Predictors of Speech Ability in Down Syndrome: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Predictors of Speech Ability in Down Syndrome (NCT05016037), a na na study. The primary outcome is Speech Intelligibility.

2. Clinical Question

3. Trial Design

NCT05016037, titled “Predictors of Speech Ability in Down Syndrome,” is recorded as completed. Vanderbilt University Medical Center is listed as the sponsor. The recorded start date is 2022-02-14, and the primary completion date is 2024-04-30. The study is classified as single group, with allocation recorded as NA and masking recorded as none. Phase is recorded as NA.

The behavioral intervention is named lexically based speech recast. The arm description says the goal was to induce change in speech intelligibility in order to study speech accuracy and prosody as predictors of change. That describes the study objective, not an observed effect. No control arm is listed, so the record does not describe a randomized or concurrent between-group comparison.

Registry enrollment is 18. The brief summary describes the project as measuring speech-articulation accuracy and intelligibility in 16 children with DS, aged 4;0 to 17;11. Both figures should be retained as recorded: the registry enrollment and the brief-summary description do not match, and the record does not explain the difference. It is not possible to determine from the available record which number represents the analyzed sample.

The record lists two outcome measures, but gives primary-outcome details only for speech intelligibility in the information available. It lists no analysis records. Participant flow, intervention attendance, and the number contributing data at each assessment are not reported in the registry record. The study is therefore described by its design and aims, but the record does not support a detailed account of how participants were analyzed or what results were obtained.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: 18 participants signed informed consent. One person did not complete the baseline assessment and withdrew from the study.

6. Primary Endpoint

The registry lists the primary outcome as Speech Intelligibility, measured over six months.

The primary outcome is speech intelligibility, recorded as a score on a scale. The registry describes it as a five-point Likert scale based on a language sample, with the score informed by the number of words spoken in the sample. A score of 1 represents very low intelligibility, and a score of 5 represents high intelligibility. The stated timeframe is six months.

Intelligibility is relevant to the study’s stated purpose because the brief summary describes difficulty understanding speech as a communication concern for individuals with Down Syndrome. The study aimed to measure intelligibility and use speech recast to induce change, while examining speech-articulation accuracy and speech-prosody skills as proposed predictors of growth in intelligibility. These are study aims; the registry record does not report whether such growth occurred or whether the proposed predictors were associated with it.

The registry specifies the mean as the summary measure and standard deviation as the measure of dispersion. These summaries describe the average score and the spread of scores, respectively. However, no mean, standard deviation, change estimate, or uncertainty interval is reported in the registry record. The scoring range and direction clarify how the measure is intended to be interpreted, but they cannot establish an outcome without observed scores.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registered study model is single group. In general, a single-group design follows participants without a separate concurrent comparison group. It can describe measurements and changes over time, but a before-and-after pattern alone does not isolate the cause of a change. For example, general factors such as development, changes in measurement circumstances, and differences in which participants contribute data at different times can affect observed patterns. These are general design considerations, not claims about what occurred in this study. The registry record does not report enough outcome information to assess any such pattern.

What does the outcome summary measure?

The primary outcome is a score on a five-point scale, based on a language sample. Its stated direction runs from very low intelligibility at 1 to high intelligibility at 5. The registry specifies a mean and standard deviation as the summary statistics. A mean describes the average score in the group, while a standard deviation describes how dispersed scores are around that average. These summaries can help characterize the distribution of scores, but they do not show individual trajectories or explain why participants differ.

The scale is described as a Likert scale, which has ordered response levels. Treating such scores with a mean is the summary approach specified in the record. As a general statistical point, a mean can be easy to interpret, while the scale’s ordered categories and bounded range remain relevant to how the summary should be understood. The record does not report the observed score distribution, so it is not possible to assess whether the mean and standard deviation alone would capture its features.

How should uncertainty be interpreted?

In general, a confidence interval expresses the range of estimates reasonably compatible with the data under the statistical method used. It communicates precision, not the probability that a particular treatment effect is true. A narrow interval indicates greater precision than a wide interval, while either interval must be interpreted in relation to the outcome and study design. No confidence interval or other uncertainty estimate for the primary outcome is reported in the registry record. Thus, the precision of any change in speech intelligibility cannot be assessed from the posted results.

A statistical test and its p-value address a question framed by a model and a null hypothesis. A p-value alone does not describe the size or practical meaning of an effect, and it does not replace an effect estimate with an uncertainty interval. The registry lists no analysis records and reports no p-value for the primary outcome. There is therefore no reported inferential result to interpret.

What do the planning assumptions describe?

The planning assumptions specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They describe an illustration for detecting a stated fraction of an observed effect. The assumptions also distinguish calculations reporting participants per arm from time-to-event calculations reporting total events; the primary outcome in this record is continuous, not time-to-event. These planning assumptions are not a description of the registered single-group study, which lists no allocation to two arms.

Such calculations are general planning tools: they indicate the sample size that might be needed under chosen assumptions about the effect and analysis. Their results depend on those assumptions, including the effect being targeted. When the target is framed as a fraction of an observed effect, that is a planning scenario, not a new result from the study. The registry record does not report a trial-specific sample-size justification or explain how enrollment was chosen. A planning illustration is not observed power, and it cannot establish whether the study had adequate precision for its actual objectives.

What can be concluded from the registered methods?

The record identifies the outcome scale, its direction, the summary statistics, and the six-month timeframe. It also describes the aim of studying speech-articulation accuracy and speech-prosody skills as predictors of intelligibility growth. It does not report the statistical model, handling of repeated measurements, covariate adjustment, or an analysis plan. Those details are not reported in the registry record. Without analysis results and their methods, readers cannot evaluate estimated change, predictor associations, or the assumptions underlying an inferential analysis.

General statistical interpretation should keep design, measurement, and uncertainty together. A mean score describes an average, but an estimate of change requires reported measurements at relevant times and a defined comparison. A predictor analysis requires both predictor data and a specified method linking those data to the outcome. A confidence interval or test can quantify uncertainty only for an estimate from an analysis. The registry record supplies the study’s aims and selected outcome description, but not those estimates or analyses.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Lexically Based Speech Intelligibility Recast")
n   <- c(16)
m   <- c(3.59)
sp  <- c(0.97)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Lexically Based Speech Intelligibility Recast  16  3.590  0.970  3.073  4.107

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures and identifies speech intelligibility as the primary outcome. It does not identify the other measure in the record details, nor does it report how multiple outcomes or multiple analyses were handled. No adjustment strategy, hierarchy of secondary outcomes, or prespecified multiplicity procedure is reported in the registry record. In general, testing many outcomes or associations can increase the chance of a chance-positive finding; methods for controlling or describing that issue depend on the analysis plan. No such plan is reported for this study.

The registry lists no analysis records. It does not report an analysis population, the number of participants with primary-outcome data, or whether all enrolled participants were included in any analysis. The enrollment figure is 18, while the brief summary describes 16 children. The record does not explain this discrepancy or state whether either number corresponds to an analysis population.

Missing-data methods, reasons for missing measurements, and the amount of missing outcome data are not reported in the registry record. As a general matter, missing data can affect the interpretation of a mean or change estimate, especially if the participants with observed measurements differ from those without them. Without a reported accounting of available measurements or a stated method for handling missingness, it is not possible to assess that issue.

The record also does not report whether analyses followed a prespecified statistical plan, whether repeated observations were modeled, or whether any sensitivity analyses were performed. These omissions do not establish that such procedures were or were not used; they mean that they are not documented in the registry record.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event record lists the Lexically Based Speech Intelligibility Recast group, with 18 participants at risk for serious adverse events and 0 affected. It also lists 18 at risk for other adverse events and 0 affected. Deaths are listed as 0, and no top serious-event terms are listed. These are the posted counts for the intervention group.

At-risk counts are the denominators against which affected counts are read. The record therefore reports no serious events or other events among the participants listed at risk, and no deaths. These entries should not be interpreted as proof that an event was impossible or that the intervention is risk-free. Adverse-event reporting depends on what was collected and entered in the registry, and the record does not describe event definitions, collection procedures, or a comparison group.

Because the study is single group, these counts do not provide a comparative estimate of safety relative to another intervention or to no intervention. They also do not describe speech outcomes. The safety figures should be read as registry counts, not as evidence that the intervention caused or prevented any event.

13. What the Result Does, and Does Not, Mean

The registry record establishes that the study was designed to examine speech ability in Down Syndrome and identifies speech intelligibility as its primary outcome. It describes lexically based speech recast as a behavioral intervention intended to induce change, and identifies speech-articulation accuracy and speech-prosody skills as proposed predictors of intelligibility growth. It also gives the intelligibility scale, its direction, and a six-month timeframe.

Those descriptions do not establish that speech intelligibility improved, remained unchanged, or declined. The record does not report outcome values, a change estimate, or uncertainty around an estimate. It also does not report an analysis of the proposed predictors. The stated goal of the intervention is not an observed finding, and the completion status does not substitute for posted results.

The single-group design has no separate comparator listed. In general, observations over time in a single group can describe change but cannot, by themselves, show what would have happened in the same participants without the intervention. Any causal interpretation would depend on design and analysis information not reported in the registry record. The planning assumptions for a hypothetical two-arm calculation are not evidence of a two-arm trial and do not answer the clinical question.

The safety record lists zero serious adverse events, zero other adverse events, and zero deaths among the participants recorded at risk. These counts describe the posted safety entries only. They do not demonstrate an effect on intelligibility or establish comparative safety. The record also does not explain why enrollment is 18 while the brief summary describes 16 children, or identify the sample with outcome data. The most defensible interpretation is therefore limited: the registry documents the research question, intervention aim, and measurement framework, but it does not provide results that answer whether intelligibility changed or whether the proposed predictors were associated with change.

14. Why This Trial Matters Statistically

This study is statistically notable for the distinction between a clearly stated research aim and the evidence needed to evaluate that aim. The record proposes measuring speech-articulation accuracy, speech-prosody skills, and intelligibility, then using an induced change in intelligibility to study possible predictors. That question involves more than measuring a score: it requires reported observations over time and an analysis connecting candidate predictors to change.

The design is listed as single group, while the planning assumptions describe equal allocation between two arms. Keeping those descriptions separate matters. A hypothetical planning calculation can help explore assumptions about sample size, but it does not turn a single-group study into a comparative trial. It also does not show that the registered study had a particular level of power or precision.

The record’s difference between registry enrollment of 18 and a brief-summary description of 16 children is also important for interpretation. A reader needs to know how many participants were enrolled, how many contributed measurements, and which participants were included in each analysis. The record does not reconcile the figures or report an analysis population. Without that accounting, even a reported average would need context about the observations contributing to it.

Finally, the endpoint is a bounded, ordered intelligibility scale, and the registry specifies a mean and standard deviation. Understanding such summaries requires attention to both the scale and the distribution of observed scores. Since the record does not post those scores or analyses, its statistical contribution as registered is primarily a description of the intended question and measurement, rather than an answer about change or predictors.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main limitation for interpreting this record is that it contains no primary-outcome values or statistical analysis results. Although the study is marked completed, speech-intelligibility means, standard deviations, change estimates, confidence intervals, and test results are not reported in the registry record. The proposed predictor analyses are also not reported.

The registry enrollment is 18, while the brief summary describes the project as involving 16 children aged 4;0 to 17;11. The record does not reconcile these figures, report the number with complete measurements, or identify an analysis population. It is therefore unclear how many participants contributed to any outcome or predictor analysis.

The design is single group, with no comparator listed. The record does not report details of timing and collection for repeated measurements beyond the primary outcome timeframe, intervention adherence, or how any observed changes would be separated from other time-related influences. These details are not reported in the registry record and should not be assumed.

The record lists two outcome measures but gives the primary outcome description without a complete analysis plan. The method for handling missing data, repeated observations, multiplicity, and predictor analyses is not reported. Nor is a trial-specific sample-size justification reported. The separate planning assumptions describe a hypothetical two-arm calculation and do not resolve these design and analysis gaps. These limitations concern what can be learned from the registry record; they do not establish what methods may have been used outside it.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Predictors of Speech Ability in Down Syndrome — NCT05016037.
• Registry record last updated 2025-08-03; status last verified 2025-07.
• Results first posted 2025-08-03.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT05016037, “Predictors of Speech Ability in Down Syndrome,” is recorded as completed and sponsored by Vanderbilt University Medical Center. It is a single-group study of lexically based speech recast, with enrollment listed as 18. The brief summary describes 16 children aged 4;0 to 17;11, a difference the registry record does not explain.

The primary outcome is speech intelligibility on a five-point scale based on a language sample, with a six-month timeframe. The record specifies a mean and standard deviation but reports no outcome values or analyses. It lists two outcome measures and no analysis records. The adverse-event entries list 0 serious events, 0 other events, and 0 deaths. The registry record describes the study’s aims and measurement approach but does not report results that establish change in intelligibility or relationships with the proposed predictors.