Respiratory Capacity and Swallowing Function in Spinal Disorders: A Pilot Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Respiratory Capacity and Swallowing Function in Spinal Disorders: A Pilot Study (NCT04114604), a registered phase not stated study. The primary outcome is Number of Participants Displaying Unsafe Swallowing.

2. Clinical Question

The broader grant goal was to collect measurements of liquid flow through the oropharynx, described in the record as the mouth and throat, during swallowing. This pilot study focused on the flow of liquids of varying consistency in the spinal disorder population. The primary endpoint operationalized swallowing safety by converting scale scores into safe and unsafe categories and counting participants in the unsafe category by bolus consistency.

This is a descriptive clinical question. The record does not describe an intervention-versus-control question, nor does it report a randomized allocation. It also does not state whether the primary question was intended to test a prespecified hypothesis, estimate prevalence, or guide a later study. Those details are not reported in the registry record.

3. Trial Design

The registry record identifies this study as a completed pilot study titled “Respiratory Capacity and Swallowing Function in Spinal Disorders: A Pilot Study.” The sponsor is University Health Network, Toronto. The listed conditions are spinal cord injuries and deglutition disorders. Enrollment is recorded as 10. The study started on 2017-03-30, and primary completion is recorded as 2019-12-31.

The described group consists of adults with a spinal cord injury at the cervical or upper thoracic level, T6 or higher. The study’s broader context was a grant aimed at collecting measurements of liquid flow through the oropharynx during swallowing. This study focused on liquid flow at varying consistencies in people with spinal disorders. The registry record does not provide further details about recruitment, eligibility beyond the group description, study visits, or how participants were selected.

The primary outcome was assessed at baseline, described as a single timepoint only. It counted participants with unsafe swallowing by bolus consistency. The record lists 3 outcome measures, but it does not give the titles or results of the other measures in the registry record for this analysis. The record lists 0 analyses. No treatment assignment, randomization procedure, masking, or parallel control group is described. Allocation is stated as not stated, and the record cautions that the arms are not a like-for-like control comparison.

These design details support reading the study as a small, descriptive pilot rather than as a randomized comparative trial. “Pilot” is part of the study title; the record does not specify a formal pilot-study design, a progression criterion, or a plan for a later trial. The protocol’s sample-size justification, analysis plan, and any planned interim analyses are not reported in the registry record. The listed enrollment should therefore be read as the recorded enrollment, not as evidence that a particular statistical precision or power target was achieved.

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: Adults who have sustained a spinal cord injury at the cervical or upper thoracic level (T6 or higher).

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 Number of Participants Displaying Unsafe Swallowing, measured over Baseline (single timepoint only).

The primary endpoint is the number of participants displaying unsafe swallowing at baseline. Swallowing safety was characterized with the Penetration-Aspiration Scale, an 8-point categorical scale. According to the registry description, levels 1 and 2 are considered safe, while scores greater than 2 are considered unsafe. Actual scores from 1–8 were to be recorded and then converted to a binary category: less than 3 versus greater than or equal to 3. The reported endpoint is the frequency, or count, of participants in the unsafe category by bolus consistency.

In general, converting a scale into safe and unsafe categories can make a clinically defined threshold easier to communicate and can support straightforward counts. It also discards distinctions among scores within each category: the endpoint does not, by itself, describe the full distribution of scale scores or how far an individual score lies from the threshold. The registry record does not state whether the original scale scores were also analyzed as an ordinal outcome.

The baseline, single-timepoint specification means this endpoint is not a measure of change over time. The record does not report the actual counts by consistency, the number of bolus observations, or how multiple observations for a participant were handled. Those details are needed to interpret the reported frequency fully and are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint converts a categorical swallowing score into a binary classification and then counts participants classified as unsafe. The threshold is set by the study description: scores greater than 2 are unsafe, while levels 1 and 2 are safe. The endpoint is therefore a count of participants meeting a defined criterion, rather than a mean score or a continuous measurement.

What does a binary count describe?

In general, a binary outcome assigns each assessed person or observation to one of two categories. A count records how many fall into the category of interest. Such a count is easy to interpret in the context of the definition used, but it does not retain the detail in the original scale. Here, the registry states that actual Penetration-Aspiration Scale scores from 1–8 were to be converted to categories, with unsafe defined as greater than 2. The record does not report the actual scores or the resulting counts.

The outcome is described by bolus consistency. In general, when outcomes are recorded under multiple conditions for the same participant, observations may be related rather than independent. Methods that treat all observations as unrelated can understate uncertainty if that dependence is ignored. Whether the same participants were assessed under each consistency, and how within-participant dependence was handled, are not reported in the registry record. The available information therefore does not establish which statistical method, if any, was used to compare consistency-specific results.

Why does the design matter?

Statistical interpretation depends on how observations were generated. This record describes a spinal cord injury group and says allocation was not stated; it also notes that the arms are not a like-for-like control comparison. It does not describe randomization or a control group. In general, a randomized comparison can help separate treatment effects from differences that existed before treatment assignment. A descriptive count from a single group does not provide that kind of causal contrast. No treatment effect should be inferred from the primary endpoint as described.

The outcome is at baseline at a single timepoint. In general, a single-timepoint measure describes status at the time of assessment; it cannot show improvement, deterioration, or a trajectory without repeated measurements. The registry record does not specify whether any later measurements were collected for other outcomes. It also does not report whether the baseline timing was anchored to an intervention or other clinical event.

What can inferential statistics add?

In general, a confidence interval describes statistical uncertainty around an estimate, while a hypothesis test evaluates data against a stated null model. Both depend on the estimand, the sampling structure, and assumptions of the chosen method. Neither can be interpreted without the underlying observed results and analysis details. The record lists 0 analyses and gives no primary-outcome estimate, confidence interval, p-value, or hypothesis-testing method. No inferential conclusion can be recovered from the endpoint definition alone.

Counts can be accompanied by proportions, but the relevant denominator and the calculation must be clear. The registry record identifies enrollment as 10, but does not provide the number assessed for the primary endpoint or the denominator for each consistency. It would not be appropriate to treat enrollment as the denominator for each result without confirmation that every enrolled participant contributed data in each condition. Missing assessments, exclusions, or incomplete measurements are not described.

How should planning calculations be distinguished from results?

In general, sample-size calculations use assumptions about the effect to detect, variability, significance level, allocation, and statistical method. They are planning illustrations, not observed outcomes and not evidence that a study achieved a target probability of detecting an effect. The record’s planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of an observed effect. For time-to-event calculations, the stated convention is a total number of events; for other calculations, it is participants per arm.

Those assumptions do not establish the actual design or analysis of this pilot. In particular, the record does not describe a randomized two-arm comparison, and it states that allocation was not stated and the arms are not a like-for-like control comparison. A study-specific sample-size justification is not reported in the registry record. No planning result should be read as an observed power estimate or as a result of the primary endpoint.

More generally, a statistical method should match the outcome and the way data were collected. Participant-level binary counts, repeated observations across consistencies, and comparisons between groups can require different approaches. The registry record does not specify a model, adjustment variables, handling of repeated observations, or a prespecified analysis population. Without those details and the observed outcome values, the statistical results cannot be independently interpreted or recalculated.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Thin Liquid Barium", "Slightly Thick Liquid Barium", "Mildly Thick Liquid Barium", "Moderately Thick Liquid Barium", "Extremely Thick Liquid Barium")
n      <- c(10, 10, 10, 10, 10)
events <- c(0, 0, 0, 0, 0)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Thin Liquid Barium  10  0  0.0  0.0  30.8  0.0  27.8  0.2  28.5
ARM  Slightly Thick Liquid Barium  10  0  0.0  0.0  30.8  0.0  27.8  0.2  28.5
ARM  Mildly Thick Liquid Barium  10  0  0.0  0.0  30.8  0.0  27.8  0.2  28.5
ARM  Moderately Thick Liquid Barium  10  0  0.0  0.0  30.8  0.0  27.8  0.2  28.5
ARM  Extremely Thick Liquid Barium  10  0  0.0  0.0  30.8  0.0  27.8  0.2  28.5

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 3 outcome measures and 0 analyses. It identifies unsafe swallowing as the primary outcome and says the count is reported by bolus consistency. The other outcome measures, the number of consistency-specific comparisons, and any planned secondary analyses are not reported in the registry record. No adjustment for multiple comparisons or other multiplicity strategy is described.

In general, testing multiple outcomes or multiple versions of an outcome can increase the chance of finding an apparently notable result by chance. A prespecified analysis plan can clarify which outcome is primary and how additional tests should be interpreted. The record identifies a primary endpoint, but does not provide enough analysis information to determine whether there were additional planned tests or how they would have been handled.

Missing-data procedures are not reported in the registry record. The record does not state how many participants had a usable primary endpoint, whether every participant was assessed for every bolus consistency, or how unavailable or unusable measurements were treated. The enrollment figure alone does not answer those questions. It also does not identify an intention-to-treat, per-protocol, or other analysis population.

These omissions matter because the denominator and analysis population affect the interpretation of a count. If some measurements were unavailable, the observed count could represent only those with recorded data, while the enrolled group would remain a different reference population. No such pattern can be asserted for this study: the number and handling of missing measurements are not reported in the registry record. The record also does not report whether any participants withdrew or were excluded from outcome analysis.

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.

For the Spinal Cord Injury group, the registry record lists 10 participants at risk for serious adverse events and 0 affected. It also lists 10 participants at risk for other adverse events and 0 affected. Deaths are recorded as 0. These are the safety figures reported for the group; they should be read as registry entries rather than as a complete description of every possible safety event or every period of observation.

The record does not provide event terms, and no serious event terms are listed. It does not define the safety observation window, describe how events were collected or adjudicated, or clarify whether the at-risk counts correspond to all enrolled participants throughout follow-up. Those details are not reported in the registry record. A zero recorded count means that no affected participants are listed in these fields; it does not establish that the study assessed every potential event in the same way or that no unrecorded events occurred.

In general, safety counts are most informative when the observation period, event definitions, and population at risk are clear. Here, those details are limited. The figures do not support a comparison of safety between groups because the record does not describe a like-for-like control comparison.

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

The study addresses a focused descriptive question: how many participants with cervical or upper thoracic spinal cord injury met the unsafe-swallowing threshold at baseline, classified by bolus consistency. The registry supplies the scale and threshold definition and identifies the intended summary as a participant count. These details clarify what the primary endpoint represents.

The registry entries available do not include the observed primary counts. They also do not include estimates of uncertainty or statistical tests. Consequently, the endpoint’s actual results and precision cannot be stated. The completed status and enrollment entry do not substitute for those outcome data.

Even with observed counts, a descriptive baseline count would not by itself demonstrate that one liquid consistency is safer than another, establish a causal relationship, or show that an intervention changed swallowing. The registry record does not describe a randomized treatment comparison, and it explicitly notes that the arms are not a like-for-like control comparison. The primary outcome is also recorded at a single baseline timepoint, not as change over time.

The outcome’s thresholded form has a specific interpretation: a score greater than 2 is classified as unsafe under the registry’s definition. It does not capture the full pattern of scores on the 8-point scale. In general, categorization can simplify communication while concealing differences among values within a category. The record does not report the underlying scale scores, so that additional detail cannot be assessed.

The title and summary refer to respiratory capacity, swallowing function, and liquid flow. The primary endpoint described in detail is the count of participants with unsafe swallowing. Findings for respiratory capacity, the other listed outcome measures, and liquid-flow measurements are not reported in the registry record available for this analysis. No conclusion about those outcomes should be drawn from the primary-endpoint description or the safety entries.

14. Why This Trial Matters Statistically

This pilot is statistically informative as an example of how an outcome definition shapes the question a study can answer. The Penetration-Aspiration Scale has an 8-point range, but the primary endpoint reduces it to safe and unsafe categories using a stated threshold. That makes the outcome a participant count, while leaving the original scale’s finer gradations outside the primary summary as described.

The focus on bolus consistency also raises a general design issue: when several conditions are assessed within the same participant, the resulting observations may be linked. Valid uncertainty estimates and comparisons depend on recognizing the data structure. The registry record does not state how repeated or condition-specific observations were handled, so the available information cannot resolve that methodological question.

The record also illustrates why design labels and analysis details need to be distinguished. The study is titled a pilot and is listed as completed, but those labels do not reveal the analysis plan, adequacy of data, or precision of results. The record lists enrollment as 10 and identifies 0 analyses; it does not include the primary outcome counts or inferential results. Statistical interpretation must therefore remain tied to the endpoint definition rather than extending to claims about results that are not reported.

Finally, the registry’s note that allocation was not stated and that the arms are not a like-for-like control comparison is important for interpreting any group labels. Without a suitable comparison and an analysis plan, group-level differences cannot automatically be attributed to a cause. This is a useful statistical distinction in small pilot research: a study can describe measurements and motivate further questions without providing a controlled estimate of an intervention effect.

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 available record leaves several trial-specific limitations unresolved. It describes the primary outcome as a baseline count by bolus consistency but does not provide the observed counts, the underlying scale scores, or the number assessed under each consistency. As a result, neither the outcome distribution nor its precision can be evaluated.

The study population is described as adults with cervical or upper thoracic spinal cord injury at T6 or higher, and enrollment is recorded as 10. Further eligibility criteria, participant characteristics, recruitment methods, and the representativeness of the group are not reported in the registry record. The record does not state how many enrolled participants contributed usable endpoint data.

The comparison structure is also limited in the available description. Allocation is not stated, and the record cautions that the arms are not a like-for-like control comparison. It does not describe a randomized control group or a causal comparison. The endpoint is at one baseline timepoint, so the primary measure as described cannot show within-participant change over time.

The endpoint is thresholded: scores greater than 2 are classified as unsafe. The record does not report an analysis of the original 8-point scores or explain whether such an analysis was planned. It also does not specify how multiple bolus observations per participant, missing measurements, or multiple outcome analyses were handled. These gaps limit assessment of the measurement and analysis strategy.

Although the study is titled a pilot and lists 3 outcome measures, formal pilot objectives, progression criteria, a sample-size justification, and a detailed statistical analysis plan are not reported in the registry record. Results for the other outcome measures are also not included in the registry record. The record thus supports a clear account of the primary endpoint’s definition, but not a full evaluation of the study’s results or methods.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Respiratory Capacity and Swallowing Function in Spinal Disorders: A Pilot Study — NCT04114604.
• Registry record last updated 2023-04-04; status last verified 2023-04.
• Results first posted 2022-07-13.
• 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

NCT04114604 is a completed pilot study sponsored by University Health Network, Toronto. The record lists 10 enrolled participants and describes adults with cervical or upper thoracic spinal cord injury at T6 or higher. The study focused on liquid flow of varying consistencies during swallowing in a spinal disorder population.

The primary outcome was the number of participants with unsafe swallowing at baseline, classified by bolus consistency using the Penetration-Aspiration Scale threshold greater than 2. The record lists 3 outcome measures and 0 analyses. It does not include the observed primary outcome counts or inferential results in the registry record for interpretation.

The safety record lists 0 participants affected by serious adverse events, 0 affected by other adverse events, and 0 deaths in the Spinal Cord Injury group. Allocation is not stated, and the record notes that the arms are not a like-for-like control comparison.