Design and Usability Testing of a Tailored Intervention About Sleep and Sleep Disorders Among Transportation Workers: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Design and Usability Testing of a Tailored Intervention About Sleep and Sleep Disorders Among Transportation Workers (NCT05039528), a randomized na study. The primary outcome is Obstructive Sleep Apnea (OSA) Self-efficacy.

2. Clinical Question

The study objective is described as conducting a focus group to identify OSA beliefs, attitudes, and knowledge among transportation-industry employees on shift schedules. The intervention and arm descriptions also specify a randomized comparison of personalized messages with a control condition. The registry record does not explain how the focus-group objective relates to that comparison. Accordingly, the recorded question can be described as a study of OSA awareness-related measures, including self-efficacy, but its results cannot be used to assess whether the messages changed those measures.

3. Trial Design

The registry record identifies this as a randomized, single-masked, parallel-group study with an enrollment of 38. The study status is completed. Brigham and Women's Hospital is listed as the sponsor. The record gives a start date of 2022-10-01 and a primary completion date of 2024-07-01. The phase is listed as NA.

There are two described arms. The intervention arm received personalized OSA messages; the control arm is described as receiving no treatment during the experiment. The adverse-event record gives 18 participants at risk in the intervention group and 20 in the control group. The registry record does not further explain the allocation procedure, how masking was implemented, or which people were masked. It also does not describe the message delivery process, participant contact, or the schedule of study activities beyond the stated outcome measurement times.

The primary outcome is OSA self-efficacy, assessed at baseline and follow-up approximately 2 months later. OSA Knowledge and OSA Readiness to Change are listed as secondary outcomes. The record lists 3 outcome measures and 0 analyses. Although it describes the study as randomized, it does not report an analyzed comparison of the arms. The study objective refers to a focus group about beliefs, attitudes, and knowledge, while the arm descriptions refer to a randomized messaging experiment; the registry record does not reconcile these descriptions. No further protocol details, sample-size justification, or statistical analysis plan are 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.

Before assignment: Worksites were randomized, using a random number generator, to intervention or control. Participants received the worksite-level assignment-related materials (e.g., intervention worksite received the intervention, control was a waitlist control, receiving information at the end of the study).

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 Obstructive Sleep Apnea (OSA) Self-efficacy, measured over Baseline and follow-up (approximately 2 months).

The primary outcome is OSA self-efficacy, measured using the self-efficacy subscale of the Survey of Obstructive Sleep Apnea Functional Health Literacy (SOFHL). The subscale asks about confidence related to OSA through 5 self-efficacy questions. Each question uses a 3-point response scale: 1, “I am confident”; 2, “I am not sure”; and 3, “I am not confident.” Only a response of 1 is counted as indicating self-efficacy.

The scoring rule sums the questions marked “I am confident,” divides by the total number of questions in the subscale, 5, and multiplies by 100. The resulting score can range from 0% to 100%. Lower scores, closer to 0%, indicate lower OSA self-efficacy; higher scores, closer to 100%, indicate higher self-efficacy. The registry describes the outcome as a mean with standard deviation and gives baseline and follow-up, approximately 2 months, as the measurement timeframe.

Self-efficacy is used as an outcome because it represents participants’ reported confidence, rather than their clinical diagnosis or a direct measure of sleep. The SOFHL also includes an OSA Knowledge subscale, and OSA Knowledge is listed as a secondary outcome. The registry record does not report the self-efficacy scores, their variability, or a change or between-group comparison. The measure’s definition therefore clarifies what was intended to be assessed, but does not establish what participants scored.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean and standard deviation describe?

General explanation: For a continuous measure such as the SOFHL self-efficacy score, a mean describes the average score among the participants included in an analysis. A standard deviation describes how dispersed individual scores are around that average. These statistics answer different questions: the mean locates the group’s score level, while the standard deviation describes variation between participants. Neither statistic alone quantifies the uncertainty in a comparison between groups.

The registry identifies the primary outcome as a mean with standard deviation, but does not report either statistic for the study arms or time points. Consequently, the recorded endpoint definition cannot be used to estimate an average score or its spread. The registry record also does not report a contrast between groups or a change from baseline.

What would a confidence interval communicate?

General explanation: A confidence interval expresses the statistical uncertainty around an estimated quantity, such as a difference in mean scores. Its width reflects how precisely the quantity has been estimated under the analysis assumptions. A confidence interval is not a guarantee about an individual participant’s score, and it does not by itself establish the practical or clinical importance of a result. Interpreting it requires knowing what was estimated, how it was calculated, and which participants and observations were included.

No confidence interval for OSA self-efficacy is reported in the registry record. Since no analyzed contrast is reported, there is no posted interval from which to assess precision. The same limitation applies to the secondary outcomes.

What can be inferred from the randomized design?

General explanation: Random allocation is intended to make groups comparable, on average, with respect to factors that could affect an outcome. It does not ensure identical groups in a particular study, and it does not remove the need to report the allocation process, participant flow, outcome data, and statistical analysis. A randomized label describes a design feature; it is not itself evidence of an effect.

The registry labels allocation as randomized and the model as parallel. It does not report the allocation method, masking details, or an analysis of the randomized groups. It therefore identifies the intended design but does not permit assessment of how the comparison was conducted or analyzed.

How should planning calculations be understood?

General explanation: A sample-size calculation is a planning exercise about the number of participants or events that might be needed to detect a specified effect under stated assumptions. It is not an estimate of the effect observed in a study, and it is not a measure of the study’s actual power after results are known. A planning illustration based on an observed effect is especially dependent on that effect estimate and should not be confused with the trial’s original design justification.

The registry record does not report a sample-size justification or the protocol’s statistical plan. Its stated planning assumptions describe a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the target effect expressed as a fraction of the observed effect. Any such illustration is a planning aid, not observed power. The registry does not report a single analyzed outcome comparison from which a reader can assess an observed effect for the primary endpoint.

Why do outcome definitions and analysis choices matter?

General explanation: A measurement definition explains how data are converted into an outcome, but an analysis also requires a clear comparison, a time point or change measure, and rules for handling the data. For repeated measurements, analysts may compare follow-up scores, changes from baseline, or use a model that incorporates both time points. These approaches can answer different questions and may rely on different assumptions. The chosen approach should be specified and its results reported to allow readers to understand the estimate.

Here the registry defines a self-efficacy score and names baseline and follow-up approximately 2 months later. It does not state which comparison was planned or used, how repeated measurements were handled, or whether the analysis adjusted for baseline scores. The registry record does not report the statistical methods used for an outcome analysis. No conclusion about the selected analysis or its assumptions can be inferred from the outcome description alone.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures, including OSA self-efficacy as the primary outcome and OSA Knowledge and OSA Readiness to Change as secondary outcomes. It does not report analyses for these measures; the record lists 0 analyses. It is therefore not possible to determine how many statistical tests were conducted, whether outcomes were analyzed at multiple time points, or whether any adjustment was planned for multiplicity. The record does not report a multiplicity strategy, such as a method to control the chance of false-positive findings across several tests. In the absence of results and analysis details, no multiplicity-adjusted interpretation is available.

Missing-data handling is not reported in the registry record. The record does not state how many participants completed each assessment, whether follow-up scores were missing, why data might be missing, or what methods were used to address missing observations. It also does not report whether any sensitivity analyses were planned or conducted. These details matter because an analysis based only on observed responses may not represent all randomized participants if outcome availability is related to participant characteristics or outcomes.

The analysis population is not reported in the registry record. It is not stated whether the analysis was intended to include all randomized participants, only participants who received the intervention, or those with complete outcome data. The record also does not report protocol deviations or exclusions from analysis. As a result, the distinction between participants enrolled, assigned to an arm, and included in any outcome analysis cannot be assessed from the posted information.

These are reporting gaps, not evidence that a particular method was or was not used outside the registry record. Without a statistical plan, participant-level analysis counts, and outcome results, readers cannot evaluate the consequences of missing data, multiple outcomes, or analysis-population decisions.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The adverse-event record gives 18 participants at risk in the intervention group and 20 in the control group. It records 0 participants affected by serious adverse events in each group and 0 deaths in each group. For other adverse events, the recorded counts are also 0 affected participants in both groups, with 18 and 20 participants at risk respectively. No top serious adverse-event terms are listed.

These figures describe what is entered in the registry record; they do not establish that no event occurred outside the recorded data or that the groups had identical safety experience. The record does not report the method or duration of safety surveillance, event definitions, completeness of reporting, or whether events were assessed as related to the intervention. It also does not provide a statistical comparison of safety outcomes. The figures should therefore be read as registry counts, not as proof of absence of risk or as a comparative safety estimate.

The denominators in this safety record are not outcome-analysis counts for self-efficacy or the secondary measures. The registry does not report how many participants posted usable scores at baseline or follow-up. Safety counts cannot fill that gap or indicate whether the intervention changed participants’ OSA-related knowledge or confidence.

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

The record establishes that a completed randomized, parallel-group study enrolled 38 participants and describes personalized OSA messages as the intervention. It identifies OSA self-efficacy as the primary outcome, measured with the SOFHL self-efficacy subscale at baseline and follow-up approximately 2 months later. It also names OSA Knowledge and OSA Readiness to Change as secondary outcomes. These details describe the intended study question and outcome measures.

They do not establish what happened to the outcome scores. The registry record does not report group means, standard deviations, changes over time, effect estimates, confidence intervals, or p-values. It lists 0 analyses. Thus, the posted information cannot show whether scores increased, decreased, or differed between the intervention and control groups. It cannot establish the size or precision of an effect, or support a conclusion about whether the personalized messages changed participants’ responses.

The record also does not report clinical outcomes such as diagnosis, treatment uptake, or sleep-related health outcomes. The named measures concern self-efficacy, knowledge, and readiness to change; they should not be treated as equivalent to clinical benefit. The stated study population and focus on shift-scheduled transportation workers define the context, but do not show that findings would apply to people outside that context.

Similarly, the adverse-event counts are limited to recorded events and do not provide a full safety assessment. No serious adverse events, other adverse events, or deaths are recorded in the listed groups, but the registry does not describe event surveillance or completeness. These counts do not determine the intervention’s safety in broader settings.

Overall, the registry supplies a design description and outcome definitions, but not analyzed efficacy results. Any interpretation should remain at that level: the study was designed to examine OSA-related measures, while the posted record does not allow an estimate of what the comparison found.

13. Why This Trial Matters Statistically

This study is statistically relevant because it illustrates the difference between registering an outcome and reporting an analyzed result. The record describes a specific self-efficacy measure, its scoring rule, and the intended measurement times. Those elements help readers understand what the investigators planned to assess. Without the score summaries and an analysis, however, readers cannot quantify an observed difference or judge its precision.

The distinction is particularly important for outcomes measured repeatedly. A baseline and follow-up schedule can support different analytic questions, such as comparing follow-up scores or examining change. The registry record does not report which comparison was used or intended. Explicitly reporting that choice would help readers understand how the estimate relates to the study question and how baseline information was handled.

The record also lists secondary measures alongside the primary outcome. Reporting the analysis plan and outcomes across all measures would allow readers to assess the scope of testing and understand whether interpretation accounts for multiplicity. In this record, no analyses are listed, so there is no basis for assessing that issue or for distinguishing analyzed from unreported outcomes.

Finally, the study descriptions combine a focus-group objective with a randomized comparison of personalized messages and a no-treatment control. The registry does not explain the relationship between these elements. Clear descriptions of the study design, intervention delivery, masking, participant flow, and analysis population would make the intended estimand and interpretation more transparent. These reporting details matter for biostatisticians and clinical researchers because design labels alone do not show which data were analyzed or what the resulting estimate means.

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.

A central limitation is that the registry record does not report primary or secondary outcome results. With no reported self-efficacy means, standard deviations, or between-group analysis, the effect and its precision cannot be assessed. The record lists 0 analyses, and no confidence intervals or p-values are reported. This prevents statistical interpretation of the intervention comparison.

The study description leaves important design details unspecified. Although allocation is labeled randomized and masking is labeled single, the allocation method and the identity of the masked parties are not reported in the registry record. The relationship between the focus-group objective and the randomized messaging arms is also not explained. The record does not describe the message content, tailoring process, or delivery.

Outcome reporting is incomplete for interpretation. The record describes the self-efficacy scoring procedure and approximate follow-up timing, but does not report participant counts for outcome assessments, the method used to compare time points, or the analysis population. Missing-data methods and multiplicity procedures are not reported in the registry record. A sample-size justification and detailed statistical analysis plan are also not reported.

The safety information is limited to counts of affected participants and participants at risk. The registry does not describe surveillance, event definitions, follow-up completeness, or attribution. The listed counts therefore do not support a comprehensive safety assessment.

Finally, the stated population is transportation-industry employees on shift schedules, but the registry record provides no further characterization of participant eligibility or study sample. The extent to which any unreported findings would apply to other populations cannot be assessed, and the absence of outcome results means that applicability of an effect cannot be considered.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Design and Usability Testing of a Tailored Intervention About Sleep and Sleep Disorders Among Transportation Workers — NCT05039528.
• Registry record last updated 2026-10-02; status last verified 2026-09.
• Results first posted 2026-10-02.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT05039528 is listed as a completed, randomized, single-masked, parallel-group study sponsored by Brigham and Women's Hospital. It enrolled 38 participants. The intervention was personalized OSA messages, and the control was described as receiving no treatment during the experiment. The study objective refers to identifying OSA beliefs, attitudes, and knowledge among transportation-industry employees on shift schedules.

The primary outcome was OSA self-efficacy measured with the SOFHL self-efficacy subscale at baseline and follow-up approximately 2 months later. OSA Knowledge and OSA Readiness to Change are listed as secondary outcomes. The registry record describes the scoring method but does not report outcome values or an analysis; it lists 0 analyses. The safety record lists 0 serious adverse events, 0 other adverse events, and 0 deaths in both groups. These counts and the design description do not substitute for outcome estimates. The registry record does not permit assessment of efficacy, statistical precision, missing-data handling, or the study’s analysis population.