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 24-hour IOP-lowering Effect of Brimonidine 0.1% (NCT00457795), a non-randomized phase 4 study. The primary outcome is Intraocular Pressure (IOP) for a 24-Hour Period at Week 4.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00457795 |
| Phase | Phase 4 |
| Condition | Open-angle Glaucoma, Ocular Hypertension |
| Allocation | Non-Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 15 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Allergan |
| Results posted | Yes |
2. Clinical Question
Population
Patients with open-angle glaucoma or ocular hypertension. Enrollment was 15. The primary-outcome population is described as all patients who started the study, with the parenthetical wording “randomized” despite the record listing non-randomized allocation.
Intervention
Brimonidine 0.1%, described in the registry as three-times-daily treatment. The study is listed as Phase 4 and has a single-group model.
Comparator
No separate comparator group is described. The registry lists non-randomized allocation and a single-group model, so the record does not describe a like-for-like control comparison.
Primary question
What was the intraocular pressure profile over a 24-hour period at Week 4 among participants in the brimonidine 0.1% group? The registry identifies the primary outcome as mean IOP in millimeters of mercury, but its numerical result is not reported in the registry record.
The registry describes an evaluation of the efficacy and safety of brimonidine 0.1% in patients with glaucoma or ocular hypertension. Its primary outcome concerns IOP across diurnal and nocturnal periods at Week 4. A separate secondary outcome concerns change from baseline in IOP over a 24-hour period at Week 4. These are related but distinct questions: a Week 4 IOP value describes pressure at that follow-up, while a change-from-baseline measure describes how the follow-up value differs from an earlier measurement. Neither can be quantified from the registry information available for this analysis.
The study design allows a description of outcomes in the treated group, but without a comparator it cannot establish how those outcomes would differ from outcomes under another treatment or no treatment. The record also does not report numerical primary or secondary outcome results, so the question can be stated but not answered with an estimate of the treatment-associated change.
3. Trial Design
This is a completed Phase 4 study of brimonidine 0.1%, sponsored by Allergan. The registry lists a single-group model, non-randomized allocation, and no masking. Enrollment was 15. The recorded study start was 2006-12 and primary completion was 2009-02. The study concerns open-angle glaucoma and ocular hypertension.
The intervention is brimonidine 0.1%, also identified by the registry name Alphagan® P. The brief description says the study evaluates brimonidine 0.1% given three times daily. The record does not describe a separate control arm, so there is no randomized treatment contrast in the design as registered. Nor does it describe masking that would reduce the possibility that participants or study personnel knew the treatment being given.
The primary outcome is mean intraocular pressure for a 24-hour period at Week 4, measured in millimeters of mercury. The registry describes diurnal measurements during the awake period and nocturnal measurements during the sleep period, with body position varying by measurement period. The secondary outcomes include change from baseline in IOP across 24 hours, ocular perfusion pressure across 24 hours, and change in ocular perfusion pressure across 24 hours, all at Week 4.
The primary-outcome population is labeled “Intent to Treat” and defined as all patients who started the study, followed by the parenthetical “randomized.” That wording does not align clearly with the separately listed non-randomized allocation. The registry record does not clarify this inconsistency or report how many participants contributed data to each outcome. Enrollment therefore should not be assumed to equal the analysis population for every measurement.
A completed status indicates the registry lists the study as completed; it does not supply the missing outcome estimates. The statistical analysis plan, handling of repeated measurements, missing-data procedures, and any prespecified sample-size justification are 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 | Brimonidine 0.1% |
|---|---|
| STARTED | 15 |
| COMPLETED | 15 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Intent to Treat defined as all patients who started the study (randomized)
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 | Brimonidine 0.1% |
|---|---|---|
| Participants analysed | 15 | |
| Age Continuous | years | 58.3 (SD 7.8) |
| Sex: Female, Male: Female | Participants | 10 |
| Sex: Female, Male: Male | Participants | 5 |
6. Primary Endpoint
The registry lists the primary outcome as Intraocular Pressure (IOP) for a 24-Hour Period at Week 4, measured over Week 4.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | Millimeters of mercury (mmHg) |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is mean intraocular pressure over a 24-hour period at Week 4, reported in millimeters of mercury. The registry describes IOP as a measurement of fluid pressure inside the eye. Measurements were planned during the diurnal awake period, specified as 7AM-11PM, and the nocturnal sleep period, specified as 11PM-7AM. During the diurnal period, measurements were taken in sitting and supine positions; during the nocturnal period, measurements were taken supine.
As general context, measuring IOP addresses the pressure feature named in the study’s clinical question. Capturing both awake and sleep periods can describe whether the measured pressure profile varies across the day-night cycle, while noting position makes clear that the recorded values were not all obtained under the same posture. These details define what the endpoint represents; they do not establish that the measurements were analyzed separately or that a particular measurement was most important.
The primary endpoint is specified as mean IOP at Week 4, not explicitly as change from baseline. Change from baseline in IOP over a 24-hour period at Week 4 is listed as a secondary outcome. That distinction matters when interpreting an estimate: an absolute Week 4 mean and a within-participant change answer different statistical questions. The numerical mean, standard deviation, and any estimate of change are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies the primary outcome and its measurement schedule, but does not report the numerical Week 4 IOP result. The mean and standard deviation for the primary outcome are not reported in the registry record. There is therefore no posted estimate to describe, no confidence interval with which to assess precision, and no reported test result from which to judge statistical compatibility with a null hypothesis. No conclusion about the magnitude or direction of the observed IOP profile can be drawn from the available record.
The study is listed as single-group and non-randomized, with no masking and no separate comparator group. Any outcome estimate, if reported, would describe measurements in the brimonidine 0.1% group. Without a control comparison, changes observed over time could not be separated statistically from other influences such as natural variation, measurement conditions, or changes occurring during the study. This is a design limitation, not evidence that any particular alternative explanation occurred.
The registry lists 15 participants enrolled. That number describes enrollment and does not by itself establish how many had complete Week 4 measurements or were included in each analysis. The number analyzed for the primary outcome is not reported in the registry record. The registry’s population description refers to all patients who started the study and also includes the word “randomized,” even though allocation is listed as non-randomized. The record does not explain the wording or specify how participants who did not complete measurements were handled.
The secondary outcomes include IOP change from baseline and ocular perfusion pressure (OPP) level and change over a 24-hour period at Week 4. Their numerical estimates are not reported in the registry record. The record lists four outcome measures and zero analyses. In this context, the absence of reported analyses means that estimates, uncertainty measures, and inferential results cannot be assessed from the registry record; it does not demonstrate that no analysis was conducted outside the record.
General statistical context: a confidence interval expresses a range of estimates compatible with the data and a stated statistical procedure. Its width helps readers judge precision, while its position helps readers judge the direction and scale of an estimate. Neither can be discussed for this primary outcome because no estimate or interval is reported. A p-value, if reported, would address compatibility with a specified null model rather than establish clinical importance. No p-value is reported for the primary outcome.
Accordingly, the posted registry information supports a description of the intended endpoint and design, but not a quantitative account of the result. It does not establish a treatment effect, its uncertainty, or a comparison with another treatment. Absence of numerical results must not be mistaken for a finding of no change or no difference.
9. Statistical Methods Explained
General statistical context: a continuous outcome is measured on a scale where values can take a range of numerical levels. The registry identifies IOP as such an outcome and specifies that the primary parameter is the mean, with standard deviation as the dispersion measure. A mean describes the central level of a set of measurements. A standard deviation describes how spread out individual measurements are around that mean. The two answer different questions and should be read together when both are reported.
In this study, the endpoint is not described as one measurement at a single clock time. It covers a 24-hour period divided into a diurnal awake period and a nocturnal sleep period, with specified body positions. General statistical context: repeated measurements from the same participant are usually related rather than independent. An analysis of such data may need to account for within-participant dependence. The registry does not report whether measurements were summarized by period or position, modeled jointly, or analyzed by another method. The statistical analysis plan is not reported in the registry record.
The primary outcome is mean IOP at Week 4. A mean alone would describe the average measurement level in the analyzed group, but would not convey how much individual values varied or how precisely the group mean was estimated. Standard deviation describes individual-level spread; a confidence interval for the mean would describe uncertainty in the estimated group mean. The registry does not report the mean, standard deviation, confidence interval, or participant count contributing to the primary outcome. No numerical primary result can therefore be interpreted.
The secondary IOP outcome is change from baseline over a 24-hour period at Week 4. General statistical context: change scores compare a follow-up measurement with a baseline measurement, and their interpretation depends on how both measurements were defined and analyzed. A change score is not interchangeable with a follow-up mean. The registry record does not report the baseline value, the Week 4 change estimate, its dispersion, or an uncertainty interval. It also does not describe whether baseline adjustment was used in an analysis of the Week 4 outcome.
The registry lists ocular perfusion pressure as another outcome, both as a 24-hour measure and as change over a 24-hour period at Week 4. The formulas, component measurements, and statistical methods used for OPP are not reported in the registry record. No numerical results for either OPP outcome are reported. Thus, the definitions identify the intended measures but do not permit comparison of their levels or changes.
General statistical context: a comparator can help distinguish an outcome observed under one intervention from what might have happened under another condition. In a randomized comparison, random allocation is intended to make treatment groups comparable in expectation, although chance differences can remain. This study is listed as non-randomized and single-group, and no comparator is described. As a result, a within-group estimate, even if available, would not have the same interpretation as a randomized between-group treatment contrast.
The record lists no masking. General statistical context: masking can reduce the influence of knowledge of assigned treatment on some aspects of behavior, measurement, or assessment. Its relevance depends on the outcome and study procedures. The record does not report whether any safeguards beyond masking were used, so none should be presumed.
General statistical context: over-dispersion occurs when observed variability is greater than a statistical model expects. If present, it can make standard errors too small and intervals too narrow when the model fails to account for it. This is a general concern for some outcome distributions, not a finding about this study. Since the primary outcome is continuous and the numerical data and analysis model are not reported, there is no basis to assess over-dispersion or model fit in this record.
The registry includes planning assumptions for a sample-size illustration: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. Such an illustration is not the trial’s observed power and is not evidence of the study’s original design rationale. The actual study is listed as single-group and non-randomized, so a hypothetical two-arm planning framework does not describe its registered design. The observed effect needed for the illustration is not reported, and no resulting participant counts are available in the registry record. The protocol’s sample-size justification is not reported in the registry record.
General statistical context: power is a property of a planned design under particular assumptions, not a retrospective measure of whether a result is true. Sample-size calculations can illustrate how planning requirements vary with assumptions about effect size, variability, significance level, and allocation. They cannot replace the observed estimate and its uncertainty. No sample-size illustration should be interpreted as the number of participants actually analyzed or as proof that the study could detect a particular effect.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists four outcome measures: the primary IOP outcome and secondary outcomes concerning IOP change, OPP, and OPP change over a 24-hour period at Week 4. It lists zero analyses. Numerical results and inferential statistics for these outcomes are not reported in the registry record.
General statistical context: when a study tests or estimates several outcomes, the chance of at least one apparently notable result can increase if each is examined without considering the set of analyses. Multiplicity methods can address this issue, but the appropriate approach depends on which outcomes and comparisons were planned and on the purpose of the analysis. A multiplicity strategy is not reported in the registry record. The record also does not describe whether secondary outcomes were treated as confirmatory or exploratory.
Missing-data procedures are not reported in the registry record. The outcome description labels the primary population as intent to treat and defines it as all patients who started the study, with wording that also says “randomized.” Because allocation is listed as non-randomized, the terminology is not fully aligned. The record does not explain the discrepancy, identify outcome-specific analysis counts, or report how incomplete measurements were handled. It is therefore not possible to determine whether all enrolled participants contributed to the reported analyses.
Interim analyses and stopping rules are not reported in the registry record. The record also does not specify a prespecified statistical analysis plan, the model used for repeated measurements, or any adjustment for baseline values. These omissions limit assessment of how the outcomes were analyzed and whether the reported result, if available elsewhere, follows a prespecified approach.
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 |
|---|---|---|---|
| Brimonidine 0.1% | 0 | 15 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Brimonidine 0.1% | 0 of 15 |
The adverse-event record lists 15 participants at risk for serious adverse events and 0 affected. It also lists 15 participants at risk for other adverse events and 0 affected. No serious adverse-event terms are listed. A death count is not reported in the registry record.
These figures describe the entries in the registry for the recorded group; they do not establish that no adverse events occurred outside the registry’s reporting definitions or observation period. The record does not provide event-level descriptions, timing, severity beyond the serious/non-serious categorization, or a detailed method for collecting events. The listed counts also do not report how much observation time each participant contributed.
General statistical context: a zero recorded count is not the same as proof that the underlying event risk is zero. With a limited number of participants, uncommon events may not be observed, and a zero count does not quantify the range of plausible underlying risks. The registry entries should therefore be read as recorded counts in the stated group, not as a guarantee of safety or a comparison with another treatment. No comparator-group safety figures are described.
12. What the Result Does, and Does Not, Mean
The registry record describes a Phase 4, single-group study of brimonidine 0.1% in patients with open-angle glaucoma or ocular hypertension. It specifies a primary endpoint of mean IOP over 24 hours at Week 4, including diurnal and nocturnal measurement periods and defined body positions. It also lists secondary outcomes for IOP change and OPP level and change.
What the registry record does not provide is the numerical primary outcome, the standard deviation, an uncertainty interval, or a primary-outcome analysis. The secondary outcome estimates and analysis results are also not reported in the registry record. Consequently, the direction, size, and precision of any observed outcome cannot be described. This absence is not evidence that there was no change.
The design also sets limits on what an outcome could establish. The record lists non-randomized allocation and a single-group model, with no separate comparator. A group’s Week 4 measurements could describe that group, but they would not by themselves establish what would have happened under another treatment or without the intervention. No comparative treatment effect is available to interpret.
General statistical context: clinical interpretation depends not only on an estimated effect but also on its precision, the measurement’s meaning, the design, and the analysis population. A small or large p-value alone does not establish whether an effect is clinically important, and a statistically uncertain estimate does not demonstrate absence of an effect. In this case, the essential numerical estimates are missing, so neither magnitude nor statistical uncertainty can be evaluated.
The registry’s safety entries record 0 participants affected among 15 at risk for serious adverse events and 0 among 15 at risk for other adverse events. These entries are descriptive counts and do not establish that risk is absent. The death count is not reported in the registry record, and the record gives no comparator safety data.
In short, the record establishes the study’s stated question, outcomes, and design characteristics, but it does not provide the results needed to determine what the measurements showed. No conclusion that brimonidine 0.1% did or did not lower IOP is supported by these registry data alone.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of the difference between a well-defined measurement plan and a reportable result. The registry describes a 24-hour IOP endpoint at Week 4 in considerable measurement detail, including awake and sleep periods and body position. Yet without the numerical mean, standard deviation, or analysis count, readers cannot assess the observed pressure profile or its precision.
The design is important to interpretation. A single-group, non-randomized study can describe measurements in the treated group, but it lacks a separate control group for estimating a between-group contrast. This does not make a descriptive outcome meaningless; it does mean that causal attribution requires caution. A change over time, if reported, would not alone show what would have occurred in the absence of treatment.
The registry also illustrates why outcome wording matters. The primary endpoint is mean IOP at Week 4, while change from baseline in IOP is listed separately as a secondary outcome. Those measures have different interpretations, and readers need the actual estimate and analysis details to know which claim the results support. The population description’s reference to randomized participants also sits uneasily alongside the non-randomized allocation, underscoring the importance of clear design and population reporting.
Finally, the safety entries need to be read as recorded counts, not as conclusive evidence about risk. The absence of numerical efficacy results, an analysis plan, and missing-data details limits a complete statistical appraisal. For clinical researchers, the key lesson is that endpoint definitions and registry status cannot substitute for transparent outcome estimates, uncertainty measures, and clear reporting of who was analyzed.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The central limitation is that the registry record does not report numerical results for the primary outcome. It does not provide the Week 4 mean IOP, standard deviation, confidence interval, or analysis count. Without these, the observed profile and its precision cannot be evaluated. Numerical secondary-outcome results are also not reported.
The study is listed as single-group and non-randomized, with no masking and no comparator group. Thus, the registry describes no controlled treatment contrast. Even if within-group measurements were available, changes could not be attributed uniquely to the intervention on the basis of this design alone.
Enrollment was 15, but the number contributing to each outcome is not reported in the registry record. The stated intent-to-treat population is defined as all patients who started the study and includes the parenthetical “randomized,” despite non-randomized allocation. The record does not resolve this wording or explain how incomplete data were handled. Missing-data methods and the analysis population for each outcome are not reported in the registry record.
The record does not describe the statistical model or how measurements within participants, across periods, or across body positions were handled. It does not report whether baseline adjustment was used, whether outcomes were analyzed separately by period or position, or whether multiplicity was addressed. The protocol’s sample-size justification, any interim analyses, and the statistical analysis plan are not reported in the registry record.
Safety interpretation is also constrained: the recorded counts do not include detailed event descriptions or a reported death count, and no comparator safety data are described. These limitations restrict what can be concluded from the registry record, without implying that unreported procedures or analyses were absent from the full study documentation.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: 24-hour IOP-lowering Effect of Brimonidine 0.1% — NCT00457795.
- Registry record last updated 2011-11-24; status last verified 2011-10.
- Results first posted 2011-11-24.
- 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
This completed Phase 4 study enrolled 15 participants with open-angle glaucoma or ocular hypertension and evaluated brimonidine 0.1%, described as given three times daily. The registry lists a single-group model, non-randomized allocation, and no masking. Its primary outcome is mean IOP over a 24-hour period at Week 4, with measurements specified for diurnal and nocturnal periods and particular body positions.
The registry lists three secondary outcomes concerning IOP change and OPP level and change at Week 4. It reports no numerical results or analyses for these outcomes. Serious and other adverse-event entries each list 0 affected among 15 at risk; the death count is not reported in the registry record. Without outcome estimates and uncertainty measures, the magnitude and precision of the study findings cannot be assessed from this record.