Rhythm-based Intervention in Aphasia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Rhythm-based Intervention in Aphasia (NCT04581564), a randomized na study. The primary outcome is Aphasia Spoken Word Assessment.

2. Clinical Question

The study’s broader aim was to investigate neural mechanisms associated with language recovery through rhythm therapy. Its description proposes rhythm as a potentially relevant part of speech practice and discusses neural plasticity as a research goal. The posted primary result, however, concerns practiced spoken words. It should be read as a small, single-group summary rather than a randomized comparison capable of separating the intervention’s effects from other explanations for change over time.

3. Trial Design

NCT04581564, titled Rhythm-based Intervention in Aphasia, was registered as a randomized, double-masked, parallel-group study. It was sponsored by The University of Texas at Dallas and listed Aphasia as its condition. The registry classifies the phase as NA. The study is marked terminated, and the record says it ended early before reaching anticipated enrollment.

The planned groups were a Rhythm Intervention and a Non-rhythm Intervention. The rhythm group was to practice speech production daily through rhythmic activity. The non-rhythm group was described as conventional speech-production therapy without rhythmic activities, using a non-rhythm-based singing application. The summary also describes training participants to use rhythmic groove with sets of sentences or phrases delivered through a video gaming platform.

The primary outcome was the Aphasia Spoken Word Assessment, measured as the number of practiced spoken words. The stated assessment timeframe was 10 weeks. The outcome description says the mean difference in practiced spoken words before and after intervention would be calculated. The primary results report 4 participants in the Rhythm Intervention group and none in the Non-rhythm Intervention group. Thus, the registry contains no observed randomized contrast between the two treatment approaches.

The procedure used to generate the random sequence, the details of allocation concealment, and which people were masked are not reported in the registry record. The record also does not report the planned enrollment target or explain the early termination. These omissions matter when assessing how the design was implemented and why the enrolled sample differed from the intended study size.

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

Analysis population for the primary outcome, as defined in the registry: The study was terminated early, before reaching the anticipated enrollment. All 4 participants enrolled were assigned to the Rhythm Intervention group.

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: The study was terminated early, before reaching the anticipated enrollment. All 4 participants enrolled were assigned to the Rhythm Intervention group.

6. Primary Endpoint

The registry lists the primary outcome as Aphasia Spoken Word Assessment, measured over 10 weeks.

The primary endpoint concerns the number of practiced spoken words assessed with the Aphasia Spoken Word Assessment. The registry describes the endpoint as a mean difference in practiced words before and after intervention, with a 10-week timeframe. It therefore focuses on change in production of words that participants had practiced, rather than on a broad measure of all language ability or everyday communication.

A repeated assessment before and after an intervention can describe whether the measured outcome changed over the study period. A mean summarizes the average outcome or change across participants, while the standard deviation describes how spread out individual values are around that mean. These are different kinds of information: the mean describes the group’s central result, and the standard deviation describes participant-to-participant variability.

The registry reports a mean of 1.5 and a standard deviation of 9.434 for 4 participants in the Rhythm Intervention group. The posted description does not provide a confidence interval or other uncertainty interval for this result. It also does not report a result for the comparison group. The endpoint is relevant to the stated focus on speech production, but the recorded outcome alone does not establish whether any observed change was caused by the intervention or whether it would generalize to unpracticed words or daily communication.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: it is expressed as a count of practiced spoken words, and the registry summarizes it using a mean and standard deviation. A mean is a measure of the center of the observed values. A standard deviation describes the spread of those values around the mean. The two statistics answer different questions and should be interpreted together rather than treating the standard deviation as an uncertainty interval for the mean.

What does the mean describe?

The reported mean of 1.5 is the central summary for the primary outcome in the Rhythm Intervention group. The outcome description says the measure is the difference in practiced spoken words before and after the intervention. The record does not explain the sign convention used for that difference. For that reason, the number should be reported as the posted mean rather than relabeled as a gain or loss. It is also not a comparison with the non-rhythm group, because that group has no enrolled participants in the results.

A mean can be useful because it condenses several participant-level observations into one summary. That condensation also hides how each participant’s result contributed to the group value. The standard deviation provides some information about dispersion, but it does not show the individual observations. Individual results and a confidence interval are not reported in the registry record. With four observations, the group summary represents a very small set of participants, so it should not be assumed to precisely characterize a wider population.

What does the standard deviation describe?

The standard deviation of 9.434 describes variability among the values contributing to the rhythm group’s outcome summary. It is not the standard error, a confidence interval, or a measure of statistical significance. General statistical interpretation: the standard deviation concerns variation among observed individuals, whereas a confidence interval concerns uncertainty about an estimated quantity. A wide range of individual responses can coexist with a particular mean, and a mean alone does not reveal that pattern. The registry does not provide enough participant-level detail to examine the shape of the outcome distribution or identify unusual observations.

Why is a between-group estimate unavailable?

The planned design included a Rhythm Intervention group and a Non-rhythm Intervention group. The results list 4 participants in the rhythm group and 0 in the non-rhythm group. A treatment contrast requires outcome information from both groups. Without a non-rhythm outcome, the difference between group means cannot be estimated from the posted results. This is why the registry record does not support an unadjusted two-arm comparison for this continuous endpoint. A statistical method cannot recover a missing comparator result simply by using the rhythm group mean and standard deviation.

Random assignment is intended to support a fair comparison between groups when outcomes are observed in both groups and the design is implemented as planned. The randomized label alone does not create a comparison when one group has no participants in the results. Here, the difference between planned design and observed group enrollment is central to interpretation. The record does not report the randomization procedure or explain how the allocation sequence was generated.

What do confidence intervals and tests add?

In general, a confidence interval expresses uncertainty around an estimated quantity by giving a range of values compatible with the data under the method’s assumptions. A p-value, when reported, summarizes how unusual the data would be under a specified statistical model and null hypothesis. Neither replaces the estimate itself, and neither resolves design limitations such as the lack of an observed comparison group. No confidence interval, p-value, or inferential test result for the primary endpoint is reported in the registry record.

The outcome summary includes a mean and standard deviation, but no adjustment model or other analysis details are reported in the registry record. The number of posted analyses is 0. It is therefore not possible to assess whether the planned analysis changed, whether any covariate adjustment was intended, or how the reported summary relates to a prespecified statistical analysis plan. Those details should not be inferred from the outcome label or from the fact that the study was randomized.

How should planning calculations be understood?

General statistical explanation: sample-size planning asks how many participants might be needed under stated assumptions to detect a chosen effect with a chosen power and significance level. Any planning illustration based on the observed effect is a hypothetical calculation, not an observed property of the trial and not observed power. Here, the planning assumptions described in the registry use a two-sided significance level of 0.05, equal allocation between the groups, a normal approximation, and a target effect expressed as a stated fraction of the observed effect. The planning calculations are not a substitute for the absent comparison-group results.

The planning assumptions are illustrations based on the observed effect, not the study’s own design justification. The sample-size justification and the statistical plan are not reported in the registry record. A planning result under an equal-allocation assumption also does not describe the actual enrollment pattern, in which all 4 participants were assigned to the rhythm group and none to the non-rhythm group. No new power or sample-size result can be inferred from the posted mean and standard deviation alone.

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("Rhythm Intervention")
n   <- c(4)
m   <- c(1.5)
sp  <- c(9.434)
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  Rhythm Intervention  4  1.500  9.434  -13.512  16.512

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures, but no secondary outcome results are posted. The number of posted analyses is 0. The record does not describe a multiplicity strategy, such as whether the study planned to adjust for testing several outcomes or analyses. Without that information and without posted secondary results, it is not possible to assess how multiple outcomes were handled or whether any reported analysis was selected from a larger set of analyses.

The primary endpoint description refers to a before-and-after difference, but details of missing observations, exclusions, or the handling of incomplete assessments are not reported in the registry record. The record does not identify an intention-to-treat, per-protocol, or other analysis population. It also does not state how participants who did not complete the intervention or assessment would have been handled. No assumptions about missing data methods should be made from the mean and standard deviation alone.

There is a separate limitation in the observed group data: 4 participants are listed in the Rhythm Intervention group and 0 in the Non-rhythm Intervention group. This is not merely a missing individual value within an otherwise observed comparator group. The registry provides no participants or primary outcome summary for the planned comparison group, so a between-group analysis is unavailable. Whether this pattern arose from recruitment, allocation, study termination, or another process is not reported in the registry record.

The study is marked terminated early, before reaching anticipated enrollment. The reason for termination and the target enrollment are not reported in the registry record. These details would help clarify the impact of early termination on the planned analyses, but they cannot be inferred from the posted outcome summary.

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 registry reports serious adverse events for the Rhythm Intervention group among 4 participants at risk: 0 serious adverse events and 0 deaths. It also reports 0 other adverse events among 4 participants at risk. For the Non-rhythm Intervention group, 0 participants were at risk, and the posted counts for serious adverse events, other adverse events, and deaths are all 0.

These figures describe the registry’s event counts in the groups and populations shown. The zero counts in the non-rhythm group should not be interpreted as evidence about safety in participants receiving that intervention, because no participants were listed as at risk in that group. Likewise, the reported zero counts in the rhythm group mean that no events were recorded in these categories for the four participants at risk; they do not establish that an event could not occur or characterize risk in a broader population.

The safety summary should be read alongside the small enrollment and early termination. The registry does not list any top serious adverse event terms. Additional information about event definitions, follow-up completeness, or how adverse events were collected is not reported in the registry record. The counts do not provide a comparative safety estimate between the two interventions.

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

The primary result documents a mean of 1.5 and a standard deviation of 9.434 for the practiced spoken-word outcome in 4 participants assigned to Rhythm Intervention. This is a descriptive summary of the enrolled rhythm group, using the endpoint described as the mean difference in practiced words before and after the intervention. The registry marks the trial as terminated early, and no participants are listed in the Non-rhythm Intervention group.

What the result does mean is limited but clear: a primary outcome summary was posted for a small group assigned to the rhythm intervention. The mean describes the group’s central result, and the standard deviation describes variability among the values. The outcome is specific to practiced spoken words. It does not, by itself, describe performance on all language tasks or functioning in daily communication.

What the result does not mean is equally important. It is not an estimate of the difference between rhythm-based and non-rhythm therapy, because the comparator group has no outcome data. It does not establish that rhythm caused the observed outcome, since a single-group before-and-after result cannot separate intervention-related change from other possible influences over time. It does not establish statistical significance; no p-value or confidence interval is reported in the registry record.

The broader study description focuses on neural mechanisms and language recovery, but the posted primary result is behavioral. No neural outcome result is reported in the registry record, so the primary result does not demonstrate a neural mechanism or change in brain structure. The registry does not report secondary outcome results either. The primary outcome should therefore not be treated as evidence for every goal described in the study rationale.

The small enrollment and early termination also limit the reach of the result. The record does not report why the study ended early or the intended enrollment target. The result cannot establish how well the mean represents people with aphasia more generally. It is best interpreted as a registry summary for the four enrolled participants in the rhythm group, not as a definitive estimate of comparative effectiveness, clinical importance, or generalizability.

14. Why This Trial Matters Statistically

This trial illustrates the difference between a randomized design on paper and an informative randomized comparison in the observed results. The registry identifies two planned interventions and describes random allocation, but the posted primary results include 4 participants in the rhythm group and 0 in the non-rhythm group. Without results from both groups, the central comparative question cannot be answered using the posted data. The distinction is important because a study’s design label does not substitute for observed outcomes in each arm.

The record also shows why a mean should not be read in isolation. The mean of 1.5 is accompanied by a standard deviation of 9.434, which describes variation among the rhythm group’s values. Neither statistic gives a confidence interval for the mean or a treatment contrast. A compact summary can appear definite while leaving substantial uncertainty about how representative it is, especially with 4 participants.

Early termination adds another layer to interpretation. The record says enrollment fell short of the anticipated amount, but the target and reason for termination are not reported in the registry record. This makes it difficult to judge the intended scale of the study or the circumstances that led to the observed group pattern. Statistical conclusions depend not only on formulas but also on what was planned, enrolled, measured, and reported.

Finally, the study’s stated interest in neural mechanisms sits alongside a primary endpoint based on practiced spoken words. Keeping the research rationale distinct from the result prevents a behavioral summary from being overinterpreted as a neural finding. This case highlights the value of reading endpoint definitions, group enrollment, uncertainty measures, and analysis reporting together when evaluating clinical trial results.

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 most consequential limitation is that the posted primary results contain no participants in the planned Non-rhythm Intervention group. All 4 enrolled participants were assigned to Rhythm Intervention. A between-group effect cannot be estimated, so the randomized comparison central to the study design is not represented in the posted primary results.

The trial was terminated early before reaching anticipated enrollment. The target enrollment and reason for stopping are not reported in the registry record. With only 4 participants in the group with results, the mean and standard deviation provide a limited basis for characterizing the outcome, and individual values could have a strong influence on the group summary. Participant-level outcome values are not reported in the registry record.

The primary result has no posted confidence interval, p-value, or inferential test. The registry also does not report the statistical analysis plan, the sample-size justification, the randomization procedure, the allocation concealment procedure, or which roles were masked. It is not possible to assess planned versus actual analyses, or to evaluate how uncertainty and missing data were handled.

The outcome is specific to practiced spoken words, and the registry’s description gives a 10-week timeframe. The result does not establish effects on unpracticed language or everyday communication. Although the study description identifies neural mechanisms as a broader aim, no neural result is reported in the registry record. The record lists 2 outcome measures but no secondary outcome results. Further participant characteristics and details of adherence or assessment completion are not reported in the registry record, limiting assessment of representativeness and implementation.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Rhythm-based Intervention in Aphasia — NCT04581564.
• Registry record last updated 2025-07-14; status last verified 2025-06.
• Results first posted 2025-07-14.
• 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

NCT04581564 was a randomized, double-masked, parallel-group study sponsored by The University of Texas at Dallas and listed for Aphasia. It compared a planned rhythm-based speech intervention with conventional speech-production therapy without rhythmic activities. The study is marked terminated early before reaching anticipated enrollment.

The primary outcome was the Aphasia Spoken Word Assessment, measuring practiced spoken words at 10 weeks. The posted summary reports a mean of 1.5 and a standard deviation of 9.434 for 4 participants assigned to Rhythm Intervention. No participants were assigned to the Non-rhythm Intervention group, so the record does not provide a two-group comparison. No secondary outcome results or statistical analyses are posted. Safety counts include 0 serious adverse events, 0 other adverse events, and 0 deaths among the 4 rhythm-group participants at risk; the comparison group has 0 participants at risk.