An Evaluation of the Effectiveness of the Lidcombe Program of Early Stuttering Intervention Mark A. Jones

Transcription

1 An Evaluation of the Effectiveness of the Lidcombe Program of Early Stuttering Intervention Mark A. Jones A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy Australian Stuttering Research Centre The University of Sydney June

2 Abstract 2

3 This thesis presents a randomised controlled trial of the Lidcombe Program of Early Stuttering Intervention. The Lidcombe Program was developed for the treatment of stuttering in preschool-age children. The effectiveness of the Lidcombe Program was compared to a control group in a parallel group randomised controlled trial with blinded outcome assessment. A number of supplementary studies were conducted in support of the trial; two literature reviews, two retrospective file audits and a statistical simulation study. A review of randomised studies of treatments for stuttering showed that there have been 27 such studies published in English language journals. Of these only one was devoted to a treatment for early stuttering and that was the Lidcombe Program. The randomised study showed that 3 months of this treatment was associated with a lower level of stuttering compared to a control group who received no treatment. However, with a sample size of 23, this study lacked power and the children did not receive a full course of treatment. Despite these limitations, this study provided evidence that a medium to large effect size could be anticipated in an adequately powered and properly conducted randomised controlled trial. Two retrospective file audit studies of children treated with the Lidcombe Program were conducted in Australia and Britain. One purpose of these file audits was to obtain information relevant to the design and conduct of the randomised controlled trial. Data from the case reports on more than 300 children from the two sites were included in a meta-analysis. Results showed that a median of 11 weekly clinic sessions were required for children to attain the criteria for low levels of stuttering for completion of Stage 1 of the Lidcombe Program. Approximately 90% of children had achieved those criteria within 6 months of beginning treatment and almost all children had achieved them within 1 year. 3

4 There were two treatment sites for the randomised controlled trial: the University of Canterbury (Christchurch, New Zealand) and the Stuttering Treatment and Research Trust (Auckland, New Zealand). A total of 54 preschool-age children were recruited: 29 to the Lidcombe Program and 25 to the control group. Analysis with t-test showed a highly statistically significant difference (p = 0.003) at 9-months post-randomisation. The mean percentage of syllables stuttered (%SS) at 9-months post-randomisation was 1.5 (SD = 1.4) for the Lidcombe Program group compared to 3.9 (SD = 3.5) for the control group, resulting in a treatment effect of 2.3 %SS (95% confidence interval: ). This treatment effect was more than double the minimum clinically worthwhile difference specified in the trial protocol. These results show that the Lidcombe Program is significantly more effective than natural recovery for reducing stuttering levels in preschool children. The Lidcombe Program is the first early stuttering treatment to be shown to be more effective than natural recovery in a randomised controlled trial. 4

5 Acknowledgments 5

6 This thesis represents the work of many and I would like to thank all those who contributed to the research it describes. In particular I acknowledge my supervisors Mark Onslow and Ann Packman who provided the wonderful opportunity for me to undertake this research as well as guidance and support to ensure it was completed satisfactorily. I also thank Val Gebski who provided much needed methodological advice and constructive criticism when it was warranted. With regard to the randomised trial I acknowledge Tika Ormond, Marjorie Blakely and Shelley Williams, who were the speech pathologists who treated the children in Christchurch and Auckland. Tika and Shelley also had the unenviable task of rating hundreds of tapes of children s speech. I also thank Ilsa Schwarz from the University of Canterbury (she is now located at the University of Tennessee) for her support as well as Peta Forder from the National Health & Medical Research Council Clinical Trials Centre who performed the randomisations for the trial. The trial would not have been possible without the generosity of the children and parents who participated. In particular I acknowledge all those families that remained in the trial until the final follow up was completed especially those in the control group. With regard to the papers that have been published I thank all the co-authors outlined in the next section as well as the many helpful editorial consultants who reviewed the manuscripts. I thank my supervisors at Queensland Health and the University of Queensland who allowed me to finish this thesis as part of my work duties and Elisabeth Harrison who loaned me her doctoral thesis. Finally I thank my family for their support, in particular my wife Mitsuyo Taya and father Colin Jones. 6

7 Preface 7

8 The section in Chapter 2 describing randomised controlled trials was largely taken from the publication by Jones, Gebski, Onslow, and Packman (2001). The majority of the material included in Chapter 3 was published as Jones, Onslow, Packman, and Gebski (2002). Mark Onslow proposed the survey of studies published in the Journal of Speech, Language and Hearing Research and the Journal of Fluency Disorders, and the author conducted the survey and wrote the manuscript. The other three authors assisted with writing the manuscript. The two retrospective studies described in Chapters 4 and 5 were published as Jones, Onslow, Harrison, and Packman (2000) and Kingston, Onslow, Huber, Jones, and Packman (2003). For the first study, Elisabeth Harrison was responsible for the data collection and treatment of some of the children. The author provided statistical analysis and contributed significantly to the scientific content of the manuscript. All four authors contributed to writing the manuscript under the direction of Mark Onslow. Mary Kingston was responsible for treatment of the children and data collection in the second study. The author contributed statistical analysis including the meta-analysis of the two studies. The five authors wrote the manuscript with Anna Huber being in charge of collating the ideas from the other authors and writing the original draft. A very preliminary version of the study outlined in Chapter 6 was presented as Jones (2002). The study as outlined in Chapter 6 has been submitted for publication as Jones, Onslow, Packman, and Gebski (2005). The author designed and conducted the study with methodological guidance from Val Gebski and clinical input from Mark Onslow and Ann Packman. The manuscript was written by the author with assistance from the other three authors. 8

9 The randomised controlled trial of the Lidcombe Program included in Chapter 7 was approved by the University of Sydney Ethics Committee and the University of Canterbury Ethics Committee. The design of the trial has been presented or published on three previous occasions: Jones, Gebski, Onslow, and Packman (2000); Jones, Gebski, Onslow, and Packman (2001); and Jones, Blakely, and Ormond (2003). Results from the trial have also been written up in a manuscript and recently published as Jones, Onslow, Packman, Williams, Ormond, Schwarz, and Gebski (2005). The author was responsible for the design and analysis of the trial with methodological input from Val Gebski and clinical input from Mark Onslow and Ann Packman. Tika Ormond and Shelley Williams treated the children as well as collected and rated the tapes of the children s speech. Writing of the manuscripts, book chapter and presentation was conducted by the author with assistance from the co-authors as listed above. No part of this thesis has been submitted for any other degree at any other institution. 9

10 References 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, Jones, M., Gebski, V., Onslow, M., & Packman, A. (2000). Rationale, Methods, and Design of a Randomised Controlled Trial of the Lidcombe Program of Early Stuttering Intervention. Poster presentation at the Society for Clinical Trials meeting in Toronto, Canada. Jones, M., Gebski, V., Onslow, M., & Packman, A. (2001). Design of Randomized Controlled Trials: Principles and Methods applied to a treatment for early stuttering. Journal of Fluency Disorders, 26, Jones, M., Onslow, M., Packman, A., & Gebski, V. (2002). Statistical power in stuttering research: A tutorial. Journal of Speech, Language and Hearing Research, 45, Jones, M. (2002). Analysis of a trial of treatment for early stuttering. Poster presentation at the International Clinical Trials Symposium in Sydney, Australia. Kingston, M., Onslow, M., Huber, A. Jones, M., & Packman, A. (2003). Predicting treatment time with the Lidcombe Program: Replication and metaanalysis. International Journal of Language & Communication Disorders, 38, Jones, M., Blakely, M., & Ormond, T. (2003). Chapter 14: The Lidcombe Program in New Zealand. The Lidcombe Program of early stuttering intervention: A clinicians guide. Austin, Texas: Pro-Ed. 10

11 Jones, M., Onslow, M., Packman, A., Williams, S., Ormond, T., Schwarz, I., & Gebski, V. (2005). A randomised controlled trial of the Lidcombe Program for early stuttering. British Medical Journal, 331, Jones, M., Onslow, M., Packman, A. & Gebski, V. (2005). Guidelines for statistical analysis of percentage of syllables stuttered data. Submitted to the Journal of Speech, Hearing and Language Research. 11

12 Acronyms 12

13 The following acronyms are used throughout the thesis. ASRC Australian Stuttering Research Centre, The University of Sydney %SS Percentage of syllables stuttered NHMRC National Health and Medical Research Council (of Australia) START Stuttering Treatment and Research Trust DMC Data Monitoring Committee TMC Trial Management Committee RCT Randomised controlled trial 13

14 Table of contents 14

15 Abstract... 2 Acknowledgments... 5 Preface... 7 Acronyms Table of contents List of Tables List of Figures PART ONE: INTRODUCTION Chapter 1: The Nature and Treatment of Stuttering Introduction...25 Early stuttering...26 Natural Recovery from Early Stuttering...29 Measurement of Stuttering...30 Treatment Programs for Early Stuttering...33 The Present Thesis...47 Chapter 2: Review of randomised studies of treatment for stuttering.. 49 Introduction...50 Methods...57 Results...59 Discussion...82 Chapter 3: Statistical Power in Stuttering Research Introduction...89 Power and errors in statistical inference...91 Fundamental Parameters that Influence Power...92 Other Parameters that Influence Power...97 Issues Associated with Failure to Consider Power a Priori...98 Example Sample Size Calculations Discussion PART TWO: PREDICTORS OF TREATMENT TIME WITH THE LIDCOMBE PROGRAM Chapter 4: Predictor Study One Introduction Method Results Discussion

16 Chapter 5: Predictor Study Two Introduction Method Results Discussion PART THREE: RANDOMISED CONTROLLED TRIAL OF THE LIDCOMBE PROGRAM Chapter 6: A Simulated Study of Analysis of the Primary Outcome Measure Introduction Methods Results Discussion Conclusions Chapter 7: The Randomised Controlled Trial Introduction Methods Conduct of the Trial Results Discussion PART FOUR: SUMMARY Chapter 8: Summary and Conclusions Summary of the Thesis Conclusions References Appendices

17 List of Tables 17

18 1.1 Mean number of disfluencies per 100 words of 68 stuttering boys and 68 non-stuttering boys Conditions under which Type I and Type II errors occur Summary of 26 included studies in chronological order Illustration of sample size (n) being inversely proportional to the 96 effect size ( ) squared 3.2 Approximate proportional increases in sample size required to maintain power for compliance rates of c 1 and c Details of papers dealing with stuttering published in the Journal of Speech, Language and Hearing Research (Vol. 39, No. 1 to 100 Vol. 40, No. 4) and the Journal of Fluency Disorders (Vol. 21, No. 1 to Vol. 22, No. 3) 3.4 The sample sizes required for different population standard 112 deviations and population mean subjective units of distress SUD anxiety scores 4.1 Details of the 11 children who failed to complete Stage Descriptive statistics on the 250 children who completed Stage Results of univariate logistic regression of treatment time Results of multivariate logistic regression of treatment time Details of the 12 children who did not complete Stage Descriptive statistics for the 66 children Results of multivariate logistic regression of treatment time 145 (British data only) 5.4 Results of multivariate logistic regression of treatment time 149 (British and Australian data combined) 6.1 Power and Type 1 error for sample size of 50 in each group, with 173 expected mean and standard deviations 3.6 for Group 1 and 2.0 for Group 2 18

19 6.2 Power and Type 1 error for sample size of 20 and 50 in each group, with expected mean and standard deviations 4.4 for Group 1 and 2.0 for Group Power and Type 1 error for sample size of 20 in each group with expected means and standard deviations 5.4 for Group 1 and 2.0 for Group Power and Type 1 error for sample size of 20 and 5 in each group, with expected mean and standard deviations 13.0 for Group 1 and 2.0 for Group Power and Type 1 error for sample size of 5 in each group, with expected mean and standard deviations 20.0 for Group 1 and 2.0 for Group Participants lost to follow up Baseline characteristics of participants lost to follow up and participants remaining on study Treatment received Baseline characteristics of all participants Stuttering severity (%SS) at pre-treatment and 9-months postrandomisation by treatment group 7.6 Comparison of stuttering severity (%SS) by treatment group at 9- months post-randomisation 7.7 Stuttering severity (%SS) at baseline and 9-months by treatment site 7.8 Number of participants achieving %SS of less than 1 at 9-months post-randomisation Estimates of treatment effect within subgroups

20 List of Figures 20

21 3.1 p-values for a measure of quality of life during the course of the Bishop et al. (1999) study at the times that various numbers of participants were recruited 3.2 p-values over the course of the Bishop et al. (1999) study for the dependent variable time to first treatment failure Number of clinic sessions required to complete Stage Number of clinic sessions required to complete Stage 1 by gender Number of clinic sessions required to complete Stage 1 by baseline severity of stuttering Number of clinic sessions required to complete Stage 1 by age Number of clinic sessions required to complete Stage 1 by time since onset of stuttering Kaplan-Meier plot of number of clinic visits to complete Stage Meta-analysis of time to complete Stage 1 by stuttering severity at first clinic visit 5.3 Meta-analysis of time to complete Stage 1 by time from onset of stuttering to treatment Meta-analysis of time to complete Stage 1 by gender Meta-analysis of time to complete Stage 1 by age Distribution of %SS in a clinical caseload of English children Distribution of %SS in a clinical caseload of Australian children Distribution of %SS in a cohort of adult stutterers before treatment Distribution of %SS in a cohort of adult stutterers after treatment Normal Q-Q plot of %SS Gamma Q-Q plot of %SS Simulated gamma distribution

22 7.1 Recruitment over time Flowchart of participants