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 Measuring Adherence in Subjects With Acne Vulgaris in a Clinic Population Subtitle: Topical Benzoyl Peroxide for Acne (NCT00658112), a na phase 4 study. The primary outcome is Adherence.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00658112 |
| Phase | Phase 4 |
| Condition | Acne Vulgaris |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 20 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Wake Forest University |
| Results posted | Yes |
2. Clinical Question
Population
Subjects with acne vulgaris in a clinic population, as described by the registry title. Enrollment is listed as 20. Further eligibility details and a description of the analyzed population are not reported in the registry record.
Intervention
Topical benzoyl peroxide 5%. The arm description says subjects would receive standard instructions and a medication supply fitted with a Medication Event Monitoring System cap.
Comparator
No comparator group is listed. The study model is single group, and allocation is recorded as not applicable. The registry explicitly does not describe a like-for-like control comparison.
Primary question
What proportion of prescribed doses was actually applied during 6 weeks, with adherence monitored using the electronic cap? The registry identifies this outcome but does not report its result.
The question is about medication-use behavior rather than a comparison of clinical outcomes between treatments. The primary outcome is defined as adherence, expressed as a percentage of prescribed doses actually applied. The cap records dates and times when the medication container assembly is opened; the arm description says those records can be downloaded at the final visit. This is an electronic monitoring approach to medication use, but a recorded opening is not itself direct confirmation that a dose was applied.
Because the study is single group, the record does not support a randomized treatment comparison or an estimate of a treatment difference against a control. It also does not report a numerical adherence estimate, range, confidence interval, or analysis result. The endpoint and monitoring approach are described, but the clinical question cannot be answered from the registry results as recorded.
3. Trial Design
The study is listed as phase 4 and completed. The registry gives a start date of 2006-07, a primary completion date of 2008-05, and enrollment of 20. Acne vulgaris is the listed condition, and Wake Forest University is the named sponsor. These are registry descriptors; they do not establish how many participants contributed data to the primary outcome.
The model is single group, allocation is not applicable, and masking is none. One benzoyl peroxide arm is described: Benzoyl Peroxide 5%. The arm description states that subjects would receive standard instructions for topical benzoyl peroxide gel and a medication supply fitted with a Medication Event Monitoring System cap. The cap records dates and times the assembly is opened, with records available for download at the final visit. The description ends mid-sentence, so any further detail about the monitoring procedure is not reported in the registry record.
The primary endpoint is adherence over 6 weeks, expressed as the percentage of prescribed doses actually applied and measured using the cap. Although the arm description gives the intended medication and monitoring method, the registry does not report a comparator arm. It also states that the arms are not a like-for-like control comparison. The design therefore addresses adherence within a single group, not a between-group treatment effect.
The registry lists one outcome measure and zero analyses. It does not report the analysis population, the number contributing endpoint data, or a statistical analysis plan. The enrollment figure should not be treated as the endpoint denominator: the registry does not say how many participants had usable monitoring records or were included in an analysis. The numerical adherence result 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 | Benzoyl Peroxide 5% |
|---|---|
| STARTED | 20 |
| COMPLETED | 11 |
| NOT COMPLETED | 9 |
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 | Benzoyl Peroxide 5% |
|---|---|---|
| Participants analysed | 11 | |
| Age, Categorical: <=18 years | Participants | 11 |
| Age, Categorical: Between 18 and 65 years | Participants | 0 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 8 |
| Sex: Female, Male: Male | Participants | 3 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 7 |
| Race (NIH/OMB): White | Participants | 3 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | Participants | 11 |
6. Primary Endpoint
The registry lists the primary outcome as Adherence, measured over 6 weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Full Range |
| Unit | percentage of doses actually applied |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is adherence, defined in the registry as the percentage of prescribed doses actually applied during 6 weeks. It is intended to describe medication use over the stated observation period, rather than a change in acne severity or another clinical outcome. The registry identifies a mean as the summary parameter and the full range as the dispersion measure.
Electronic monitoring can capture when a medication container is opened, providing a time-stamped record of container use. The arm description says the Medication Event Monitoring System cap records dates and times of openings and that the data can be downloaded at the final visit. Such records can support an adherence measure, but an opening is a behavioral proxy: it does not by itself establish that the medication was dispensed, applied, or used according to instructions. The registry's endpoint description calls the measure doses actually applied, but does not explain how opening records were translated into that measure.
The outcome is useful for describing observed medication-taking behavior in the study group. However, the registry does not report the mean, full range, participant-level data, or an uncertainty interval. It also does not describe how missing monitoring records or uncertain opening events were handled. Consequently, the endpoint's definition is available, but its observed value and the precision of that value are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record establishes the study question and the planned way of monitoring medication use, but it does not provide a numerical primary outcome. Although adherence is listed as the primary measure, no mean percentage, full range, confidence interval, or statistical test result is reported in the registry record. Without those results, the amount and variability of adherence in the study group cannot be characterized.
The study is single group and has no listed comparator. Accordingly, even if a group-level adherence estimate were available, it would describe the measured behavior in this study population; it would not estimate a difference from another treatment or from an untreated control. The record specifically indicates that the arms are not a like-for-like control comparison. No causal conclusion about treatment assignment can be drawn from this design.
The measurement method also matters to interpretation. The cap records container openings, while the endpoint is described as the percentage of doses actually applied. In general, an electronic opening record is an indirect measure of use. It can document an opening time, but does not by itself confirm application or show whether the prescribed amount was used. The registry does not report a validation procedure or a rule for translating openings into applied doses. Thus, even with a reported adherence estimate, the operational definition and handling of the monitoring data would be important for judging what that estimate represents.
The registry lists enrollment of 20, but does not report the number with usable cap records or the denominator used for the adherence summary. Enrollment alone cannot establish how many participants contributed to the endpoint. The registry also lists zero analyses, so it does not provide a reported inferential analysis to assess uncertainty or test a hypothesis. Missing-data handling and the analysis population are not reported in the registry record.
In general, a confidence interval describes uncertainty around an estimate under the assumptions of the method used. No confidence interval is reported for adherence, so precision cannot be evaluated from the record. Likewise, the absence of a reported statistical test is not evidence for or against a particular adherence level. The appropriate interpretation is limited: the registry describes a completed, single-group electronic-monitoring study, but its primary numerical result and supporting analysis are not reported.
9. Statistical Methods Explained
The registry identifies the primary outcome as a mean percentage of prescribed doses actually applied and identifies the full range as the measure of dispersion. A mean is a way to summarize a set of observations with one central value. The full range describes the lowest and highest observed values, so it can show the span of observations but does not reveal how densely values are distributed between those endpoints. The actual mean and range are not reported in the registry record.
What does the electronic measure capture?
The arm description says the Medication Event Monitoring System cap records dates and times of container assembly openings. This creates a record of opening events, not a direct observation of medication application. In general, electronic monitoring can provide detail about timing that a participant's retrospective report may not capture, while still leaving uncertainty about what happened after each opening. An opening may not equal an applied dose, and an application may not necessarily correspond neatly to one opening. These are general measurement considerations, not findings about what participants did in this study.
The registry defines the endpoint as doses actually applied but does not explain the conversion from cap records to that endpoint. The rule used to define an expected dose, classify an opening, or handle multiple openings is not reported in the registry record. Nor is there a reported description of how the monitoring equipment was checked or how data quality was assessed. Without these details, readers cannot independently determine how the stated endpoint was derived from the electronic records.
What can a mean and range tell a reader?
In general, a mean gives a compact description of the average observed outcome, while the full range indicates its observed extremes. Neither measure alone describes the complete distribution. A range can be sensitive to extreme observations, and it does not indicate whether most participants had similar values or whether observations were concentrated near one end. A standard deviation, quantiles, or individual-level display can provide other views of variability, but those summaries are not reported in the registry record.
Precision is distinct from variability. Variability describes differences among observed outcomes; precision concerns uncertainty about an estimate. A confidence interval is a common way of expressing the uncertainty around an estimated mean. It depends on the data and assumptions of the method. No confidence interval or standard error is reported for the adherence endpoint. The registry therefore does not establish how precisely the mean is estimated, even apart from the fact that the mean itself is not reported.
What analysis is documented?
The registry lists one outcome measure and zero analyses. It does not report a statistical test, model, confidence interval, or adjustment procedure for the primary endpoint. An analysis plan, including the method for calculating the adherence summary, is not reported in the registry record. No particular statistical method should be inferred from the mean and range fields alone.
In general, statistical methods should match the outcome's structure and the study question. For a single-group descriptive outcome, a summary of observed values may answer a descriptive question without requiring a comparison test. If repeated observations or incomplete monitoring data are present, decisions about dependence and missingness can affect the summary. The registry does not report whether the endpoint was formed from participant-level summaries, pooled dose-level records, or another approach, so those possible analytic issues cannot be resolved from the record.
How should the planning illustration be read?
The registry's sample-size assumptions describe a planning illustration computed from an observed effect, with two-sided significance level 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are assumptions for an illustration, not evidence that the trial itself was designed as a two-arm comparison. They do not align with the listed single-group model and no-comparator design. The illustration is not observed power, and it does not establish the study's original sample-size justification. That justification is not reported in the registry record.
Sample-size calculations are generally prospective planning tools: they express how much information might be needed under specified assumptions. They do not indicate the probability that a result is true, and a calculation based on an observed effect is not a substitute for reporting the estimate and its uncertainty. The record does not report the numerical adherence result used for the illustration or the resulting participant requirements. The listed assumptions therefore cannot be used to reconstruct the study's analysis or to judge its precision.
Overall, the statistical fields describe the intended endpoint summary and a separate planning illustration, but they do not provide the underlying outcome data or inferential results. The registry record does not report enough detail to reproduce the adherence calculation or evaluate its uncertainty.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure and zero analyses. The primary outcome is adherence over 6 weeks, but a numerical result is not reported. The registry does not describe whether additional outcomes were measured outside the listed outcome, whether multiple statistical tests were planned, or whether any adjustment for multiple comparisons was used. A multiplicity strategy is not reported in the registry record.
In general, multiplicity can arise when several outcomes, time points, subgroups, or statistical tests are examined. When many tests are conducted, the chance of at least one apparently notable result can increase unless the analysis accounts for that testing structure. This general issue cannot be assessed for this study from the registry information because the analysis plan and results are not reported. The single listed outcome does not establish that no other analyses were conducted.
Missing-data methods and the endpoint analysis population are also not reported. The registry does not state how many participants had usable cap records, whether any monitoring periods were incomplete, how missing observations were treated, or whether an analysis required a minimum amount of monitoring data. Enrollment is listed as 20, but that does not define the denominator for the primary outcome.
In general, missingness can affect both the amount of information available and the interpretation of an estimate. For electronically monitored adherence, absent records could have several explanations, and an analysis needs a prespecified way to distinguish or handle them. The record does not describe such rules. It is therefore not possible to determine whether the posted outcome, if one were available, would represent all enrolled subjects or a subset with usable endpoint data.
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 |
|---|---|---|---|
| Benzoyl Peroxide 5% | 0 | 11 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Benzoyl Peroxide 5% | 0 of 11 |
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 |
|---|---|
| Benzoyl Peroxide 5% | 0 of 11 |
The registry's safety figures are listed for the Benzoyl Peroxide 5% group. The serious adverse event count is 0 among 11 at risk, and the other adverse event count is 0 among 11 at risk. Deaths are listed as 0. These are the recorded counts and denominators for the safety entries; the enrollment figure of 20 is not the denominator shown for these entries.
Zero recorded events in these entries means that the registry reports no events in the specified categories for the listed at-risk group. It does not establish that no adverse events could occur, nor does it show that all possible events were captured or reported. In general, an observed zero is compatible with uncertainty about the underlying event frequency, especially when the amount of observation is limited. The registry does not provide a confidence interval or further safety-analysis details.
The registry does not report the duration or completeness of safety follow-up, the methods used to collect adverse events, or a breakdown of non-serious events by type. The serious-event terms list is empty. These safety figures should be read as registry-reported counts, not as a comparison with another group or as proof of absence of risk. No comparator arm is listed.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a completed, single-group study examined adherence to topical benzoyl peroxide 5% for acne vulgaris using an electronic cap-monitoring approach. Its primary endpoint is defined as the percentage of prescribed doses actually applied over 6 weeks. The record also identifies the intended summary as a mean with full range as dispersion.
What the record does not establish is the observed adherence level. No mean, range, confidence interval, or primary analysis result is reported in the registry record. It is therefore not possible to say from this record how often medication was applied, how much participants varied, or how precisely adherence was estimated. The enrollment entry does not supply an endpoint denominator, and the number contributing usable monitoring data is not reported.
The design also limits the kinds of conclusions that can be drawn. With a single group and no listed comparator, the study does not provide a randomized contrast against another treatment or a control group. The record explicitly indicates that the arms are not a like-for-like control comparison. A descriptive adherence result, if reported, would characterize the measured group and would not by itself establish comparative treatment effects.
The monitoring method should be interpreted in light of what it records. An opening timestamp is evidence of container opening, not direct evidence that a dose was applied. The registry describes the outcome as doses actually applied but does not report the rule used to translate openings into applied doses. This does not invalidate the method; it identifies a measurement distinction that matters when interpreting an adherence estimate.
The most defensible conclusion is narrow: the registry documents a study designed to monitor medication use electronically, but the primary result and its analysis are not reported. The record does not support claims about the level of adherence, treatment effectiveness, or comparative safety.
13. Why This Trial Matters Statistically
This study raises a useful statistical distinction between measuring a behavior and measuring a clinical outcome. The listed primary endpoint concerns adherence, not acne improvement. Electronic monitoring can record opening times, creating a detailed behavioral trace, but the interpretation depends on how those traces relate to actual dose application. That measurement distinction is relevant to many studies in which device records are used as proxies for behavior.
The design also highlights the difference between a descriptive question and a comparative one. A single-group study can be framed around describing adherence in its participants. It cannot, without a suitable comparator, estimate a randomized between-group difference. The registry identifies the model as single group and states that the arms are not a like-for-like control comparison. Those details set the scope for statistical interpretation independently of the treatment name.
Another important issue is the distinction between enrollment and endpoint information. The registry reports enrollment of 20, while the safety entries use a denominator of 11 at risk. The denominator for the primary adherence outcome is not reported. These figures serve different roles and should not be treated as interchangeable. For any endpoint, readers need to know which participants contributed data and how incomplete observations were handled.
Finally, the record shows why outcome definitions and analysis reporting matter. It identifies a mean and full range but does not report their values, an uncertainty interval, or the analysis method. Without those elements, readers cannot evaluate the magnitude, spread, or precision of the primary outcome. The statistical interest lies not in assuming an unreported finding, but in recognizing what the record does and does not allow readers to conclude.
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 principal limitation for interpretation is that the registry does not report the numerical primary adherence result. The mean and full range are identified as intended summaries, but their values are absent. No confidence interval or statistical analysis is reported, so the outcome's magnitude, variability, and precision cannot be assessed.
The study is listed as single group, with allocation not applicable and masking none. There is no comparator group in the registry record, and the record warns that the arms are not a like-for-like control comparison. This limits interpretation to description of the study group and precludes a randomized comparison based on the listed design.
The measurement process is not fully specified. The cap records dates and times of openings, while the endpoint is described as doses actually applied. The registry does not report how openings were converted into applied doses, how unusual records were handled, or whether the electronic data were checked against another measure. Because the arm description is incomplete, further procedural details are not reported in the registry record.
The endpoint denominator and analysis population are not reported. Although enrollment is listed as 20, the number with usable monitoring data and the number included in the mean are not stated. Missing-data rules, follow-up completeness, and reasons for any unavailable observations are not reported. These omissions prevent assessment of how representative the endpoint summary would be of enrolled participants.
Finally, the registry lists zero analyses and does not report an analysis plan, multiplicity approach, or the study's own sample-size justification. The planning assumptions describe a two-arm illustration, whereas the registered study is single group. These limitations do not establish that the study was conducted improperly; they identify information that is not available in the registry record and that is needed for fuller statistical evaluation.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Measuring Adherence in Subjects With Acne Vulgaris in a Clinic Population Subtitle: Topical Benzoyl Peroxide for Acne — NCT00658112.
- Registry record last updated 2018-08-28; status last verified 2018-07.
- Results first posted 2017-03-17.
- 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
NCT00658112 is a completed phase 4, single-group study sponsored by Wake Forest University. The registry lists acne vulgaris as the condition, enrollment of 20, and dates of 2006-07 to 2008-05 for study start and primary completion. Masking is listed as none, and allocation is not applicable.
The study concerns topical benzoyl peroxide 5% and electronic monitoring of adherence. Its primary outcome is the percentage of prescribed doses actually applied over 6 weeks, summarized as a mean with full range. The cap records dates and times of container openings.
The registry lists one outcome measure and zero analyses. It does not report the primary numerical result, its uncertainty, the endpoint denominator, or the analysis population. Safety entries report 0 serious adverse events and 0 other adverse events among 11 at risk, with 0 deaths. The record describes no comparator and cautions that the arms are not a like-for-like control comparison.