Spoken language outcome measures for treatment studies in Down syndrome: feasibility, practice effects, test-retest reliability, and construct validity of variables generated from expressive language sampling

Angela John Thurman, Jamie O. Edgin, Stephanie L. Sherman, Audra Sterling, Andrea McDuffie, Elizabeth Berry-Kravis, Debra Hamilton, Leonard Abbeduto

Research output: Contribution to journalArticlepeer-review

Abstract

Background: The purpose of this study was to evaluate expressive language sampling (ELS) as a procedure for generating spoken language outcome measures for treatment research in Down syndrome (DS). We addressed (a) feasibility, (b) practice effects across two short-term administrations, (c) test-retest reliability across two short-term administrations, (d) convergent and discriminant construct validity, and (e) considered comparisons across the conversation and narration contexts. Method: Participants were 107 individuals with DS between 6 and 23 years of age who presented with intellectual disability (IQ < 70). The utility of ELS procedures designed to collect samples of spoken language in conversation and narration were evaluated separately. Variables of talkativeness, vocabulary, syntax, utterance planning, and articulation quality, derived from transcripts segmented into C-units (i.e., an independent clause and its modifiers), were considered. A 4-week interval was used to assess practice effects and test-retest reliability. Standardized direct assessments and informant report measures were collected to evaluate construct validity of the ELS variables. Results: Low rates of noncompliance were observed; youth who were under 12 years of age, had phrase-level speech or less, and had a 4-year-old developmental level or less were at particular risk for experiencing difficulty completing the ELS procedures. Minimal practice effects and strong test-retest reliability across the 4-week test-retest interval was observed. The vocabulary, syntax, and speech intelligibility variables demonstrated strong convergent and discriminant validity. Although significant correlations were found between the variables derived from both the conversation and narration contexts, some differences were noted. Conclusion: The ELS procedures considered were feasible and yielded variables with adequate psychometric properties for most individuals with DS between 6 and 23 years old. That said, studies of outcome measures appropriate for individuals with DS with more limited spoken language skills are needed. Context differences were observed in ELS variables suggest that comprehensive evaluation of expressive language is likely best obtained when utilizing both contexts.

Original languageEnglish (US)
Article number13
JournalJournal of Neurodevelopmental Disorders
Volume13
Issue number1
DOIs
StatePublished - Dec 2021
Externally publishedYes

Keywords

  • Clinical trials
  • Down syndrome
  • Expressive language
  • Expressive language sampling
  • Outcome measures
  • Psychometrics
  • Treatment

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Pathology and Forensic Medicine
  • Clinical Neurology
  • Cognitive Neuroscience

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