Predicting which children will normalize without intervention for speech sound disorders

The following manuscript has been accepted for publication:

To, C. K. S., McLeod, S., Sam, K. L & Law, T. (2022, in press). Predicting which children will normalize without intervention for speech sound disorders. Journal of Speech, Language, and Hearing Research.

During peer review we received the following very positive comments:

Editor: 

• “We are all enthusiastic about this rigorously conducted work and believe that the topic has important clinical implications and will be of substantial interest to the JSLHR readership” 

Reviewers: 

• “This is one of the most clinically significant and important papers I have read in a while. My impression of this paper is highly positive…”
• “The paper was prepared … with exceptional clarity, as well as a rigorous statistical and quantitative methods.” 
  
• “...this is the nicest paper with the clearest set of impactful results that I have seen in a while. I think it has potential to "make a splash" in the field, and I hope it gets read a lot.” 
• “This is a standout study in terms of quantitative rigor and clinical usefulness and value. The study design is careful and overall very clear. The authors executed the research design carefully and prepared the paper with exceptional clarity, as well as used rigorous statistical and quantitative methods. I am pleased to endorse this paper toward publication in JSLHR.”

Here is the abstract:

Purpose: The speech of some children does not follow a typical normalization trajectory and they develop speech sound disorders (SSD). The current study investigated predictive correlates of speech sound normalization in children who were at risk of SSD. 

Method: A prospective population cohort study of 845 Cantonese-speaking preschoolers was conducted over 2.5 years to examine children (a) who resolved non-adult realizations of consonants (normalized) and (b) those who had persisting speech sound difficulties (did not normalize). From these 845, a sample of 82 participants characterized as having SSD (1.25 SD below the mean in a standardized speech assessment, with a delay in initial consonant acquisition, or with one or more atypical errors) were followed for 2 years at six-month intervals or until the completion of their initial consonant inventory. Data from 43 children who did not receive speech-language pathology services were analysed with survival analysis to model time-to-normalization while controlling for covariates. The target event (outcome) was completion of their initial consonant inventory. 

Results: Under the no-intervention condition, the estimated median time-to-normalization was 6.59 years of age. Children who were more likely to normalize or normalized in a shorter time were stimulable to all errors and more intelligible as rated by caregivers using the Intelligibility in Context Scale. Those who showed atypical error patterns did not necessarily take longer to normalize. Similarly, expressive language ability was not significantly associated with speech normalization. 

Conclusion: Stimulability and intelligibility were more useful prognostic factors of speech normalization when compared to (a)typicality of error patterns and expressive language ability. Children with low intelligibility and poor stimulability and should be prioritized for speech-language pathology services given that their speech errors are less likely to resolve naturally.

Natural history study of children with speech sound disorders

Dr Carol Kit Sum To and I have continued having regular meetings to work on writing up our grant to document a natural history study of children with speech sound disorders who do not receive speech-language pathology intervention in Hong Kong, SAR China. We are almost ready to submit the manuscript to be considered for publication. Here is a blog post about a meeting we held earlier this year: https://speakingmylanguages.blogspot.com/2021/04/investigating-prognosis-and-risk.html

Investigating prognosis and risk factors of speech sound disorder: A natural history study using a survival analysis

Some time ago, Dr Carol Kit Sum To and I collaborated (with others) on a grant to undertake a natural history study using a survival analysis approach of children with speech sound disorder in Hong Kong (see below).

To, C. K-S., Cheung, K. Y., Law, T., Lee, K. Y. S., McLeod, S., & Ng, M. L. (2014-2015). Investigating prognosis and risk factors of speech sound disorder: A natural history study using a survival analysis approach [利用存活分析調查構音問題的自然史 – 預後及誘發因素的研究 ]. General Research Fund, Research Grants Council (RGC) of Hong Kong, China (GRF 17409214). (HKD = 710,002; AUD = $104,256) (The order of the names of co-investigators is alphabetical)

Here is the "layman's summary of the completed report" that can be found here https://cerg1.ugc.edu.hk/ (Search: Year = 2014-2015, Surname = To, Subject = Psychology and linguistics): 

Speech sound disorder (SSD) is a prevalent childhood communication disorder and forms a significant caseload of speech-and-language-therapy services in Hong Kong. SSD in preschool children can be persistent and may lead to long-term literacy difficulties. At the other end of the spectrum, a sizable subgroup of children originally demonstrates speech problems outgrow their errors without clinical attention and follow the typical growth trajectory in later years. In the current study, we made use of a new statistical method known as survival analysis to enable us to predict if children, showing a slower start in speech sound ability but without any other developmental disorders will catch up later. We found that most children with an initial delay of speech sound production skills still showed speech normalization but the normalization process was protracted and takes about 80 months. Boys appeared to be more likely to show a longer normalization process. In addition, children’s perceptual sensitivity in the temperament scale is more predictive than a number of children’s language proficiency and family characteristics such as parental education level.

We met today to work on writing up one of the papers from the analysis. A paper that has been published from this analysis is:

Kok, E. C. E., & To, C. K. S. (2019). Revisiting the cutoff criteria of Intelligibility in Context Scale-Traditional Chinese. Language, Speech, and Hearing Services in Schools, 50(4), 629-638.  https://doi.org/10.1044/2019_LSHSS-18-0073