This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Auto Continuous Positive Airway Pressure (CPAP) Based Energy Spectrum Analysis of Flow for Treatment of Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) (NCT00750165), a na na study. The primary outcome is Apnea Hypopnea Index (AHI).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00750165 |
| Phase | NA |
| Condition | Sleep Apnea, Obstructive |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 32 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Fisher and Paykel Healthcare |
| Results posted | Yes |
2. Clinical Question
Population
People with obstructive sleep apnea hypopnea syndrome who require CPAP. The registry lists Sleep Apnea, Obstructive as the condition and describes recruitment from the NYU sleep disorders center. The brief summary refers to 30 subjects to be recruited, while the registry enrollment is 32; the record does not explain the difference.
Intervention
Treatment on a titration night with the Fisher & Paykel SleepStyle 200 Auto Series CPAP Humidifier. The study concerns automatic pressure adjustment based on analysis of breathing-flow signals.
Comparator
No separate comparator group is listed. The registry describes a single-group study with no allocation and no masking. It does not report a randomized or concurrent control comparison.
Primary question
Can flow-signal energy spectrum analysis guide automatic CPAP pressure adjustment in a way that normalizes sleep-disordered breathing during treatment? The primary endpoint is the Apnea Hypopnea Index (AHI) measured over 1 night. The registry record does not report the AHI result.
The study focuses on a practical source of variation in CPAP pressure needs. Its summary notes that therapeutic pressure may vary with sleep stage and body position within a night and may change across nights. An automatically adjusting device is intended to respond to breathing patterns rather than rely on one individualized fixed pressure. The clinical question is therefore about the response of sleep-disordered breathing during a device-treated night, not about a comparison of two assigned treatment groups.
The registry lists secondary measures of the percent of time with less than 90% oxygen saturation, Respiratory Disturbance Index (RDI), and Arousal Index (AI). These outcomes describe additional aspects of breathing disturbance, oxygen saturation, and arousals during sleep. Their results are not reported in the registry record, so the recorded clinical question cannot be answered from outcome estimates in this record.
3. Trial Design
This completed study is registered as NCT00750165 and is listed as a single-group study with no allocation and no masking. The registry enrollment is 32. The brief summary states that 30 subjects requiring CPAP would be recruited from the NYU sleep disorders center. The record does not explain the difference between those enrollment figures or identify how many participants contributed data to each outcome.
The intervention is the SleepStyle 200 Auto Series CPAP Humidifier, described in the arm information as the Fisher & Paykel Sleep Style 200 Auto CPAP device. The listed arm is “Titration Night.” The brief summary says that participants would first have diagnostic studies, either split night or full night, and then undergo a night of treatment with the AutoPAP. The primary outcome timeframe is 1 night. These descriptions indicate a device-treated night, but the registry does not report additional procedural details or a full protocol.
The study start is recorded as 2007-05, and primary completion as 2008-01. Its status is completed. The sponsor is Fisher and Paykel Healthcare. The phase is listed as NA, and the registry does not identify a control arm. Because there is no randomized allocation or separate comparison group in the record, the design does not support a between-group treatment contrast.
The primary outcome is mean AHI, with dispersion specified as the full range. Three secondary outcomes are listed: percent of time with less than 90% oxygen saturation, RDI, and AI. Although four outcome measures are recorded, the registry lists 0 analyses. It does not report outcome values, analysis populations, methods for handling missing observations, or the number contributing to each endpoint. A sample-size justification for the trial is 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
| Stage | Titration Night |
|---|---|
| STARTED | 32 |
| COMPLETED | 21 |
| NOT COMPLETED | 11 |
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.
| Characteristic | Unit | Titration Night |
|---|---|---|
| Participants analysed | 21 | |
| Age, Continuous | years | 51 (29 to 76) |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 21 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | participants | 21 |
6. Primary Endpoint
The registry lists the primary outcome as Apnea Hypopnea Index (AHI), measured over 1 night.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Full Range |
| Unit | events per hour |
| Endpoint classification | Event-Rate Endpoint |
AHI is the number of apnea and hypopnea events divided by total sleep time, expressed in events per hour. It is used as a measure of the severity of obstructive sleep apnea and provides a rate that accounts for how long the participant slept rather than simply counting events. The registry identifies mean AHI as the primary endpoint and gives the timeframe as 1 night.
The registry description characterizes mild OSA as 5-15 events per hour, moderate OSA as 15-30 events per hour, and severe OSA as greater than 30 events per hour. The categories as written meet at 15, so the record does not make the boundary convention clear. Those category descriptions do not substitute for participant-level results or an estimate of the study’s mean AHI.
Mean AHI can summarize the average event rate in the group, while the specified full range describes the lowest and highest observed values. The range conveys the spread between extremes but does not by itself show how observations are distributed or how precisely the mean is estimated. No mean, range, confidence interval, or other AHI result is reported in the registry record. The endpoint’s stated purpose is to assess sleep-disordered breathing during the treated night; the posted record does not show whether it was normalized.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry describes a single-group device study, not a randomized comparison. Its primary clinical measure is mean AHI during 1 night of treatment, and the stated study aim is to assess whether automatic adjustment based on flow-signal energy spectrum analysis can improve sleep variables. However, the registry record reports no AHI value and lists 0 analyses. It therefore does not provide an observed primary outcome estimate with which to assess the study aim.
The same limitation applies to the three listed secondary measures: percent of time with less than 90% oxygen saturation, RDI, and AI. The registry gives their names but no values, estimates of variability, or inferential results. The fact that these outcomes are listed does not establish that they were measured for all enrolled participants or analyzed. Their analysis status is not reported in the registry record.
Even if a treated-night AHI estimate were available, a single-group result would describe the participants observed under that treatment condition; without a separate comparator, it would not establish how that result differs from an alternative device, fixed pressure, or no treatment. A within-person pre-treatment measure could be informative if collected and analyzed, but the registry record does not report such a comparison. It also does not provide a treatment effect estimate, confidence interval, or p-value.
Precision cannot be assessed from the posted outcome information. A confidence interval, when reported, describes a range of values compatible with the data and the analysis assumptions; a narrow interval indicates greater precision than a wide interval. Here, no endpoint estimate or interval is reported, so the degree of uncertainty around the primary outcome cannot be quantified from this record. The enrollment figure alone is not an outcome estimate and does not indicate the magnitude or precision of an effect.
The adverse-event information is separate from efficacy. The record lists 0 serious adverse events among 21 at risk, 6 other adverse events among 21 at risk, and 0 deaths. These counts do not provide the missing sleep-outcome results. The difference between the registry enrollment of 32 and the safety denominator of 21 is not explained, and the record does not describe event definitions or the period during which events were collected.
Accordingly, the registry establishes the study’s topic, device, single-group structure, listed endpoints, and selected safety counts. It does not establish the magnitude of change in AHI, the precision of any effect, a comparison with another approach, or a conclusion about the study’s stated efficacy objective. Any such interpretation would require results that are not reported in the registry record.
9. Statistical Methods Explained
The statistical information available in the registry is limited. It identifies a mean primary endpoint with full-range dispersion, lists three secondary endpoints, and records 0 analyses. It does not state a statistical analysis plan, an outcome model, a hypothesis test, or a method for estimating uncertainty. The concepts below are general explanations, not a description of methods confirmed for this study.
What does a mean AHI represent?
AHI is a rate: apnea and hypopnea events divided by total sleep time, expressed in events per hour. A group mean combines participants’ AHI values into an average. It can provide a compact description of the group, but it does not show whether most participants had values near that average or whether the average is influenced by unusually high or low values. Participant-level distributions or other summaries can add context, but they are not reported in the registry record.
The record specifies full range as the dispersion measure. A range gives the smallest and largest observations and makes the extremes visible. It is sensitive to those extremes and does not describe the concentration of observations between them. In general, a standard deviation or interquartile range answers a different descriptive question by conveying typical variability or the middle spread. Neither is listed for the primary outcome in this record.
How does a confidence interval help?
In general, a confidence interval expresses uncertainty around an estimate under the assumptions of the method used. It is not a guarantee that the true value lies in the interval, and its width matters when interpreting precision. A point estimate without an interval can conceal substantial uncertainty. No confidence interval or other uncertainty estimate for AHI is reported, so the precision of the primary endpoint cannot be evaluated from the registry record.
What would a comparison require?
A treatment contrast needs an explicitly defined comparator and a way to estimate the difference between conditions. Random allocation can help make groups comparable with respect to measured and unmeasured factors, while masking can reduce some forms of measurement or assessment bias. These are general design principles. The registry lists no allocation, no masking, and a single group; it does not describe a concurrent control group. Thus, there is no reported between-group contrast to interpret.
Repeated measurements from the same participant can sometimes be compared within person, but that approach requires the measurement schedule, analysis population, and statistical method to be specified. The brief summary mentions diagnostic studies before the treated night, but the registry does not report a paired pre-treatment AHI analysis or its results. It would be inappropriate to infer that such an analysis was performed from the study description alone.
Why can over-dispersion matter?
In general, event counts or rates may vary more across observations than a simple statistical model assumes. This is called over-dispersion. If it is ignored in a model for counts or rates, uncertainty estimates can be too small and statistical tests can appear more decisive than warranted. Methods that allow extra variation may be appropriate in some settings, but whether over-dispersion was assessed or how any outcome was modeled is not reported in the registry record. The listed primary measure is a mean rate, and the record does not provide enough detail to identify a fitted model.
What do the planning assumptions mean?
The record includes a description of a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not evidence that this single-group study used a two-arm randomized design. The record does not report the resulting planning values or a trial-specific sample-size justification. Such illustrations are not observed power, and they do not replace an estimate and uncertainty interval for the actual outcome.
What can be concluded from the listed analyses?
The registry lists four outcome measures in total: the primary AHI and three secondary outcomes. It records 0 analyses. This means the registry record does not contain analysis results for those measures; it does not by itself explain whether analyses were never conducted, were conducted but not entered, or were reported elsewhere. No significance tests or effect estimates can be reconstructed from endpoint names and enrollment alone. General statistical interpretation requires the outcome data, analysis method, and relevant uncertainty information, none of which is reported for efficacy in this record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome, AHI, and three secondary outcomes: percent of time with less than 90% oxygen saturation, RDI, and AI. Considering several endpoints raises the general issue of multiplicity: when many hypotheses are tested, the chance of at least one apparently unusual result can increase unless the analysis plan addresses that issue. The registry record does not report a multiplicity adjustment, hierarchy among secondary outcomes, or other strategy for interpreting multiple tests. It also lists 0 analyses, so no endpoint-specific inference is available to assess.
Missing-data methods are not reported in the registry record. It does not state how many participants had valid AHI measurements, whether any measurements were incomplete, or how missing outcomes would be handled. The enrollment is 32, while the adverse-event denominator is 21; the record does not explain whether that difference reflects availability of safety information, follow-up, or another reason. The safety denominator should not be treated as the analysis population for the sleep endpoints.
The registry does not identify an intention-to-treat population, a per-protocol population, or another analysis population. Nor does it describe interim analyses or stopping rules. These details are important for understanding which participants contributed to each result and whether planned analyses were changed, but they are not reported in the registry record. Without outcome counts and analysis methods, neither the impact of missing data nor the consequences of testing multiple outcomes can be evaluated.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Titration Night | 0 | 21 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Titration Night | 0 of 21 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Titration Night | 6 of 21 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Titration Night |
|---|---|---|
| Disruption of Sleep Due to Lab Environment | Investigations | 4 of 21 |
| Mask Discomfort | Respiratory, thoracic and mediastinal disorders | 1 of 21 |
| Difficulty Exhaling Due to Pressure | Respiratory, thoracic and mediastinal disorders | 1 of 21 |
The registry lists 0 serious adverse events among 21 participants at risk, 6 other adverse events among 21 at risk, and 0 deaths for the Titration Night group. These are event counts and denominators as recorded; they are not estimates of comparative risk because no separate control group is listed. The record does not define “other” adverse events or provide descriptions of the events.
The safety denominator is 21, whereas total registry enrollment is 32. The reason for that difference is not reported in the registry record. It is also not clear from the record what period of observation was used for safety reporting, how events were collected, or whether all participants at risk had the same observation period. The counts therefore should be read as registry-reported figures rather than as a complete account of safety during every participant’s follow-up.
A count of 0 serious events does not establish that no events could occur; it states that none were recorded in the listed group and denominator. Likewise, the 6 other events cannot be interpreted for severity or relationship to the device from the information recorded. These safety figures do not provide evidence about the primary AHI outcome.
12. What the Result Does, and Does Not, Mean
The record documents a completed single-group study of an automatically adjusting CPAP device that uses flow-signal energy spectrum analysis. It identifies the primary endpoint as mean AHI over 1 night and names three secondary sleep measures. It also records selected safety counts. These details clarify what the study set out to examine and what outcomes were registered.
The record does not report results for AHI or any secondary endpoint, despite listing 0 analyses. Consequently, it does not show the observed level of sleep-disordered breathing during treatment, the spread of participant outcomes, or how precisely an outcome was estimated. It also does not report a comparison group or an alternative treatment condition. The registry therefore cannot establish a relative treatment effect or support a causal comparison with another approach.
The absence of outcome results in the registry record should not be interpreted as evidence that the device had no effect, nor as evidence that it achieved the stated objective. It means only that the relevant results are not reported in this record. Similarly, the stated study aim is not itself an outcome finding. The safety counts are limited to the listed group and denominator, and the record does not provide enough detail to characterize the nature, timing, or relationship of reported events.
Any fuller assessment would require outcome estimates, uncertainty measures, analysis details, and clarification of the participants included in each analysis. Without those items, the most defensible reading is descriptive: the registry records the design, intervention, endpoints, enrollment, and selected safety counts, but not the efficacy findings needed to quantify the primary question.
13. Why This Trial Matters Statistically
This study is statistically notable as a device evaluation whose stated aim concerns the use of breathing-flow signals to adjust CPAP pressure. The brief summary identifies a reason for studying automatic adjustment: therapeutic pressure may vary with sleep stage and body position during a night and may change across nights. The registered endpoint, AHI, is a rate based on apnea and hypopnea events relative to sleep time, making it a direct measure of the sleep-disordered breathing the study sought to assess during treatment.
Its single-group structure is important to interpretation. A treated-night observation can describe outcomes under the device, but it does not by itself distinguish the device’s contribution from other factors or establish how outcomes compare with another treatment condition. This design feature is not a flaw in every context; it defines the kinds of questions the available data could answer. Here, the registry does not report even the descriptive primary endpoint result, so the most basic assessment of the recorded clinical aim is unavailable.
The record also illustrates why endpoint registration and outcome reporting are distinct. Four outcome measures are identified, yet the registry lists 0 analyses. Without estimates and uncertainty, readers cannot judge the scale, variability, or precision of the outcomes. Safety counts add useful limited information, but the unexplained denominator and absence of event detail constrain interpretation.
Statistically, the main lesson is that a clear endpoint and an enrollment count are not substitutes for reported results. The study’s design and question can be understood from the record, while its outcome performance and inferential strength cannot be determined from the results recorded there.
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 principal limitation for interpreting this study is that the registry record contains no efficacy estimates or analyses. It lists mean AHI as the primary outcome and three secondary outcomes, but provides no values, ranges, confidence intervals, or p-values. As a result, neither the direction nor precision of any observed sleep-outcome result can be assessed.
The design is recorded as single group, with no allocation and no masking. No separate comparator is listed, limiting the kinds of treatment contrasts the design could support. The brief summary mentions diagnostic studies before the treated night, but no pre-treatment analysis or paired comparison is reported. The registry also does not explain how participants were selected beyond the summary’s reference to people requiring CPAP at the NYU sleep disorders center.
Enrollment is recorded as 32, while the brief summary refers to recruiting 30 subjects. The reason for this difference is not reported in the registry record. The safety denominator is 21, and the record does not explain its relationship to enrollment or identify outcome-specific analysis populations. Missing-data handling and follow-up procedures are not reported.
The record does not state a trial-specific sample-size justification, a statistical analysis plan, or methods for addressing multiple outcomes. It does not report whether interim analyses were planned. These absences prevent evaluation of the planned inferential approach and the relationship between design assumptions and the analyses conducted. The safety summary also lacks event descriptions, definitions, and a specified observation period, limiting interpretation of the reported counts.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Auto Continuous Positive Airway Pressure (CPAP) Based Energy Spectrum Analysis of Flow for Treatment of Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) — NCT00750165.
- Registry record last updated 2019-04-09; status last verified 2019-03.
- Results first posted 2019-04-09.
- 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.
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18. Record Summary
NCT00750165 is a completed, single-group study sponsored by Fisher and Paykel Healthcare. The registry records enrollment of 32, no allocation, no masking, a study start of 2007-05, and primary completion of 2008-01. The intervention is the SleepStyle 200 Auto Series CPAP Humidifier, listed for a titration night.
The primary endpoint is mean AHI in events per hour over 1 night, with full range specified as dispersion. The listed secondary outcomes are percent of time with less than 90% oxygen saturation, RDI, and AI. The registry lists 0 analyses and does not report efficacy results or a trial-specific sample-size justification.
Safety information records 0 serious adverse events, 6 other adverse events, and 0 deaths among 21 at risk. The relationship between that denominator and the enrollment of 32 is not explained in the registry record.