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 Validation of Sleep Apnea Screening Device (NCT02814227), a na na study. The primary outcome is Specificity.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02814227 |
| Phase | NA |
| Condition | Obstructive Sleep Apnea |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 52 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Michigan |
| Results posted | Yes |
2. Clinical Question
Population
The registry record concerns people assessed for obstructive sleep apnea (OSA). It records enrollment of 52, but does not report participant characteristics, eligibility details, or the setting in which participants were recruited. The record’s summary identifies underserved communities as a motivation for developing an accessible screening tool; it does not establish that the enrolled participants represented those communities.
Intervention
The device under evaluation was the Zansors® sleep screening device, described as a wireless sensor patch. Its intended role in this study was screening for apnea events during sleep. The registry record does not report detailed device procedures, technical specifications, or how device readings were processed.
Comparator
The device was compared with overnight polysomnography, which the record describes as the gold-standard comparator. The registry identifies a single-group design and does not describe a randomized control group. Details about how measurements from the device and polysomnography were matched for analysis are not reported in the registry record.
Primary question
The primary question was how specifically the device identified true negatives relative to polysomnography. The registry defines the outcome as the percentage of true negatives and gives an 8-hour timeframe, with apnea events assessed at 30-second intervals. The primary specificity estimate and its uncertainty are not reported in the registry record.
3. Trial Design
The registry describes a completed, single-group device evaluation sponsored by the University of Michigan. Enrollment was 52. The study was intended to compare the Zansors® sleep screening device with overnight polysomnography to assess the device’s preliminary validity for OSA screening. This is an evaluation of a screening device against a reference assessment, not a randomized comparison of treatments.
The record lists allocation as NA and masking as NONE. It therefore does not describe randomized allocation or masking. The registry’s design information also cautions that this is not a randomized comparison and that the arms are not a like-for-like control comparison. The record names the device group and describes the device as compared with overnight polysomnography, but it does not give detailed information about the participant-level measurement structure or matching procedure.
The study start is recorded as 2014-09, and primary completion is recorded as 2015-12. Its status is COMPLETED. Completion status indicates the recorded study status; it does not establish that results were reported or that the primary question was resolved. The registry lists no analyses. A protocol-level account of recruitment, data collection, quality control, or departures from the intended procedures is not reported in the registry record.
The stated motivation was to evaluate a potentially accessible home screening approach, with particular interest in barriers to screening. The record’s summary describes a need for an affordable, easy-to-use, over-the-counter home-based tool, but this motivation should not be mistaken for evidence that the device is affordable, approved, or effective. Those claims are not established by the design description alone.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Zansors® Sleep Screening Device |
|---|---|
| STARTED | 52 |
| COMPLETED | 52 |
| NOT COMPLETED | 0 |
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 | Zansors® Sleep Screening Device |
|---|---|---|
| Participants analysed | 52 | |
| Age, Continuous | years | 47.8 (SD 13.3) |
| Sex: Female, Male: Female | Participants | 29 |
| Sex: Female, Male: Male | Participants | 23 |
| Region of Enrollment: United States | participants | 52 |
6. Primary Endpoint
The registry lists the primary outcome as Specificity, measured over 8 hours.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of true negatives |
| Endpoint classification | not reduced to a single comparison |
Specificity is the primary endpoint. In general, specificity describes how often a test classifies observations without the target condition as negative. The registry defines this outcome as the percentage of true negatives for the Zansors® device compared with polysomnography. A higher specificity estimate would indicate fewer false-positive classifications among observations identified as negative by the reference assessment, but the registry record does not report an estimate.
The recorded timeframe is 8 hours, with apnea events assessed at 30-second intervals. This definition makes clear that the outcome concerns the device’s classification relative to the reference method during the specified sleep period. However, the record does not explain how a person-level result was derived from interval-level readings, how indeterminate or unusable readings were handled, or whether the endpoint was calculated at the event, interval, or participant level.
Specificity is used to characterize one aspect of screening accuracy. It does not describe sensitivity, which concerns detection among observations with the target condition, nor does it by itself state the probability that an individual has OSA after a positive or negative device result. The registry separately lists sensitivity, positive predictive value, and negative predictive value as secondary outcomes. The result and uncertainty for the primary specificity endpoint are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies specificity as the primary outcome, but it does not report the outcome estimate, a confidence interval, or a statistical test. Consequently, the posted record does not show how often the device classified true negatives correctly, how uncertain such an estimate might be, or whether the observed data met any prespecified performance criterion. The study’s COMPLETED status does not substitute for a reported result.
The comparison is described as the Zansors® device against overnight polysomnography. Polysomnography serves as the reference in the registry’s description; the study therefore addresses agreement with that reference rather than establishing an independent, error-free measure of OSA. The record does not provide details about the reference assessment, classification thresholds, or procedures for resolving disagreement between methods.
Specificity addresses only negative classifications. The registry also lists sensitivity, positive predictive value, and negative predictive value as secondary outcomes, but their estimates are not reported in the registry record. These measures answer different questions. In general, sensitivity concerns detection among reference-positive observations, while predictive values concern the proportion of device classifications that correspond to the reference classification. None should be inferred from specificity alone.
The record describes a single-group evaluation, with allocation listed as NA and masking as NONE. It does not describe a randomized control group or a like-for-like comparison between treatment arms. Those design features are consistent with an assessment of screening performance, but they do not provide evidence about comparative treatment effects. The registry does not report participant characteristics or enough information to assess how well the study sample reflects people who might use a home screening device.
The record lists 0 analyses. It also does not report the primary estimate, uncertainty, missing-data handling, or analysis population. In the absence of those details, statistical precision and the robustness of the result cannot be assessed. The enrollment figure alone cannot establish precision: precision depends on the data structure, the number and distribution of positive and negative classifications, and the analysis method. No conclusion about screening performance should be drawn from enrollment or completion status alone.
Overall, the registry record describes the question and the reference comparison but does not report the evidence needed to answer the primary question. Any numerical interpretation of specificity, sensitivity, predictive values, or uncertainty would require results that are not reported in the registry record.
9. Statistical Methods Explained
The registry record names a diagnostic performance question: how well the Zansors® device identifies true negatives relative to overnight polysomnography. It identifies specificity as the primary outcome and lists sensitivity, positive predictive value, and negative predictive value as secondary outcomes. It does not report the estimates or statistical methods used to calculate them. The explanations below are general and do not describe an analysis confirmed for this study.
What does specificity measure?
In general, specificity is the fraction of reference-negative observations that a test also classifies as negative. A false positive occurs when the device classifies an observation as positive while the reference method classifies it as negative. Specificity therefore focuses on performance within the reference-negative group. The registry’s description frames the outcome as a percentage of true negatives, but it does not provide the underlying counts, estimate, or calculation details.
Specificity must be interpreted alongside other aspects of test performance. A device might classify reference-negative observations well while missing some reference-positive observations. Sensitivity describes the latter aspect: the ability to identify observations that are positive according to the reference. The registry lists sensitivity as a secondary outcome but does not report its result. A statement about specificity alone would not establish overall screening accuracy.
How do predictive values differ?
In general, positive predictive value describes the share of positive test classifications that are positive according to the reference. Negative predictive value describes the share of negative test classifications that are negative according to the reference. These measures answer questions about the meaning of a device result in the studied sample. Unlike sensitivity and specificity, predictive values can vary with how common the target condition is in the population being assessed. The registry lists both predictive values as secondary outcomes but does not report their estimates or describe the population’s OSA frequency.
That distinction matters when considering whether results from a study would transfer to another setting. Even if sensitivity and specificity were stable, predictive values may differ when the mix of people assessed differs. General clinical context in the registry summary does not provide the prevalence among study participants, so the predictive values cannot be reconstructed or generalized from that background information.
Why does the observation unit matter?
The registry describes an 8-hour timeframe and assessment at 30-second intervals. General statistical reasoning cautions that repeated observations from the same person or night may be related rather than independent. If interval-level readings are treated as independent when they are correlated, conventional uncertainty calculations can be too optimistic. A participant-level or appropriately clustered analysis can account for such dependence. The registry record does not state the analysis unit or whether dependence among readings was addressed.
The record also does not explain how interval readings were combined into a final classification, how incomplete recordings were handled, or how device and reference observations were aligned. Those choices can affect both the estimate and its precision. They are important details for interpreting a device comparison, particularly when the outcome is defined over repeated intervals.
What would uncertainty communicate?
In general, a confidence interval describes the range of values compatible with the observed data under a specified statistical procedure. A narrow interval indicates greater precision than a wide interval, though the interval’s interpretation depends on the method and assumptions. A point estimate without an interval can conceal substantial uncertainty. The registry does not report a confidence interval for specificity or identify an interval procedure.
A statistical test and a confidence interval serve related but different purposes. A test evaluates compatibility with a specified null hypothesis, while an interval conveys the estimated effect and its precision across a range of values. Neither answers whether the device is useful in practice without a relevant performance standard and appropriate context. No hypothesis, threshold, or test result for the primary outcome is reported in the registry record.
What analysis plan is documented?
The registry lists 0 analyses and does not report the statistical analysis plan. In particular, the record does not state the classification threshold, confidence-interval method, handling of repeated observations, or approach to missing and unusable readings. These details are not reported in the registry record, so no method should be attributed to the study.
The record includes sample-size planning assumptions for illustrations: two-sided significance level 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. It also specifies that such calculations are planning illustrations based on the observed effect, not the trial’s own design; time-to-event calculations refer to total events, while other calculations refer to participants per arm. These assumptions do not establish that the study used that design or analysis. Planning illustrations are not observed power, and their interpretation depends on inputs and results not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists specificity as the primary outcome and sensitivity, positive predictive value, and negative predictive value as secondary outcomes. Considering multiple outcomes can create a multiplicity issue: in general, the more inferential claims assessed, the greater the chance that at least one appears noteworthy by chance if each is evaluated separately. Whether and how to address that issue depends on the study’s objectives and analysis plan.
A multiplicity procedure, hierarchy for interpreting outcomes, or prespecified strategy for controlling error rates is not reported in the registry record. The record also lists 0 analyses, so it does not show which outcomes were analyzed or how any results were selected for reporting. It would not be appropriate to assume that an adjustment was or was not used.
Missing-data methods are not reported in the registry record. The record does not describe whether recordings could be incomplete or unusable, how such observations would be classified, or whether missingness would affect inclusion in the analysis. These details matter because excluding observations can affect both the estimated performance and its uncertainty, especially if the likelihood of a usable recording differs across people or readings.
The analysis population is not reported in the registry record. It does not specify which enrolled participants or readings contributed to each endpoint, or whether any exclusions occurred. Interim analyses, stopping rules, and a prespecified statistical analysis plan are also not reported. These absences limit assessment of the analysis process; they do not establish what procedures were or were not carried out.
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 |
|---|---|---|---|
| Zansors® Sleep Screening Device | 0 | 52 | 0.0% |
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 |
|---|---|
| Zansors® Sleep Screening Device | 0 of 52 |
The registry’s adverse-event record lists 52 people at risk for serious adverse events and 0 affected by serious adverse events in the Zansors® Sleep Screening Device group. It also lists 52 at risk for other adverse events and 0 affected by other adverse events. These are the registry’s recorded counts; the record does not provide event-level descriptions or further detail about collection and reporting procedures.
The deaths field is null. A null entry is not the same as a reported count of zero; the number of deaths is not reported in the registry record. The record also lists no serious adverse-event terms. This should be read as the absence of listed terms in the registry entry, not as evidence about unreported events.
Adverse-event counts describe what the registry reports for this study. They do not establish that an event was caused by the device, and the record does not provide a causal assessment. The single-group design also does not offer a randomized comparison of event rates. These figures should therefore be read as registry-reported safety information, with the scope and completeness of reporting left unclear.
12. What the Result Does, and Does Not, Mean
This record establishes that a completed study was registered to compare the Zansors® sleep screening device with overnight polysomnography, with specificity as its primary outcome. It also establishes the stated timeframe of 8 hours and interval assessment at 30-second intervals. The registry’s summary gives the project’s goal as preliminary validation for OSA screening. These are descriptions of the study question and design, not evidence of a particular level of diagnostic performance.
The primary specificity estimate is not reported in the registry record. Neither are its confidence interval, the results for the listed secondary outcomes, or the analyses. As a result, the record does not show how closely device classifications matched polysomnography, how precise any estimate was, or how the device performed across positive and negative classifications. It is not possible to infer those results from the enrollment figure or the study’s completed status.
The record also does not establish that the device is affordable, easy to use, approved, or suitable for broad use. Those ideas appear as motivations in the study summary, not as outcomes reported in the registry. The record does not report enough information about participants or the analysis to determine how well findings would apply in underserved communities or other settings.
In general, a screening device’s performance is only one part of its potential role. The meaning of a positive or negative result depends on the test’s sensitivity and specificity, the frequency of the condition in the population assessed, and how the result is used. The registry lists several relevant accuracy outcomes but does not report their values. Thus, the record describes an important validation question, while leaving the answer to that question unreported.
13. Why This Trial Matters Statistically
Statistically, this study addresses the distinction between evaluating a screening device against a reference method and comparing interventions. The registry describes a single-group evaluation of the Zansors® device against overnight polysomnography, not a randomized treatment comparison. That distinction determines what the design can address: its stated focus is preliminary screening validity, particularly specificity, rather than a causal effect of one treatment relative to another.
The outcome definition also raises a general measurement issue. The registry defines specificity over an 8-hour period using observations at 30-second intervals. When data are collected repeatedly within a person or night, the analysis must consider whether observations are related. The registry does not report how readings were aggregated or how their dependence was handled. Such decisions can affect uncertainty and the interpretation of a performance estimate.
The registry’s summary describes a motivation to reduce barriers to home OSA screening, including barriers in underserved communities. For that motivation to translate into evidence about performance in a target population, participant characteristics and the match between the study sample and intended users matter. Those characteristics are not reported in the registry record. Nor are the primary accuracy results, which are necessary to evaluate the device’s performance relative to the stated reference.
The record therefore illustrates why a clearly stated endpoint is not enough by itself to support a conclusion. Interpretation also requires reported estimates, uncertainty, analysis methods, and information about the observations included. Here, the registry sets out the comparison and outcome but does not report the analyses needed to judge their statistical precision or relevance.
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 for interpretation is that the registry record does not report the primary specificity result. It also does not report estimates for sensitivity, positive predictive value, or negative predictive value. Without those values and their uncertainty, the device’s observed performance cannot be assessed from this record.
The design is described as single-group, with allocation listed as NA and masking as NONE. The registry cautions that the study is not a randomized comparison and that its arms are not a like-for-like control comparison. This is relevant when interpreting the study as a device evaluation rather than a comparative trial. The record does not provide enough information about the participant-level relationship between device and polysomnography measurements to characterize the analysis structure further.
Participant characteristics, eligibility criteria, recruitment details, and the distribution of OSA among participants are not reported in the registry record. This limits assessment of representativeness and the context needed to interpret predictive values. The registry also does not describe classification thresholds, the handling of incomplete recordings, the analysis unit, or methods for accounting for repeated readings at 30-second intervals.
The record lists 0 analyses and does not report a statistical analysis plan, uncertainty estimates, missing-data methods, or analysis populations. It also does not provide details about the polysomnography procedures or how discordant readings were handled. These omissions prevent evaluation of analytic choices and robustness. They should be understood as limits of the information reported in the registry record, not as proof that procedures were absent from the study itself.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Validation of Sleep Apnea Screening Device — NCT02814227.
- Registry record last updated 2023-01-30; status last verified 2023-01.
- Results first posted 2017-07-26.
- 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
NCT02814227 is a completed, single-group evaluation sponsored by the University of Michigan. It records enrollment of 52 and compares the Zansors® sleep screening device with overnight polysomnography for obstructive sleep apnea screening. The listed primary outcome is specificity, defined as the percentage of true negatives over an 8-hour period with apnea events assessed at 30-second intervals. Secondary outcomes are sensitivity, positive predictive value, and negative predictive value.
The record lists allocation as NA, masking as NONE, and 0 analyses. It reports no primary or secondary outcome estimates, confidence intervals, or analysis details. Serious and other adverse-event counts are recorded as 0 affected among 52 at risk in each listed category; the deaths field is null. The registry describes the study as completed, but its outcome results are not reported in the registry record.