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 Evaluation of an Algorithm to Detect Sleep and Wake in Continuous Positive Airway Pressure (CPAP) (NCT01031914), a na na study. The primary outcome is Sleep/Wake Algorithm.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01031914 |
| Phase | NA |
| Condition | Sleep Apnea, Obstructive |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 36 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Philips Respironics |
| Results posted | Yes |
2. Clinical Question
Population
Participants with obstructive sleep apnea who were current CPAP users and completed the sleep study. The registry record says that all participants completing the study were included in the analysis; it does not report how many completed it.
Intervention
Paced Breathing, described as a device intervention. The algorithm was intended to identify sleep and wake while a participant wore the device during a sleep study.
Comparator
Standard polysomnography (PSG) served as the reference, or gold standard, for classifying sleep and wake. This was not a randomized comparison between intervention and control groups.
Primary question
How accurately did the Sleep/Wake algorithm identify sleep and wake periods compared with PSG during the sleep study? The registry record defines accuracy but does not report its observed value.
The clinical question is a measurement question, not a comparison of treatment outcomes. The trial was designed to evaluate whether an algorithm could classify sleep and wake in people using CPAP, with PSG classifications as the reference. Its stated purpose also included developing and validating the algorithm for use with paced breathing as a ramp feature.
The intended evaluation occurred in real time while participants wore the device during the sleep study, described as an average of 08 hours. The record identifies obstructive sleep apnea and current CPAP use as population characteristics. It does not report further eligibility details, participant characteristics, or the observed accuracy result.
Because the design is single-group, the central comparison is between two ways of classifying the same sleep-study periods: the algorithm and PSG. There is no separate control arm from which to estimate a treatment effect. Results would therefore speak to agreement with the reference classification under the studied conditions, not to a treatment benefit or to performance in populations not described in the registry record.
3. Trial Design
This is a completed, single-group device evaluation registered as NCT01031914. The intervention is Paced Breathing, and the single-group description concerns sleep/wake detection in people with obstructive sleep apnea who were current CPAP users. Enrollment was 36. Allocation is listed as NA, and masking is listed as none.
The study’s stated purpose was to develop and validate an algorithm that would deliver paced breathing as a ramp feature to people with obstructive sleep apnea using CPAP. The evaluation focused on the algorithm’s ability to distinguish sleep from wake. PSG was used as the reference standard against which the algorithm’s classifications were assessed.
The outcome timeframe describes real-time evaluation while the participant wore the device during a sleep study, an average of 08 hours. The primary outcome is titled “Sleep/Wake Algorithm” and is expressed as accuracy (%). The analysis population is described as all participants completing the sleep study. Although the record reports enrollment, it does not report the number completing the study.
The study start is recorded as 2009-10, and primary completion as 2010-09. Its status is COMPLETED. The registry record lists no analysis entries. It does not report a randomized allocation procedure, an independent control group, or masking. It also does not report further operational details such as the algorithm’s decision thresholds, the PSG scoring procedure, or how repeated classifications within a sleep study were handled.
These design features matter when interpreting the outcome. A single-group diagnostic or classification evaluation can describe performance relative to a reference, but it does not estimate a randomized treatment contrast. The record’s design information also does not establish how broadly results would apply beyond the described CPAP-using population and sleep-study setting.
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: N/A All participants enrolled in the trial have completed the study
Overall Study
| Stage | Paced Breathing Sleep/Wake Detection |
|---|---|
| STARTED | 36 |
| COMPLETED | 36 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: All the participants completing the sleep study were included in the analysis
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 | Paced Breathing Sleep/Wake Detection |
|---|---|---|
| Participants analysed | 36 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 35 |
| Age, Categorical: >=65 years | Participants | 1 |
| Age Continuous | years | 48.1 (SD 11.9) |
| Sex: Female, Male: Female | Participants | 11 |
| Sex: Female, Male: Male | Participants | 25 |
| Region of Enrollment: United States | participants | 36 |
6. Primary Endpoint
The registry lists the primary outcome as Sleep/Wake Algorithm, measured over The performance of the algorithm will be evaluated in real time while the subject is wearing the device during the sleep study, an average of 08 hours..
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | accuracy (%) |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the accuracy of the Sleep/Wake algorithm, expressed as a percentage. The registry defines accuracy as the proportion of true results among all classifications: true positives plus true negatives, divided by true positives, false positives, false negatives, and true negatives together. A true positive is a sleep period correctly identified as sleep; a false positive is an awake period incorrectly identified as sleep. A true negative is an awake period correctly rejected as sleep, and a false negative is a sleep period incorrectly rejected as sleep.
PSG served as the reference standard for deciding whether periods were sleep or wake. The endpoint therefore describes how often the algorithm’s classifications matched that reference across the evaluated observations. It is used because the stated goal was to assess the algorithm’s ability to distinguish sleep from wake, rather than to measure a change in a health outcome.
Accuracy combines correct sleep classifications and correct wake classifications into one overall measure. As a general statistical consideration, the combined measure can be affected by how much of the evaluated time belongs to each state. Separate measures of performance for sleep and wake, such as sensitivity and specificity, can help characterize those components, but the registry record does not report them.
The registry record gives the endpoint definition and timeframe but not a numerical accuracy result, uncertainty interval, or underlying classification counts. Thus the definition explains what was intended to be measured, while the actual magnitude and precision of performance are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes that the primary outcome was algorithm accuracy relative to PSG, but it does not report the observed accuracy percentage. It also lists no analysis entries. Accordingly, the record cannot support a numerical statement about how often classifications agreed with PSG, how precise that estimate was, or which type of classification error was more common.
Accuracy has a straightforward interpretation: it is the share of evaluated classifications that were correct under the registry’s definition. It combines correct sleep identifications and correct wake identifications. That makes it an overall summary, but it does not reveal whether performance was similar for sleep and wake. As a general statistical point, an overall accuracy measure can appear favorable when the more common state is classified well, even if classification of the less common state is weaker. The registry record does not report the distribution of sleep and wake observations or state-specific performance measures.
The reference comparison is with PSG, which the registry describes as the gold standard. That framing makes the question one of classification agreement relative to PSG, not a comparison of paced breathing against an untreated group. The single-group design and absence of masking are relevant context. They do not, by themselves, quantify the direction or size of any bias, and the registry record does not report information that would allow such a quantification.
Enrollment was 36, but the record says the analysis included participants who completed the sleep study and does not give the completion count. The numerical result and its uncertainty are also absent. These omissions prevent assessment of whether the estimate is stable, whether some participants or observations were excluded, and how much sampling variability surrounds the performance estimate.
The record’s status is COMPLETED, but completion status is not a substitute for a posted outcome result. Nor does the stated purpose of developing and validating an algorithm establish that the algorithm achieved a particular level of accuracy. The appropriate reading is limited: the record documents an evaluation objective, a reference method, and an endpoint definition, while leaving the actual performance result unreported in the registry record.
9. Statistical Methods Explained
The endpoint is an accuracy measure based on a 2 X 2 classification table. Such a table cross-classifies the algorithm’s sleep/wake calls against PSG’s sleep/wake classifications. The four cells represent correct sleep identifications, incorrect sleep calls during wake, correct wake identifications, and missed sleep identifications. The registry record gives these meanings as true positive, false positive, true negative, and false negative, respectively.
Accuracy combines the two correct-classification cells and divides by all classifications. This makes it an intuitive overall summary: it answers what proportion of classifications matched PSG in the evaluated observations. It does not, on its own, show the pattern of errors. For example, a false positive and a false negative have different meanings for sleep/wake detection even though both count as incorrect classifications in the accuracy calculation.
As a general statistical explanation, sensitivity measures the share of reference-positive observations identified as positive, while specificity measures the share of reference-negative observations identified as negative. These measures would distinguish performance for sleep from performance for wake, depending on which state is treated as positive. The registry record does not report sensitivity, specificity, or the cell counts needed to inspect the error pattern. No additional measure should be inferred from the overall accuracy definition.
Accuracy also depends on the composition of the observations. If sleep and wake periods are not equally common, the more frequent state can contribute more heavily to the overall measure. This is a general property of accuracy, not a reported feature of this trial. The registry record does not state how much of the sleep study was classified as sleep or wake, nor does it report whether classification performance was examined separately across periods or participants.
PSG is identified as the reference or gold standard. In a reference-based evaluation, the meaning of the estimated accuracy depends on the reliability and procedures of that reference classification. The registry record does not report who scored PSG, whether scoring was blinded to the algorithm, how disagreements were resolved, or how the reference data were synchronized with the algorithm’s calls. Those details are not available for assessing possible measurement or classification effects.
The timeframe is real-time evaluation while a participant wore the device during the sleep study, described as an average of 08 hours. This indicates the intended setting for measurement, but the record does not explain the unit of analysis: it does not state whether accuracy was calculated across time intervals, individual classifications, or another defined unit. It also does not report how repeated observations within a participant were accounted for. As a general matter, observations from the same participant may be related, so treating every observation as independent can affect uncertainty estimates. The registry record does not provide enough analysis detail to determine how this issue was handled.
A confidence interval, in general, expresses the uncertainty around an estimated quantity under a stated statistical procedure. It helps distinguish a precise estimate from one that is compatible with a broad range of values. No confidence interval or other uncertainty measure for accuracy is reported in the registry record. Without the observed estimate and its uncertainty, neither the magnitude nor precision of performance can be evaluated from this record.
The record lists no analysis entries and does not report a statistical analysis plan, method for constructing uncertainty intervals, handling of repeated observations, or a threshold for a successful validation. These items should not be assumed. The endpoint definition alone is not a complete analysis specification: it states what accuracy means but does not establish how the estimate was calculated in detail or how uncertainty was quantified.
Planning illustrations are distinct from observed results. The stated planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect set as a stated fraction of the observed effect. The assumptions also distinguish total events for time-to-event calculations from participants per arm for other calculations. Those are planning conventions, not evidence that this single-group algorithm evaluation used a two-arm design. Any sample-size illustration under those assumptions is not observed power, and the registry record does not report the observed accuracy effect or a trial-specific sample-size justification.
For this endpoint, the central methodological distinction is between defining a measure and reporting its estimate. The registry supplies a definition and reference standard, but not the result, cell counts, uncertainty, or detailed computational procedure. Statistical interpretation must therefore remain at the level of what the planned measure was intended to represent.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists one primary outcome measure and no analysis entries. It does not report a multiplicity adjustment, a hierarchy of outcomes, or a plan for controlling error across multiple statistical tests. Because no numerical analysis is posted, the record also does not show whether multiple versions of the endpoint or subgroup analyses were conducted. These procedures are not reported in the registry record and should not be inferred from the single listed outcome.
The analysis population is described as all participants completing the sleep study. Enrollment was 36, but the record does not report how many participants completed the study or how many contributed usable algorithm and PSG classifications. It does not describe missing observations, exclusions, failed recordings, or any method for handling incomplete data. Therefore, the effect of missingness on the accuracy estimate cannot be assessed.
As a general statistical consideration, excluding incomplete evaluations can affect an estimate if completion or data usability is related to classification performance. That is a possibility to consider in evaluation design, not a finding about this trial. The registry record does not report enough information to determine whether such a pattern occurred.
The record also does not report a prespecified statistical analysis plan, rules for defining evaluable periods, or methods for handling the within-participant structure of repeated sleep/wake classifications. Those omissions limit assessment of analysis reproducibility and precision. They do not establish that a particular method was or was not used outside the registry record; the relevant information is simply not reported in the registry record.
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 |
|---|---|---|---|
| Paced Breathing Sleep/Wake Detection | 0 | 36 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Paced Breathing Sleep/Wake Detection | 10 of 36 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Paced Breathing Sleep/Wake Detection |
|---|---|---|
| Central Sleep apnea | Nervous system disorders | 10 of 36 |
The registry’s adverse-event figures list 36 participants at risk for serious events and 0 affected. For the other adverse-event category, the record lists 36 at risk and 10 affected. These are the posted counts for the categories; they do not provide a description of the individual events or their relationship to the device or study procedures.
The serious-event terms list is empty. The deaths field is recorded as null, which is not the same as a reported count of zero. The registry record does not provide further detail about event definitions, collection methods, timing, severity within the other category, or attribution. No conclusion about causation should be drawn from these figures alone.
As a general statistical point, counts of affected participants are descriptive safety summaries. They do not establish that an intervention caused an event, and a zero posted count does not establish that the underlying risk is absent. Interpretation depends on how events were defined, collected, and followed, details that are not reported in the registry record. These figures should be read as registry entries, not as a complete account of safety monitoring.
12. What the Result Does, and Does Not, Mean
This registry record documents an engineering evaluation of a Sleep/Wake algorithm for CPAP users with obstructive sleep apnea. It identifies PSG as the reference method and defines the primary measure as the proportion of correct sleep and wake classifications. That information clarifies the intended statistical question: agreement of the algorithm’s classifications with the reference during a sleep study.
The record does not report the measured accuracy, classification counts, or uncertainty around any estimate. As a result, it does not establish how closely the algorithm matched PSG, how precise any estimate was, or whether performance differed between sleep and wake. The fact that the study is marked COMPLETED does not fill that reporting gap.
This is not a randomized trial comparing treatment groups. The registry record describes a single-group device evaluation, so it does not provide a randomized estimate of a treatment effect. The stated intention to develop and validate the algorithm is a study purpose, not a result. No claim that the intervention did or did not work follows from the information posted.
The findings, if reported elsewhere, would also need to be interpreted in light of the specific population and setting described: people with obstructive sleep apnea who were current CPAP users, evaluated while wearing the device during a sleep study. The registry record does not establish performance in other populations or settings. It does not report enough detail about reference scoring, data completeness, or analysis methods to assess those issues fully.
The most defensible conclusion from the registry record is therefore about what was evaluated, not how well the algorithm performed. It states the intended classification task, reference standard, and accuracy definition, but the numerical outcome and its precision are not reported in the registry record.
13. Why This Trial Matters Statistically
This trial is statistically notable because it asks a measurement question: whether an algorithm’s classification of sleep and wake agrees with PSG. In this kind of evaluation, the outcome definition and reference standard are essential. Accuracy is meaningful only in relation to the classifications counted as correct and the observations included in the calculation.
The registry defines the four classification outcomes and combines correct sleep and wake calls into one accuracy measure. That makes the target measure understandable, while also highlighting what an overall measure leaves unresolved. Without the underlying classification counts or separate sleep and wake performance measures, readers cannot see the kinds of errors that contribute to the overall result.
The single-group design is also important. A classification algorithm is being assessed against a reference, rather than an intervention being compared with a control group. This distinction prevents a common interpretive error: an accuracy evaluation is not, by itself, evidence of a clinical treatment effect. The record’s design, outcome, and intended use should be considered on those terms.
Finally, this record illustrates the difference between an endpoint definition and a reportable result. The registry provides the former but not a numerical estimate or its precision. Without those, statistical assessment of performance is not possible from the registry record. Clear outcome reporting—including the estimate, uncertainty, classification details, and analysis population—is central to judging how informative an algorithm evaluation is.
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 largest limitation for interpretation is that the registry record does not report the primary accuracy result. It also provides no confidence interval, classification counts, or separate measures for sleep and wake. The endpoint can be defined, but its observed performance and precision cannot be assessed.
The analysis population is described as participants who completed the sleep study, while the record does not state how many completed or contributed usable data. No information is reported about missing classifications, excluded recordings, or reasons for noncompletion. This leaves the relationship between enrollment and the analyzed data unclear.
Methodological details relevant to a classification evaluation are also absent. The record does not report the algorithm’s decision rules, the unit of analysis, PSG scoring procedures, synchronization of classifications, handling of repeated observations, or uncertainty-estimation method. These details would help readers assess reproducibility and potential sources of measurement error.
The study is single-group and unmasked, with allocation listed as NA. It therefore does not offer a randomized treatment comparison. Its stated population is limited to participants with obstructive sleep apnea who were current CPAP users, and the evaluation setting was a sleep study while wearing the device. The registry record does not establish generalizability beyond that context.
Finally, the registry lists no analysis entries and does not report a statistical analysis plan or sample-size justification. The planning assumptions recorded for illustrations do not establish the design or analysis actually used in this evaluation. These gaps limit what can be concluded from the registry record, without implying that unreported procedures were necessarily absent from the conduct of the study.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Evaluation of an Algorithm to Detect Sleep and Wake in Continuous Positive Airway Pressure (CPAP) — NCT01031914.
- Registry record last updated 2013-05-14; status last verified 2013-04.
- Results first posted 2013-05-14.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT01031914 is a completed, single-group device evaluation sponsored by Philips Respironics. The intervention is Paced Breathing, and the stated purpose was to develop and validate an algorithm for distinguishing sleep from wake in people with obstructive sleep apnea using CPAP. Enrollment was 36; allocation is listed as NA, and masking as none.
The primary outcome is Sleep/Wake Algorithm accuracy (%) compared with PSG, which the record identifies as the gold standard. Evaluation was to occur in real time during device use in a sleep study, described as an average of 08 hours. The analysis population is described as all participants completing the sleep study.
The registry record does not report a numerical accuracy result, uncertainty interval, or analysis entries. It reports serious adverse events as 0 affected among 36 at risk, and other adverse events as 10 affected among 36 at risk. Serious-event terms are not listed, and deaths are recorded as null.