Physiological Flow of Liquids Used in Dysphagia Management (Neuro): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Physiological Flow of Liquids Used in Dysphagia Management (Neuro) (NCT03192358), a registered phase not stated study. The primary outcome is Number of Participants With Residue of Concern (Observational).

2. Clinical Question

3. Trial Design

This was a completed observational study sponsored by University Health Network, Toronto. The registry lists a total enrollment of 40 and two cohorts: 20 adults with ALS and 20 adults with Parkinson disease. Participants were described as having speech or swallowing problems. Allocation is not stated, and the registry explicitly cautions that the cohorts are not a like-for-like control comparison. The study should therefore be understood as an assessment of swallowing physiology, not as a randomized comparison of treatments.

Each participant was to attend one data-collection session and undergo the same protocol, including a videofluoroscopic swallowing examination and tongue strength measurement. The examination considered five liquid thicknesses: thin, slightly-thick, mildly-thick, moderately-thick, and extremely-thick. The registry describes the primary outcome as a baseline measure in a single timeframe. It also lists secondary observational outcomes concerning maximum posterior isometric tongue pressure, multiple swallows per bolus, and prolonged pharyngeal bolus transit.

The registry dates the study start to 2017-11-01 and primary completion to 2020-12-31; its status is completed. Some data were missing for particular consistencies because of data-quality issues. The registry record does not report the detailed analysis plan, a sample-size justification for the study, or whether interim analyses were planned. The record lists seven outcome measures and two analyses, but does not report enough detail to characterize the analyses further. No randomized treatment assignment or separate control protocol is described.

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: Two cohorts of participants were enrolled in this observational study: 1) A cohort of 20 adults with Amyotrophic Lateral Sclerosis (ALS); and 2) A cohort of 20 adults with Parkinson disease. Due to data quality issues, partial data were missing for some consistencies.

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 With Residue of Concern (Observational), measured over Single timeframe (baseline only).

The primary endpoint is the number of participants with residue of concern, assessed separately by liquid consistency. Residue means material remaining in the pharynx after a swallow. In this study, it was measured by tracing the visible barium area on a lateral-view x-ray, recording that area in pixels, and dividing it by the squared length of the C2-C4 cervical spine. The spine measurement serves as an anatomical reference intended to account for differences in neck length and pharyngeal size between people.

The resulting normalized residue measure was compared with the stated 75th percentile healthy reference value for each consistency: 1.7% for thin liquids, 1.9% for slightly thick liquids, 2.2% for mildly thick liquids, 1.6% for moderately thick liquids, and 1.5% for extremely thick liquids. The registry defines values above the applicable threshold as atypical and of clinical concern. The primary outcome is a count of participants exceeding these consistency-specific cutoffs, rather than the continuous residue value itself.

This endpoint was selected to describe how often residue crossed a reference boundary across the tested consistencies. The registry says smaller residue values are considered better, and frames the study as exploring the balance between airway safety and residue accumulation. However, the registry record does not report the observed per-consistency counts or the underlying residue measurements. It therefore does not establish from the posted primary outcome whether any particular consistency was associated with fewer participants above threshold.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the primary count represent?

The primary endpoint counts participants whose normalized pharyngeal residue value was above the healthy reference threshold for a given liquid consistency. The measurement begins with a traced area of visible barium after swallowing, then scales that area using the squared C2-C4 cervical spine length. In general, a common anatomical reference can make measurements more comparable across people whose body and pharyngeal dimensions differ. The registry describes this measure as a proxy for pharyngeal size, not a direct measurement of the full geometry or function of the pharynx.

The endpoint turns a continuous measurement into a binary classification: a value is either above the stated threshold or it is not. This makes the count straightforward to describe, but it discards information about how far values lie from the cutoff. In general, a participant just above a threshold and a participant far above it both contribute one to the count. The continuous residue values would be needed to understand the range and distribution behind that count; they are not reported in the registry record.

How should the reference thresholds be understood?

The registry identifies each threshold as a 75th percentile healthy reference value and defines values above it as atypical and of clinical concern. Each liquid consistency has its own cutoff. These values are classification references, not estimates of outcomes in the enrolled cohorts. In general, a reference threshold provides a rule for interpreting individual measurements; it does not by itself show how many study participants crossed the rule, nor does it establish what degree of difference is meaningful for every clinical purpose.

Because each consistency has its own reference value, the binary classifications are tied to distinct cutoffs. Comparing counts across consistencies describes the frequency of values above their respective reference thresholds, not necessarily the difference in raw residue amount under a shared numeric cutoff. The registry does not report additional analysis details, such as whether continuous values were also compared statistically or how within-participant correlations across consistencies were handled.

What can a count tell us about uncertainty?

In general, an observed count is a description of the participants with classified outcomes, not a measure of how precisely a broader population frequency is known. A confidence interval, when reported, expresses statistical uncertainty around an estimate under a specified method and assumptions. The registry record does not report confidence intervals or other uncertainty estimates for the primary endpoint. Since it also does not report the observed counts or consistency-specific denominators, the precision of any frequency estimate cannot be assessed from the posted record.

The study includes two diagnosis cohorts, but the record does not give a randomized comparison or detail an inferential model for comparing them. In general, a difference in observed counts between groups can reflect variation in the enrolled participants as well as any relationship with the group characteristic. An observational comparison cannot by itself establish that diagnosis or liquid thickness caused an outcome. The registry also does not report adjustment variables, subgroup methods, or a prespecified model for the repeated measurements across consistencies.

Why does missing data matter?

The primary outcome description states that partial data were missing for some consistencies because of data-quality issues. In general, missing measurements can alter the set of participants represented in a consistency-specific count. If the number or characteristics of participants with usable data differ across consistencies, apparent differences in counts may partly reflect different data availability. The registry does not report the amount of missingness by consistency, the reasons in greater detail, or the method used to address missing measurements. It is therefore not possible to determine from the record whether the endpoint used complete cases, another rule, or a sensitivity analysis.

How should planning calculations be read?

Any planning illustration based on an observed effect is not observed power and does not show the probability that the completed study detected a real effect. The registry’s stated illustration assumptions concern 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 the observed effect. Such an illustration is distinct from a prospective sample-size justification for the study. The registry record does not report the study’s own sample-size justification, and an observational study with cohorts that are not like-for-like control arms should not be treated as a randomized two-arm trial merely because an illustration uses equal allocation.

The registry reports seven outcome measures and two analyses, but does not describe a complete statistical plan. It does not report inferential test choices, multiplicity adjustments, analysis populations, or interim analyses. General statistical methods can clarify what counts, thresholds, missingness, and uncertainty mean, but they cannot supply unreported analytic decisions or recover outcome results absent from the registry record.

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("Amyotrophic Lateral Sclerosis: Thin Liquids", "Amyotrophic Lateral Sclerosis: Slightly Thick Liqu", "Amyotrophic Lateral Sclerosis: Mildly Thick Liquid", "Amyotrophic Lateral Sclerosis: Moderately Thick Li", "Amyotrophic Lateral Sclerosis: Extremely Thick Liq", "Parkinson Disease: Thin Liquid")
n      <- c(20, 19, 18, 17, 17, 17)
events <- c(6, 6, 3, 6, 4, 2)
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  Amyotrophic Lateral Sclerosis: Thin Liquids  20  6  30.0  11.9  54.3  14.5  51.9  14.6  52.2
ARM  Amyotrophic Lateral Sclerosis: Slightly Thick Liqu  19  6  31.6  12.6  56.6  15.4  54.0  15.4  54.3
ARM  Amyotrophic Lateral Sclerosis: Mildly Thick Liquid  18  3  16.7  3.6  41.4  5.8  39.2  6.1  39.6
ARM  Amyotrophic Lateral Sclerosis: Moderately Thick Li  17  6  35.3  14.2  61.7  17.3  58.7  17.3  59.0
ARM  Amyotrophic Lateral Sclerosis: Extremely Thick Liq  17  4  23.5  6.8  49.9  9.6  47.3  9.7  47.6
ARM  Parkinson Disease: Thin Liquid  17  2  11.8  1.5  36.4  3.3  34.3  3.6  34.7

11. Multiplicity, Missing Data and Analysis Populations

The registry lists seven outcome measures, including the primary residue count and secondary observational measures related to tongue pressure, multiple swallows per bolus, and prolonged pharyngeal bolus transit. The record reports two analyses, but does not describe the analyses or explain how outcomes were prioritized beyond identifying the primary endpoint. It does not report whether the investigators planned adjustments for testing multiple outcomes or multiple liquid consistencies. In general, evaluating many outcomes or comparisons can increase the chance of observing an apparently notable result by chance; adjustment or a clear prespecified hierarchy can address that issue. No such approach is reported, so none should be assumed.

Partial data were missing for some consistencies because of data-quality issues. The registry does not state how many measurements were unavailable for each consistency, which participants were affected, or how missing values were handled. It also does not report whether analyses used only participants with usable data for each particular consistency, or whether any sensitivity analysis assessed the effect of missingness. Consequently, consistency-specific denominators and the potential influence of missing data cannot be assessed from the registry record.

The record describes the two cohorts as observational and does not state allocation. It does not identify an analysis population beyond the cohort descriptions, or specify exclusions, protocol deviations, or rules for including participants in each outcome analysis. It also does not report interim-analysis plans. These absences do not establish that particular methods were or were not used; those details are not reported in the registry record. The observed outcome counts and their denominators would be needed to interpret the endpoint frequencies, but the primary counts are not reported.

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 lists zero serious adverse events among 20 participants at risk in the ALS cohort and zero among 20 participants at risk in the Parkinson disease cohort. It also lists zero other adverse events among 20 participants at risk in each cohort, and zero deaths in each cohort. These are the recorded figures for the study population and should be read as counts in the registry, not as proof that no adverse events could occur in other participants or settings.

The registry lists no serious adverse event terms. It does not provide further detail in the safety information about event definitions, collection procedures, observation duration, or how completely events were ascertained. The study protocol is described as a single data-collection session, but the safety record does not state the precise period over which the adverse-event counts were collected. These limits matter when interpreting zero recorded events: a zero count describes what was recorded in this study, while the completeness and scope of monitoring are not fully detailed in the registry record.

Safety counts do not answer the primary question about residue of concern, and they do not establish comparative safety between liquid consistencies. The cohorts are observational and are not treatment and control groups. The posted figures should therefore be kept separate from the swallowing physiology outcomes.

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

The study addresses an important measurement question: how swallowing physiology and pharyngeal residue vary across five liquid thicknesses in adults with ALS or Parkinson disease. It specifies a way to normalize measured residue to an anatomical reference and defines consistency-specific healthy reference cutoffs. That gives readers a framework for understanding how the investigators intended to classify residue of concern.

The record does not, however, report the observed number of participants above each cutoff. It therefore cannot establish which consistency had the highest or lowest frequency of residue of concern, how large any differences were, or how precisely those frequencies were estimated. The cutoffs are not substitutes for the missing study outcome counts. Nor can the record show the distribution of continuous residue values, because those results are not reported.

The observational design also limits causal interpretation. The record describes ALS and Parkinson disease cohorts undergoing a shared assessment, without randomized assignment or a like-for-like control comparison. Although the study examines multiple consistencies, any association between consistency and measured swallowing function is not by itself proof of a causal effect. The record does not detail adjustment methods or the handling of repeated observations, and partial data were missing for some consistencies.

The study’s stated purpose was to explore possible boundaries of an optimal liquid thickness, balancing airway safety with residue accumulation. The primary outcome concerns residue; other listed outcomes relate to tongue pressure, multiple swallows, and pharyngeal transit. Without the observed results for these outcomes, the registry record cannot show whether a balance was identified or support a conclusion about a specific thickness. The zero adverse-event counts are limited to the safety record and do not fill this outcome gap.

Thus, the registry establishes the study question, cohort structure, measurement approach, and reference criteria, but not the primary outcome findings. Any claims about which liquid thickness is preferable or how the measured outcomes differed would require results not reported in the registry record.

14. Why This Trial Matters Statistically

This study is statistically interesting because its primary endpoint combines an anatomical normalization step with a threshold-based classification. Normalizing traced residue area using a cervical spine reference is intended to improve comparability across participants with different neck lengths and pharyngeal sizes. The subsequent thresholding gives a clinically framed count, but changes the question from how much residue was measured to how many people crossed a defined boundary. That distinction matters when interpreting any reported count.

The use of five consistency-specific reference cutoffs also illustrates that a threshold is part of the outcome definition, rather than a neutral property of the data. Counts across consistencies would describe participants classified above different reference values. Continuous measurements, threshold counts, and clinical interpretation can provide related but non-identical information. The registry explains the intended classification but does not report the observed counts or underlying measurements, leaving the empirical comparison unavailable.

The study also highlights common interpretive challenges in observational research: two diagnosis cohorts are not necessarily comparable as if one were a randomized control arm, and missing measurements can change the participants represented in consistency-specific analyses. The registry gives the broad cohort sizes and identifies data-quality issues but not the denominators or missing-data approach. Those details are necessary to evaluate the stability and comparability of the endpoint estimates.

Finally, a question with multiple outcomes and repeated assessments across consistencies requires clear reporting of analysis choices and uncertainty. The registry record identifies several measures but does not report a full statistical plan, multiplicity approach, or precision estimates. The study remains useful as an example of how outcome definitions, reference thresholds, observational design, and missingness shape what can be concluded from clinical research records.

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 primary limitation for interpreting the registry results is that the observed primary endpoint counts are not reported. The record gives the outcome definition and reference thresholds, but not the number of participants above each threshold, the consistency-specific denominators, or uncertainty estimates. As a result, the central descriptive comparison cannot be reconstructed from the registry information.

Partial data were missing for some liquid consistencies because of data-quality issues. The registry does not state the amount or pattern of missingness, whether the same participants contributed data at every consistency, or how missing measurements were handled. This is particularly relevant when an outcome is counted separately by consistency, since the underlying participant sets could differ. The registry record does not report sensitivity analyses that would show how robust any findings were to missing data.

The study was observational, and allocation is not stated. The two cohorts were recruited because participants had ALS or Parkinson disease and swallowing or speech problems; the record cautions that the cohorts are not a like-for-like control comparison. The available description does not report adjustment for participant characteristics or detail how within-person measurements across consistencies were analyzed. Causal or direct between-cohort claims would therefore be unsupported by the registry description.

The primary outcome classifies measurements using healthy reference thresholds. The registry does not provide the underlying continuous measurements, so readers cannot assess how close values were to the cutoff or whether conclusions depend on thresholding. It also does not report the full statistical plan, multiplicity handling, outcome-specific analysis populations, or a study sample-size justification. These details are not reported in the registry record and limit assessment of analytic choices, precision, and the scope of the findings.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Physiological Flow of Liquids Used in Dysphagia Management (Neuro) — NCT03192358.
• Registry record last updated 2022-09-15; status last verified 2021-03.
• Results first posted 2022-07-14.
• 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

NCT03192358 is a completed observational study sponsored by University Health Network, Toronto. The registry lists enrollment of 40 adults: 20 with ALS and 20 with Parkinson disease. Participants were assessed in a single data-collection session using videofluoroscopic swallowing examination and tongue strength measurement, across five liquid thicknesses.

The primary outcome was the number of participants with residue of concern, classified using consistency-specific healthy reference values. The registry reports partial missingness for some consistencies due to data-quality issues, but does not report the primary outcome counts or their denominators. It lists secondary observational outcomes concerning tongue pressure, multiple swallows, and prolonged pharyngeal transit. The record gives zero serious adverse events, zero other adverse events, and zero deaths in each cohort. Detailed analysis methods and the study’s sample-size justification are not reported in the registry record.