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 Effects of Clobazam on Sleep and Daytime Function in Patients With Epilepsy (NCT02911025), a registered phase not stated study. The primary outcome is Change in Sleep (Total Sleep Time) in Patients With Epilepsy Treated With Clobazam.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02911025 |
| Phase | Phase not stated |
| Condition | Epilepsy |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 13 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Brigham and Women's Hospital |
| Results posted | Yes |
2. Clinical Question
Population
People with epilepsy treated with clobazam by their treating physician. The registry lists an enrollment of 13. Further eligibility details and the characteristics of those enrolled are not reported in the registry record.
Intervention
There was one group: patients treated with clobazam. Treatment was managed by the treating physician, with no interventions from the principal investigator. Participants were followed longitudinally for 1 week after reaching an effective clobazam dose. Dose details and how an effective dose was determined are not reported in the registry record.
Comparator
No separate control or comparison group is described. The registry identifies the study as a single-group follow-up, not a randomized comparison. A before-and-after comparison may be suggested by the word “change,” but the measurement used as the reference is not reported in the registry record.
Primary question
The primary question concerns change in total sleep time, measured in minutes, 1 week after reaching an effective clobazam dose. The registry identifies the outcome as a mean with standard deviation. It does not report a numerical mean change, its standard deviation, or an analysis of the outcome. A secondary sleep outcome is change in wake after sleep onset.
The study’s stated purpose was to monitor the effect of clobazam on sleep and daytime alertness in people with epilepsy. The registry does not provide a separate numerical measure of daytime alertness among the listed outcomes. Without a reported change estimate and its uncertainty, the posted record does not establish the direction or size of any observed sleep change.
3. Trial Design
This completed study, NCT02911025, is titled “Effects of Clobazam on Sleep and Daytime Function in Patients With Epilepsy.” Brigham and Women’s Hospital is listed as the sponsor. The registry gives a start of 2015-01 and a primary completion of 2017-12. Enrollment is listed as 13.
The design description identifies a single group of patients treated with clobazam by their treating physician. The principal investigator did not provide interventions. Participants were followed longitudinally for 1 week after reaching an effective clobazam dose. This description does not establish that treatment assignment was randomized; the registry does not state an allocation method. It also does not describe a separate untreated group, placebo group, or other active-treatment group. The registry explicitly notes that the arms are not a like-for-like control comparison.
The primary outcome is change in total sleep time, expressed in minutes and described using a mean and standard deviation. Its timeframe is 1 week after reaching an effective clobazam dose. Change in wake after sleep onset is listed as a secondary outcome. The registry identifies two outcome measures but lists zero analyses. It does not describe the timing or procedures for collecting the sleep measurements, the reference measurement for change, or the statistical analysis used.
The record’s sample-size assumptions describe a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Those assumptions do not match the described single-group follow-up, and the registry does not report that they were the study’s design or analysis plan. The actual design justification, if any, is not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Patients Treated With Clobazam |
|---|---|
| STARTED | 13 |
| COMPLETED | 10 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | Patients Treated With Clobazam |
|---|---|
| Lost to Follow-up | 3 |
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 | Patients Treated With Clobazam |
|---|---|---|
| Participants analysed | 13 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 13 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age, Continuous | years | 41 (SD 11.2) |
| Sex: Female, Male: Female | Participants | 7 |
| Sex: Female, Male: Male | Participants | 6 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | participants | 13 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Sleep (Total Sleep Time) in Patients With Epilepsy Treated With Clobazam, measured over 1 week after reaching effective clobazam dose.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | minutes |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change in total sleep time in patients with epilepsy treated with clobazam. Total sleep time is the duration of sleep, and the registry specifies minutes as the unit. The outcome timeframe is 1 week after reaching an effective clobazam dose. The endpoint is described as a mean, with standard deviation used to describe variation.
In general, total sleep time can summarize sleep duration over a measurement period. A change measure can describe how that duration differs between a reference measurement and a later measurement. However, the reference point, measurement instrument, aggregation method, and handling of repeated sleep observations are not reported in the registry record. The record also does not define what counts as an effective dose.
In general, the mean conveys the average change across measured participants, while the standard deviation describes the spread of individual values around that average. Neither alone communicates the precision of an estimated mean as fully as a confidence interval would. The registry does not report a mean change, standard deviation, confidence interval, or endpoint analysis, so the size, direction, and precision of the primary result cannot be assessed from the posted outcome information.
The secondary outcome concerns wake after sleep onset, another sleep measure. Its numerical result and analysis are also not reported in the registry record. The endpoint descriptions therefore identify what the study intended to monitor, but do not provide the result needed to quantify any observed change.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies a primary sleep outcome and a follow-up timeframe, but does not report the outcome’s numerical result. In particular, no mean change in total sleep time, standard deviation, confidence interval, or analysis is listed. The direction and magnitude of the observed change are therefore not available in the registry record. The secondary outcome, change in wake after sleep onset, is listed without a numerical result or analysis as well.
The distinction between an endpoint description and an outcome result matters. Naming change in minutes tells readers what was intended to be measured; it does not say whether sleep time increased, decreased, or remained similar. The specified mean and standard deviation indicate a planned way to summarize a continuous measure, but they are not themselves reported estimates. No conclusion about the observed sleep pattern can be drawn from an endpoint title alone.
Even if a change estimate were available, interpretation would depend on how change was defined and measured. The reference measurement, sleep-assessment method, and approach to repeated measurements are not reported in the registry record. It is consequently unclear from the record what measurements were contrasted or how the reported outcome, if any, would represent participants’ sleep across the follow-up period.
The study is described as a single group treated by patients’ physicians, without a like-for-like control group. A change within a group can describe what was observed over time, but, in general, it cannot by itself separate the influence of treatment from other changes that occur over time or differences in measurement. No causal interpretation is supported by the design description alone. The registry does not report a randomized comparison.
The record lists an enrollment of 13 and zero analyses. Enrollment is not the same as the number with complete primary outcome data or the number included in an analysis; those counts are not reported in the registry record. The record also does not provide information about missing sleep measurements, exclusions, or analysis populations. This leaves both the completeness of the outcome data and the precision of any estimate unknown.
The adverse-event counts are separate safety reporting information, not evidence of the primary sleep outcome. The record lists zero serious adverse events, one other adverse event, and zero deaths for the clobazam-treated group. It does not identify the other event or establish whether it was attributed to clobazam. These counts should not be used to infer the direction or size of a sleep change.
Overall, the registry record describes a small single-group follow-up and names the sleep outcomes, but supplies no numerical outcome analysis. The record therefore supports a description of the question and design, not an estimate of the change in sleep or a comparative treatment effect.
9. Statistical Methods Explained
The statistical information in the registry is limited. It describes the primary endpoint as a continuous measure summarized by a mean and standard deviation, but lists zero analyses and no numerical outcome estimates. The explanations below describe general statistical concepts; they do not imply that a particular method was used in this study.
What does a mean change describe?
For a continuous outcome such as total sleep time in minutes, a mean summarizes the average value across the observations included in an analysis. When the outcome is change, the mean would summarize the average difference between a reference and a follow-up measurement, provided those points and the calculation of change are defined. The registry names a change outcome but does not report the reference measurement or calculation details. It also does not report the resulting mean.
A mean can be informative but does not show whether individual participants had similar or very different changes. The standard deviation is a descriptive measure of spread around the mean. A larger standard deviation indicates greater variability in the observations relative to a smaller one, in general. The registry specifies standard deviation as the dispersion measure but does not provide its value. Neither the mean nor standard deviation should be mistaken for a confidence interval.
How is a confidence interval different?
In general, a confidence interval gives a range of values compatible with an estimate under the assumptions of the statistical method. It communicates the uncertainty in an estimated population quantity, whereas a standard deviation describes variability among observations. A narrow interval generally indicates greater precision than a wide interval, but precision depends on the data and model. No confidence interval for either sleep outcome is reported in the registry record.
A confidence interval also does not remove limitations in design or measurement. It cannot correct a missing comparison group, establish how the endpoint was measured, or show that an observed change was caused by treatment. It addresses statistical uncertainty under specified assumptions, not every source of uncertainty or bias.
What can a single-group change show?
In general, repeated measurement in one group can describe the group’s observed course over time. If a reference and follow-up measurement are available, an analysis may estimate the average within-person change. But without a concurrent comparison group, that change does not isolate the effect of treatment. Time trends, other care, measurement variation, and other factors may also influence observed measurements. This is a general limitation of interpreting uncontrolled changes, not a finding about what occurred in this study.
The registry describes one group treated by their physicians and explicitly notes that there is no like-for-like control comparison. It does not report how the change outcome was calculated, whether observations were paired, or which participants contributed data at each time. Those details are needed to understand the exact analysis and its assumptions.
Why can over-dispersion matter?
In general, over-dispersion means that the observed variability is greater than a statistical model expects. If a model assumes less variability than the data actually contain, its uncertainty estimates may be too small and its conclusions may appear more precise than warranted. Model choices should reflect the outcome’s distribution and data structure. The primary outcome is described as continuous and summarized by a mean and standard deviation; the registry does not report a model, an over-dispersion assessment, or an analysis. Over-dispersion is therefore a general concept, not a reported feature of this study.
What do the planning assumptions mean?
The registry’s sample-size assumptions describe a planning illustration, not an observed result or the documented design of this single-group study. The stated illustration uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect defined as a stated fraction of an observed effect. The assumptions do not report the actual sample-size justification for this trial, and no such justification is reported in the registry record.
In general, sample-size planning asks how much information a proposed design would need to detect a specified effect under stated assumptions. Such a calculation is not “observed power” after results are collected, and it does not indicate the probability that a finding is true. Equal allocation between two arms is particularly distinct from the registry’s description of a single group. Any planning illustration based on a two-arm comparison should not be treated as a description of the actual trial or as evidence about its outcome.
The registry does not report a statistical analysis plan, test statistic, model, significance test, or interim analysis. It is not possible to determine from the record whether analyses were adjusted, how repeated measurements were handled, or how uncertainty was calculated. Statistical terms can explain what such methods generally do, but they cannot fill in methods or results that are not reported.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two outcome measures: change in total sleep time as the primary outcome and change in wake after sleep onset as a secondary outcome. It lists zero analyses. A count of outcomes does not establish how many statistical tests were conducted, and the record does not report a multiplicity strategy. It is therefore not possible to determine whether any adjustment for examining multiple outcomes was planned or performed. In general, testing multiple outcomes can increase the chance of at least one apparently notable result by chance; methods for addressing that issue depend on the analysis plan.
The record does not report missing-data counts, reasons for missing measurements, or methods for handling missingness. It also does not state how many enrolled participants contributed primary or secondary endpoint data. The enrollment figure alone cannot establish the analysis population or the completeness of follow-up. In general, missing observations can affect both the estimate and its precision, particularly when the likelihood of missingness is related to the outcome or participant characteristics.
The analysis population is not described. The record does not say whether outcomes were analyzed for everyone enrolled, only those with paired measurements, or another group. It also does not report exclusions or protocol deviations. No approach to imputation, sensitivity analysis, or adjustment for missing data is reported in the registry record.
These omissions limit assessment of whether the posted endpoint descriptions correspond to analyses of all enrolled participants or a subset. They also prevent evaluation of how missingness and multiple outcomes may have affected the reported evidence. Since no outcome analyses are listed, there are no reported analysis estimates to assess for these issues.
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 |
|---|---|---|---|
| Patients Treated With Clobazam | 0 | 13 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Patients Treated With Clobazam | 0 of 13 |
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 |
|---|---|
| Patients Treated With Clobazam | 1 of 13 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Patients Treated With Clobazam |
|---|---|---|
| Sedation Side Effect | Product Issues | 1 of 13 |
For the group titled “Patients Treated With Clobazam,” the registry lists 13 at risk for serious adverse events and zero affected. It lists 13 at risk for other adverse events and one affected. The death count is zero. These are registry counts; they do not provide an event description for the other adverse event.
The serious-adverse-event terms list is empty. The record does not report whether the other adverse event was considered related to clobazam, how it was defined, when it occurred, or how severity was assessed. It also does not provide further context about ascertainment or follow-up for safety reporting. A count alone cannot answer those questions.
These figures are descriptive for the recorded group and should not be read as a comparison between treatments. There is no separate control group in the design description, and the counts do not establish that clobazam caused or did not cause an event. The absence of a listed serious event in this record is not a general estimate of risk; the registry does not provide the detail needed for broader inference.
12. What the Result Does, and Does Not, Mean
The record identifies a clinical question about sleep and daytime alertness in people with epilepsy treated with clobazam. It specifies a primary measure—change in total sleep time in minutes—at 1 week after reaching an effective clobazam dose, and it lists change in wake after sleep onset as a secondary outcome. These details describe what the study set out to monitor.
The record does not report a numerical result or analysis for either outcome. It therefore does not show how much total sleep time changed, whether the change was positive or negative, how variable participant measurements were, or how precisely an average change was estimated. The same absence of outcome results applies to wake after sleep onset. An endpoint’s title is not a result.
The single-group design also limits what any change over time could establish. In general, an uncontrolled before-and-after observation can describe a course of measurements, but it cannot by itself distinguish treatment-related change from other influences over time. The registry does not describe a like-for-like control comparison or randomized allocation. It also does not specify the reference measurement used to define change.
The safety record lists zero serious adverse events, one other adverse event, and zero deaths in the clobazam-treated group. The type and attribution of the other event are not reported. These figures do not answer the sleep-outcome question and cannot establish a comparative safety profile.
Accordingly, the registry record documents a completed study, its single-group follow-up, its intended sleep endpoints, and limited adverse-event counts. It does not provide the outcome estimates needed to quantify observed sleep changes or their precision. This is a statement about what the record reports, not a conclusion about what the study may have found outside the registry entry.
13. Why This Trial Matters Statistically
This study illustrates why registry entries need to be read as structured records of design and reporting rather than as complete statistical reports. The record gives a specific primary endpoint, its unit, an outcome timeframe, and the intended descriptive summary. Yet it lists zero analyses and does not provide a numerical estimate. Without an estimate and its uncertainty, readers cannot assess the size or direction of a result.
The design description also matters. A single group followed after physician-managed clobazam treatment can raise a useful question about measurements over time, but it is not equivalent to a randomized comparison. General statistical interpretation must distinguish observed change from a treatment effect. The record explicitly notes that the arms are not a like-for-like control comparison, and describes just one treated group.
Several basic elements needed to assess the endpoint are not reported: the reference measurement for change, the measurement method, analysis population, missing-data handling, and statistical analysis. These are not technical details without consequence. They determine what the outcome represents, which observations contribute to it, and how precisely an estimate can be interpreted.
The planning assumptions offer another statistical lesson. Their equal-allocation, two-arm framework is not the single-group design described for the study. A planning illustration is not evidence of observed power, a result, or a documented rationale for the actual study. Distinguishing a hypothetical calculation from the design that was carried out prevents a misleading reading of planning language.
For biostatisticians and clinical researchers, the record is a reminder to separate endpoint definitions, study design, analysis methods, and results. Each answers a different question, and one cannot substitute for another. Here, the design and intended measures are described, but the numerical outcome evidence is not reported in the registry record.
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 most direct limitation for interpretation is that the registry lists zero analyses and does not report numerical results for the primary or secondary sleep outcome. There is no mean change, standard deviation, confidence interval, or test result to assess. Consequently, the result’s direction, magnitude, and precision are unknown from this record.
The single-group design has no like-for-like control comparison, and randomized allocation is not stated. Any observed change over time, if measured, could not by itself distinguish treatment-associated change from other influences. The registry also does not identify the reference measurement underlying the primary change endpoint, or describe the sleep-measurement method or data-collection procedures.
The enrollment is listed as 13, but the number with endpoint data, the analysis population, and the completeness of follow-up are not reported in the registry record. Missing-data counts and handling, exclusions, and reasons for any incomplete measurements are also not reported. The registry does not describe an analysis plan, model, or method for uncertainty estimation.
Only limited safety detail is listed. The other adverse event is not named or attributed, and the serious-adverse-event terms list is empty. The record does not give enough information to characterize event definitions or ascertainment. Finally, the planning assumptions describe an equal-allocation, two-arm illustration, which is not the single-group design described. The actual sample-size justification is not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Effects of Clobazam on Sleep and Daytime Function in Patients With Epilepsy — NCT02911025.
- Registry record last updated 2021-02-08; status last verified 2021-02.
- Results first posted 2021-02-08.
- 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
NCT02911025, “Effects of Clobazam on Sleep and Daytime Function in Patients With Epilepsy,” is listed as completed and sponsored by Brigham and Women’s Hospital. The registry gives a start of 2015-01, a primary completion of 2017-12, and enrollment of 13.
The design describes one group treated with clobazam by their treating physician, without principal-investigator interventions, followed for 1 week after reaching an effective dose. The primary outcome is change in total sleep time in minutes; change in wake after sleep onset is secondary. The record lists two outcome measures and zero analyses.
No numerical sleep-outcome results, analysis population, or missing-data approach are reported in the registry record. Safety counts for the treated group are zero serious adverse events, one other adverse event, and zero deaths. The other event is not identified.