This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Use of the Passy Muir Swallowing Self Trainer (NCT02848664), a registered phase not stated study. The primary outcome is Change in Dysphagia Outcome and Severity Scale (DOSS) Rating.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02848664 |
| Phase | Phase not stated |
| Condition | Stroke, Brain Injury, Head and Neck Cancer |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 11 |
| Arms in the primary outcome | n/a |
| Lead sponsor | James Madison University |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned people with chronic dysphagia described as severe or moderate to severe. The record specifies dysphagia lasting more than 6 months, nutrition by enteric means, and that a person may be able to ingest one consistency with supervision. The listed conditions include stroke, brain injury, and head and neck cancer. The registry reports enrollment of 11.
Intervention
Participants received training in using the Passy Muir Swallowing Self-Training Device at home. The device provides external vibratory stimulation to the larynx during swallowing and swallowing training. The study description says participants used it for 3 months before returning for reassessment and device feedback.
Comparator
The record describes an uncontrolled pilot study and lists the device retraining intervention, but no like-for-like control comparison. Allocation is not stated. The study therefore does not provide a randomized comparison between device use and a control intervention.
Primary question
The primary outcome was whether participants’ Dysphagia Outcome and Severity Scale rating changed between the assessment before device use and the return assessment 3 months later. The record describes this as a count of participants, but the outcome results and the number of participants whose ratings changed are not reported in the registry record.
3. Trial Design
This was a completed, uncontrolled pilot study of the Passy Muir Swallowing Self-Training Device, sponsored by James Madison University. The registry lists the study as starting in 2013-08 and reaching primary completion in 2015-08. Enrollment was 11. The stated purpose was to develop appropriate training methods and gather participant feedback about using the device. A secondary purpose was to examine how 3 months of use related to swallowing physiology, brain activation, oral intake, and quality of life.
The described study process began with baseline testing of dysphagia and dysphagia handicap. Participants then received training to use the vibrotactile device for self-training at home. After 3 months of use, they returned for repeat testing and feedback about the device. The intervention is listed as “Dysphagia retraining with device.” The record does not describe a parallel control group, and it states that allocation was not specified. As a result, the design does not support a like-for-like treatment comparison.
The primary outcome was change in Dysphagia Outcome and Severity Scale rating from before device use to the return visit 3 months later. The listed secondary outcomes concern laryngeal elevation relative to hyoid elevation for vestibule closure and cortical activation for swallowing. The registry lists 4 outcome measures and 4 analyses, but detailed results for the primary outcome are not reported in the registry record. The statistical analysis plan, including how the repeated measurements were analyzed, is not reported in the registry record.
An uncontrolled pilot can document the study procedures and describe what was observed among enrolled participants. It cannot, by itself, separate changes associated with device use from changes that might have occurred over time or for other reasons. The record’s stated emphasis on training methods and participant feedback is consistent with an exploratory purpose, but the protocol’s sample-size justification is 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: Exclusion of those with psychiatric, epilepsy, severe speech/language communication disorders, cognitive impairment, esophageal disorders, and inability to tolerate a nasal endoscopic examination. Inclusion criteria: 13 years or older, parental consent if under 18, stable medical condition and oropharyngeal dysphagia.
Overall Study
| Stage | Laryngeal Vibrotactile Stimulation |
|---|---|
| STARTED | 11 |
| COMPLETED | 7 |
| NOT COMPLETED | 4 |
Reasons for not completing this period:
| Reason | Laryngeal Vibrotactile Stimulation |
|---|---|
| Withdrawal by Subject | 2 |
| Adverse Event | 1 |
| no assistance for device training | 1 |
Analysis population for the primary outcome, as defined in the registry: Patients with Severe/Moderate to Severe dysphagia, chronic for more than 6 months, nutrition is by enteric means, may be able to ingest one consistencies with supervision
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.
| Characteristic | Unit | Laryngeal Vibrotactile Stimulation |
|---|---|---|
| Participants analysed | 7 | |
| Age, Continuous | years | 56.4 (SD 20.1) |
| Sex: Female, Male: Female | Participants | 2 |
| Sex: Female, Male: Male | Participants | 5 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 |
| Race (NIH/OMB): White | Participants | 6 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 7 |
| Functional Oral Intake Scale: 1-Severe | Participants | 6 |
| Functional Oral Intake Scale: 2-Moderate/Severe | Participants | 1 |
| Functional Oral Intake Scale: 3-Moderate | Participants | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Dysphagia Outcome and Severity Scale (DOSS) Rating, measured over From before onset of device use to return 3 months later.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint was change in the Dysphagia Outcome and Severity Scale rating between the assessment before device use and the return assessment 3 months later. The DOSS is described as an ordinal scale with 7 levels of swallowing-disorder severity: level 1 is the lowest level and level 7 is the highest. Its descriptions range from severe dysphagia with nothing by mouth, through varying levels of assistance, supervision, or dietary restriction, to functional independence and normal swallowing in all situations.
An ordinal measure preserves the ordering of severity levels, but the distance between adjacent levels is not necessarily equal. A change of one level therefore describes a move on the ordered scale; it should not automatically be interpreted as a fixed amount of physiological change. The registry describes the outcome unit as participants and the parameter as a count of participants. It does not report how participants’ ratings were distributed before or after device use, which individual transitions occurred, or how many participants experienced a change.
DOSS is relevant to the study question because it records swallowing-disorder severity in a clinically interpretable ordered form. Reassessing the same participants after the period of home training can describe whether their ratings differed over time. However, without posted outcome results, the direction and size of any change cannot be assessed. Without a control comparison, any observed before-and-after change would also not establish that device use caused it.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies an outcome of interest but does not report the primary outcome results. It gives no before-and-after DOSS ratings, count of participants with a change, effect estimate, confidence interval, or p-value. The direction, size, and precision of any observed change are therefore not reported in the registry record. No conclusion about the pattern of DOSS change can be drawn from the outcome information available in the record.
The trial’s uncontrolled design is central to interpretation. A before-and-after assessment can describe the participants’ status at two points, but it has no concurrent control group to indicate what might have happened over the same period without device training. Even if results had shown improvement or worsening, the design alone could not distinguish an effect of device use from time-related change, other care, measurement variability, or other influences. The registry does not report details that would resolve these possibilities.
The enrollment of 11 places the study in the context of a small pilot. That does not make the study uninformative about feasibility or participant feedback, which were explicit aims, but it limits how much can be inferred about outcome patterns beyond the enrolled group. The record does not provide numerical results for the stated secondary outcomes of laryngeal elevation relative to hyoid elevation for vestibule closure or cortical activation for swallowing. It also does not provide results for oral intake or quality of life in the registry record described by the registry record.
Safety information is presented separately from the primary outcome. For the Laryngeal Vibrotactile Stimulation group, the record lists 7 at risk for serious adverse events and 0 affected, and 7 at risk for other adverse events and 3 affected. It lists 0 deaths. These counts describe the record’s adverse-event reporting; they do not supply the missing swallowing outcome results or establish comparative safety, because there is no like-for-like control group.
A sample-size planning illustration is described using the observed effect as its basis, with two-sided significance level 0.05, equal allocation between two hypothetical arms, and a normal approximation. Such an illustration is not evidence of observed power and does not describe the actual uncontrolled study design. The underlying effect estimate and numerical planning results are not reported in the registry record. The sponsor’s own analysis cannot be assessed from the information available because its detailed outcome results are not reported in the registry record.
9. Statistical Methods Explained
The primary measure is an ordered severity rating collected before device use and at the return assessment 3 months later. The registry identifies the scale as having 7 levels, ordered from the lowest severity level to the highest. That ordering matters statistically: ordinal data tell us which values represent more or less severe states, but do not establish that each step on the scale represents an equal-sized change.
What does a before-and-after endpoint capture?
In a repeated-measures design, the same participant is assessed at more than one time. A useful description can include the distribution of ratings at each assessment and the transitions from the initial rating to the later rating. These summaries answer different questions: the distributions describe the group at each time, while transitions show how individual ratings changed. General statistical principle: retaining the ordered categories can be more informative than reducing the scale to a simple average, especially when the spacing between categories is not known to be equal.
The registry describes the primary result as a count of participants. A count requires a clear definition of what qualifies as a change, such as whether any movement between rating levels is counted, and how an unchanged rating is handled. The definition used for a participant-level change is not reported in the registry record. Nor are the participant-level transitions or the resulting count reported in the registry record. Without those details, the outcome cannot be reconstructed or independently checked in the registry record in the record.
How would uncertainty be assessed?
General statistical principle: an estimate describes the observed data, while a confidence interval conveys how imprecisely that estimate is measured under the analysis assumptions. A narrower interval indicates greater precision, while a wider interval indicates greater uncertainty. A confidence interval does not remove design limitations, and it cannot establish causation in an uncontrolled study. No confidence interval for the primary endpoint is reported in the registry record.
A p-value, when used, describes how compatible the observed data are with a specified statistical model under a null hypothesis. It is not a measure of clinical importance and does not state the probability that a treatment works. The registry record does not report a p-value for the primary outcome or identify the statistical test used. The analysis plan, including any adjustment for baseline severity or other variables, is not reported in the registry record.
Why does the study design matter for the analysis?
Because the study was uncontrolled, a statistical analysis of before-and-after observations would describe change over time among enrolled participants, not isolate the effect of the device from other explanations. General statistical principle: randomization and a suitable comparison group can help make treatment groups comparable with respect to both measured and unmeasured factors. This record does not describe such a comparison. Allocation is not stated, and the record cautions that its arms are not a like-for-like control comparison.
The registry lists 4 outcome measures and 4 analyses. When a study examines multiple outcomes, the chance of at least one apparently notable result can increase if each is tested separately without a plan for interpretation. General approaches include specifying a primary outcome in advance, defining a hierarchy, or adjusting for multiple testing. Which approach, if any, was used is not reported in the registry record. The registry entries identify the primary outcome and two secondary outcomes, but do not describe the full analysis strategy.
What do the planning calculations represent?
The record describes a sample-size planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not a description of the uncontrolled study’s design. The illustration’s numerical results and the observed effect on which it is based are not reported in the registry record. A planning calculation estimates the sample needed under specified assumptions; it is not observed power and does not show that a study with a particular enrollment has adequate precision.
General statistical principle: count outcomes may have more variability than a simple model assumes, a property called over-dispersion. When it is present, standard errors from an overly restrictive model can be too small and uncertainty can be understated. Whether over-dispersion is relevant depends on the outcome and model. The registry record does not report enough detail about the primary analysis to determine whether it was considered. No distributional model or variance adjustment is reported in the registry record.
Overall, the available information supports describing the endpoint, assessment timing, and study structure, but not evaluating the numerical outcome analysis. The statistical model, handling of repeated observations, assumptions checks, uncertainty estimates, and sponsor’s detailed analysis are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 4 outcome measures and 4 analyses. It identifies change in DOSS rating as the primary outcome and lists laryngeal elevation relative to hyoid elevation for vestibule closure and cortical activation for swallowing among the secondary outcomes. The full outcome and analysis details, including whether each measure had more than one analysis, are not reported in the registry record. A strategy for handling multiplicity, such as a testing hierarchy or adjustment for multiple comparisons, is not reported in the registry record.
Multiplicity matters because examining several outcomes or analyses can make isolated findings harder to interpret. General statistical principle: a prespecified primary outcome helps distinguish the main question from exploratory analyses, while an explicit multiplicity plan clarifies how evidence across outcomes is judged. The presence of a named primary outcome does not itself reveal whether any adjustment was planned or applied.
Missing-data methods are not reported in the registry record. The registry entries do not state whether all enrolled participants completed the return assessment, whether any outcome values were missing, or how missing measurements were handled. The analysis population is also not reported in the registry record: it is not specified whether analyses included everyone enrolled, only those who completed follow-up, or another defined group.
These omissions limit interpretation of any estimated change because missing follow-up data can affect both the observed group description and the uncertainty around it. No assumptions about missingness or imputation should be attributed to the study without a reported analysis plan.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Laryngeal Vibrotactile Stimulation | 0 | 7 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Laryngeal Vibrotactile Stimulation | 0 of 7 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Laryngeal Vibrotactile Stimulation | 3 of 7 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Laryngeal Vibrotactile Stimulation |
|---|---|---|
| Increase in temperature for more than 3 days | Respiratory, thoracic and mediastinal disorders | 3 of 7 |
The registry lists one adverse-event group, “Laryngeal Vibrotactile Stimulation.” It records 7 at risk for serious adverse events, with 0 affected; 7 at risk for other adverse events, with 3 affected; and 0 deaths. These are the counts recorded for the group, and the record lists no top serious adverse-event terms.
The “at risk” counts are the denominators attached to the registry’s adverse-event entries. They should be read alongside the corresponding affected counts, not treated as a comparison between treatment groups. The study is described as uncontrolled, and there is no like-for-like control comparison in the record. The figures therefore do not estimate how these events compare with what would have occurred without the device.
The record does not specify the safety observation window or provide further event descriptions in the registry record. A count of 0 serious adverse events in this record means none are listed as affected in this group; it does not demonstrate that serious events are impossible or exclude uncommon risks. The safety counts also do not answer the primary question about change in DOSS rating. The adverse-event reporting and the swallowing outcome are distinct parts of the study record.
12. What the Result Does, and Does Not, Mean
The study’s stated aims were exploratory: to develop appropriate training methods, gather participant feedback about the Passy Muir Swallowing Self-Training Device, and examine outcomes after 3 months of use. The record establishes that an uncontrolled pilot was conducted, describes the intervention and assessment schedule, and identifies DOSS change as the primary outcome. Enrollment was 11.
The registry record does not report the numerical primary outcome results. It therefore does not show how DOSS ratings changed, how many participants had a change, or how precisely any change was estimated. No treatment effect, confidence interval, or p-value for the primary outcome is reported in the registry record. The secondary outcome results are likewise not reported in the registry record for interpretation.
Even if a before-and-after difference were reported, an uncontrolled study would not establish that device use caused the difference. A comparison group can help distinguish changes associated with an intervention from changes that might occur over time or alongside other care. This record does not supply such a like-for-like control comparison. The allocation method is not stated.
The study can still be understood as a pilot investigation with a focus on training and participant feedback. Its design and stated aims can inform how the research question was approached, but the absence of posted outcome detail prevents assessment of the observed swallowing changes. The adverse-event counts are limited to the reported group and do not provide comparative safety evidence. The registry record does not report a protocol-based sample-size justification, missing-data approach, multiplicity plan, or detailed statistical analysis. Those absences should not be filled by assumptions.
13. Why This Trial Matters Statistically
This trial illustrates the difference between an outcome being named and an outcome being quantitatively interpretable. The registry identifies a clinically oriented primary measure, specifies that ratings were taken before device use and at the return visit 3 months later, and describes the direction of the DOSS scale. But the numerical results needed to judge the amount and precision of change are not reported in the registry record. A well-described endpoint does not substitute for a reported estimate.
It also highlights how design determines what an analysis can answer. Repeated assessments can describe the course of participants’ ratings, but without a control comparison they cannot isolate the effect of device use. This is a design limitation, not a problem that can be fixed by choosing a more elaborate statistical model. The study is explicitly described as an uncontrolled pilot, with no like-for-like control comparison and allocation not stated.
The registry’s stated focus on training methods and participant feedback is important context for interpreting an exploratory pilot. A pilot may be useful for developing procedures and understanding how participants engage with an intervention. However, a planning illustration based on an observed effect is not evidence that the study had adequate power, and it is not a substitute for a reported outcome analysis. The protocol’s sample-size justification is not reported in the registry record.
Finally, the record lists multiple measures and analyses but does not report a multiplicity strategy, missing-data approach, or analysis populations. These details affect how outcome evidence should be interpreted. This study therefore serves as a reminder to separate the research question, the design’s inferential limits, the reported numerical evidence, and the planning assumptions.
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 most direct limitation for interpreting the primary endpoint is that its results are not reported in the registry record. The outcome is described as change in DOSS rating, but no initial or follow-up ratings, change count, effect estimate, confidence interval, or p-value is included in the registry record. Without these, the observed direction, magnitude, and precision cannot be evaluated.
The study is uncontrolled. The record describes device training and follow-up but no like-for-like comparison group; allocation is not stated. Any before-and-after change, if present, could not be attributed to device use alone on the basis of this design. Other influences and natural change cannot be separated from an intervention effect using the information described.
Enrollment was 11, and the registry describes the work as a pilot focused partly on training methods and participant feedback. The protocol’s sample-size justification is not reported in the registry record. The results needed to judge outcome precision are also unavailable. The record does not report how many participants returned for reassessment or how missing data were handled.
The record lists secondary outcomes related to laryngeal elevation and cortical activation, as well as broader aims concerning oral intake and quality of life. Numerical results for these outcomes are not reported in the registry record. It also does not report the detailed analysis plan, analysis populations, multiplicity strategy, or safety observation window. These limitations prevent a fuller assessment of efficacy-related outcomes, statistical uncertainty, and the scope of safety follow-up.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Use of the Passy Muir Swallowing Self Trainer — NCT02848664.
- Registry record last updated 2019-03-11; status last verified 2018-11.
- Results first posted 2019-03-11.
- 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.
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18. Record Summary
The registry describes a completed, uncontrolled pilot sponsored by James Madison University, with enrollment of 11. The study began in 2013-08 and reached primary completion in 2015-08. Participants with dysphagia received baseline testing, training in home use of the Passy Muir Swallowing Self-Training Device, and reassessment after 3 months.
The primary outcome was change in DOSS rating, an ordinal measure with 7 severity levels. Listed secondary outcomes concern laryngeal elevation relative to hyoid elevation for vestibule closure and cortical activation for swallowing. The record also describes participant feedback and broader aims involving swallowing physiology, oral intake, and quality of life.
The primary and secondary numerical outcome results are not reported in the registry record. The safety entry lists 0 serious adverse events among 7 at risk, 3 other adverse events among 7 at risk, and 0 deaths. The record does not describe a control comparison or state the allocation method.