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 Safety and Efficacy Study of Bimatoprost in the Treatment of Men With Androgenic Alopecia (NCT01325337), a randomized phase 2 study. The primary outcome is Change From Baseline in Target Area Hair Count (TAHC).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01325337 |
| Phase | Phase 2 |
| Condition | Alopecia, Alopecia, Androgenetic, Baldness |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 307 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Allergan |
| Results posted | Yes |
2. Clinical Question
Population
Men with androgenic alopecia were eligible for the study. The primary outcome population was the Modified Intent-to-Treat Population: randomized participants who received treatment and had both baseline and post-baseline measurements, with data available for the outcome. The registry record reports enrollment of 307 participants overall.
Intervention
The study evaluated three bimatoprost formulations. Each was described as an approximately one mL dose applied evenly to a prespecified scalp area once daily for 6 months. The record does not state the formulation concentrations or other details that would allow the formulations to be distinguished pharmacologically.
Comparator
The comparators were bimatoprost vehicle solution and minoxidil 5% solution. Vehicle was applied once daily, while minoxidil 5% solution was applied twice daily; both were described as approximately one mL per application for 6 months. The study summary says minoxidil was open-label, while other treatments were double-blinded.
Primary question
The primary outcome was change from baseline to Month 6 in target area hair count, measured in terminal hairs/cm^2. The question was whether the measured count changed during treatment in the study groups. The registry record does not report the group results or a numerical comparison, so it does not permit a conclusion about the size or precision of any difference between treatments.
3. Trial Design
This was a randomized, parallel-group phase 2 study, with 307 participants enrolled. The registry record classifies the study as triple-masked. Its study summary describes a more specific masking arrangement: treatments were double-blinded except for minoxidil 5% solution, which was open-label. The record does not identify which groups of people were masked under the triple-masking classification.
The interventions were bimatoprost Formulations A, B, and C, bimatoprost vehicle solution, and minoxidil 5% solution. Each bimatoprost formulation and the vehicle were applied once daily for 6 months; minoxidil was applied twice daily for 6 months. The record describes an approximately one mL dose applied evenly to a prespecified scalp area. It does not report the allocation ratio or the number randomized to each intervention group.
The study began in 2011-06, had primary completion in 2012-08, and is marked completed. The primary outcome was change from baseline in target area hair count at Month 6. Secondary outcomes included response categories from the Investigator Global Assessment and Global Panel Review, as well as change in target area hair width and darkness. The registry record does not report the detailed randomization procedure, the protocol’s statistical analysis plan, or a sample-size justification. Those details should not be inferred from the study’s phase or enrollment.
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 | Bimatoprost Formulation A | Bimatoprost Formulation B | Bimatoprost Formulation C | Vehicle to Bimatoprost | Minoxidil 5% Solution |
|---|---|---|---|---|---|
| STARTED | 61 | 61 | 62 | 62 | 61 |
| COMPLETED | 56 | 52 | 53 | 52 | 53 |
| NOT COMPLETED | 5 | 9 | 9 | 10 | 8 |
Reasons for not completing this period:
| Reason | Bimatoprost Formulation A | Bimatoprost Formulation B | Bimatoprost Formulation C | Vehicle to Bimatoprost | Minoxidil 5% Solution |
|---|---|---|---|---|---|
| Adverse Event | 0 | 2 | 2 | 1 | 2 |
| Lost to Follow-up | 2 | 2 | 2 | 1 | 2 |
| Personal Reasons | 2 | 5 | 4 | 8 | 3 |
| Withdrawal by Subject | 1 | 0 | 1 | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: Participants from the Modified Intent-to-Treat Population (all randomized participants who received treatment and had both Baseline and post-Baseline measurements) who had data available for this outcome measure.
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 | Bimatoprost Formulation A | Bimatoprost Formulation B | Bimatoprost Formulation C | Vehicle to Bimatoprost | Minoxidil 5% Solution | Total |
|---|---|---|---|---|---|---|---|
| Participants analysed | 61 | 61 | 62 | 62 | 61 | 307 | |
| Age, Customized: 18 to 34 years | Participants | 19 | 18 | 20 | 18 | 18 | 93 |
| Age, Customized: 35 to 50 years | Participants | 42 | 43 | 42 | 44 | 43 | 214 |
| Sex: Female, Male: Female | Participants | 0 | 0 | 0 | 0 | 0 | 0 |
| Sex: Female, Male: Male | Participants | 61 | 61 | 62 | 62 | 61 | 307 |
6. Primary Endpoint
The registry lists the primary outcome as Change From Baseline in Target Area Hair Count (TAHC), measured over Baseline, Month 6.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | terminal hairs/cm^2 |
| Endpoint classification | Continuous Endpoint |
The primary endpoint was change from baseline to Month 6 in target area hair count (TAHC), measured by digital imaging analysis and expressed in terminal hairs/cm^2. A positive change was defined as an increase in the number of terminal hairs. This is a continuous measure: each participant’s result can be represented by a numerical change rather than only by a category such as improved or not improved.
Hair count is used to quantify the number of terminal hairs in a specified scalp area. Digital imaging offers a way to measure that target area, while the baseline-to-Month 6 change focuses on how the measured count moved over the treatment period. The endpoint description does not establish that a measured change is perceptible, important to participants, or sustained beyond Month 6.
The primary outcome population was the Modified Intent-to-Treat Population. It included randomized participants who received treatment and had both baseline and post-baseline measurements, provided data were available for the outcome. This definition means the endpoint population was not simply all participants enrolled. Numerical group means, standard deviations, participant counts for the endpoint, and comparisons are not reported in the registry record. The direction of the endpoint is defined, but the actual observed changes cannot be assessed.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the study question and measurement plan but does not report the primary outcome’s numerical results. Although the endpoint is defined as change in target area hair count from baseline to Month 6, there are no group means, standard deviations, estimates of between-group differences, or confidence intervals in the record described by these registry entries. There are also no reported p-values or analysis results. Therefore, the record does not support a numerical interpretation of change in any group or a comparison among bimatoprost, vehicle, and minoxidil.
The endpoint description states that a positive change indicates an increase in terminal hairs. This is a definition, not a report that any group experienced a positive change. No direction or magnitude of observed change can be inferred from the treatment descriptions, the enrollment total, or the study’s completed status.
The safety information reports serious adverse event counts by group. One participant in each of Bimatoprost Formulations B and C and the vehicle group was recorded with a serious adverse event; none were recorded in Formulation A or the minoxidil group. The group denominators were 61, 61, 62, 62, and 61, respectively. These descriptive counts do not establish whether an event was caused by treatment, and they do not replace a complete assessment of safety. The record lists six serious-event terms, each at 1.6%, without assigning those terms to a particular group in the information.
The record also gives counts for participants with other adverse events: 6 for Formulation A, 11 for Formulation B, 4 for Formulation C, 7 for vehicle, and 10 for minoxidil. These counts describe what was recorded; they do not indicate comparative risk without additional context about event definitions, follow-up, severity, and analysis. Death counts are not reported in the registry record.
Overall, the posted information is insufficient to judge the primary outcome’s size, precision, or comparative pattern. It is also insufficient to establish the relative safety of the treatments. A completed trial designation does not itself supply evidence about the endpoint results.
9. Statistical Methods Explained
The registry record describes a randomized, parallel-group study with a continuous primary outcome, but does not report the statistical analysis used for that outcome. The distinction matters: a description of the endpoint and its population is not the same as an analysis plan or a result. No inferential procedure, adjustment method, confidence interval, or p-value is reported in the registry record.
What does a continuous outcome mean?
In general, a continuous outcome can take a range of numerical values. Here, the endpoint was change in target area hair count, expressed in terminal hairs/cm^2. The record specifies a mean as the summary parameter and standard deviation as the dispersion measure. In general, a mean describes the central value of a group, while a standard deviation describes how dispersed individual measurements are around that mean. Neither can be interpreted for the study groups because their numerical results are not reported in the registry record.
Change from baseline compares a participant’s measurement at follow-up with that participant’s baseline measurement. In general, analyzing change can describe how measurements moved over time, but the interpretation depends on the chosen statistical method and the available observations. The endpoint definition gives the measurement times as baseline and Month 6. It does not report how missing measurements were handled, whether baseline values were included as covariates, or whether the analysis accounted for other factors.
What does randomization contribute?
In general, random allocation is intended to reduce systematic differences between groups at the start of a trial. A parallel design assigns participants to treatment groups that are followed concurrently rather than having each participant receive every treatment in sequence. Randomization does not guarantee that groups will be identical, especially in a particular realized trial, and it does not by itself establish the validity of an analysis. The registry record identifies randomization and a parallel model, but does not report the sequence-generation method, allocation concealment details, or allocation ratio.
How should precision be understood?
In general, a confidence interval expresses a range of values compatible with the data under the assumptions of the statistical method. Its width indicates precision: wider intervals indicate more uncertainty about the estimated quantity. A p-value, in general, evaluates how compatible data are with a specified null model under stated assumptions; it is not the probability that a treatment works or that the null hypothesis is true. Neither confidence intervals nor p-values for the primary endpoint are reported in the registry record, so statistical precision and evidence against a null comparison cannot be evaluated.
Standard deviations and standard errors have different roles. In general, a standard deviation describes variation among individual measurements, while a standard error describes uncertainty in an estimated quantity, such as a mean. The endpoint is specified with a standard deviation, but no values are reported. It would not be appropriate to derive a standard error, interval, or comparison without the needed results and a specified analysis.
What can planning calculations tell readers?
The stated sample-size illustration uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes effects to detect as fractions of an observed effect. Such calculations are planning illustrations, not observed power and not evidence that an effect was present. The underlying observed effect is not reported in the registry record, and the record does not report the trial’s own sample-size justification. The planning assumptions therefore should not be treated as the trial’s prespecified design rationale or as proof that the study could detect a particular effect.
For continuous outcomes, general planning calculations depend on assumptions about the effect of interest and variability, in addition to the test and allocation assumptions. If those inputs are uncertain or differ from the eventual data, calculated sample sizes may not describe the actual precision achieved. No numerical planning results are stated in the registry record information, so no arm-level sample-size target or power claim can be made.
Why does variability matter?
In general, greater variability among participants makes a group mean less precise when other features are unchanged. Unequal variability across groups or unusually dispersed data may also make simple model assumptions less suitable. Over-dispersion is a concept most often discussed for count data: it means the observed variability exceeds what a chosen count model assumes. Although the endpoint is a count of hairs, it is analyzed as a continuous measure with mean and standard deviation in the endpoint description. The registry record does not report the distribution of measurements or whether over-dispersion was assessed. No claim about the suitability of a particular model can therefore be made.
Finally, a statistically detectable difference and a meaningful difference are distinct concepts in general. Statistical evidence concerns compatibility with a null model and uncertainty under an analysis; practical meaning depends on context and an interpretable threshold. The registry record does not state a threshold for an important change in hair count. With no reported endpoint estimates, neither statistical nor practical interpretation is possible.
10. Multiplicity, Missing Data and Analysis Populations
The study lists several outcomes: the primary change in target area hair count and secondary measures covering Investigator Global Assessment response categories, Global Panel Review response categories, hair width, and hair darkness. The record reports six outcome measures overall, but does not describe how many hypotheses were formally tested or how comparisons were grouped. It does not report a multiplicity adjustment, a testing hierarchy, or a prespecified strategy for interpreting multiple outcomes. The statistical plan is not reported in the registry record.
In general, evaluating multiple outcomes or multiple treatment comparisons can increase the chance of observing an apparently unusual result by chance if each is interpreted independently. Adjustment methods and prespecified hierarchies are possible ways to address that issue, but the registry record does not say whether any were used. No conclusion about the handling of multiplicity should be inferred.
The primary outcome population included randomized participants who received treatment and had baseline and post-baseline measurements, with outcome data available. This definition identifies a restricted analysis population, but the record does not report the number of participants included in the primary endpoint analysis or the extent and pattern of missing measurements. It does not state whether missing data were imputed, whether sensitivity analyses were conducted, or how participants without usable endpoint data were handled.
Missing data can affect interpretation in general, particularly when the likelihood of missingness is related to participant characteristics or outcomes. The record does not provide enough information to assess that possibility. The Modified Intent-to-Treat definition should not be mistaken for a complete account of missing-data methods or for an analysis of every randomized participant.
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 |
|---|---|---|---|
| Bimatoprost Formulation A | 0 | 61 | 0.0% |
| Bimatoprost Formulation B | 1 | 61 | 1.6% |
| Bimatoprost Formulation C | 1 | 62 | 1.6% |
| Vehicle to Bimatoprost | 1 | 62 | 1.6% |
| Minoxidil 5% Solution | 0 | 61 | 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 |
|---|---|
| Bimatoprost Formulation A | 6 of 61 |
| Bimatoprost Formulation B | 11 of 61 |
| Bimatoprost Formulation C | 4 of 62 |
| Vehicle to Bimatoprost | 7 of 62 |
| Minoxidil 5% Solution | 10 of 61 |
Most frequent serious adverse event terms
| Event term | Organ system | Bimatoprost Formulation A | Bimatoprost Formulation B | Bimatoprost Formulation C | Vehicle to Bimatoprost | Minoxidil 5% Solution |
|---|---|---|---|---|---|---|
| Femur fracture | Injury, poisoning and procedural complications | 0 of 61 | 0 of 61 | 1 of 62 | 0 of 62 | 0 of 61 |
| Humerus fracture | Injury, poisoning and procedural complications | 0 of 61 | 0 of 61 | 1 of 62 | 0 of 62 | 0 of 61 |
| Radius fracture | Injury, poisoning and procedural complications | 0 of 61 | 0 of 61 | 1 of 62 | 0 of 62 | 0 of 61 |
| Tibia fracture | Injury, poisoning and procedural complications | 0 of 61 | 0 of 61 | 1 of 62 | 0 of 62 | 0 of 61 |
| Wrist fracture | Injury, poisoning and procedural complications | 0 of 61 | 0 of 61 | 1 of 62 | 0 of 62 | 0 of 61 |
| Back pain | Musculoskeletal and connective tissue disorders | 0 of 61 | 1 of 61 | 0 of 62 | 0 of 62 | 0 of 61 |
| Osteonecrosis | Musculoskeletal and connective tissue disorders | 0 of 61 | 0 of 61 | 0 of 62 | 1 of 62 | 0 of 61 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Bimatoprost Formulation A | Bimatoprost Formulation B | Bimatoprost Formulation C | Vehicle to Bimatoprost | Minoxidil 5% Solution |
|---|---|---|---|---|---|---|
| Nasopharyngitis | Infections and infestations | 5 of 61 | 7 of 61 | 4 of 62 | 7 of 62 | 3 of 61 |
| Application site pruritis | General disorders | 1 of 61 | 4 of 61 | 0 of 62 | 0 of 62 | 7 of 61 |
Serious events with the highest arm-level rate: back pain (1.6%), femur fracture (1.6%), humerus fracture (1.6%), radius fracture (1.6%), tibia fracture (1.6%).
The serious adverse event counts are presented with the number at risk in each group. Formulation A had 0 of 61 participants with a serious adverse event; Formulation B had 1 of 61; Formulation C had 1 of 62; vehicle had 1 of 62; and minoxidil 5% solution had 0 of 61. These are descriptive participant counts. The registry record does not report a comparative statistical analysis of these counts.
Six serious-event terms are listed: back pain, femur fracture, humerus fracture, radius fracture, tibia fracture, and wrist fracture. Each is reported as 1.6%. The record information does not assign these terms to particular treatment groups, so they should not be attributed to a specific intervention. Death figures are not reported in the registry record.
Counts for participants with other adverse events were 6 of 61 for Formulation A, 11 of 61 for Formulation B, 4 of 62 for Formulation C, 7 of 62 for vehicle, and 10 of 61 for minoxidil. These figures do not, on their own, describe event severity, duration, relatedness to treatment, or the number of events per participant. They also do not establish causation or support a treatment ranking. The registry record does not report further detail on these events in the information.
12. What the Result Does, and Does Not, Mean
The record describes a randomized comparison of three bimatoprost formulations with vehicle and minoxidil 5% solution in men with androgenic alopecia. Its primary endpoint was change in target area hair count from baseline to Month 6, with a positive value defined as an increase in terminal hairs. The record also identifies secondary measures of investigator and panel assessments, hair width, and hair darkness.
What the posted information does not establish is the observed change in hair count for any group, the difference between any pair of groups, or the precision of such a difference. Numerical primary outcome results, confidence intervals, and p-values are not reported in the registry record. Accordingly, it is not possible to determine from this record whether measurements increased or decreased, how large any changes were, or how consistent they were across participants. The fact that the study is marked completed does not fill that gap.
The study’s total enrollment and safety counts are not substitutes for endpoint results. Safety counts are descriptive, and the record does not present a comparative safety analysis. Nor do counts of participants with other adverse events indicate whether those events were related to treatment. A treatment assignment in a randomized study can support comparisons when the outcomes and analysis are reported, but the design alone does not provide the missing estimates.
These limits also apply to claims about precision and importance. Without estimates and intervals, the uncertainty around the primary comparison cannot be described. Without a stated threshold for an important hair-count change, even a numerical difference would require careful interpretation in context. No clinical recommendation follows from the information in the registry record. The appropriate statistical conclusion is limited: the study question and outcome definitions are recorded, but the primary outcome findings are not reported in the registry record.
13. Why This Trial Matters Statistically
This trial is statistically notable for bringing together multiple active and control groups under a randomized, parallel-group design. It evaluated three bimatoprost formulations, a vehicle solution, and minoxidil 5% solution, while defining a common primary endpoint: change in target area hair count from baseline to Month 6. That structure makes clear what kinds of comparisons the study was designed to examine, even though the numerical comparison results are not reported in the registry record.
The endpoint also illustrates why a precise outcome definition matters. The record specifies digital imaging analysis, a target scalp area, a unit of terminal hairs/cm^2, measurement times, and the direction interpreted as an increase. Those details help establish what the measurement represents. At the same time, a defined measurement is not enough to judge the evidence: group summaries, between-group estimates, and uncertainty are needed to assess the results.
The study highlights the importance of distinguishing design labels from analysis details. Randomization and masking describe aspects of trial conduct, but they do not reveal the statistical model, missing-data handling, multiplicity strategy, or precision of estimates. Those analytic details are not reported in the registry record. Similarly, a planning illustration based on an observed effect is not a report of observed power or a substitute for outcome results.
Finally, the primary endpoint population is explicitly restricted to participants who received treatment and had baseline and post-baseline data. This makes clear that enrollment and outcome-analysis populations need not be identical. Without the endpoint analysis count and missing-data details, readers cannot assess how much data contributed to the main outcome. The trial therefore provides a useful example of why design, outcome definition, analysis population, and numerical results must be considered separately.
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 important limitation for interpreting efficacy is that the primary outcome estimates are not reported in the registry record. There are no group-level changes, standard deviations, between-group estimates, confidence intervals, or p-values in the record information. The secondary outcomes are named, but their numerical results are also not reported in the registry record used for this analysis. Consequently, no efficacy comparison can be quantified.
The record does not report the allocation ratio, group sizes at randomization, or detailed randomization procedures. The safety denominators are available, but they are not necessarily endpoint-analysis counts. The primary population definition requires treatment and baseline and post-baseline measurements; the number meeting that definition is not reported. Missing-data methods and sensitivity analyses are not reported in the registry record.
Masking is described at two levels: the registry classification is triple-masked, while the study summary says treatments were double-blinded except for open-label minoxidil. The record does not identify the masked roles or explain this distinction further. This limits interpretation of precisely who was unaware of treatment assignment.
The record does not report the statistical analysis plan, treatment-comparison strategy, adjustment for multiple outcomes or comparisons, or the trial’s sample-size justification. The listed planning assumptions are illustrative and do not establish the design rationale. The record also does not provide an important-difference threshold for the hair-count endpoint, making practical interpretation of any hypothetical estimate uncertain.
Safety interpretation is limited to counts, a set of serious-event terms, and the listed percentages. Detailed event-level information, treatment relatedness, duration, and comparative analysis are not reported in the registry record. These limitations prevent a complete assessment of efficacy or safety from the information described.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Safety and Efficacy Study of Bimatoprost in the Treatment of Men With Androgenic Alopecia — NCT01325337.
- Registry record last updated 2014-04-10; status last verified 2014-04.
- Results first posted 2014-04-10.
- 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
The registry record describes a completed randomized, parallel-group phase 2 study enrolling 307 men with androgenic alopecia. Participants were assigned to one of three bimatoprost formulations, bimatoprost vehicle solution, or minoxidil 5% solution. Bimatoprost formulations and vehicle were applied once daily for 6 months; minoxidil was applied twice daily for 6 months. The summary describes minoxidil as open-label and the other treatments as double-blinded, while the registry classification is triple-masked.
The primary outcome was change from baseline to Month 6 in target area hair count, measured by digital imaging and expressed in terminal hairs/cm^2. The primary outcome population was a Modified Intent-to-Treat group with treatment received and baseline and post-baseline measurements. Numerical primary outcome results and the statistical analysis plan are not reported in the registry record. Safety counts are listed by group, but do not constitute a comparative analysis.