in Table 5. The adjusted r-square value obtained with this model was 0.34. For each 1%SS increase in pretreatment %SS, the number of clinic visits to complete Stage 1 is estimated to increase by 16% (95% confidence interval: 5–27%). For each 10 unit increase in CELF Receptive Score, the number of clinic visits to complete Stage 1 is estimated to increase by 27% (95% CI: 7–49%) and for each 1 unit increase in MLU, the number of clinic visits to complete Stage 1 is estimated to decrease by 18% (95% CI: 2–32%). Table 5 Best model for log(number of Stage 1 visits) Variable Pre %SS CELF Receptive MLU
Estimate (%) 16 27 18
95% confidence interval
p-Value
5–27 7–49 2 to
0.005 0.008 0.038
32
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Table 6 Best model for log(number of weeks in Stage 1) Variable Pre %SS CELF Receptive MLU
Estimate (%) 21 23 19
95% confidence interval
p-Value
10–32 6–45 3 to 32
0.0003 0.013 0.024
A similar result was found for log(number of weeks in Stage 1) and the best predictor model is presented in Table 6. This model had an adjusted r-square value of 0.44. For each 1%SS increase in pre-treatment %SS, the number of weeks to complete Stage 1 is estimated to increase by 21% (95% CI: 10–32%). For each 10 unit increase in CELF Receptive Score, the number of weeks to complete Stage 1 is estimated to increase by 23% (95% CI: 6–45%) and for each 1 unit increase in MLU, the number of weeks to complete Stage 1 is estimated to decrease by 19% (95% CI: 3–32%). The estimated effect for receptive language and treatment time is adjusted for the severity of stuttering; therefore, it appears that receptive language has predictive power independent of severity of stuttering. During the course of exploratory correlation analyses, significant relationships were found between two language measures and pre-treatment %SS: CELF Total, r = 0.44 ( p = 0.02) and CELF Receptive, r = 0.46 ( p = 0.01). The correlation between CELF Expressive and Pre-treatment %SS was non-significant with r = 0.31, p = 0.10).
4. Discussion The primary aim of this study was to determine whether pre-treatment language and phonological development predict treatment time with the Lidcombe Program. No relationship was found between phonological development and time taken to complete Stage 1. However, the analyses yielded some intriguing findings in relation to language and treatment time. CELF Receptive Score and MLU both correlated significantly with treatment time in multiple regression analyses. The data showed that higher MLU was associated with shorter treatment time and a higher CELF Receptive Score was associated with longer treatment time. CELF Receptive Score also significantly correlated with pretreatment stuttering frequency with higher CELF Receptive Scores being associated with lower pre-treatment %SS scores. Together, %SS, MLU and CELF Receptive Score explain a large portion of the variance in treatment time; namely, 34% for the number of clinic visits taken to complete Stage 1 and 44% for the number of weeks taken to complete Stage 1. These proportions of treatment time that can be explained by stuttering severity and language variables are far greater than those reported to date. It should be noted that the significant relationship between CELF Receptive Score and treatment time was only apparent when pre-treatment stuttering frequency was included in the regression model. In other words, receptive language in this cohort of children added incremental predictive value on top of that provided by stuttering frequency. It is possible that this is a spurious finding (type 1 error); therefore, it needs to be confirmed or otherwise in a second prospective study.
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The finding that children whose expressive language is more advanced – in terms of length of utterance – tended to take less time to complete Stage 1 is of interest. Given the known relationship between cognitive development and performance on certain language tests, it may be that children who are more advanced cognitively respond more quickly to the program. Future research should take this into account. However, the CELF findings are more difficult to interpret. On the face of it, there is no reason to think that children with better comprehension would respond more slowly to the program. Perhaps this puzzling relationship reflects the presence of other variables not included in this study. It is interesting, however, that children with more severe stuttering before treatment had poorer comprehension and general language function (as scored on the CELF) than children whose stuttering was less severe. This needs to be investigated further in future research. In terms of predicting time taken to complete Stage 1, the present study is the first to use prospective methodology. The results replicate the findings of Jones et al. (2000) and Kingston et al. (2003) that relied on retrospective file audits. Once again, pre-treatment stuttering frequency predicted time taken to complete Stage 1 of the program. This finding provides face validity for using the within-clinic %SS measures made by the treating SLP for predicting treatment time, rather than using those made from naturalistic speech samples for the purposes of establishing trial outcomes. Other case history variables – gender, age and onset-to-treatment interval – were not related to treatment time. The median treatment time of 16 clinic visits in this study is higher than the 11 visits reported by Jones et al. (2000) and Kingston et al. (2003) file audits. The most likely reason for this is that when the children in those studies were treated it was not stipulated that low criterion levels of stuttering be maintained for three visits before concluding Stage 1. However, it is not clear whether other differences between this and the previous regression studies may have contributed to this longer treatment time. It is possible that demographics may have played a part. The present study was conducted in a generalist clinic that drew participants from a small area of Sydney, while the range of specialist clinics involved in the Jones et al. and Kingston et al. studies drew clients from all parts of Sydney, Australia, and Norwich, England, respectively. It is not clear, however, in what way this might influence treatment time. It is also the case that treatment in the present study was conducted by one SLP, whereas treatment in the previous studies was provided by many. The SLPs in the previous studies were in the main working in specialist stuttering clinics, and it could be argued that they had shorter treatment times because they were more experienced than the SLP in the present study. As a way of investigating this, median treatment times for each child in the present study were plotted against the time in weeks after the start of the study at which treatment began. No sign of any relationship was found. In other words, there was no indication that the present SLP initially lacked clinical skills that improved over the course of the study. Given the fact that the program manual now stipulates that Stage 1 criteria be maintained for three consecutive visits, and in light of the results of present study, it seems reasonable to raise the benchmark for median time to complete Stage 1 of the program. A clinician trained in the Lidcombe Program can expect that below 1.0%SS within the clinic and parent severity ratings of 1–2 would be attained in a median of 11–13 clinic visits, with Stage I normally concluding after another 3–5 visits. Further prospective studies are
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needed to confirm this benchmark. Of course, treatment times for individual children will vary around that median. However, the clinical implications of the findings for pre-treatment language scores in this study are not so clear. This was a preliminary study; subject numbers were quite small and the findings suggest that further investigation of the relationship between language variables and responsiveness is warranted. If the findings of this study are replicated with a more highly powered study, they have the potential to be of considerable value to SLPs in planning when to implement the Lidcombe Program with a preschooler who stutters. In closing, it must be remembered that none of the children in this study had serious language and/or phonological impairments. Given that children frequently present to a speech clinic with both stuttering and other speech and/or language disorders, there is a pressing need for further research to establish the responsiveness to the Lidcombe Program – and indeed to other interventions for early stuttering – of children who have concomitant speech and language disorders.
Acknowledgments The authors thank the children and families who participated in this research.
References Anderson, J. D., & Conture, E. G. (2000). Language abilities of children who stutter: A preliminary study. Journal of Fluency Disorders, 25, 283–304. Australian Stuttering Research Centre. (2004). Manual for the Lidcombe Program of early stuttering intervention, from http://www.fhs.usyd.edu.au/asrc. Bernstein-Ratner, N. (1997). Stuttering: A psycholinguistic perspective. In R. F. Curlee, & G. Siegel (Eds.), Nature and treatment of stuttering: New directions (2nd ed.). Boston: Allyn & Bacon. Bloodstein, O. (1995). A handbook on stuttering (5th ed.). San Diego, CA: Singular Publishing Group. Bonelli, P., Dixon, M., Ratner, N. B., & Onslow, M. (2000). Child and parent speech and language following the Lidcombe Programme of early stuttering intervention. Clinical Linguistics and Phonetics, 14, 427–446. Brown, R. (1973). A first language: The early stages. Cambridge, MA: Harvard University Press. Dunn, L. M., & Dunn, L. M. (1997). Peabody Picture Vocabulary Test (3rd ed.). Circles Pines, MN: American Guidance Service. Hodson, B. W. (1986). The assessment of phonological processes—Revised. Austin, TX: Pro-Ed. Homzie, M. J., & Lindsay, J. S. (1984). Language and the young stutterer: A new look at old theories and findings. Brain & Language, 22, 232–252. Jones, M., Onslow, M., Harrison, E., & Packman, A. (2000). Treating stuttering in young children: Predicting treatment time in the Lidcombe Program. Journal of Speech Language and Hearing Research, 43, 1440–1450. Jones, M., Onslow, M., Packman, A., Williams, S., Ormond, T., Schwarz, I., et al. (2005). Randomised controlled trial of the Lidcombe programme of early stuttering intervention. British Medical Journal, 331, 659–661. Kingston, M., Huber, A., Onslow, M., Jones, M., & Packman, A. (2003). Predicting treatment time with the Lidcombe Program: Replication and meta-analysis. International Journal of Language & Communication Disorders, 38, 165–177. Lincoln, M., & Onslow, M. (1997). Long-term outcome of early intervention for stuttering. American Journal of Speech-Language Pathology, 6, 51–58. Lincoln, M., Onslow, M., & Reed, V. (1997). Social validity of the treatment outcomes of an early intervention program for stuttering. American Journal of Speech-Language Pathology, 6, 77–84.
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Long, S. H., Fey, M. E., & Channel, R. W. (2000). Computerized profiling (CP) (Version 9.6.0). Cleveland, OH: Department of Communication Sciences, Case Western Reserve University. Miller, J., & Chapman, R. (1981). The relation between age and mean length of utterance in morphemes. Journal of Speech and Hearing Research, 24, 154–161. Nippold, M. A. (1990). Concomitant speech and language disorders in stuttering children: A critique of the literature. Journal of Speech and Hearing Disorders, 55, 51–60. Nippold, M. A. (2001). Phonological disorders and stuttering in children: What is the frequency of co-occurrence? Clinical Linguistics and Phonetics, 15, 219–228. Nippold, M. A. (2002). Stuttering and phonology: Is there an interaction? American Journal of Speech-Language Pathology, 11, 99–110. Nippold, M. A. (2004). Phonological and language disorders in children who stutter: Impact on treatment recommendations. Clinical Linguistics and Phonetics, 18, 145–159. Onslow, M., Andrews, C., & Lincoln, M. (1994). A control/experimental trial of an operant treatment for early stuttering. Journal of Speech and Hearing Research, 37, 1244–1259. Onslow, M., Costa, L., & Rue, S. (1990). Direct early intervention with stuttering: Some preliminary data. Journal of Speech and Hearing Disorders, 55, 405–416. Onslow, M., & Packman, A. (2001). The Lidcombe Program of early stuttering intervention: Awaiting the results of a randomized controlled trial. Asia Pacific Journal of Speech, Language & Hearing, 6, 85–89. Onslow, M., Packman, A., & Harrison, E. (Eds.). (2003). The Lidcombe Program of early stuttering intervention: A clinician’s guide. Austin, TX: Pro-Ed. Packman, A., Onslow, M., & Attanasio, J. S. (2003). The timing of early intervention with the Lidcombe Program. In M. Onslow, A. Packman, & E. Harrison (Eds.), The Lidcombe Program of early stuttering intervention: A clinician’s guide (pp. 41–55). Austin, TX: Pro-Ed. Paden, E. P., Ambrose, N. G., & Yairi, E. (2002). Phonological progress during the first two years of stuttering. Journal of Speech Language and Hearing Research, 45, 256–267. Paden, E. P., & Yairi, E. (1996). Phonological characteristics of children whose stuttering persisted or recovered. Journal of Speech and Hearing Research, 39, 981–990. Paden, E. P., Yairi, E., & Ambrose, N. G. (1999). Early childhood stuttering II: Initial status of phonological abilities. Journal of Speech, Language and Hearing Research, 42, 1113–1124. Postma, A., & Kolk, H. (1993). The covert repair hypothesis: Prearticulatory repair processes in normal and stuttered disfluencies. Journal of Speech and Hearing Research, 36, 472–487. Semel, E., Wiig, E. H., & Secord, W. A. (1995). Clinical evaluation of language fundamentals—3rd ed.. San Antonio, TX: The Psychological Corporation Harcout Brace Jonanovich Inc. Starkweather, C. W. (1997). Therapy for younger children. In R. F. Curlee, & G. M. Siegel (Eds.), Nature and treatment of stuttering: New directions (2nd ed., pp. 257–279). Boston: Allyn & Bacon. Watkins, R. V., Yairi, E., & Ambrose, N. G. (1999). Early childhood stuttering III. Initial status of expressive language abilities. Journal of Speech Language and Hearing Research, 42, 1125–1135. Wiig, E. H., Secord, W., & Semel, E. (1992). Clinical evaluation of language fundamentals—Preschool. San Antonio, TX: Harcourt Brace Jonanovich Inc. Woods, S., Shearsby, J., Onslow, M., & Burnham, D. (2002). Psychological impact of the Lidcombe Program of early stuttering intervention. International Journal of Language & Communication Disorders, 37, 31–40. Yairi, E., & Ambrose, N. (1992). Onset of stuttering in preschool children: Selected factors. Journal of Speech and Hearing Research, 35, 782–788. Yairi, E., & Ambrose, N. G. (1999). Early childhood stuttering I: Persistency and recovery rates. Journal of Speech, Language and Hearing Research, 42, 1097–1112.
An investigation of language and phonological development and the responsiveness of preschool age children to the Lidcombe Program Isabelle Rousseau a, Ann Packman a,*, Mark Onslow a, Elisabeth Harrison b, Mark Jones c a
Australian Stuttering Research Centre, The University of Sydney, Australia b Department of Linguistics, Macquarie University, Australia c Queensland Clinical Trials Centre, University of Queensland, Australia
Received 6 February 2006; received in revised form 19 July 2006; accepted 5 October 2006
Abstract Knowledge of variables that predict treatment time is of benefit in deciding when to start treatment for early stuttering. To date, the only variable clearly related to treatment time with the Lidcombe Program is pre-treatment stuttering frequency. Previous studies have shown that children whose stuttering is more severe take longer to complete Stage 1 of the program. However, studies to date have not investigated phonology and language as predictors of treatment time. In the context of a Phase II clinical trial, the present prospective study showed that phonological development does not predict treatment time but that, together, stuttering severity, MLU and CELF Receptive Score predict 35–45% of the variance for time taken to complete Stage 1. Learning outcomes: The reader should be able to (1) understand guidelines developed for the timing of intervention with the Lidcombe Program based on previous retrospective studies, (2) determine whether pre-treatment language and phonological development play a role in treatmentled recovery with the Lidcombe Program and (3) understand recent empirical evidence on time taken by preschool children to complete Stage 1 of the Lidcombe Program. # 2006 Elsevier Inc. All rights reserved.
* Corresponding author at: Australian Stuttering Research Centre, The University of Sydney, P.O. Box 170, Lidcombe, NSW 1825, Australia. Tel.: +61 2 93519061; fax: +61 2 93519392. E-mail address: [email protected] (A. Packman). 0021-9924/$ – see front matter # 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.jcomdis.2006.10.002
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1. Introduction The Lidcombe Program of early stuttering intervention is a behavioral treatment developed for preschool age children who stutter. In this program, the parent presents verbal contingencies for stuttering and for stutter-free speech, at prescribed times in everyday speaking situations. During Stage 1 of the program, the parent and child visit the speech clinic once a week. At each visit, the speech–language pathologist (SLP) trains the parent in how to deliver the treatment at home. The parent demonstrates how treatment had been conducted during the previous week and the SLP gives feedback to ensure that treatment is appropriate. The SLP then demonstrates any adjustments that need to be made in the coming week taking into account, for example, the extent to which the child is responding to treatment. The SLP monitors the child’s stuttering by measuring the percentage of syllables that are unambiguously stuttered (%SS) at the start of the visit and collecting the daily ratings of stuttering severity made by the parent during the previous week. The parent uses a 10-point scale for these severity ratings, where 1 = no stuttering, 2 = extremely mild stuttering and 10 = extremely severe stuttering. Stage 2 commences when stuttering levels reach program criteria on both these measures for 3 consecutive weeks. These criteria reflect an absence – or a very low level – of stuttering both within and beyond the clinic. Parental verbal contingencies are withdrawn and frequency of clinic visits decreases during Stage 2. The aim of Stage 2 is to maintain program speech criteria. A treatment manual (Australian Stuttering Research Centre, 2004) and detailed clinician guide (Onslow, Packman, & Harrison, 2003) are available for the Lidcombe Program. The Lidcombe Program is supported by extensive evidence. A randomised controlled trial has shown that it is more effective than natural recovery (Jones et al., 2005). Safety and social validity have been demonstrated (Lincoln, Onslow, & Reed, 1997; Woods, Shearsby, Onslow, & Burnham, 2002) and Phase I and Phase II trials have shown that low levels of stuttering are maintained 2–7 years after treatment (Lincoln & Onslow, 1997; Onslow, Andrews, & Lincoln, 1994; Onslow, Costa, & Rue, 1990). Recovery plots are available from retrospective file audits of clinics in Australia and England (Jones, Onslow, Harrison, & Packman, 2000; Kingston, Huber, Onslow, Jones, & Packman, 2003), and research to date indicates that time taken to complete Stage 1 varies around a median of 11 clinic visits, with 90% of children completing Stage 1 in 22 visits. It should be noted, however, that when the children in those two studies were treated there was no stipulation that low within- and beyond-clinic stuttering criteria be maintained for three consecutive visits before concluding Stage 1. Guidelines have been developed for the timing of intervention with the Lidcombe Program (Packman, Onslow, & Attanasio, 2003). These have relied largely on regression studies that have investigated predictors of responsiveness to the program. The individual Jones et al. (2000) and Kingston et al. (2003) studies found that children with more severe stuttering took longer to complete Stage 1, but that neither gender, age, nor period elapsed since reported onset were related to this. However, meta-analysis of the two studies (see Kingston et al., 2003), employing large subject numbers, showed that children who had been stuttering for longer tended to take less time to complete Stage 1 than those who had been stuttering for a shorter period. In light of these findings, it is considered safe to wait for some period after stuttering onset, within the preschool years, before implementing the
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program, to see if natural recovery occurs. Around 75% of children who start to stutter recover naturally (Yairi & Ambrose, 1999), typically within 2 years of onset, although this figure is likely to be lower in clinical populations. It is considered prudent to intervene somewhat earlier with children whose stuttering is severe, as treatment times tend to be longer for these children. A striking feature of data from these regression studies is their inconsistency with case history variables known to be associated with natural recovery (Onslow & Packman, 2001). Time since reported onset and gender predict natural recovery, with stuttering severity apparently not salient (Bloodstein, 1995; Yairi & Ambrose, 1999). However, to date nothing is known about language and phonological development and responsiveness to the Lidcombe Program, although many studies have investigated language and phonological development and stuttering more generally (see Nippold, 1990, 2001, 2002, 2004 for reviews). Children who stutter frequently present with concomitant speech and language disorders, although the extent to which this occurs is still unclear (Nippold, 1990, 2001). Also, the onset of stuttering occurs at a time of rapid phonological and language development (Bernstein-Ratner, 1997; Yairi & Ambrose, 1992) and some have argued for a causal relationship between language and stuttering (Anderson & Conture, 2000; Homzie & Lindsay, 1984). The possible interaction between stuttering and phonology has also prompted the development of theoretical explanations of stuttering, such as the Covert Repair Hypothesis (Postma & Kolk, 1993). There has also been interest in the relationship between phonological and language development and natural recovery from stuttering. Children who recover naturally score somewhat higher on tests of phonological development than those who do not (Paden, Yairi, & Ambrose, 1999). However, persistent and recovered children score no differently on tests of language ability (Watkins, Yairi, & Ambrose, 1999). One study has investigated whether the reductions in stuttering that result from the Lidcombe Program come at the expense of curtailment of language use (Bonelli, Dixon, Ratner, & Onslow, 2000). No reductions were found in child and parental language functioning after treatment, although the data suggested that some children did not meet developmental expectancies at the end of Stage 1. Establishing whether language and phonological development predict treatment time with the Lidcombe Program has both clinical and theoretical significance. As with other known predictors, if there is a relationship between these variables and time taken to complete Stage 1, then the results of speech and language assessment could be incorporated into clinical decision-making about the timing of intervention. Theoretically, it would be interesting to determine whether phonological development has a role in treatment-led recovery, as appears to be the case in natural recovery. Further, while language development appears unrelated to natural recovery, children whose language is advanced may respond more quickly to the Lidcombe Program, given the known relationship between cognitive development and performance on certain language tests, such as the Peabody Picture Vocabulary Test (PPVT-R, PPVT-3) (Dunn & Dunn, 1997) and the Clinical Evaluation of Language Function (CELF-P, CELF-3) (Semel, Wiig, & Secord, 1995; Wiig, Secord, & Semel, 1992). On the other hand, it has been argued that advanced language development can contribute to stuttering (Starkweather, 1997), and so these children may take longer to respond to the Lidcombe Program.
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A clear strength of the Jones et al. and Kingston et al. studies is their large subject numbers that were able to sustain regression analyses and meta-analysis. However, their retrospective file audit methods involved some weaknesses. First, independent measures of treatment outcome were not obtained. Second, the variable onset-to-treatment interval was not established optimally using a standard protocol such as that used by Yairi and Ambrose (1992). Third, the children in those file audits were treated prior to the publication of the treatment manual in 1999 (Australian Stuttering Research Centre, 2004), which stipulates that children must maintain the low Stage 1 stuttering criteria for three consecutive visits before moving to Stage 2. Finally, in those studies it was not possible to investigate the effects of language and phonology on treatment times with the Lidcombe Program, because data pertaining to these variables were not collected in a standardised fashion. The present study, then, is a further investigation of predictors of treatment time for preschool age children treated with the Lidcombe Program. It is a replication and extension of the retrospective Jones et al. (2000) and Kingston et al. (2003) studies, conducted within the prospective context of a Phase II clinical trial involving objective measures of treatment outcome. The present study investigated whether there is a relationship between speech and language development at the start of treatment and time taken to complete Stage 1 of the program. It was not intended to specifically study children with identified concomitant speech and/or language disorders, which will be the topic of future research. A secondary aim of the study, using trial outcome data, was to generate new information on the mean and median times taken by preschoolers to complete Stage 1 of the program, given the relatively recent stipulation in the treatment manual that Stage 1 stuttering criteria be maintained for three consecutive visits before Stage 2 can commence.
2. Method 2.1. Participants Participants were 34 children recruited in order from the treatment waiting list of a public speech pathology clinic in Sydney. Treatment at this clinic is provided without direct cost to clients. The children had been brought to the clinic by parents who were concerned about their child’s stuttering. At the clinic intake assessment, children were referred to the study if they were identified as stuttering by the assessing SLP. When the children’s names reached the top of the waiting list, the treating SLP reassessed them and offered participation in the study if they met the following criteria: (1) age 3–6 years, (2) English the main language spoken at home, (3) onset of stuttering more than 3 months previously, (4) stuttering frequency above 1%SS in one of the pre-treatment samples (see measurement of treatment outcomes below) and (5) no treatment for stuttering in the previous 6 weeks. The mean time elapsed from clinic intake assessments to when children’s names reached the top of the waiting list was 6 months (range 1–10 months). Twenty-nine children completed Stage 1 and were included in the subsequent data analysis. Twenty-one (72%) of them were boys. Although English was the main language
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spoken by all children and parents, eight children were exposed to a second language at home. The reasons for children dropping out of the study are provided in detail below, in Clinical Progress. Three of the 29 children who completed Stage 1 had previously received treatment for their stuttering. Details of those treatments were obtained from the SLP who had treated them. The number of treatment sessions completed ranged from 3 to 13 and reported speech measures showed improvement in only one case (from a reported 4.2 to 2.9%SS). The time elapsed between the last treatment session completed and admission to the study ranged from 7 to 12 weeks. In the cases of recently discontinued treatment, parents were carefully instructed to stop implementing any procedures related to that treatment. 2.2. Assessment and treatment Before the start of treatment, children were assessed during two clinic visits, over a 2–4week period. At Assessment Visit 1, one or both parents were interviewed and relevant case history information was obtained. Testing of expressive and receptive language and phonological development (see Section 2.5 below) was conducted during Assessment Visits 1 and 2. Once the assessments were completed, all children were treated by the same SLP (the first author) with the Lidcombe Program, according to the treatment manual (Australian Stuttering Research Centre, 2004). The treating SLP had completed Lidcombe Program training. Treatment fidelity was ensured in two ways. First, the developers of the Lidcombe Program regularly observed clinic visits and provided feedback to the treating SLP. Second, as described above, at each clinic visit during the Lidcombe Program parents demonstrate how they had conducted home treatment during the previous week. This forms the basis of parent training. The parents in this study audio recorded at least one home treatment session to confirm that they were conducting treatment at home as they had been trained to do in the clinic. In this way, treatment fidelity was established for the 29 children. 2.3. Trial outcome measure Percent syllables stuttered was the trial outcome measure. This is measured in real-time with a button-press counter, with one button pressed for each syllable that is judged to be unambiguously stuttered and another button pressed for all other syllables. The measures were gathered from recordings made in naturalistic speaking situations before, during and after treatment. Parents made pre-treatment recordings at the time of Assessment Visits 1 and 2 and at the start of Stage 1. Post-Stage 1 measures of %SS were made from recordings made around the time of the last Stage 1 visit, and at 6, 12 and 24 months after starting Stage 2. At each of these seven measurement occasions, two beyond-clinic audio taped conversation samples were made by parents, one at home with a parent and another with a familiar adult away from home. Parents were supplied with an audiotape recorder if they did not have access to one. Additionally, at each measurement occasion a within-clinic recording was made of the children while conversing with the clinician and the parent.
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Most of these recordings were video recordings. All recorded conversations were approximately 10 min in duration. A total of 594 recordings were obtained in this fashion for the purposes of measuring outcome. In order to complete the study in a timely manner, %SS measures were obtained by two independent observers who were not associated with the study. Both were SLPs with extensive experience in measuring stuttering. A preliminary analysis was conducted to determine if data from the two observers could be pooled. Each observer rated the same 20 samples containing an equal number of pre- and post-Stage 1 recordings. A Pearson r of 0.90 showed high agreement between the two observers, and hence their %SS measures were pooled. All recordings were then randomised and presented blind to the independent observers who measured %SS using a Sony Professional Walkman WM-D6C tape recorder, Sennheiser HD 500 headphones and a button-press electronic counting device. Recordings that contained fewer than 200 syllables or were inaudible for the purpose of measuring %SS were deleted from the data set. On some measurement occasions, parents collected more than the required number of recordings. All recordings were rated for %SS and ratings of additional samples were pooled with another sample collected in the same speaking situation at the same data point. After these criteria and procedures were applied, a total of 509 speech measures remained for analysis. Reliability of %SS measures was assessed from 58 (10%) of the recordings. An even number of pre- and post-Stage 1 recordings were selected for each child who completed Stage 1. Thirty-eight of these recordings were beyond-clinic samples and 20 were withinclinic samples. Intrajudge agreement was assessed by having each independent observer re-measure %SS on the 58 recordings 6–8 weeks after the original measures were made. Interjudge agreement was assessed by presenting the 58 recordings to a third blinded independent observer, a SLP who was also experienced in measuring %SS. Intrajudge Pearson r was 0.95 and interjudge Pearson r was 0.82. Table 1 shows that in the case of intrajudge agreement 98% of the original and repeated ratings were within 2.0%SS, and in the case of interjudge agreement 79% of the original and independent ratings were within 2.0%SS. Intrajudge reliability was very high, and although interjudge reliability was lower, overall the data were deemed to be trustworthy, given the large treatment effect (see Section 3). Table 1 Intrajudge and interjudge agreement for %SS scores (n = 58) %SS scores Intrajudge agreement
Interjudge agreement
Difference (%SS)
No. of measures
% of total
Cumulative %
Difference (%SS)
No. of measures
% of total
Cumulative %
0 0–0.9 1–1.9 2–2.9
8 41 8 1
13.8 70.7 13.8 1.7
13.8 84.5 98.3 100.0
0 0–0.9 1–1.9 2–2.9 3–3.9 4–4.9
3 32 11 9 1 2
5.2 55.2 19.0 15.5 1.7 3.4
5.2 60.4 79.4 94.9 96.6 100.0
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2.4. Dependent variables The time taken to complete Stage 1 of the Lidcombe Program (treatment time) was number of Stage 1 visits and number of weeks in Stage 1. The former is of most relevance for SLPs, as it can help them plan the management of their caseload. However, children sometimes miss clinic visits, which is why the latter is included, as it is a more realistic guide for clinical time management. It comprises the total weeks elapsed between the first and last Stage 1 clinic visits. Stage 1 concludes when the child maintains criterion speech performance for 3 consecutive weeks, the criteria being beyond-clinic parent severity ratings of 1–2, and within-clinic %SS below 1.0. 2.5. Predictor variables 2.5.1. Case history variables Gender, age at first clinic visit and reported onset-to-treatment interval were the case history predictor variables. Reported onset-to-treatment interval was determined during the parent interview conducted at Assessment Visit 1. In order to establish this, Yairi and Ambrose’s (1992) protocol was used and cross-validated with information noted in the file at the clinic intake assessment and at the first contact of the family with the health service, when parents telephoned to request an assessment. When discrepancies were found between parents’ reports at Assessment Visit 1 and the file notes, parents were questioned again carefully. This procedure yielded onset-to-treatment interval data deemed to be accurate to the week, or at least the month, of onset. 2.5.2. Pre-treatment %SS At the three pre-treatment measurement occasions, when recordings were made of each child for the purpose of outcome assessment (see above), the treating SLP also made an online measure of %SS during conversation with the child and mother within the clinic. As in the two previous predictor studies (Jones et al., 2000; Kingston et al., 2003), the SLP-%SS measures generated within the clinic were used to calculate the predictor variable pretreatment %SS. The SLP measures were used because the criteria for completing Stage 1 and moving to Stage 2 (the dependent variables, see above) are based on %SS measures made in the clinic by the SLP, along with parental severity ratings. As will be seen in Section 3, the mean SLP within-clinic %SS and the mean outcome %SS differed by only 0.2. 2.5.3. Language Language development was assessed at Assessment Visit 2 with the Peabody Picture Vocabulary Test–Third Edition (PPVT-3) (Dunn & Dunn, 1997) and the Clinical Evaluation of Language Function–Preschool (CELF-P) (Wiig et al., 1992). For each child, one pre-treatment 10-min video speech sample was orthographically transcribed and analysed for MLU in morphemes (Brown, 1973) using the relevant module of Computerized Profiling Version 9.6.0 (Long, Fey, & Channel, 2000). Each sample consisted of a conversation between parent and child while playing with a standard set of toys within the clinic. Parents had been instructed to engage in play with their child as if
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they were at home and to attempt to limit their use of closed questions. Two trained research assistants transcribed the recordings and checked the other’s transcripts for transcription conventions and coding errors, utterance boundaries, intelligibility decisions and morpheme decisions. Interjudge agreement for transcriptions was assessed by measuring the pre-resolution percentage of agreement for utterance boundary decisions, intelligibility decisions and morpheme decisions, yielding overall levels of 97, 88 and 99%, respectively. All transcription disagreements were then resolved through consensus. Predictor variables for language were PPVT-3 Standard Score, CELF-P Total Standard Score, CELF-P Receptive Standard Score, CELF-P Expressive Standard Score and MLU in morphemes. 2.5.4. Phonology Phonological development was measured at Assessment Visit 1 using the Assessment of Phonological Processes–Revised (APP-R) (Hodson, 1986). The APP-R was scored according to the instruction manual. Level of phonological impairment was determined by counting the number of failures to produce each of the 10 phonological patterns. The percentage of error for each pattern was then calculated, followed by the Mean Percentage of Error for all 10 patterns. To account for decreases in errors with phonological development, the APP-R prescribes the addition of age-compensatory points to the Mean Percentage of Error for children aged 4 years and above (4 years, add 5 points; 5 years, add 10 points; 6 years, add 15 points; 7 years and above, add 20 points). The final score obtained, the Phonological Deviancy Score (PDS), indicates the severity of phonological impairment. A higher score indicates poorer phonological performance. Because the children were at the stage of rapid phonological development, it was deemed necessary to use a more precise compensation for age than that prescribed in the manual. The procedure used was that of Paden and colleagues (Paden, Ambrose, & Yairi, 2002; Paden & Yairi, 1996; Paden et al., 1999) for the APP-R with stuttering preschool children. That is, 0.417 was added to the Mean Percentage of Error for each month in age past 3 years. The predictor variable was APP-R Phonological Deviancy Score. Reliability of phonological productions on the APP-R was conducted for nine children (31%) chosen randomly. An independent SLP who had no knowledge of the participants but had considerable experience in the assessment of speech in young children listened to the children’s audio recorded productions on the APP-R and calculated the PDS scores following the same procedure. Agreement was deemed acceptable (r = 0.82). 2.6. Statistical methods The dependent variables, namely number of clinic sessions and number of weeks to complete Stage 1, were positively skewed. These variables were log transformed to remove skew and linear regression was used for analysis. As pre-treatment %SS has been shown to clearly predict treatment time in two previous studies (Jones et al., 2000; Kingston et al., 2003) this variable was included in all models tested. The remaining nine predictor variables were then added to the model individually to determine which, if any, were also potentially predictive. Finally, a forward selection technique was used to obtain the best multiple regression predictive model based on a cut-off p-value of <0.05 for acceptance of
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independent predictor variables in the final model. The adjusted r-square value for the best model is provided as a measure of how well the model fits the data. Estimates obtained from the best model were back transformed for the purpose of interpretation.
3. Results 3.1. Clinical progress Of the 34 children enrolled in the study, 29 completed Stage 1. The reasons for five children failing to complete Stage 1 are presented in Table 2. Table 2 shows that in only one case (Subject 3) could failure to complete Stage 1 be attributed to unsatisfactory clinical progress. This child also had a high stuttering frequency; however, this is not typically a barrier to completing the Lidcombe Program, as can be seen in Jones et al. (2000) and Kingston et al. (2003). Frequency of failure to complete Stage 1 in the present study was higher than reported by Jones et al. (2000) but similar to that reported by Kingston et al. (2003). The 29 children completed Stage 1 in a median of 16 clinic visits (mean 18), and in a median of 27 weeks (mean 24). Ninety percent of children had completed Stage 1 within 31 visits. 3.2. Trial outcomes The stuttering outcomes for the 29 children who completed Stage 1 are presented in Table 3. Of these 29 children, 24 had completed Stage 2 and two were still in Stage 2 at the time of data analysis. Of the remaining three children, one did not start Stage 2 and two discontinued Stage 2 for unremarkable reasons. As is usually the case in outcome studies of stuttering, a small amount of data is missing. Reasons include faulty equipment and recordings lost or not collected by parents. The majority of the missing data are at the 24-months measurement occasion because not all children had reached that point at the time of data analysis. Mean pre-Stage 1 stuttering frequency was 3.0%SS, which is lower than for previous trials of the Lidcombe Program, and mean post-Stage 1 stuttering frequencies were, with few exceptions, below 1.0%SS. A paired t-test for the difference between pre- and post-treatment %SS scores was significant (t = 7.195, d.f. = 28, p < 0.0001). The pooled mean number of syllables spoken was determined for all pre- and post-Stage 1 speech samples up to 24 months, for all children. The mean number of syllables spoken was 581 pre-Stage 1 and 715 post-Stage 1, indicating that treatment outcome was not associated with reduced speech output. 3.3. Prediction of treatment time Table 4 presents treatment times and continuous predictor variables for the 29 children who completed Stage 1. As was the case for the outcome %SS scores (see above), mean SLP pre-treatment stuttering frequency of 3.2%SS was lower than in previous regression
Gender
Previous treatment for stuttering (no. of sessions)
Age at start of Stage 1 (months)
Average pre-treatment within-clinic %SSa
No. of Stage 1 clinic visits
Reason treatment was not completed
%SS at last Stage 1 clinic visit attended a
1
M
Y (10)
37
10.9
11
2.4
2
F
N
38
7.4
12
3
M
Y (26)
51
21.3
32
4
M
N
58
3.0
5
5
M
N
61
1.8
8
Baby brother became very ill and mother could not continue weekly clinic visits. Wanted to resume Stage 1 after a 6-month break Mother had chronic depression and could not attend weekly clinic visits. Wanted to resume Stage 1 after 3 months Stage 1 was discontinued due to lack of progress. Child had a long history of unsuccessful treatment prior to entering study and was becoming adverse to any form of treatment Child had very challenging behavior and mother found it too difficult to attend weekly clinic visits with two younger siblings. She also reported not being overly concerned with the stuttering after the last clinic visit Family moved and travelling to clinic became impossible. Mother kept doing the treatment and at phone contacts 2 weeks and 3 months after last clinic visit, the child was not stuttering
a
As measured by the treating clinician.
2.2 3.4
1.8
0.2
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Table 2 Details of the five children who did not complete Stage 1
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Table 3 Mean, standard deviation, median, minimum and maximum pre- and post-treatment %SS outcome measures for 29 preschool age children who completed Stage 1 (At all data points, speech samples were collected (A) at home, (B) away from home with a familiar adult and (C) within the clinic) No. of measures
Mean
S.D.
Median
Min
Max
Pre-Stage 1 Assessment Visit 1 A 29 B 20 C 28
3.1 3.2 3.3
1.6 1.8 2.2
2.8 2.9 3.2
0.2 0.3 0.0
6.3 7.1 8.5
Assessment Visit 2 A 28 B 24 29 Ca
3.4 3.5 2.4
2.4 2.2 1.6
2.8 3.0 2.0
0.3 0.7 0.0
10.3 9.6 6.7
First Stage 1 visit A 28 B 22 C 27
2.6 2.5 2.6
1.7 1.8 2.0
2.3 2.3 2.4
0.0 0.3 0.2
6.9 8.1 8.6
Post-Stage 1 Last Stage 1 visit A 28 B 23 29 Ca
1.2 0.9 1.0
0.8 0.7 0.7
1.2 0.8 0.9
0.0 0.0 0.0
3.0 2.8 2.8
6 months post-Stage 1 A 25 B 23 26 Ca
1.1 1.0 0.8
0.8 0.7 0.7
1.1 1.0 0.6
0.0 0.0 0.0
2.7 2.8 2.7
12 months post-Stage 1 A 23 B 23 23 Ca
1.0 0.8 0.6
0.9 0.6 0.8
0.7 0.7 0.0
0.0 0.0 0.0
3.3 2.8 2.4
24 months post-Stage 1 A 15 B 13 16 Ca
0.3 0.3 0.1
0.4 0.3 0.1
0.2 0.2 0.0
0.0 0.0 0.0
1.6 1.1 0.4
a
These %SS scores were obtained from a video recording of the child in the clinic.
studies (Jones et al., 2000; Kingston et al., 2003). The reason for this is unknown but it may have partially been due to the fact that one of the dropouts had extremely severe stuttering. Most children scored within normal limits on the CELF-P. Only two children scored below the average range (<1S.D.) and six children scored above the average range (>1S.D.). Overall, children performed slightly better on receptive language tasks. Ten children scored above average in the receptive component whereas six children scored above average in the expressive component. Most children performed within normal limits on the PPVT-3; one child scored below the average range and eight scored above the average range. Most children (69%) were included in the ‘mild’ category as defined by the APP-R (PDS between 1 and 19 points). Twenty-eight percent had a PDS in the ‘moderate’ category
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Table 4 Treatment time and predictor variables (continuous) Variable
No. of measures
Mean
S.D.
Median
Min
Max
Treatment time variables Number of Stage 1 visits Number of weeks in Stage 1
29 29
17.9 27.2
9.7 16.2
16 24
6 9
40 80
Predictor variables Age at first Stage 1 clinic visit (months) Onset-to-treatment interval (months) Pre-treatment %SS PPVT-3 Standard Score CELF-P Total Standard Score CELF-P Receptive Standard Score CELF-P Expressive Standard Score MLU (in morphemes) APP-R
29 29 29 29 29 29 29 29 29
46.7 12.7 3.2 106.7 104.6 106.4 103.0 4.01 13.4
7.5 5.6 2.0 12.8 11.0 11.6 12.2 0.93 8.9
47 13 2.8 110 105 108 102 4.2 9.8
36 4 0.3 84 82 83 79 2.2 0
67 25 7.6 132 127 122 126 6.3 35.5
and no children were categorized as ‘severe’ or ‘profound.’ One child had no speech sound errors. The 29 conversations transcribed for MLU-m had an average length of 116 utterances (range: 68–240; S.D.: 39). Based on age at time of language sampling and on Miller and Chapman’s (1981) criteria, MLU in morphemes was 1S.D. below the predicted performance for seven children and 2S.D. below for one child; four children were 1S.D. above and one child was 2S.D. above the predicted performance. Although most children (55%) performed within normal age expectancies, the mean difference between the predicted MLU and the actual MLU for all children was 0.25. A paired t-test was not significant ( p = 0.21), suggesting that as a group the children had normally developing expressive language. Using multiple linear regressions and the forward selection technique it was found that pre-treatment %SS, CELF Receptive Score and MLU were all independent predictors of log(number of Stage 1 visits). The best predictor model is presented in Table 5. The adjusted r-square value obtained with this model was 0.34. For each 1%SS increase in pretreatment %SS, the number of clinic visits to complete Stage 1 is estimated to increase by 16% (95% confidence interval: 5–27%). For each 10 unit increase in CELF Receptive Score, the number of clinic visits to complete Stage 1 is estimated to increase by 27% (95% CI: 7–49%) and for each 1 unit increase in MLU, the number of clinic visits to complete Stage 1 is estimated to decrease by 18% (95% CI: 2–32%). Table 5 Best model for log(number of Stage 1 visits) Variable Pre %SS CELF Receptive MLU
Estimate (%) 16 27 18
95% confidence interval
p-Value
5–27 7–49 2 to
0.005 0.008 0.038
32
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Table 6 Best model for log(number of weeks in Stage 1) Variable Pre %SS CELF Receptive MLU
Estimate (%) 21 23 19
95% confidence interval
p-Value
10–32 6–45 3 to 32
0.0003 0.013 0.024
A similar result was found for log(number of weeks in Stage 1) and the best predictor model is presented in Table 6. This model had an adjusted r-square value of 0.44. For each 1%SS increase in pre-treatment %SS, the number of weeks to complete Stage 1 is estimated to increase by 21% (95% CI: 10–32%). For each 10 unit increase in CELF Receptive Score, the number of weeks to complete Stage 1 is estimated to increase by 23% (95% CI: 6–45%) and for each 1 unit increase in MLU, the number of weeks to complete Stage 1 is estimated to decrease by 19% (95% CI: 3–32%). The estimated effect for receptive language and treatment time is adjusted for the severity of stuttering; therefore, it appears that receptive language has predictive power independent of severity of stuttering. During the course of exploratory correlation analyses, significant relationships were found between two language measures and pre-treatment %SS: CELF Total, r = 0.44 ( p = 0.02) and CELF Receptive, r = 0.46 ( p = 0.01). The correlation between CELF Expressive and Pre-treatment %SS was non-significant with r = 0.31, p = 0.10).
4. Discussion The primary aim of this study was to determine whether pre-treatment language and phonological development predict treatment time with the Lidcombe Program. No relationship was found between phonological development and time taken to complete Stage 1. However, the analyses yielded some intriguing findings in relation to language and treatment time. CELF Receptive Score and MLU both correlated significantly with treatment time in multiple regression analyses. The data showed that higher MLU was associated with shorter treatment time and a higher CELF Receptive Score was associated with longer treatment time. CELF Receptive Score also significantly correlated with pretreatment stuttering frequency with higher CELF Receptive Scores being associated with lower pre-treatment %SS scores. Together, %SS, MLU and CELF Receptive Score explain a large portion of the variance in treatment time; namely, 34% for the number of clinic visits taken to complete Stage 1 and 44% for the number of weeks taken to complete Stage 1. These proportions of treatment time that can be explained by stuttering severity and language variables are far greater than those reported to date. It should be noted that the significant relationship between CELF Receptive Score and treatment time was only apparent when pre-treatment stuttering frequency was included in the regression model. In other words, receptive language in this cohort of children added incremental predictive value on top of that provided by stuttering frequency. It is possible that this is a spurious finding (type 1 error); therefore, it needs to be confirmed or otherwise in a second prospective study.
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The finding that children whose expressive language is more advanced – in terms of length of utterance – tended to take less time to complete Stage 1 is of interest. Given the known relationship between cognitive development and performance on certain language tests, it may be that children who are more advanced cognitively respond more quickly to the program. Future research should take this into account. However, the CELF findings are more difficult to interpret. On the face of it, there is no reason to think that children with better comprehension would respond more slowly to the program. Perhaps this puzzling relationship reflects the presence of other variables not included in this study. It is interesting, however, that children with more severe stuttering before treatment had poorer comprehension and general language function (as scored on the CELF) than children whose stuttering was less severe. This needs to be investigated further in future research. In terms of predicting time taken to complete Stage 1, the present study is the first to use prospective methodology. The results replicate the findings of Jones et al. (2000) and Kingston et al. (2003) that relied on retrospective file audits. Once again, pre-treatment stuttering frequency predicted time taken to complete Stage 1 of the program. This finding provides face validity for using the within-clinic %SS measures made by the treating SLP for predicting treatment time, rather than using those made from naturalistic speech samples for the purposes of establishing trial outcomes. Other case history variables – gender, age and onset-to-treatment interval – were not related to treatment time. The median treatment time of 16 clinic visits in this study is higher than the 11 visits reported by Jones et al. (2000) and Kingston et al. (2003) file audits. The most likely reason for this is that when the children in those studies were treated it was not stipulated that low criterion levels of stuttering be maintained for three visits before concluding Stage 1. However, it is not clear whether other differences between this and the previous regression studies may have contributed to this longer treatment time. It is possible that demographics may have played a part. The present study was conducted in a generalist clinic that drew participants from a small area of Sydney, while the range of specialist clinics involved in the Jones et al. and Kingston et al. studies drew clients from all parts of Sydney, Australia, and Norwich, England, respectively. It is not clear, however, in what way this might influence treatment time. It is also the case that treatment in the present study was conducted by one SLP, whereas treatment in the previous studies was provided by many. The SLPs in the previous studies were in the main working in specialist stuttering clinics, and it could be argued that they had shorter treatment times because they were more experienced than the SLP in the present study. As a way of investigating this, median treatment times for each child in the present study were plotted against the time in weeks after the start of the study at which treatment began. No sign of any relationship was found. In other words, there was no indication that the present SLP initially lacked clinical skills that improved over the course of the study. Given the fact that the program manual now stipulates that Stage 1 criteria be maintained for three consecutive visits, and in light of the results of present study, it seems reasonable to raise the benchmark for median time to complete Stage 1 of the program. A clinician trained in the Lidcombe Program can expect that below 1.0%SS within the clinic and parent severity ratings of 1–2 would be attained in a median of 11–13 clinic visits, with Stage I normally concluding after another 3–5 visits. Further prospective studies are
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needed to confirm this benchmark. Of course, treatment times for individual children will vary around that median. However, the clinical implications of the findings for pre-treatment language scores in this study are not so clear. This was a preliminary study; subject numbers were quite small and the findings suggest that further investigation of the relationship between language variables and responsiveness is warranted. If the findings of this study are replicated with a more highly powered study, they have the potential to be of considerable value to SLPs in planning when to implement the Lidcombe Program with a preschooler who stutters. In closing, it must be remembered that none of the children in this study had serious language and/or phonological impairments. Given that children frequently present to a speech clinic with both stuttering and other speech and/or language disorders, there is a pressing need for further research to establish the responsiveness to the Lidcombe Program – and indeed to other interventions for early stuttering – of children who have concomitant speech and language disorders.
Acknowledgments The authors thank the children and families who participated in this research.
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