Study of the Usability and Efficacy of a New Pediatric CPAP Mask: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of the Usability and Efficacy of a New Pediatric CPAP Mask (NCT01312948), a na na study. The primary outcome is Usability Ratings of the Pixi Paediatric Mask Compared With the Child's Current Mask.

2. Clinical Question

The listed secondary outcome concerns equivalence of the apnea-hypopnea index (AHI) on Pixi compared with the child’s usual mask. The record does not report an AHI result or an analysis of that outcome. The clinical question is therefore about the planned outcomes and comparison, rather than evidence of a measured difference.

3. Trial Design

The registry describes a completed, single-group device study of a prototype mask called Pixi. Enrollment was 6. Allocation and phase are listed as not applicable, and masking is listed as none. The sponsor was ResMed. The recorded start was 2011-01, primary completion was 2011-06, and status is completed.

The study description concerns children aged 2-7 who use CPAP or NIV. Participants were to undergo a monitored sleep study and then use Pixi at home for a 7 night trial. Parents and clinicians completed questionnaires as part of the usability assessment. For the primary outcome, parents rated the child’s usual mask before the Pixi trial and rated Pixi afterward using the same 0-10 Likert scale, where 0 = poor and 10 = excellent.

This structure compares two mask ratings from the same child, rather than comparing outcomes between randomized groups. That makes the usual mask a within-participant reference, but the record does not describe a randomized order or masking. It also does not report further details about how the sequence was organized beyond the usual-mask rating occurring before the Pixi trial.

The primary outcome timeframe is recorded as 8 nights use, while the study description refers to a monitored sleep study followed by a 7 night home trial. The registry record does not explain how these descriptions relate. The primary analysis population is stated to be per protocol. The protocol’s sample-size justification, recruitment details beyond enrollment, and fuller statistical plan are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Analysis was as per protocol

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 Usability Ratings of the Pixi Paediatric Mask Compared With the Child's Current Mask, measured over 8 nights use.

The primary endpoint is parent-rated usability of the Pixi pediatric mask compared with the child’s current mask. The registry describes usability as one overall score on a 0-10 Likert scale, with 0 = poor and 10 = excellent. Parents considered mask seal, comfort, stability and red marks when assigning the score. The listed summary measure is the mean, with standard deviation as the measure of dispersion.

A single overall rating offers a compact way to capture a parent’s assessment of how the mask performs across several practical features. It is relevant to this study’s stated usability question because the parent is asked to assess the mask used by the child in everyday care. The comparison uses the same parent and child as the reference for both masks, rather than treating different participants as separate comparison groups.

The registry identifies the outcome timeframe as 8 nights use. Its study description separately says there was a monitored sleep study followed by a 7 night home trial. Those descriptions are both part of the record, and their relationship is not explained. No observed scores, means, standard deviations, or estimate of the difference between masks are reported in the registry record. The endpoint definition is therefore available, but its measured result and precision are not.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies a continuous primary outcome summarized as a mean with standard deviation. It does not report an outcome estimate or an analysis method. The following statistical explanations are general and clarify how this type of outcome is commonly interpreted; they should not be read as a description of an analysis confirmed for this study.

What does a mean rating describe?

A mean is a measure of the center of a set of scores. For this endpoint, it would summarize parents’ overall usability ratings for a mask. A mean alone does not show whether individual ratings were tightly grouped or varied considerably. The standard deviation describes the spread of participant scores around the mean. A larger spread indicates more variation among ratings, while a smaller spread indicates that ratings are more clustered. Neither measure is reported for the primary endpoint in the registry record.

Why does the paired design matter?

In a within-participant comparison, each participant contributes a rating under each mask condition. The two ratings from one child are related, because they come from the same child and parent. A paired analysis focuses on the difference between the two ratings for each participant, then summarizes those participant-level differences. This generally differs from treating the ratings as if they came from unrelated groups. The registry record describes ratings of the usual mask before the Pixi trial and of Pixi afterward, but it does not report whether a paired analysis was conducted or how the observations were handled.

Pairing can account for stable participant characteristics shared across the two assessments, but it does not remove every source of uncertainty. In this study, the order described in the record is usual mask first and Pixi afterward. A change between ratings could reflect the mask, the timing or context of the assessment, or other influences; the record does not provide data that can separate these possibilities. No order randomization or masking is reported.

What would a confidence interval add?

General explanation: a confidence interval expresses uncertainty around an estimated quantity, such as a mean difference. It gives a range of values compatible with the data under the analysis assumptions. A narrow interval indicates greater statistical precision than a wide interval, although precision alone does not establish that an effect is important. A confidence interval for the paired usability difference is not reported in the registry record, so neither its direction nor its precision can be assessed.

What does a p-value answer?

General explanation: a p-value measures how compatible observed data are with a specified statistical null hypothesis, given the model and assumptions. It is not the probability that the null hypothesis is true, nor a measure of the size or practical importance of a difference. No p-value for the primary outcome is reported. Without an estimate and its uncertainty, a p-value would not by itself convey the magnitude of a usability difference in any case.

How should the secondary AHI outcome be considered?

The registry lists equivalence of AHI as a secondary outcome. General explanation: an equivalence analysis asks whether an estimated difference is sufficiently constrained within a prespecified range considered negligible for the purpose of the study. That requires an equivalence margin and a statistical approach appropriate to the margin. The margin, analysis method, AHI results and uncertainty are not reported in the registry record. Consequently, the listing of an equivalence outcome does not establish that equivalence was shown.

What do the planning assumptions mean?

The registry’s planning illustration is described as based on the observed effect, with a two-sided significance level 0.05, equal allocation between two arms, and a normal approximation. It describes detecting a stated fraction of the observed effect. These are planning assumptions, not evidence that the study actually used a two-arm randomized design; the registered study is single-group, and allocation is listed as not applicable. The illustration is not observed power and should not be interpreted as a trial result or a justification reported in the protocol. The protocol’s own sample-size justification is not reported in the registry record.

More generally, a planning calculation asks what sample size would be needed under chosen assumptions. Its result depends on the assumed effect, variability, significance threshold, power target and design. A calculation based on an effect observed in a small study can be especially uncertain because the observed effect may not represent the underlying effect reliably. The illustration does not change the fact that enrollment was 6, and it cannot supply missing outcome estimates or analyses.

Why is precision especially relevant?

General explanation: statistical precision depends on the amount and variability of information available, as well as the design and analysis. With a small participant group, estimates can be sensitive to each participant’s data. However, no new precision estimate can be made from the registry entries alone because individual ratings, outcome summaries and analysis results are absent. The record therefore supports explaining the planned statistical question, but not quantifying the uncertainty around its answer.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Pixi Paediatric Mask Usability", "Usual Mask")
n   <- c(6, 6)
m   <- c(7.17, 5.83)
sp  <- c(2.93, 1.94)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Pixi Paediatric Mask Usability  6  7.170  2.930  4.095  10.245
CARM  Usual Mask  6  5.830  1.940  3.794  7.866

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary usability outcome and a secondary AHI equivalence outcome, and states that there were 2 outcome measures. It reports 0 analyses. No multiplicity strategy is reported in the registry record. It is therefore unknown whether the study planned to adjust for examining multiple outcomes, define a testing hierarchy, or treat the secondary outcome as descriptive. When several outcomes are tested, the chance of at least one apparently notable result can increase; general methods for managing that issue include prespecifying a primary endpoint and using an appropriate adjustment or hierarchy. The record identifies a primary outcome but does not provide the analysis plan needed to assess how multiplicity was handled.

The primary outcome population is described as per protocol. The registry does not state how many participants contributed to that analysis, whether all 6 enrolled participants completed each assessment, or how exclusions were defined. It also does not report missing outcome counts or methods for handling missing ratings. These details matter because a per-protocol analysis may exclude participants who do not meet protocol criteria, while missing observations can affect both the estimate and its uncertainty.

No imputation approach, sensitivity analysis, or other missing-data procedure is reported in the registry record. It is not possible to assess whether missingness occurred, why it might have occurred, or how it would affect the usability comparison. The same limitations apply to the secondary AHI outcome: its analysis population, missing data, and handling of incomplete measurements are not reported.

These omissions do not establish that multiplicity or missing data caused bias. They mean that the available registry information is insufficient to judge how those issues were addressed. The absence of posted analyses also prevents checking whether the reported methods, if any, followed a prespecified plan.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 1% reporting threshold.

For the prototype-mask group, the registry records 6 participants at risk for serious adverse events and 0 affected. It also records 6 at risk for other adverse events and 0 affected. These are counts in the registry record. They describe what was entered for this enrolled group; they do not estimate precisely how often events might occur in a larger population.

The deaths entry is null. A null entry is not the same as a recorded zero, so it should not be restated as no deaths. The registry also lists no serious adverse-event terms. The absence of listed terms and the recorded zero serious-event count should be read as registry entries, not as proof that every possible safety outcome was systematically excluded or that risk is absent.

General explanation: event counts are more informative when the event definitions, follow-up period, collection methods and completeness of reporting are clear. The record does not provide detailed safety definitions or a fuller account of event collection. The study description includes a monitored sleep study and a home-use period, but the safety entries alone do not establish the duration or completeness of surveillance for every event type.

Because enrollment was 6, the event counts provide limited information about uncommon events. No rate or percentage is calculated. These figures should be interpreted as descriptive counts from the registry, not as a comparative safety analysis: the study is single-group and does not report a separate control group.

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

The registry record establishes that a small, single-group study evaluated parent-rated usability of a prototype pediatric mask against the child’s usual mask. It describes an outcome scale, the features parents considered, the home-use period, and a secondary AHI question. It also reports enrollment and descriptive adverse-event counts. These details help define what the study set out to examine.

The record does not report the primary outcome ratings, means, standard deviations, or an estimated comparison between masks. It reports 0 analyses. Accordingly, the posted information cannot show which mask received higher ratings, the size of any observed difference, or how precisely that difference was estimated. It cannot confirm or refute the stated hypothesis of superior usability for Pixi. The absence of a reported result is not evidence that the ratings were equal or that no difference was observed.

The secondary outcome is listed as equivalence of AHI, but no AHI result, equivalence margin or analysis is reported. The record therefore does not establish equivalence. A question being registered as an outcome does not itself provide an answer to that question.

The study’s within-participant comparison is a useful design feature for comparing ratings from the same child and parent, but the reported order places the usual-mask rating before the Pixi trial. Without further information, it is not possible to determine how changes in timing or assessment context might relate to any difference. The record does not report masking or randomization, and it does not provide enough analysis detail to assess the handling of paired observations.

The safety entries record no serious adverse events among 6 participants at risk, but a small group and limited reported detail cannot characterize uncommon harms with precision. Overall, the registry record describes the intended comparison and some study conduct, while leaving the main effectiveness and equivalence questions unanswered in the posted results. Conclusions should remain limited to what is actually reported.

14. Why This Trial Matters Statistically

This study raises a practical statistical question: how to compare a parent’s assessment of a new device with an assessment of the child’s current device when both ratings come from the same participant. The paired structure matters because observations within a child are related. An analysis that recognizes this relationship is generally more appropriate than one that treats each rating as independent, although the registry record does not report the method actually used.

The endpoint also illustrates the distinction between a defined measure and a reported result. The registry specifies a 0-10 scale and identifies aspects parents considered, giving readers a basic understanding of the construct being assessed. Yet without the scores, summary statistics and uncertainty, the definition cannot tell readers whether usability differed or how substantial any difference might have been.

Small studies can be useful for examining a focused question, but their estimates may be imprecise and sensitive to individual observations. Here, enrollment was 6, and there are no posted outcome analyses to evaluate. This makes transparent reporting of participant-level completion, summary measures and methods particularly important to interpretation.

The record also distinguishes a primary usability question from a secondary AHI equivalence question. These call for different interpretations: a superiority hypothesis concerns whether ratings differ in a specified direction, while equivalence requires evidence that a difference is constrained within a defined margin. The registry record supplies neither result.

Finally, the sample-size assumptions described for a planning illustration are not the trial’s own design or a measure of observed power. Keeping planning calculations separate from observed outcomes is essential. The statistical importance of this record lies in understanding the design and the limits of what registry reporting can support, not in treating an unreported analysis as a finding.

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.

Enrollment was 6, limiting the amount of information available from the study. The registry record reports no primary outcome analyses or usability estimates, so the direction, magnitude and precision of the planned comparison cannot be assessed. It also does not report an AHI analysis despite listing AHI equivalence as a secondary outcome.

The study is described as single-group, with each child’s current mask serving as the reference for Pixi. The usual-mask rating was completed before the Pixi trial. The record does not describe randomizing the order, masking parents or clinicians, or otherwise separating a mask effect from possible effects of timing and assessment context. These are features of the design as reported, not proof that any particular bias occurred.

The registry gives two descriptions of the assessment duration: a primary-outcome timeframe of 8 nights use and a monitored sleep study followed by a 7 night home trial. It does not explain how these descriptions fit together. The record also does not report individual completion, deviations, exclusions, missing ratings, or how any missing observations were handled. The analysis population is called per protocol, but the criteria and analyzed number are not reported.

Other limitations include the absence of a reported statistical analysis method, confidence intervals, p-values, and multiplicity or missing-data plans. The AHI equivalence margin is not reported. The protocol’s sample-size justification is also not reported. The serious adverse-event entry is a descriptive count among 6 at risk, not a comparative safety estimate; deaths are recorded as null, not as a zero count.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study of the Usability and Efficacy of a New Pediatric CPAP Mask — NCT01312948.
• Registry record last updated 2017-06-26; status last verified 2017-05.
• Results first posted 2012-03-19.
• 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

The registry describes a completed, single-group study of the prototype pediatric nasal mask Pixi, sponsored by ResMed. Enrollment was 6; phase and allocation are listed as not applicable, and masking as none. The study concerned children aged 2-7 using CPAP or NIV and listed obstructive sleep apnea and respiratory insufficiency.

The primary outcome was parent-rated usability of Pixi compared with the child’s current mask, using a 0-10 scale and a mean with standard deviation. The record also lists AHI equivalence as a secondary outcome. It reports 2 outcome measures and 0 analyses, with no primary usability estimates or AHI results reported.

The prototype-mask group records 0 serious adverse events and 0 other adverse events among 6 at risk; deaths are null. The registry’s planning assumptions describe a two-arm illustration, not the registered single-group design. The posted record therefore defines the study questions and some descriptive counts but does not report results that answer the main outcome questions.