Exploratory Subjective Sleep Study of a Prototype Nasal Dilator: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Exploratory Subjective Sleep Study of a Prototype Nasal Dilator (NCT01122849), a randomized phase 2 study. The primary outcome is Change From Baseline in Mean Average Score Using Pittsburgh Insomnia Rating Scale (PIRS) in Q1, Q3, Q17 and Q18 at Day 7.

2. Clinical Question

3. Trial Design

The record describes a randomized, double-masked, parallel-group, phase 2 study. Its title is “Exploratory Subjective Sleep Study of a Prototype Nasal Dilator.” The study was marked completed, with enrollment of 61. The record lists a start date of 2009-10-01 and a primary completion date of 2010-02-01.

Three device groups are listed: Prototype Nasal Dilator, Marketed Nasal Strip and Placebo Nasal Strip. The parallel-group design means participants were assigned to a study arm rather than the record describing a crossover between devices. The registry lists randomized allocation and double masking, but the details of the randomization sequence, allocation concealment and which people were masked are not reported in the registry record.

The stated aim was to evaluate subjective measures of congestion and sleep quality among people with chronic nasal congestion who reported trouble with sleep. The primary outcome focused on a selected average PIRS score at baseline and Day 7. Other listed outcomes include PIRS questions and daily diary visual analogue scale questions around strip application at bedtime and removal in the morning. The record lists 26 outcome measures and 90 analyses, but does not provide the detailed analysis outputs in the information available for this description.

The registry record does not report the planned allocation ratio, group-specific enrollment, treatment-use instructions, study setting or duration of exposure beyond the stated primary outcome timeframe. It also does not report a sample-size justification or the rationale for choosing the exploratory design. These omissions limit the ability to reconstruct how the trial was planned or how closely its execution followed a detailed protocol.

4. Participant Flow and Accounting

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

Before assignment: A total of 97 participants were screened for this study, out of which 61 participants were randomized to the study and 36 participants did not meet study criteria.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Analysis for this outcome was performed on intent-to-treat (ITT) population, defined as all participants who were randomized and had at least one post-baseline efficacy assessment.

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 Change From Baseline in Mean Average Score Using Pittsburgh Insomnia Rating Scale (PIRS) in Q1, Q3, Q17 and Q18 at Day 7, measured over At Baseline and Day 7.

The primary endpoint is change from baseline in the mean average score for PIRS questions Q1, Q3, Q17 and Q18 at Day 7. The measure combines selected questions about sleep disruption and perceived sleep quality. Q1 concerns awakenings after getting to sleep, Q3 concerns sleep that does not fully refresh, Q17 compares sleep quality with that of most people, and Q18 concerns satisfaction with sleep.

According to the record, Section A questions such as Q1 and Q3 are scored from 0, “Not at all bothered,” to 3, “severely bothered.” Section C questions such as Q17 and Q18 are scored from 0, “Excellent,” to 3, “Poor.” The record states that lower PIRS scores indicate better sleep quality. Thus, a decrease in the selected score would correspond to a more favorable direction on the scale, while an increase would correspond to a less favorable direction. This describes the scale’s direction, not an observed trial result.

Subjective sleep measures can capture participants’ perceptions of sleep and related concerns that are not represented by a device-use measure alone. General statistical context: repeated measurement at baseline and follow-up can describe change during the study period. A between-group comparison of change can help distinguish a pattern in one arm from changes that also occur in comparator arms. The registry record does not report the observed endpoint values or comparison estimates, so the size and precision of any change cannot be assessed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of outcome is this?

The primary measure is continuous: it is a score assembled from selected PIRS questions. The record identifies the reported parameter as a least-squares mean and the measure of dispersion as a 95% confidence interval. A continuous outcome can take values along a scale rather than being limited to categories such as event or no event. The question is change in the selected average score between baseline and Day 7, with lower scores indicating better sleep quality.

General statistical context: an average describes the center of a set of measurements, but it does not reveal how spread out individual scores are. Model-based least-squares means can account for specified model terms. Which terms were included in the model, and the detailed model specification, are not reported in the registry record. The label alone is not enough to reproduce the analysis or determine the precise adjustment used.

How to read a confidence interval

A confidence interval expresses uncertainty about an estimated quantity under the statistical model and its assumptions. For a group estimate, it conveys uncertainty about that estimate; for a between-group contrast, it conveys uncertainty about the contrast. These are not interchangeable interpretations. The registry record names a 95% confidence interval for the primary outcome but does not provide its endpoints. Consequently, the interval cannot be assessed for width, compatibility with different directions of effect or consistency with a particular comparison.

General statistical context: an interval is not a guarantee that the true value lies within its endpoints. It is a procedure with a defined long-run coverage property when its assumptions hold. Precision is assessed from the interval’s width in the context of the scale and the question. Because no numerical interval is reported, no assessment of precision is possible for this outcome.

Change and between-group comparisons

Change from baseline summarizes how a measurement differs from its starting value at follow-up. In a randomized study, a comparison of changes between arms can help account for changes that occur over the same study period in the comparator groups. The registry outcome title identifies change from baseline in a mean average score, but the numerical changes and any contrast among the prototype, marketed-strip and placebo groups are not reported in the registry record.

General statistical context: within-arm change and between-arm difference answer different questions. A change in one arm alone does not establish that its change differs from another arm. Interpretation also depends on the analysis model, the amount and pattern of missing data, and the uncertainty around the comparison. Those details and estimates are unavailable in the registry record.

Multiplicity and exploratory analyses

The registry record lists 26 outcome measures and 90 analyses, including secondary questions about PIRS and daily diary measures. When many outcomes or comparisons are examined, the chance of finding an apparently unusual result somewhere among them can increase. General statistical context: multiplicity procedures can control or describe that issue, but the appropriate method depends on which outcomes and comparisons were planned and how they relate to one another.

The record does not report a multiplicity strategy, a hierarchy of outcomes, or whether the listed analyses were planned in advance. It also does not report interim analyses. These omissions mean the reader cannot determine from the registry information whether a particular analysis was treated as primary for inference, how repeated testing was addressed, or whether the statistical plan changed during the study.

Planning calculations are not trial results

General statistical context: sample-size planning estimates describe the number of participants that might be required under stated assumptions. They are not observed effects, and they are not a substitute for the trial’s actual estimates and uncertainty. The record describes planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation; it states that the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not evidence about the primary endpoint’s result. The registry record does not report the trial’s own sample-size justification.

The primary outcome is not reduced in the registry information to one comparison, so the reported planning assumptions should not be mistaken for a trial-specific design rationale or an observed treatment effect. A planning illustration also does not establish that a study had a particular probability of detecting a result after it was conducted. General statistical context: power calculations are prospective design tools, not retrospective evidence that a result is true or false.

What can be concluded from the methods description

The record permits identification of the endpoint’s scale, timing, direction and analysis population definition. It does not permit reconstruction of the fitted model, evaluation of its assumptions, or interpretation of the estimate’s magnitude and precision. Those require the actual outcome estimates and analysis details, which are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome analysis population is described as the intent-to-treat population, defined in the record as all participants who were randomized and had at least one post-baseline efficacy assessment. Because this definition requires a post-baseline assessment, it does not include randomized participants with no such assessment. The number of participants meeting this definition in each arm is not reported in the registry record.

The record does not report how missing Day 7 scores were handled, whether baseline or follow-up scores were imputed, or whether sensitivity analyses were conducted. It also does not report the amount or reasons for missing outcome data. General statistical context: missingness can affect an estimate if the likelihood of missing data is related to outcome values or treatment assignment. Different assumptions about why data are missing can lead to different analyses, so the approach should be described rather than inferred.

There are multiple listed outcomes and analyses: the record lists 26 outcome measures and 90 analyses. It does not report whether multiplicity was controlled, whether outcomes were arranged in a prespecified hierarchy, or how secondary analyses were to be interpreted. General statistical context: examining many outcomes or contrasts without an appropriate plan can make isolated findings harder to interpret. This does not establish that any particular reported result is false; it describes why a transparent analysis plan matters.

The record also does not report whether there were interim analyses or any rules for stopping or modifying the study. The sample-size justification and detailed statistical analysis plan are not reported in the registry record. These gaps leave important features of the inferential approach unknown, including how the primary outcome was modeled and how analyses with incomplete data or multiple comparisons were handled.

11. 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 1% reporting threshold.

Most frequent non-serious adverse event terms

The serious adverse event figures recorded for the Marketed Nasal Strip group are 0 among 20 participants at risk; for the Placebo Nasal Strip group, 0 among 21 participants at risk; and for the Prototype Nasal Dilator group, 0 among 19 participants at risk. The record lists no serious adverse event terms.

These figures describe what was recorded in the registry for the participants counted as at risk. They do not establish that no adverse events of any kind occurred. The record also lists 1 other, non-serious adverse event affected participant among 21 at risk in the Placebo Nasal Strip group, and 0 among 20 at risk in the Marketed Nasal Strip group and 0 among 19 at risk in the Prototype Nasal Dilator group. No deaths are listed in any group.

General statistical context: a count of zero reported serious events is not proof that the underlying risk is zero. Small groups and limited observation can leave uncertainty about uncommon events. The registry record does not provide event descriptions for the non-serious event, the observation period for safety, or a fuller account of how adverse events were collected. The safety figures should therefore be read as registry-recorded counts, not as a complete characterization of safety.

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

The registry record establishes that a randomized, double-masked, parallel-group study compared a prototype nasal dilator with a marketed nasal strip and a placebo nasal strip. Its primary outcome was a change in a selected average PIRS score from baseline to Day 7. The record explains the questions included in that score and states that lower scores indicate better sleep quality.

It does not report the numerical primary outcome results. There are no reported group estimates, between-group differences, confidence interval endpoints or p-values in the registry information used for this analysis. As a result, the direction, size and precision of the primary comparison cannot be described. The outcome definition alone cannot show whether the groups changed, whether their changes differed, or how uncertain any difference may be.

The study’s exploratory purpose and its subjective sleep and congestion focus help define what it set out to examine. They do not establish that a measured change would be clinically important. The registry record does not report a threshold for meaningful change, and it does not provide enough analysis detail to assess the role of missing observations or multiple outcomes.

The safety record lists no serious adverse events in the three groups and one other adverse event in the placebo-strip group. These are recorded counts and do not establish the absence of unrecorded or uncommon events. The registry information does not supply event descriptions for the non-serious event.

Accordingly, the posted information supports a description of the study design, endpoint and recorded safety counts, but not a conclusion about comparative effectiveness or the precision of a treatment effect. General statistical context: a result is most informative when the estimate, uncertainty, analysis population and methods are considered together. Several of those elements are not reported in the registry record.

13. Why This Trial Matters Statistically

This trial raises statistical questions that commonly arise in exploratory clinical studies: how to define a subjective endpoint, how to compare change over time, and how to interpret results when there are multiple outcomes and analyses. The PIRS score combines selected questions concerning awakenings, refreshing sleep, perceived sleep quality and satisfaction. Its direction is explicit, but numerical results are not reported in the registry record.

The three-arm, parallel-group randomized design makes the comparison structure important. Results for a prototype device might be considered relative to either a marketed device or a placebo device, but the registry record does not identify a single numerical comparison for the primary endpoint. General statistical context: the choice of comparator determines the question answered, and multiple possible comparisons can create a multiplicity issue if they are all treated as confirmatory without an appropriate plan.

The record lists 26 outcome measures and 90 analyses, yet does not report a multiplicity strategy or detailed analysis plan. This illustrates why transparent distinctions among primary, secondary and exploratory analyses matter. The endpoint and its timing can be read from the registry, but the inferential status of additional analyses cannot be reconstructed.

The outcome population is also defined by having at least one post-baseline efficacy assessment. Without group-specific analysis counts, missing-data details and sensitivity analyses, readers cannot assess how much information contributed to the primary analysis or how robust it might be to assumptions about missing outcomes.

Finally, the registry records zero serious adverse events in each group, but such counts are not equivalent to evidence of no risk. The study’s enrollment of 61 and the at-risk group counts document the size of the observed groups; they do not, by themselves, establish precision for uncommon events. The statistical importance of this record lies in the distinction between a clearly stated study question and the absent outcome estimates needed to answer it.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The central limitation of the registry information is that it does not report numerical results for the primary outcome. Although the endpoint is defined and a least-squares mean with a 95% confidence interval is specified, no estimates or interval endpoints are available. This prevents assessment of the observed change, between-group differences or precision.

The record does not provide group-specific enrollment or the number of participants in the stated intent-to-treat analysis population. It defines that population as randomized participants with at least one post-baseline efficacy assessment, but does not report missing Day 7 data, reasons for missingness, or methods for handling incomplete observations.

The detailed statistical analysis plan is not reported in the registry record. The model terms, handling of baseline values, contrast definitions, assumptions and any sensitivity analyses are therefore unknown. The record also lists numerous outcomes and analyses without describing a multiplicity strategy or hierarchy. Interim analysis procedures and the trial’s sample-size justification are not reported.

Additional design details are absent, including the randomization procedure, allocation concealment, who was masked, device-use instructions and relevant study setting details. The registry states that the trial was double-masked, but does not explain how masking was implemented or assessed. The reported safety information is also limited: there are no serious event terms and no description of the other adverse event.

These limitations do not show that the study was poorly conducted; they mark what cannot be assessed from the registry information. They constrain interpretation of both the primary endpoint and the safety counts, and make it impossible to judge whether any observed comparison was robust to analytic choices.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Exploratory Subjective Sleep Study of a Prototype Nasal Dilator — NCT01122849.
• Registry record last updated 2018-04-09; status last verified 2018-01.
• Results first posted 2018-04-09.
• 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.

18. Record Summary

The registry record describes a completed phase 2, randomized, double-masked, parallel-group study titled “Exploratory Subjective Sleep Study of a Prototype Nasal Dilator.” Enrollment was 61. The listed groups were Prototype Nasal Dilator, Marketed Nasal Strip and Placebo Nasal Strip.

The primary outcome was change from baseline in the mean average PIRS score for Q1, Q3, Q17 and Q18 at Day 7. The record states that lower PIRS scores indicate better sleep quality and defines the primary analysis population as randomized participants with at least one post-baseline efficacy assessment. Numerical primary outcome results are not reported in the registry record.

The registry lists 26 outcome measures and 90 analyses. Serious adverse events are recorded as 0 among 20 at risk in the marketed-strip group, 0 among 21 at risk in the placebo-strip group and 0 among 19 at risk in the prototype-dilator group. One other adverse event is listed in the placebo-strip group; none are listed in the other groups.