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 Efficacy of Changing to TRAVATAN® From Prior Therapy (NCT01510145), a na phase 4 study. The primary outcome is Change in Intraocular Pressure (IOP) at 12 Weeks From Prior Therapy (Baseline).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01510145 |
| Phase | Phase 4 |
| Condition | Open-angle Glaucoma, Ocular Hypertension |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 191 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Alcon Research |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned patients with open-angle glaucoma or ocular hypertension who had previously used latanoprost ophthalmic solution 0.005% as monotherapy and changed therapy because of tolerability issues. The primary analysis population was narrower than everyone who might have entered the study: it included patients who instilled at least one drop of study product and had primary endpoint measurements available for at least one on-therapy study visit. The registry record does not report further eligibility details or the characteristics of this analysis population.
Intervention
The study product was BAK-free travoprost 0.004%. The regimen was one drop, self-administered to the study eye or eyes once daily in the evening, at around 8:00 pm, for 12 weeks. Only one eye was selected as the study eye for efficacy analysis, and only that eye's data were used for the efficacy outcome.
Comparator
This was a single-group study, not a randomized comparison. Participants had been receiving latanoprost before the change, and the primary outcome compares intraocular pressure at baseline with the measurement at Week 12 after the change. The registry record does not describe a concurrent control group. The earlier therapy is therefore a baseline reference, not a like-for-like control arm.
Primary question
The primary question was how intraocular pressure changed from baseline, defined as the prior-therapy measurement, to Week 12 after changing to BAK-free travoprost. The outcome was the mean change in pressure, measured in mmHg. The registry explains that a more negative change represents a greater decrease from baseline. The numerical estimate and its uncertainty are not reported in the registry record, so the size and precision of the observed change cannot be stated.
3. Trial Design
The registry describes a completed Phase 4, multicenter study sponsored by Alcon Research. The study title and summary concern changing from prior latanoprost ophthalmic solution 0.005% monotherapy to BAK-free travoprost 0.004% in patients with open-angle glaucoma or ocular hypertension. The registry lists enrollment as 191. The study started in 2012-02, reached primary completion in 2013-05, and has a completed status.
The design is classified as single-group, with allocation listed as NA and masking listed as none. This is not a randomized, masked comparison between treatment arms. Instead, the primary outcome uses a before-and-after framework: the baseline measurement is described as being from prior therapy, and the later measurement is at Week 12 after changing to the study product. Consequently, changes over time cannot be separated from other possible influences using a concurrent control group in this design.
The intervention description specifies one drop of study product to the study eye or eyes, self-administered once daily in the evening, at around 8:00 pm, for 12 weeks. The efficacy analysis used only the selected study eye. Although the regimen refers to study eye or eyes, the registry says that one eye was chosen for the efficacy analysis; it does not report how that eye was selected.
The primary analysis population included patients who used at least one drop and had primary endpoint measurements available for at least one on-therapy study visit. That definition does not establish that every included patient had a Week 12 measurement. The registry record does not report the number of participants included in the primary analysis, the number with Week 12 data, or a detailed account of participant flow. It also does not report a sample-size justification or the detailed statistical analysis plan.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: This reporting group includes all enrolled patients (191).
Overall Study
| Stage | TRAVATAN® BAK-free |
|---|---|
| STARTED | 191 |
| COMPLETED | 173 |
| NOT COMPLETED | 18 |
Reasons for not completing this period:
| Reason | TRAVATAN® BAK-free |
|---|---|
| Adverse Event | 6 |
| Lost to Follow-up | 5 |
| Withdrawal by Subject | 6 |
| Relative reported subject withdrew | 1 |
Analysis population for the primary outcome, as defined in the registry: This analysis population includes all patients who instilled at least one drop of study product and who had primary endpoints measures available for at least one on-therapy study visit.
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.
Population: This analysis population includes all enrolled patients.
| Characteristic | Unit | TRAVATAN® BAK-free |
|---|---|---|
| Participants analysed | 191 | |
| Age, Continuous | years | 67.5 (SD 11.3) |
| Sex: Female, Male: Female | Participants | 139 |
| Sex: Female, Male: Male | Participants | 52 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Intraocular Pressure (IOP) at 12 Weeks From Prior Therapy (Baseline), measured over Baseline, Week 12.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | mmHg |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the change in intraocular pressure from baseline, described as prior therapy, to Week 12. Intraocular pressure is the fluid pressure inside the eye, and the registry states that it was measured using Goldmann applanation tonometry. The outcome is a continuous measure reported as a mean change in mmHg, with standard deviation specified as the measure of dispersion.
The registry explains the clinical rationale for measuring this pressure: higher intraocular pressure can be a greater risk for developing glaucoma or for glaucoma progression leading to optic nerve damage. It also defines the direction of change: a more negative value indicates a greater decrease from baseline. This directional definition is useful when interpreting a change score because the sign conveys whether the measured pressure went down or up relative to baseline.
In general, a continuous endpoint preserves information about the magnitude of measurements rather than reducing each participant's result to a category. A mean describes the average change in the analysis population, while a standard deviation describes how much individual changes vary around that average. Neither statistic alone conveys the uncertainty in the estimated mean. The registry record does not report the primary mean change, its standard deviation, a confidence interval, or a test result, so the outcome's observed magnitude and precision cannot be assessed from the reported information.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies a clinically relevant continuous endpoint and defines how to read its direction: a more negative change in intraocular pressure represents a greater decrease from baseline. However, the registry record does not report the numerical primary outcome result. There is no reported mean change, standard deviation, confidence interval, or p-value for the Week 12 comparison. Therefore, the direction, size, and precision of the observed change cannot be described from this record.
This distinction matters because an endpoint definition is not itself an outcome finding. Knowing what was measured and when does not show what values participants had, how much they changed, or how consistent those changes were. Similarly, the registry's statement that higher intraocular pressure can be a greater risk for glaucoma development or progression provides context for the measure; it does not substitute for a reported study result.
The design also shapes what a change score can establish. The comparison is between baseline on prior therapy and a later measurement after changing to the study product, within a single-group study. Without a concurrent control arm, the observed before-and-after change, if reported, would not by itself distinguish an effect associated with the change in therapy from other changes over time or other influences. This is a general limitation of interpreting uncontrolled before-and-after comparisons, not a claim about what occurred in this study.
The stated analysis population required at least one dose and endpoint measurements for at least one on-therapy study visit. The registry record does not report how many participants met that definition, whether all had measurements at Week 12, or how missing measurements were handled. These omissions limit assessment of how representative the analyzed participants were of the enrolled group and how missing observations might affect an estimate.
The record lists a secondary outcome concerning the percentage of subjects reaching target intraocular pressure at or below 18 mmHg, but it does not report that outcome's result. It also lists two outcome measures and zero analyses. No numerical efficacy finding should be inferred from those entries. Overall, the record supplies the study question, design, endpoint definition, analysis-population criterion, and limited safety counts, but not the numerical primary or secondary efficacy results needed to describe observed treatment-period changes.
9. Statistical Methods Explained
What does a mean change describe?
The primary endpoint is a mean of a continuous measure. In general, a participant's change score is calculated by comparing a later measurement with a baseline measurement, and the mean summarizes those participant-level changes in the analysis population. The registry defines baseline as the measurement from prior therapy and the later time point as Week 12. It states that a more negative change indicates a greater decrease in intraocular pressure.
A mean is a concise description of the average, but it does not show the full pattern of individual measurements. In general, the mean can be affected by unusually large or small changes, and different distributions of participant-level changes can share the same mean. The standard deviation, which the registry identifies as the dispersion measure, describes spread around the mean. It is not the same as the uncertainty of the estimated mean. The numerical mean and standard deviation are not reported in the registry record, so neither the average change nor its variability can be evaluated.
What would a confidence interval add?
In general, a confidence interval expresses the precision of an estimate by giving a range of values compatible with the data and the method used to calculate the interval. A narrow interval indicates greater precision than a wide interval, while the interval's location helps show which values remain plausible under that method. A confidence interval does not guarantee that the true value lies within a particular realized interval, and it does not on its own establish clinical importance. No confidence interval for the primary endpoint is reported in the registry record.
A p-value, if reported, would address how compatible the observed data are with a specified null hypothesis under the test's assumptions. It would not quantify the size of the change or its practical importance. The registry record does not report a primary-outcome p-value or specify the test used. The record lists zero analyses, so no inferential analysis results are available to interpret.
Why does the design affect interpretation?
In general, a single-group before-and-after design measures participants at different times without a concurrent control group. It can describe the change between the recorded time points, but the comparison alone cannot isolate why a change occurred. Changes over time, measurement variation, or other influences can contribute to a before-and-after difference. These are general considerations; the registry does not report whether such influences occurred in this study.
The design is listed as single-group, allocation as NA, and masking as none. Thus, the study should not be read as a randomized comparison between separate treatment arms. Prior latanoprost therapy is the baseline context for the change, not a concurrent control. The primary outcome used data from one selected study eye, but the method for selecting that eye is not reported in the registry record.
What do planning illustrations mean?
In general, a sample-size calculation asks how many participants a future study might need under specified assumptions about the effect to detect, variability, significance level, allocation, and analysis method. Such a calculation is a planning exercise, not evidence about the results of the completed study. The record's planning assumptions describe an illustrative calculation based on the observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is framed as a stated fraction of the observed effect. The record also distinguishes how totals are expressed for time-to-event outcomes from other outcomes.
Those assumptions do not describe the actual single-group design, which has no equal allocation between two treatment arms. The planning illustration is not the study's own design or a reported sample-size justification. The record does not report the protocol's sample-size rationale or the numerical planning outputs. Such illustrations must not be interpreted as observed power. In general, observed power calculated from an observed effect largely restates the result and does not replace an estimate with an uncertainty interval.
Why can over-dispersion matter?
In general, over-dispersion means that variability in the data is greater than a statistical model assumes. If a model understates variability, its standard errors may be too small and its uncertainty estimates too optimistic. The primary endpoint is described as a continuous mean with standard deviation, but the registry record does not report a model or an over-dispersion assessment. This concept is therefore general background, not a description of an analysis used in this study.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists the primary outcome as mean change in intraocular pressure at 12 weeks from the baseline measurement on prior therapy. It also lists a secondary outcome: the percentage of subjects reaching target intraocular pressure at or below 18 mmHg. The record does not report the numerical result for either outcome. It lists two outcome measures and zero analyses, but does not describe a multiplicity strategy or state whether any adjustment for multiple outcome testing was planned or used. That information is not reported in the registry record.
In general, multiplicity arises when multiple outcomes, time points, or statistical tests are considered. Testing multiple hypotheses can increase the chance of at least one apparently noteworthy result under a null scenario. Statistical plans may address this in different ways, but the registry does not identify a method for this study. No adjustment should be assumed.
The primary analysis population is defined as patients who instilled at least one drop of study product and had primary endpoint measurements available for at least one on-therapy study visit. This definition is reported, but the number meeting it is not. The record does not report how missing baseline or Week 12 values were handled, whether any imputation was used, or how many participants lacked endpoint data. Those details are not reported in the registry record.
In general, missing-data methods matter because conclusions can depend on why values are missing and on assumptions about the unobserved measurements. A requirement for at least one on-therapy visit does not, by itself, establish how missing Week 12 measurements were treated. The registry record also does not report sensitivity analyses examining alternative assumptions. Accordingly, the extent to which missing data could influence the primary estimate cannot be assessed from the record.
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 |
|---|---|---|---|
| TRAVATAN® BAK-free | 0 | 191 | 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 |
|---|---|
| TRAVATAN® BAK-free | 0 of 191 |
The registry reports that 191 participants were at risk for serious adverse events in the TRAVATAN® BAK-free group and that zero serious adverse events were recorded for that group. This is a reported count for the study group; it should not be interpreted as proof that serious adverse events are impossible or that the risk is zero in other settings. A count of zero is an observed count within the registry's reporting, not a guarantee about future experience.
The registry lists no top serious adverse event terms. Deaths are recorded as null, which is different from a reported count of zero. The number of deaths is therefore not reported in the registry record. The record also does not provide event-level descriptions or further detail on the period or method used to collect safety information, so those details should not be inferred from the count alone.
In general, safety counts are most informative when considered alongside the number of participants observed, the duration of observation, and clear definitions of the events being counted. The study regimen lasted 12 weeks, but the registry does not provide further safety follow-up details. These reported figures describe what the registry records for this study group; they do not establish a comparative safety result because there is no concurrent control group.
12. What the Result Does, and Does Not, Mean
The record establishes that the study examined a change from prior latanoprost monotherapy to BAK-free travoprost and defined a primary endpoint based on intraocular pressure at baseline and Week 12. It also describes the dose schedule, the selected study eye used for efficacy analysis, and the criterion for inclusion in the primary analysis population. These details clarify the question and the setting in which the endpoint was intended to be measured.
However, the primary endpoint's numerical result is not reported in the registry record. It is therefore not possible to state whether the mean pressure changed, the direction or size of any change, how much participant measurements varied, or how precise an estimated mean would be. The secondary target-pressure outcome is also listed without a reported result. No efficacy conclusion should be drawn from the outcome descriptions alone.
Even if a before-and-after estimate were available, this single-group design would not provide the same basis for comparison as a randomized concurrent control. In general, a change between baseline and a later visit may reflect multiple influences, and the design alone cannot attribute the entire difference to the study product. This is a design-based caution, not a conclusion that any particular influence affected the participants.
The serious adverse event count is reported as zero among 191 participants at risk in the study group. That count describes the registry record and does not establish absence of risk. The registry does not report a death count, and no top serious event terms are listed. The available safety information is therefore limited in detail and does not support a comparative safety assessment.
In general, a study result is best understood by considering the estimated effect, its uncertainty, the analysis population, missing data, and the study design together. Here, the endpoint and design are described, but the numerical efficacy findings and several analysis details are absent. The record can support an account of what the study set out to measure, not a quantitative conclusion about the observed efficacy change.
13. Why This Trial Matters Statistically
This study is statistically notable because it asks a within-participant, before-and-after question rather than comparing randomized treatment groups. The baseline is tied to prior latanoprost therapy, and the later measurement is at Week 12 after changing to BAK-free travoprost. This structure can be useful for describing change over time in the studied population, while also requiring care about what can be attributed to the treatment change.
The endpoint is continuous and has a clear direction: a more negative change means a larger decrease from baseline. Reporting a mean together with its variability and uncertainty would allow readers to assess both the average change and how precisely it was estimated. Those numerical results are not reported in the registry record. The difference between a well-defined endpoint and a reported result is important: the former establishes what was intended to be measured, but does not reveal what the measurements showed.
The stated analysis population also makes the analysis criteria explicit at a basic level: participants needed at least one dose and primary endpoint measurements available for at least one on-therapy study visit. Yet the record does not report the size of that analysis population, Week 12 completeness, or missing-data methods. These details matter because the analyzed group and the handling of unavailable measurements affect how an estimate should be interpreted.
Finally, the zero serious adverse event count is a descriptive safety observation in a single group, not a comparative estimate. Taken together, the record illustrates how design, endpoint definition, analysis-population rules, and result reporting each contribute different information. It also shows why an endpoint description and a safety count cannot replace the numerical efficacy estimates and uncertainty needed for a full statistical interpretation.
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 main limitation for interpreting efficacy is that the registry record does not report the numerical primary outcome result. It identifies mean change in intraocular pressure at Week 12 and specifies standard deviation as the dispersion measure, but provides no mean change, standard deviation, confidence interval, or p-value. The secondary target-pressure outcome is listed without a result as well. The size and precision of any observed efficacy change therefore cannot be evaluated from the record.
The single-group, unmasked design has no concurrent control arm. The baseline comparison with prior therapy can describe a change between time points, but does not provide a randomized comparison that separates the change associated with the new regimen from other influences over time. The record does not report whether participants or outcome assessors were masked; masking is listed as none. The method for selecting the study eye is also not reported in the registry record.
The primary analysis population is defined by at least one dose and primary endpoint measurements at at least one on-therapy visit, but the record does not state how many participants were analyzed or how many contributed a Week 12 measurement. Missing-data handling, imputation, and sensitivity analyses are not reported. This leaves uncertainty about completeness and about the influence of unavailable measurements.
The registry does not report the detailed statistical analysis plan, a sample-size justification, or a multiplicity approach. The planning assumptions describe an illustration rather than the single-group study's design and do not supply evidence about observed power. Safety reporting is also limited: a zero serious adverse event count is recorded among 191 at risk, no top serious terms are listed, and deaths are null rather than reported as a count. These limitations restrict both efficacy and safety interpretation.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Efficacy of Changing to TRAVATAN® From Prior Therapy — NCT01510145.
- Registry record last updated 2014-06-13; status last verified 2014-05.
- Results first posted 2014-06-13.
- 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 describes a completed, multicenter Phase 4, single-group study sponsored by Alcon Research, with enrollment listed as 191. The study examined BAK-free travoprost 0.004% after prior latanoprost ophthalmic solution 0.005% monotherapy in patients with open-angle glaucoma or ocular hypertension. The regimen was one drop in the evening for 12 weeks.
The primary endpoint was mean change in intraocular pressure from baseline on prior therapy to Week 12, measured by Goldmann applanation tonometry. The efficacy analysis used one selected study eye. The numerical primary and secondary outcome results, detailed analysis methods, missing-data handling, and sample-size justification are not reported in the registry record. The record reports zero serious adverse events among 191 participants at risk; deaths are null.