Sleep Schedules Modifications in Sleep Apnea Patients Treated by nCPAP: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Sleep Schedules Modifications in Sleep Apnea Patients Treated by nCPAP (NCT01355419), a registered phase not stated study. The primary outcome is Change in Total Sleep Time Before and After CPAP Therapy in Obstructive Sleep Apnea Patients.

2. Clinical Question

3. Trial Design

The registry record identifies the study as completed and lists an enrollment of 150. It gives a start date of 2010-08 and a primary completion date of 2014-08. The sponsor is Centre Hospitalier Universitaire Saint Pierre. The condition is obstructive sleep apnea, and the listed treatment group is described as people with moderate to severe obstructive sleep apnea requiring CPAP therapy.

The primary outcome was change in total sleep time before and after CPAP therapy, with assessments at baseline and at 3 months. Total sleep time was assessed by actigraphy. The registry also lists change in physical activity, measured as number of steps per day before and after CPAP therapy, as a secondary outcome.

The record does not state an allocation method. It does not describe a randomized comparison, and the listed arm is not a like-for-like control comparison. This matters for interpretation: a before-and-after change can describe how measurements differed over time in the assessed group, but by itself it does not separate changes associated with treatment from other changes over the same period. The registry record does not report further design details that would clarify that distinction.

The record lists two outcome measures and two analyses, but does not report the analysis methods or numerical results for the primary outcome. Details such as the analysis population, the number of participants contributing paired measurements, and the handling of missing measurements are not reported in the registry record. The enrollment figure should therefore not be assumed to be the number included in the primary analysis.

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

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 in Total Sleep Time Before and After CPAP Therapy in Obstructive Sleep Apnea Patients, measured over baseline and at 3 months.

Total sleep time is the duration of sleep recorded for a participant. The primary endpoint concerns how that duration changed from baseline to 3 months after CPAP therapy began. The registry specifies actigraphy as the assessment method and identifies the outcome as a continuous measure summarized using a mean and standard deviation.

Actigraphy records movement over time and is used to estimate sleep and wake patterns. Repeated assessment can characterize an individual's sleep schedule over a period rather than relying only on a single retrospective account. In general, a change in total sleep time can describe whether recorded sleep duration differed between assessments. It does not, by itself, explain why a difference occurred or establish that treatment caused it.

The registry's stated rationale is that sleep is disrupted in obstructive sleep apnea and that sleep quality may improve with CPAP, raising a question about whether sleep needs or schedules change during treatment. The primary endpoint addresses sleep duration, not every aspect of sleep quality. Duration and quality are related concepts, but they are not interchangeable outcomes.

The registry record does not report the observed mean change, its standard deviation, a confidence interval, or a test result. It also does not report the number of paired actigraphy assessments used in the analysis. Thus the endpoint is identifiable, but its estimated change and precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: total sleep time is measured in minutes, and the registry identifies the summary measure as a mean with standard deviation. In general, a mean represents the average value in the analyzed group. A standard deviation describes the spread of observations around that average. It is not the same as a confidence interval: the standard deviation concerns variability among observations, whereas a confidence interval expresses uncertainty about an estimated quantity such as the mean.

The endpoint compares measurements at baseline and at 3 months. When the same participants are measured at both times, an analysis can focus on each participant's change and then summarize those changes. This approach preserves the pairing between a participant's baseline and follow-up measurements. An alternative analysis may compare the two time-specific means without fully using that pairing. The registry record does not describe which approach was used, whether the reported mean would represent individual changes, or how the associated standard deviation was defined.

In general, the uncertainty of an average change depends on both the variation in individual changes and the number of participants with usable paired observations. The relation between measurements from the same participant also matters. A participant whose follow-up measurement is close to their baseline measurement contributes differently to the uncertainty than one whose measurements vary substantially. The registry record does not report the required summary information or the number of paired observations, so this uncertainty cannot be reconstructed from the record.

Actigraphy is the stated method for assessing total sleep time. As with any measurement approach, estimates can depend on how recording periods are defined, how device data are processed, and how sleep is distinguished from wakefulness. These general considerations affect interpretation of the endpoint, but the specific actigraphy procedures and processing rules are not reported in the registry record.

For a continuous endpoint, an analysis may report an estimated mean change, an uncertainty interval, and a statistical test. The estimate conveys the scale and direction of the observed difference; the interval conveys how precisely it is estimated under the analysis assumptions; and a test result assesses compatibility with a specified null model. These elements answer different questions and should be read together. The registry record does not report a primary estimate, confidence interval, or p-value, and it does not identify the test used.

The distinction between a within-group change and a treatment comparison is especially important for this study. The registry describes measurements before and after CPAP therapy, with allocation not stated and no like-for-like control comparison described. A within-group analysis can estimate change across the assessment period. It cannot, on its own, distinguish an effect of treatment from time-related influences or other explanations. In general, a controlled comparison supports a different causal interpretation than an uncontrolled before-and-after contrast.

Statistical significance and practical importance are also distinct. A test result, if available, would not by itself establish whether a difference is meaningful in daily life. That judgment depends on the size and precision of the estimated change and on relevant clinical context. The registry record does not report a numerical estimate or a threshold for an important change in total sleep time. No conclusion about the clinical importance of a change can therefore be drawn from the posted information.

The record lists two outcome measures and two analyses. When several outcomes or analyses are examined, the chance of at least one apparently unusual result can increase if each is assessed separately without accounting for multiplicity. In general, investigators may specify one primary outcome, use a hierarchy, or apply an adjustment. The registry record does not describe whether multiplicity was considered or how the two analyses relate to the listed outcomes.

Planning calculations and observed results serve different purposes. A sample-size calculation may illustrate how many participants would be needed under specified assumptions; it is not an observed treatment effect or evidence that a study had adequate power. The registry record does not report the trial's sample-size justification. Although generic planning assumptions may be stated for an illustration, the primary outcome estimate needed to assess any effect-based illustration is not reported in the registry record. Such an illustration should not be interpreted as observed power or as a trial result.

Finally, missing follow-up measurements can affect both the analyzed sample and the estimate. If participants without follow-up differ from those with follow-up, an analysis limited to complete pairs may not represent all enrolled participants. Other methods can use incomplete observations under particular assumptions, but their validity depends on the missing-data process and the model. The registry record does not report missing-data methods, reasons for missing measurements, or the analysis population. These omissions limit assessment of whether the reported endpoint, if available elsewhere, would represent the enrolled group.

10. Confidence Intervals for Each Arm

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

R code and output

arm <- c("Obstructive Sleep Apnea, CPAP")
n   <- c(142)
m   <- c(29)
sp  <- c(17)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Obstructive Sleep Apnea, CPAP  142  29.000  17.000  26.180  31.820

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures and two analyses: the primary outcome concerns change in total sleep time, and the secondary outcome concerns change in steps per day. It does not describe the relationship between the analyses, identify which tests were performed, or report whether an adjustment for multiple outcomes or tests was used. In general, examining multiple outcomes can make isolated nominal findings harder to interpret unless the analysis plan accounts for that multiplicity. No multiplicity strategy is reported in the registry record.

The record does not state how missing baseline or follow-up measurements were handled. It does not report the number of participants with complete actigraphy data, whether the primary analysis required paired observations, or whether any imputation or other missing-data method was used. Reasons for missing data and the assumptions behind any handling method are also not reported in the registry record.

Although the registry lists enrollment of 150 and the safety results identify 142 participants at risk, it does not specify the population used for the primary endpoint analysis. It is not reported whether the analysis included all enrolled participants, only those who began CPAP, or only those with measurements at both assessment times. The analysis population and the number contributing data are therefore not reported in the registry record.

The registry record also does not report a statistical analysis plan, interim analyses, or a sample-size justification. These omissions mean that the intended analysis rules and safeguards against selective reporting cannot be assessed from the posted information.

12. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The safety results identify 142 participants at risk in the listed obstructive sleep apnea, CPAP group. The record reports 0 serious adverse events among those participants and 0 other adverse events among those participants. No serious adverse event terms are listed. The deaths field is null, so deaths are not reported in the registry record.

These entries describe what is recorded in the safety results; they do not establish that no adverse events of any kind occurred outside the categories or reporting period represented by the record. A zero count is not proof that an event is impossible, and it does not by itself establish the completeness of safety surveillance. The registry record does not provide definitions, event-collection methods, or details about the period of safety follow-up.

The 142 participants at risk should not be assumed to be the number included in the primary outcome analysis. The registry lists enrollment of 150, but the relation between enrollment, the safety population, and the endpoint analysis population is not reported in the registry record. The safety figures also do not provide a comparison with an untreated or alternative-treatment group, since no like-for-like control comparison is described.

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

The record identifies a question about sleep duration during CPAP treatment in people with moderate to severe obstructive sleep apnea. Its primary endpoint is the change in total sleep time from baseline to 3 months, assessed by actigraphy. This tells readers what investigators intended to measure and when, but it does not reveal what the measurements showed: the numerical primary result is not reported in the registry record.

Without an estimate and a measure of uncertainty, it is not possible to describe the direction or size of the observed change, how variable participant changes were, or how precisely an average change was estimated. The record also does not report a statistical test or confidence interval. The registry's listed enrollment cannot substitute for those results, and the safety population cannot be assumed to match the endpoint analysis population.

The before-and-after structure also sets a limit on causal interpretation. The registry does not state allocation and does not describe a like-for-like control comparison. In general, a change measured over time in a treated group may have several explanations. It cannot by itself show what would have happened over the same period without treatment or under another treatment.

The endpoint measures duration of sleep, not all dimensions of sleep quality or daily functioning. The registry's description gives the investigators' rationale for studying sleep schedules, but the posted record does not report results that could establish whether total sleep time or physical activity changed. Even a documented statistical difference would need to be considered alongside its precision, measurement context, and clinical importance.

Accordingly, the record supports a description of the study question, timing, and stated measurement method. It does not support a conclusion about the treatment's effect on sleep time, whether any change was clinically important, or whether the study ruled out meaningful differences.

14. Why This Trial Matters Statistically

This study addresses a statistical question about repeated measurements: how to describe change in a continuous outcome when sleep time is measured before and after treatment. The endpoint is stated as mean total sleep time in minutes, assessed by actigraphy at baseline and at 3 months. That framing makes clear that the relevant quantity is a change across assessments, rather than a single follow-up value considered without its baseline context.

The design description also illustrates why the comparison matters as much as the measurement. A before-and-after assessment can characterize temporal change within the treated group, while a suitable control comparison is needed to distinguish that change from other influences. The registry does not state allocation or describe a like-for-like control group, so readers should not interpret the design as a randomized treatment comparison.

The record further illustrates the importance of complete statistical reporting. A defined endpoint is not enough to assess evidence: readers also need the estimate, its uncertainty, the analysis population, and the methods used to handle repeated observations and missing data. Those numerical results and details are not reported in the registry record. The enrollment and safety counts cannot replace an endpoint estimate or clarify who contributed measurements.

Finally, the listing of primary and secondary outcomes raises a general question about multiplicity. When more than one outcome is analyzed, the prespecified testing strategy affects how results should be interpreted. The record lists two outcome measures and two analyses but does not describe any adjustment or hierarchy. The study therefore offers a useful example of how registry design information can identify a research question while leaving important parts of the evidential interpretation unresolved.

15. Limitations

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

The most direct limitation for interpreting the primary outcome is that its numerical result is not reported in the registry record. There is no reported mean change, standard deviation for the change, confidence interval, or test result. The endpoint's direction, magnitude, and precision cannot therefore be evaluated.

The registry describes assessment at baseline and at 3 months but does not report the number of participants with measurements at both times. It lists enrollment of 150 and a safety population of 142, but the number analyzed for total sleep time and the relationship among these groups are not reported. The analysis population and handling of missing measurements are also not reported in the registry record.

The study description concerns a before-and-after assessment, and allocation is not stated. The record does not describe a like-for-like control comparison. As a result, any change over time could not be attributed to CPAP alone on the basis of this design description. The registry record also does not provide details of treatment adherence, actigraphy processing, or other procedures that could affect interpretation of the measured change.

The record lists a secondary physical-activity outcome and two analyses, but it does not report their numerical results or explain the analysis methods. It does not describe whether multiplicity was addressed, how the primary outcome was modeled, or whether any interim analyses occurred. A sample-size justification and the intended analysis plan are not reported in the registry record. Together, these omissions prevent a detailed assessment of the analysis choices and the robustness of any outcome finding.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Sleep Schedules Modifications in Sleep Apnea Patients Treated by nCPAP — NCT01355419.
• Registry record last updated 2015-05-12; status last verified 2015-04.
• Results first posted 2015-05-12.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry record describes a completed study sponsored by Centre Hospitalier Universitaire Saint Pierre, with enrollment of 150. It lists a start date of 2010-08 and a primary completion date of 2014-08. The study concerns people with moderate to severe obstructive sleep apnea requiring CPAP therapy.

The primary outcome is change in total sleep time, measured by actigraphy at baseline and at 3 months. Change in number of steps per day is listed as a secondary outcome. The record identifies a mean and standard deviation as the summary approach for the continuous primary measure, but the primary numerical result is not reported in the registry record.

Allocation is not stated, and no like-for-like control comparison is described. The safety results report 0 serious and 0 other adverse events among 142 participants at risk; deaths are not reported in the registry record. The endpoint analysis population, missing-data methods, and statistical analysis plan are not reported in the registry record.