Assessment of a Novel Tracheostomy Tie: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Assessment of a Novel Tracheostomy Tie (NCT02820181), a randomized na study. The primary outcome is Visual Analogue Scale to Measure the Difficulty Level of Exchanging or Cleaning the Tracheostomy Ties (0 to 10 ) Higher Scores Mean a Worse Outcome.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group study with no masking. It lists an enrollment of 60 and two device groups: novel tracheostomy bi-ties and traditional tracheostomy ties. The arm records list 30 participants for each group. The registry status is completed. The recorded study start was 2016-08-01, and primary completion was 2019-05-01.

The primary outcome was a mean score on a visual analogue scale assessing nurses’ perceived difficulty exchanging or cleaning the ties. The stated scale runs from 0 to 10, with higher scores meaning worse outcomes, and the measurement timeframe is 14days. The posted result is expressed as a mean and standard deviation for each group, with a comparison reported as a mean difference.

The registry also lists patient comfort during wearing or exchanging ties and the actual frequency of exchanging dressing as secondary outcomes, both assessed over 14days. The record describes these as continuous outcomes and reports means and standard deviations. Additional outcome measures are indicated in the registry, but their details are not reported in the registry record.

The record names The First Affiliated Hospital of Shanxi Medical University as sponsor and lists the phase as not applicable. It does not report eligibility criteria, the randomization procedure, allocation concealment, specific analysis populations, or the original design assumptions. Those omissions limit how fully the design can be reconstructed from the registry record alone.

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

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 Visual Analogue Scale to Measure the Difficulty Level of Exchanging or Cleaning the Tracheostomy Ties (0 to 10 ) Higher Scores Mean a Worse Outcome, measured over 14days.

The primary endpoint is nurses’ rating of the difficulty of exchanging or cleaning a tracheostomy tie. The registry specifies a visual analogue scale from 0 to 10 and states that higher scores represent worse outcomes. Results are summarized as group means and standard deviations, making the endpoint a continuous measure.

This endpoint addresses a practical aspect of device use: the effort or difficulty staff experience during tie exchange or cleaning. A scale can capture a graded judgment rather than forcing a simple yes-or-no classification. Comparing group means provides a concise description of how the average ratings differed between the randomized device groups. The standard deviations describe variation in individual ratings within each group.

As a general measurement consideration, a rating scale reflects the judgment of the person completing it and may not capture every aspect of usability or performance. The registry identifies nurses as the raters for the primary outcome. It does not report the scale’s validation, instructions for raters, or procedures intended to make ratings consistent. Nor does this endpoint directly establish a difference in clinical complications, decannulation, or patient health. Those outcomes should not be inferred from a staff-rated difficulty score.

7. Results Posted in the Registry

• Traditional Tracheostomy Tie: mean 7.50 versus 1.20 on control; difference 6.30 (95% CI 6.02 to 6.58), standardized effect d = 11.41; z-test p = <0.001.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Visual Analogue Scale of Comfort of Patients During Wearing or Exchanging Tracheostomy Ties (0-10) Higher Scores Mean Worse Outcome.

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Traditional Tracheostomy Tie: mean 8.90 versus 1.00 on control; difference 7.90 (95% CI 7.52 to 8.28), standardized effect d = 10.51; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Traditional Tracheostomy Tie than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Objective Index:the Actually Frequency of Exchanging Dressing

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Traditional Tracheostomy Tie: mean 2.00 versus 0.00 on control; difference 2.00 (95% CI 1.77 to 2.23), standardized effect d = 4.42; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Traditional Tracheostomy Tie than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The posted secondary outcomes cover two related but distinct aspects of tie use: patient comfort while wearing or exchanging ties, and the actual frequency of dressing exchanges. Their broad pattern is aligned with the primary result in that the posted group comparisons favor lower scores or frequency for the novel bi-ties under the outcomes’ stated directions. This consistency can add context to the primary finding, because the measures address experiences and tasks related to device handling.

The secondary measures do not simply duplicate the primary endpoint. The primary outcome concerns nurses’ ratings of task difficulty, while comfort reflects the patient experience and exchange frequency is an objective count-like measure reported as a mean. Agreement across different types of outcomes can be informative, but it does not establish that they measure the same construct or independently confirm a causal explanation.

The registry posts comparisons for both secondary outcomes, but reports no analyses for them in its reported-analysis listings. The record does not state whether these outcomes were prespecified as confirmatory, whether multiplicity was considered, or whether missing data were handled consistently across outcomes. Without those details, the secondary results should carry less inferential weight than a primary outcome supported by a clearly documented analysis plan.

When several outcomes are tested, the chance of obtaining at least one apparently strong result by chance can increase. General methods for addressing this issue include prespecifying a hierarchy or adjusting inference across a family of tests. The registry does not report whether either approach was used. This does not erase the posted secondary patterns, but it argues for reading them as supportive descriptive evidence rather than treating each unadjusted p-value as a separate definitive finding.

The registry’s description also leaves the measurement context incomplete. It does not report details such as the instructions for collecting comfort ratings or the operational definition used for dressing exchanges. The secondary measures therefore provide useful breadth, while their interpretation remains bounded by the information recorded.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Visual Analogue Scale of Comfort of Patients During Wearing or Exchanging Tracheostomy Ties (0-10) Higher Scores Mean Worse Outcome.
• Objective Index:the Actually Frequency of Exchanging Dressing

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous and is reported as a mean with a standard deviation. A mean is the arithmetic average of the observed ratings in a group. A standard deviation describes how spread out individual ratings are around that average. It is not the uncertainty of the mean itself: the standard error, which is affected by both variability and the amount of information available, describes that uncertainty more directly.

The registry comparison is a mean difference. Its orientation is traditional ties compared with novel bi-ties: the reported group means are 7.5 and 1.2, respectively, and the reported difference is 6.3. Because higher scores indicate worse outcomes, a positive difference in this orientation means that the traditional-tie group had a higher average difficulty rating. This is a direction-of-scoring interpretation, not a separate clinical outcome.

In general, a confidence interval gives a range of values compatible with the observed data under the statistical model and method used. It expresses uncertainty about an estimated quantity, rather than a range containing a specified proportion of individual ratings. The reported interval for the primary mean difference extends from 6.021 to 6.579. The registry does not report the confidence level or the method used to construct this interval, so those details should not be inferred.

The posted p-value for the primary comparison is unadjusted and reported as <0.001. In general, a p-value describes how unusual data at least as incompatible with a null model as the observed data would be, if the null model and analysis assumptions held. It does not measure the size or importance of an effect. It also does not account for the possibility of selecting among multiple outcomes unless an adjustment or prespecified testing strategy is used. The registry record does not report such a strategy.

The record identifies the trial as randomized and parallel-group, but the detailed statistical method for the primary comparison is not reported in the registry record. The summary values make a mean-difference comparison readable; they do not reveal whether the sponsor’s analysis included covariates, how assumptions were checked, or how any departures from assumptions were handled. No adjustment or model should be attributed to the trial without that information.

As a general matter, a mean-based analysis is most directly interpretable when the scale behaves sufficiently like a quantitative measure and the group summaries represent the intended analysis population. Visual analogue scores are bounded by the scale limits, and ratings may cluster near an endpoint or show skewness. Those features can matter for statistical modeling, especially when sample sizes are limited. The registry does not report distribution checks or alternative analyses, so the reader cannot assess their use from this record.

Dispersion matters because it indicates how consistently participants’ ratings cluster around the group average. Similar means can arise with very different amounts of individual variation; conversely, an average difference may coexist with overlap between individual observations. Standard deviations do not show the full shape of the data, and the registry does not provide participant-level ratings or distributions. Accordingly, the means and standard deviations describe central tendency and spread but cannot reveal every feature of the observed responses.

Randomization is intended, in general, to make treatment-group comparisons less vulnerable to systematic differences in participant characteristics. Its value depends on implementation and on preserving the allocation process. The registry does not report sequence generation, concealment, adherence, crossover, or post-randomization exclusions. The designation “randomized” alone does not establish how these procedures were carried out.

No reported-analysis entries are listed for the secondary outcomes, while comparative results are posted. This distinction means the registry record does not provide a detailed account of the analysis procedures behind those results. In general, analyses chosen after viewing data may be more vulnerable to selective reporting than analyses specified in advance. Whether that occurred cannot be determined from the registry record.

11. Confidence Intervals and Precision

The primary comparison is reported as a mean difference of 6.3, with an interval from 6.021 to 6.579. The relatively narrow interval indicates that the posted estimate is not highly imprecise under the statistical procedure used to produce it. The interval lies entirely on the positive side of the reported traditional-versus-novel contrast, which is consistent with higher average difficulty ratings for traditional ties on a scale where higher is worse.

A confidence interval is about uncertainty in an estimated group contrast, not about the range of ratings among individual nurses or participants. The primary group means and standard deviations describe those summaries separately. The standard deviations are 0.6 for novel bi-ties and 0.5 for traditional ties. The registry does not report the interval’s confidence level or construction method; precision should therefore be interpreted from the reported endpoints without assuming an unrecorded procedure.

Precision is not the same as validity. A narrow interval does not address possible measurement bias, lack of masking, incomplete outcome data, or limitations in how the study population was selected. It also does not establish that the scale difference crosses a threshold of practical importance. The registry does not report a clinically meaningful threshold for the nurse-rated scale.

The unusually separated group means relative to the stated scale range make the result important to interpret in context, including how ratings were collected and whether all observations were handled as planned. The record does not report missing-data methods, distributions, or sensitivity analyses. These omissions do not change the values posted, but they leave aspects of uncertainty and robustness undocumented.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are expressed as participants per arm, not as total participants. The record’s stated planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is specified as a stated fraction of the observed effect. These are planning illustrations based on the observed results, not the original trial’s design assumptions; the original assumptions are not reported in the registry record.

The 80% power column represents a planning calculation aimed at an 80% chance of detecting the specified effect under the stated assumptions, if that effect and model were appropriate. The 90% power column represents the corresponding calculation for a higher target chance of detection. Power is a property of a planned design under assumptions, not a measure of whether an observed result is true.

The primary-outcome planning entries are very small, and some other outcome entries are also small. These figures follow from using the observed effects in the calculation; they should not be treated as a recommended trial size or as evidence that the completed trial had adequate power for every purpose. Smaller effects need more participants to detect under otherwise comparable assumptions. That is why the planning figures are presented for reduced fractions of the observed effect as well as the full observed effect.

This is not observed power. It is a forward-looking illustration derived from the posted effect estimate and stated assumptions, not a retrospective measure of the study’s success. The registry’s own sample-size justification and original design calculations are not reported in the registry record.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 6.300; pooled standard deviation σ = 0.552.
2. n = 2 × (1.96 + 0.842)² × 0.552² / 6.300² = 0.1, rounded up to 1 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 6.3                      # observed difference in means
sigma <- 0.552268050859363                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(2820181)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 1 (80% power), 1 (90% power)
 75% of observed effect: n per arm = 1 (80% power), 1 (90% power)
 50% of observed effect: n per arm = 1 (80% power), 1 (90% power)
power.t.test: 1.6 
Simulated power at n = 1 per arm: NA (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures, while the posted results include a primary endpoint and two secondary endpoints. The details of any further outcome measure are not reported in the registry record. The record does not describe a multiplicity plan, a hierarchy of hypotheses, or an adjustment to account for testing several outcomes. It also lists no reported analyses, despite comparative results being posted.

Multiplicity matters because interpreting each of several unadjusted comparisons as if it were the only test can overstate the strength of the overall evidence. A prespecified primary endpoint can help distinguish the main trial question from supporting analyses, but it does not by itself establish how secondary comparisons should be interpreted. The registry does not report whether the outcome hierarchy or analysis strategy was specified before results were known.

Missing-data procedures are not reported in the registry record. The posted arm summaries include 30 participants for each group, but that information alone does not establish whether all randomized participants contributed to every outcome, whether any observations were missing, or how missing values were treated. The registry also does not name an intention-to-treat, per-protocol, or other analysis population.

These are reporting gaps rather than evidence that a particular problem occurred. They limit the ability to assess whether the posted comparisons preserve the randomized groups, whether outcomes were selectively available, and how sensitive results might be to alternative handling of missing observations. No assumptions about exclusions, imputation, or analysis populations should be made without further reporting.

15. 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 5% reporting threshold.

The registry reports zero serious adverse events in the novel-bi-tie group and zero in the traditional-tie group, with 30 participants at risk in each group. It also reports zero other adverse events in each group and zero deaths in each group. These are the recorded event figures for this trial.

Zero reported events does not establish that an event is impossible or that the devices have equivalent safety. In general, an absence of observed events during a study can reflect the experience captured in that study and does not exclude uncommon events or events outside the observation period. The registry does not provide further adverse-event terms, event definitions, or details about surveillance and reporting procedures.

The primary and secondary efficacy-style outcomes measure ratings and exchange frequency; they are not substitutes for safety outcomes. The adverse-event record should therefore be read separately from the task-difficulty and comfort comparisons. The registry reports the study timeframe for the listed outcomes as 14days but does not give additional detail about adverse-event follow-up in the posted record.

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

The results describe a randomized comparison in which nurses rated the difficulty of exchanging or cleaning two types of tracheostomy tie. The posted primary means and mean difference indicate substantially higher average difficulty ratings for traditional ties than for novel bi-ties over 14days, on the scale where higher scores indicate worse outcomes. The interval and unadjusted p-value indicate that the posted primary comparison is statistically separated from a no-difference value under the analysis used.

That finding should be kept within its measurement boundaries. It is evidence about a nurse-rated task in the recorded trial, not a direct estimate of complication risk, decannulation, long-term performance, or patient health. The secondary measures add information about comfort and dressing-exchange frequency, but their unadjusted status and undocumented analysis details warrant a more cautious role.

The study was randomized and parallel-group, which is relevant to interpreting a comparison between devices. Yet the registry does not report how randomization was implemented, and it lists no masking. It also does not report eligibility criteria, detailed measurement procedures, missing-data handling, analysis populations, or the original sample-size rationale. These omissions make it difficult to assess all possible sources of bias and the extent to which the results generalize beyond the recorded study context.

The registry does not state a threshold for a meaningful difference on the visual analogue scale. Statistical significance therefore should not be equated with a demonstrated level of practical importance. Nor does the posted comparison imply that every nurse or patient would report the same experience.

The appropriate conclusion is descriptive and bounded: the recorded primary ratings favored the novel-device group on the specified difficulty measure, while important design and analysis details remain undocumented in the registry record. The findings do not, by themselves, settle broader questions about effectiveness, safety, or performance in other populations and settings.

17. Why This Trial Matters Statistically

This trial is statistically informative because it compares a practical device-use question with a continuous, staff-rated endpoint and reports group means, standard deviations, a mean difference, an interval, and an unadjusted p-value. Those summaries allow readers to distinguish the direction and scale of the observed contrast from the uncertainty reported around it.

It also illustrates why statistical evidence needs more than a small p-value. Interpretation depends on what the outcome measures, how it was collected, how the comparison was analyzed, and whether several outcomes were tested. Here, the primary measure reflects nurses’ ratings of task difficulty, while the secondary measures concern patient comfort and exchange frequency. Each contributes a different perspective, but the registry does not document a multiplicity strategy or detailed analysis plan.

The record also highlights the difference between precision and methodological transparency. A reported interval can be narrow while important information about randomization procedures, masking, missing data, and analysis populations remains unavailable. These gaps do not invalidate the posted estimates, but they constrain how confidently readers can assess their robustness and broader applicability.

Finally, the planning illustrations use observed effects rather than the original design assumptions. That distinction matters: an estimate based on an observed result is not a substitute for prospective design justification, and it is not observed power. Reading the results with these statistical distinctions in mind helps separate the comparison actually reported from claims that the registry does not establish.

18. 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.

Several limitations are specific to the information recorded for this trial. The primary endpoint is a nurse-rated visual analogue score, and the registry does not report validation evidence, rater instructions, or procedures for standardizing assessments. Because the trial lists no masking, the possibility that knowledge of the device influenced subjective ratings cannot be excluded, although the record does not describe what raters knew in practice.

The registry does not report eligibility criteria or detailed participant characteristics. It is therefore not possible to judge from the record how closely the study population represents people receiving tracheostomy care in other settings. The recorded measurement timeframe is 14days, so longer-term outcomes are not established by these posted results.

Important implementation and analysis details are also missing: the randomization procedure, allocation concealment, adherence, outcome-specific analysis populations, missing-data handling, distribution checks, and prespecified statistical plan are not reported in the registry record. No reported-analysis entries are listed. This limits assessment of bias, robustness, and whether reported comparisons followed a plan specified before outcome data were reviewed.

The registry indicates four outcome measures but posts only two secondary outcomes alongside the primary result. Further outcome details, a multiplicity strategy, and an original sample-size justification are not reported. The available summary statistics also do not show individual-level distributions or all aspects of outcome variation. These limitations concern what can be evaluated from the registry record and should not be interpreted as proof that unreported procedures were absent.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Assessment of a Novel Tracheostomy Tie — NCT02820181.
• Registry record last updated 2021-11-02; status last verified 2021-10.
• Results first posted 2021-11-02.
• 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.

22. Record Summary

NCT02820181 is a completed randomized, parallel-group study with no masking, comparing novel tracheostomy bi-ties with traditional tracheostomy ties. The registry lists an enrollment of 60, with 30 participants in each arm record. The sponsor is The First Affiliated Hospital of Shanxi Medical University.

The primary outcome was nurses’ visual analogue scale rating of difficulty exchanging or cleaning ties, measured over 14days. The posted group means were 1.2 for novel bi-ties and 7.5 for traditional ties; the reported mean difference was 6.3, with an interval from 6.021 to 6.579 and an unadjusted p-value of <0.001.

Secondary outcomes concerned patient comfort and dressing-exchange frequency. The registry also reports zero serious adverse events, zero other adverse events, and zero deaths in each group. Further details about the original design assumptions, analysis plan, missing data, and analysis populations are not reported in the registry record.