Expiratory Muscle Training in Stroke: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Expiratory Muscle Training in Stroke (NCT04569968), a non-randomized na study. The primary outcome is Change in Masticatory Performance.

2. Clinical Question

3. Trial Design

The registry describes a completed, parallel-group, non-randomized study of expiratory muscle training in patients with stroke. Enrollment is listed as 146. The study began on 2020-08-18, and primary completion is listed as 2021-09-09. The phase is recorded as NA. The sponsor is Abant Izzet Baysal University.

One group was assigned daily expiratory muscle training for four weeks. The control group was described as receiving no study intervention apart from the hospital conventional physiotherapy program. The registry identifies masking as single, but does not say who was masked or which parts of the study were masked. It also does not report the method by which participants entered either group, or whether group assignment depended on clinical or practical considerations.

Non-randomized allocation matters for interpretation. Random assignment is one way of balancing measured and unmeasured characteristics between groups; without it, differences between groups may reflect who entered each arm as well as the intervention. This is a general design consideration, not evidence that any particular imbalance occurred. The registry itself warns that these arms are not a like-for-like control comparison, so a direct causal interpretation of a group contrast would require caution.

The primary outcome is change in masticatory performance, with measurements described at the beginning and after three weeks. This assessment timing does not match the four-week duration stated for training, and no explanation of the discrepancy is reported in the registry record. The record lists 12 outcome measures but reports no analysis results. Further details of the protocol, allocation process, and conduct of the study are not reported in the registry record.

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.

Before assignment: Patients who had the following situations were excluded from the study; stroke onset of time higher than 3 months, hemorrhagic stroke, cooperation problem, age of 64 or younger, denial of participation to the study, head and/or neck surgery existence, discharge, free of temporomandibular joint dysfunction, existence of infection, incisor and/or canin tooth absence, quarantine, insufficient mastication.

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.

6. Primary Endpoint

The registry lists the primary outcome as Change in Masticatory Performance, measured over Two measurements: At the beginning and after three weeks.

The primary endpoint is change in masticatory performance, expressed as a percentage of masticated peanuts. The registry describes asking patients to chew 3 gr of peanuts with 20 chewing stroke, then spit the material onto a sieve. The residue and sieved content are collected and processed, including centrifugation, and the two resulting values are divided and recorded as a percentage for the masticatory performance index. The registry specifies a mean and standard deviation as the summary measures.

Masticatory performance is used as a measure of the ability to break down food by chewing. In general, an endpoint based on a defined chewing task can turn an aspect of function into a measurement that can be compared across assessment times or groups. Interpretation depends on consistent administration, sample handling, and calculation of the index. The registry record does not report the exact calculation beyond describing division of the two values, nor does it provide information about measurement reliability or assessor training.

The record states that the outcome is measured at the beginning and after three weeks. It does not report the observed means, standard deviations, individual changes, or a between-group estimate. Therefore, the endpoint definition is available, but the magnitude and precision of any change are not reported in the registry record. The difference between the three-week assessment timeframe and four-week training description is also not explained.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean and standard deviation describe?

The primary endpoint is described as a mean of a continuous measure, with standard deviation as the measure of dispersion. In general, a mean gives a central summary of the observed measurements, while a standard deviation describes how spread out those measurements are around the mean. These summaries can help characterize a group, but they do not by themselves show how groups differ or whether an estimated difference is precise. The registry record does not include the mean or standard deviation for this outcome.

What would a change estimate represent?

For an outcome assessed at the beginning and at follow-up, a change estimate summarizes how the measured outcome differs across assessment times. A comparison between groups may then focus on whether those changes differ. These are related but not identical questions: change within a group is not, on its own, evidence that the intervention caused that change. A group contrast is also affected by how participants came to be in each arm. The registry describes two assessment times but does not post change estimates or a between-group estimate.

Why does allocation affect interpretation?

Random allocation is a design method intended to make groups comparable, on average, with respect to factors that could affect outcomes. This is a general statistical principle. In a non-randomized study, measured and unmeasured characteristics may differ across groups, and observed group differences can reflect those characteristics as well as the intervention. Statistical adjustment can address some measured differences when appropriate information is available, but it cannot automatically remove bias from unmeasured factors. The allocation process and any adjustment methods are not reported in the registry record. The registry specifically cautions that the study arms are not a like-for-like control comparison.

How should uncertainty be assessed?

A confidence interval is a general way to express the uncertainty around an estimated effect. It shows a range of values that are compatible with the data and statistical model used for the analysis. A narrow interval indicates greater precision than a wide interval, while the interval’s location helps describe which effect sizes remain plausible. It does not correct weaknesses in the design or guarantee that the estimate is unbiased. No confidence interval for the primary outcome is reported in the registry record. Nor is a p-value or other inferential result posted, so statistical significance cannot be assessed from the record.

What role do assumptions play?

Statistical analyses rely on assumptions appropriate to the outcome and design. For a continuous measure, an analysis may rely on assumptions about the distribution of values or model errors, the relationship between observations, and the way variability is handled. These are general considerations; the record does not identify a specific analysis model or its assumptions. The registry states that the primary summary is a mean and standard deviation, but that does not establish which inferential method was planned or used.

Over-dispersion is a general issue for count outcomes when observed variability exceeds what a chosen count model assumes. It can make standard errors too small if the extra variability is ignored. The primary outcome in this study is described as continuous, not as a count outcome, so over-dispersion is not identified as an issue for the primary measure. There is no need to infer an analysis method from the endpoint description alone.

What do sample-size illustrations mean?

In general, a sample-size calculation is a planning tool that estimates the number of participants needed to detect a specified effect under stated assumptions. A calculation based on an observed effect is only an illustration of planning under those assumptions; it does not tell whether a trial had adequate power after completion, and it is not observed power. The registry gives assumptions for an illustrative calculation, including a two-sided significance level of 0.05, equal allocation, a normal approximation, and effect sizes defined as stated fractions of an observed effect. It says that non-time-to-event illustrations are expressed as participants per arm. Specific numerical planning estimates are not reported in the registry record. The registry also does not report its own sample-size justification, so the illustrative assumptions should not be taken as the original design rationale.

Can the planned analysis be reconstructed?

No. The record lists zero analyses and provides no analysis results. It does not specify an outcome model, covariate adjustment, handling of repeated measurements, treatment of missing values, or approach to multiplicity. It would be inappropriate to infer a statistical plan from the fact that the outcome is summarized by a mean and standard deviation. The endpoint definition, design description, and planning assumptions each provide limited information, but they do not substitute for a documented analysis plan.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 12 outcome measures, including the primary measure of change in masticatory performance and secondary outcomes named as Mini Mental State Exame Test and Change in Labial Commissure Angle. Considering multiple outcomes can raise multiplicity concerns: when many statistical tests are conducted, the chance of at least one apparently noteworthy result can increase. This is a general issue, not a claim about what happened in this study. The registry does not report which outcomes were analyzed, how the primary outcome was distinguished in the analyses, or whether any adjustment for multiple testing was planned or used.

The record lists zero analyses and contains no posted outcome estimates. It therefore provides no basis for determining whether all planned outcomes were reported, whether analyses followed a prespecified plan, or whether results were selected for reporting. The statistical analysis plan and protocol details needed to make those assessments are not reported in the registry record.

Missing-data handling is also not reported. The registry does not state how many participants completed each assessment, whether outcome values were missing, why any values might be absent, or how missing observations were handled. In general, missingness can affect the interpretation of an analysis, especially when the likelihood of missing data is related to participant characteristics or outcome values. No missing-data assumption or sensitivity analysis can be identified from the record.

The analysis populations are not reported. The enrollment figure alone does not identify who contributed to each outcome analysis, and the safety-group denominators should not be treated as primary-outcome analysis counts. Without participant flow and analysis-population details, the relationship between enrollment, follow-up, and the results cannot be assessed.

11. 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 safety information for two groups. In the Expiratory Muscle Training Group, 15 were listed as at risk for serious events and 15 for other events; serious events, other events, and deaths are each recorded as 0. In the Control Group, 16 were listed as at risk for serious events and 16 for other events; serious events, other events, and deaths are also each recorded as 0. No serious adverse event terms are listed.

These figures describe the safety entries in the registry and their stated denominators. They do not establish that every enrolled participant was included in safety monitoring: enrollment is listed as 146, while the safety groups have the smaller denominators stated above. The record does not explain the relationship between those figures or report the reason for the safety denominators. It also does not provide additional detail about how events were collected, the observation period for safety, or whether all events were actively solicited.

Zero recorded events should be read as zero events listed in these safety entries, not as proof that no adverse events occurred in any participant or setting. These figures do not determine treatment effect or establish safety beyond the reported record.

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

The registry record shows that a study was designed to examine expiratory muscle training and masticatory performance in patients with stroke. It identifies a non-randomized, parallel-group design, describes the intervention and control conditions, and specifies a peanut-chewing measure as the primary endpoint. Those details explain the study question and how the primary outcome was intended to be assessed.

The record does not report the primary outcome values or analysis results. It therefore cannot establish whether masticatory performance increased, decreased, or remained similar, nor how large or precise any change might have been. The absence of reported results must not be interpreted as evidence of no effect. It means the registry entry does not contain the evidence needed to describe the effect.

The design also limits what a group comparison could establish. Assignment was non-randomized, and the registry warns that the groups are not a like-for-like comparison. In general, this leaves open the possibility that group differences reflect factors other than the training. The record does not state how participants were allocated or whether analyses addressed differences between groups.

The timing details require care: the primary outcome description specifies assessment at the beginning and after three weeks, while training is described as daily for four weeks. No explanation is reported. The entry also lacks information on the number of participants with outcome measurements, missing-data procedures, and the analysis population. The registry’s safety figures record zero events in the listed groups but do not answer the primary efficacy question.

Thus, the record supports a description of the intended comparison and measurement procedure, not a conclusion about whether the intervention changed the endpoint. Any conclusion about effect size, statistical significance, or clinical importance would require outcome results and sufficient detail about their analysis and context, none of which is reported in the registry record.

13. Why This Trial Matters Statistically

This study raises several important statistical issues for clinical research. First, its non-randomized allocation makes the construction of a fair comparison central to interpretation. A measured difference between arms can be influenced by how participants entered each group, so design and allocation details matter alongside any statistical estimate. The registry itself cautions that the groups are not a like-for-like control comparison.

Second, a functional endpoint must be defined and measured consistently. The record gives a specific chewing and sieve procedure and describes the outcome as a percentage-based index. Such detail helps readers understand what is being measured, while missing information about the precise calculation and measurement reliability limits assessment of reproducibility.

Third, the study description contains an unresolved timing difference: the primary outcome is assessed after three weeks, while the training is described as lasting four weeks. Outcome timing affects the interpretation of change and the relationship between exposure and measurement. The record does not explain that difference.

Finally, statistical interpretation depends on transparent reporting of estimates, uncertainty, missing data, and analysis populations. Although the registry identifies 12 outcome measures, it lists zero analyses and provides no primary outcome results. The safety counts are not a substitute for outcome reporting. This record is therefore a useful reminder that an endpoint and a trial design do not, by themselves, reveal the result; transparent reporting is needed to assess both the size and precision of an effect.

14. 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 registry entry leaves important design and reporting details unresolved. Allocation is non-randomized, but the process by which participants entered the training and control groups is not reported. The registry warns that the arms are not a like-for-like control comparison. Without a description of group formation and baseline characteristics, readers cannot assess the extent to which the groups were comparable.

Masking is recorded as single, but the identity of the masked party and the procedures used to maintain masking are not reported. The primary outcome depends on a measurement procedure involving chewing, sieving, and processing collected material. Details about assessor training, measurement reliability, and the exact calculation of the index are not reported.

The schedule is unclear: the primary outcome timeframe is described as beginning and after three weeks, while the training program is described as lasting four weeks. The registry does not explain the discrepancy. It also does not report participant flow, primary-outcome completion, missing-data handling, or analysis populations. These omissions prevent assessment of attrition and the analytic sample for the primary endpoint.

No primary outcome estimates or analyses are posted, and the record does not specify the statistical analysis plan or sample-size justification. The illustrative planning assumptions listed in the record do not establish how the study itself was designed or analyzed. With 12 outcomes listed and zero analyses recorded, the analysis and reporting of the outcome set cannot be evaluated. These limitations concern what is documented in the registry record; they should not be taken as evidence that unreported procedures or analyses did or did not occur.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Expiratory Muscle Training in Stroke — NCT04569968.
• Registry record last updated 2023-03-31; status last verified 2022-06.
• Results first posted 2023-03-31.
• 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.

18. Record Summary

NCT04569968 is a completed, non-randomized, parallel-group study sponsored by Abant Izzet Baysal University. Enrollment is listed as 146. The intervention group was described as receiving daily expiratory muscle training for four weeks; the control group was described as receiving hospital conventional physiotherapy without the study intervention. The registry records single masking but does not identify who was masked.

The primary outcome is change in masticatory performance, assessed using a peanut-chewing and sieve procedure and summarized as a mean with standard deviation. The stated measurements are at the beginning and after three weeks. This timing is not reconciled with the four-week training description.

The registry lists 12 outcome measures and zero analyses. It does not report primary outcome results, analysis populations, missing-data procedures, or the allocation method. Safety entries list zero serious events, zero other events, and zero deaths in each of the two reported groups, with denominators of 15 and 16. The registry cautions that the non-randomized arms are not a like-for-like control comparison.