Tolerability of Bimatoprost 0.01% vs Latanoprost Eye Drops: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Tolerability of Bimatoprost 0.01% vs Latanoprost Eye Drops (NCT02138461), a registered phase not stated study. The primary outcome is Tolerability of Medications as Measured by the COMTOL Validated Instrument.

2. Clinical Question

The study is framed around patients’ subjective assessment rather than a randomized treatment comparison. Its official title refers to overall tolerability and satisfaction, while the primary outcome is described as tolerability measured by the COMTOL instrument. The modified questionnaire was intended to focus on the medication a participant was already using, rather than ask participants to compare two medications directly.

That distinction shapes what the record can answer. It documents an effort to collect patient-reported experience in routine ophthalmology practice, but it does not report findings that establish how participants rated either medication. Nor does the record describe a design that would isolate medication effects from differences between the people taking each medication. The central clinical question is therefore descriptive: what tolerability did patients report for their current medication? The posted record gives the measurement approach, but not the outcome data needed to answer it.

3. Trial Design

This completed study is registered as NCT02138461 and is titled “Tolerability of Bimatoprost 0.01% vs Latanoprost Eye Drops.” The sponsor is MDbackline, LLC. The registry lists an enrollment of 211, a study start of 2013-10, and primary completion in 2014-09. The condition listed is glaucoma.

The design described in the outcome text is an enrollment-time questionnaire study. Patients already taking one of the medications of interest were to be enrolled from a general ophthalmology practice. After consenting, each participant would immediately complete a modified version of the Comparison of Ophthalmic Medication for Primary Outcome Measure Tolerability questionnaire, or COMTOL. The record says participants would continue taking the medication prescribed as part of their glaucoma therapy. It describes no crossover: a participant assessed while taking one medication was not described as switching to the other for comparison.

The registry lists groups for bimatoprost and latanoprost, with 101 and 110 participants at risk, respectively, in the adverse-event record. Those group counts do not establish random allocation. In fact, allocation is not stated, and the record cautions that the arms are not a like-for-like control comparison. The description is consistent with assessing existing medication users, but details of how patients entered either group are not reported in the registry record.

The registry lists one outcome measure and zero analyses. It does not report an analysis plan, participant flow, or a statistical method used to compare the two groups. The record is marked completed, but completion status does not supply missing outcome results. The stated timeframe places questionnaire completion at enrollment, followed by exit from the study; no later assessment schedule is described.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as Tolerability of Medications as Measured by the COMTOL Validated Instrument, measured over at the time of enrollment in the clinic, patients will immediately complete the questionnaire and exit the study.

The primary endpoint is titled “Tolerability of Medications as Measured by the COMTOL Validated Instrument.” Its unit is percentage of patients, and the outcome description identifies the number of patients as the parameter. The questionnaire is described as a validated survey instrument, modified to focus on the tolerability of the single medication a participant was already taking. It was to be completed immediately after consent at enrollment.

Patient-reported tolerability is relevant because the experience of taking a medication is not fully represented by clinical measurements alone. In general, a structured questionnaire can make subjective experience more consistent to collect across participants than an unstructured account. A validated instrument is intended to measure a defined construct using established questions, although the record does not give the scoring rules, thresholds, or interpretation of the modified version used in this study.

The registry does not report the actual number or percentage of patients meeting an endpoint definition, and it does not state a threshold distinguishing acceptable from unacceptable tolerability. It also does not report group-specific questionnaire summaries or a comparison. Consequently, the endpoint’s planned purpose is clear, but its results and the precise rule for translating responses into the stated percentage are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Interpreting a clinical study begins with identifying its design, endpoint, and analysis population. In this record, the design description concerns people already taking one of two glaucoma medications, assessed by questionnaire at enrollment. The endpoint is patient-reported tolerability using a modified COMTOL instrument. The record does not describe random allocation, and it states that the arms are not a like-for-like control comparison. These design details matter because the strength of a treatment comparison depends not only on the measurement but also on how the groups were formed.

What does a percentage endpoint represent?

In general, a percentage endpoint expresses the number of participants meeting a specified condition relative to a defined denominator. It is useful when the research question concerns how common a response or event is in a group. To interpret it, readers need to know exactly which questionnaire responses count as meeting the endpoint, which participants are included in the denominator, and how unanswered items or incomplete questionnaires are treated. Here, the registry gives the unit as percentage of patients and names the COMTOL questionnaire, but does not report the scoring threshold, denominator definition for the primary outcome, or outcome values.

A questionnaire can measure an experience that is not captured by an objective clinical measurement. In general, a validated instrument has undergone evaluation for its intended measurement purpose. Modifying an instrument may change the questions or interpretation, so the details of the modification and scoring can be important. The registry says that questions comparing two medications were to be eliminated, leaving a focus on tolerability of the single medication being taken. It does not give the modified instrument’s complete items, scoring algorithm, or validation information specific to this use. Those details are not reported in the registry record.

Why does allocation matter?

In general, random allocation helps balance measured and unmeasured participant characteristics between treatment groups on average. It supports a causal interpretation of a difference in outcomes, subject to the study’s other assumptions and conduct. This record does not state that allocation was randomized. It describes patients already taking the medications and says they would continue the medication prescribed in their glaucoma therapy. It also cautions that the arms are not a like-for-like control comparison. A comparison of reported tolerability between the groups, if one were available, would therefore be descriptive and could be influenced by differences in who was taking each medication.

For example, in general, participants can differ in clinical history, treatment duration, preferences, or reasons for receiving a particular medication. These are possible sources of group differences in observational comparisons, not established characteristics of this study’s participants. The registry does not report baseline characteristics or adjustment methods that would allow those differences to be examined.

What do the analysis entries tell us?

The registry lists one outcome measure and zero analyses. This means that the posted record identifies an endpoint but does not present an associated analysis. In general, a complete statistical report for a two-group endpoint would identify the group summaries, an estimate of the difference or other target quantity, a measure of uncertainty, and the method used to calculate them. For a percentage outcome, methods may account for the fact that each participant contributes a binary response, if that is how the endpoint was defined. The registry does not report such estimates or methods for this endpoint.

In general, a confidence interval conveys uncertainty around an estimate. A narrow interval indicates greater precision under the method’s assumptions, while a wide interval indicates less precision. A significance test addresses a different question: how compatible the observed data are with a specified null hypothesis under the test assumptions. A p-value is not the probability that a treatment works, nor does it measure the size or practical importance of an effect. No p-value, confidence interval, or test result for the primary endpoint is reported in the registry record, so those concepts cannot be applied to quantify this study’s result.

How should sample-size calculations be read?

In general, a planning calculation estimates how many participants might be needed to detect a chosen effect under specified assumptions. Such a calculation is not an observed result and does not describe the probability that a completed study has found a true effect. The registry’s planning description says its illustration is based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; it also says the target effect is a stated fraction of the observed effect. These are described as planning assumptions, not as the trial’s own design justification. The corresponding numerical planning outputs and the underlying observed effect are not reported in the registry record. No sample-size justification for the trial itself is reported in the registry record.

In general, planning based on an observed effect should be interpreted cautiously because the observed effect can be uncertain, particularly when estimated from a study. A planning illustration does not replace a reported outcome analysis, and a completed sample size does not establish that an endpoint difference was detected. It is not appropriate to infer study power from enrollment alone. The registry does not report an original power calculation or a sample-size rationale.

Why can over-dispersion matter?

In general, over-dispersion occurs when the observed variability in data is greater than a statistical model expects. It can make standard errors too small and uncertainty intervals too narrow if the model does not account for the extra variability. This concept may matter for some outcome models, but the registry does not report a model for the questionnaire endpoint, an estimate of dispersion, or evidence of over-dispersion. It therefore cannot be claimed as a feature of this study’s data or analysis.

Overall, the method description is sparse: it identifies a patient-reported instrument and timing, but does not provide the scoring details, outcome data, analysis method, uncertainty estimates, or participant-level analysis information needed to reproduce or assess an endpoint comparison. General statistical principles clarify what such information would mean; they do not fill the gaps in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure, the tolerability outcome assessed with the modified COMTOL questionnaire, and zero analyses. It does not report a statistical analysis plan, a hierarchy of outcomes, or any approach to controlling for multiple comparisons. With one listed outcome, the record does not establish whether other questionnaire domains, subgroup comparisons, or additional analyses were planned or conducted. The scope of multiplicity control is therefore not reported in the registry record.

In general, multiplicity arises when several hypotheses or outcomes are tested. Repeated testing can increase the chance of finding at least one apparently notable result by chance. A prespecified testing strategy can clarify which outcome is primary and how other analyses should be interpreted. No such strategy is reported, and there are no posted endpoint analyses to evaluate.

The registry describes questionnaire completion immediately after consent at enrollment and exit from the study. It does not report how many enrolled participants completed the questionnaire, whether any responses were incomplete, or how missing items or missing questionnaires were handled. In general, missing data can affect both the denominator and the interpretation of a percentage endpoint. If missingness differs between groups or is related to participants’ experience, a complete-case result may not represent all enrolled participants. Those possibilities cannot be assessed without response and missingness information.

The record also does not define an intention-to-treat or other analysis population for the primary outcome. Because the described participants were already taking their medication, the registry does not report whether all enrolled patients were included in the endpoint analysis or how any departures from the intended assessment were handled. Neither an analysis population nor a missing-data method is reported in the registry record.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event record lists 101 participants at risk in the bimatoprost group and 110 in the latanoprost group. It records zero serious adverse events and zero other adverse events in each group. No serious adverse-event terms are listed. Death counts are not reported in the registry record.

These entries should be read as the counts recorded in the registry, not as a complete account of all possible safety outcomes. The record does not describe how adverse events were collected, what period they cover, how events were classified, or whether the entries represent a systematic safety assessment. The study description emphasizes a questionnaire completed at enrollment and does not describe ongoing follow-up for safety.

In general, a zero count in a posted event category means no events were recorded in that category in the registry entry; it does not demonstrate that an event is impossible or that no unrecorded events occurred. The group sizes at risk provide context for the listed counts, but they do not resolve limitations in event collection or reporting. These safety entries also do not answer the primary question about questionnaire-based tolerability: the registry does not report the primary tolerability results.

12. What the Result Does, and Does Not, Mean

The record establishes that a completed study enrolled 211 patients with glaucoma who were already taking bimatoprost or latanoprost. It describes an immediate, enrollment-time assessment using a modified COMTOL questionnaire focused on tolerability of the medication each patient was taking. It also identifies the two medication groups and lists their participant counts in the adverse-event record.

It does not establish what the participants reported. No questionnaire scores, percentages, group differences, confidence intervals, or statistical tests for the primary endpoint are reported in the registry record. The absence of posted primary results should not be interpreted as evidence that the groups had the same tolerability or that one group had better tolerability. It means the registry record does not show the data needed to decide between those possibilities.

Even if group summaries were available, the design description would constrain their interpretation. Participants were already taking their medications, allocation is not stated, and the record cautions that the arms are not a like-for-like control comparison. In general, a difference between groups in a nonrandomized comparison may reflect treatment experience, differences in the people receiving each medication, or both. The registry does not report baseline characteristics or adjustment analyses that could help assess this issue.

The endpoint focuses on subjective experience and is therefore distinct from other possible clinical outcomes. A tolerability questionnaire does not, by itself, establish effects on glaucoma progression or other clinical outcomes; those outcomes are not described as the primary endpoint in this record. Similarly, the title’s reference to satisfaction does not supply a separately reported satisfaction result. The primary outcome is named as tolerability measured by COMTOL, and no result for it is posted.

In short, the study record documents an approach to asking patients about their current medication, but does not provide the findings needed to quantify or compare their answers. The listed adverse-event counts are separate registry entries and do not substitute for the missing tolerability outcome data.

13. Why This Trial Matters Statistically

This study is statistically notable for the gap between a clearly stated patient-centered measurement goal and the limited results available in the registry. Tolerability is an experience patients can report, and a structured questionnaire offers a defined way to collect such information. The record specifies the intended instrument, the setting, and the timing of assessment. Those design details help identify the question being asked, even though they do not provide an answer.

The study also illustrates why the word “comparison” requires attention to design. Two medication groups are named, but allocation is not stated, and the registry explicitly says the arms are not a like-for-like control comparison. In general, a numerical difference between groups is not automatically attributable to the medication when participants were not randomly assigned and baseline comparability has not been demonstrated. Statistical adjustment can sometimes address measured differences, but the record does not report baseline data or an adjusted analysis.

Another important statistical lesson is that a named endpoint is not the same as a reported result. A percentage outcome needs a definition, a denominator, and a result with some description of uncertainty to support quantitative interpretation. Here, the registry identifies the endpoint and unit but does not report the questionnaire values, scoring threshold, analysis, or uncertainty. The study’s completed status and enrollment count cannot fill those gaps.

Finally, the record shows why safety counts and patient-reported tolerability should not be conflated. The registry lists zero serious and zero other adverse events in each group, while the primary endpoint is a questionnaire-based tolerability measure. These are different types of information, and the event counts do not establish the questionnaire findings. For clinical researchers, the key lesson is to distinguish an outcome’s planned measurement from its observed result, and a descriptive group comparison from a causal treatment effect.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most direct limitation of the registry record is that it does not report the primary outcome results. Although the record identifies the modified COMTOL questionnaire and says it was to be completed at enrollment, it gives no participant responses, group summaries, endpoint percentages, or uncertainty estimates. The extent and direction of reported tolerability therefore cannot be assessed.

The measurement description is incomplete for statistical interpretation. The record does not give the questionnaire scoring procedure, the threshold used to define the percentage endpoint, or the handling of incomplete responses. Although the instrument is described as validated, the record does not explain how the modified version was scored or whether the modification affects interpretation. The denominator used for the primary endpoint is not reported.

The study design also limits any comparison. Participants were already taking their medications, allocation is not stated, and the registry cautions that the arms are not a like-for-like control comparison. Baseline characteristics, reasons for treatment choice, duration on medication, and any adjustment for group differences are not reported in the registry record. Without these details, a group comparison could not be treated as an isolated medication effect.

Further details about conduct and analysis are absent. The record does not report questionnaire completion rates, missing-data methods, analysis populations, a statistical analysis plan, or the method for any between-group estimate. It lists one outcome measure and zero analyses. No sample-size justification for the trial itself is reported in the registry record; the described planning illustration is not stated to be the trial’s own design calculation.

The safety entries also have limited context. The registry lists zero serious and zero other adverse events for the stated at-risk groups, but does not describe ascertainment, follow-up, or event-classification procedures. Death counts are not reported in the registry record. These limitations concern what can be learned from the registry entry and should not be taken as evidence about unreported results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Tolerability of Bimatoprost 0.01% vs Latanoprost Eye Drops — NCT02138461.
• Registry record last updated 2014-09-25; status last verified 2014-09.
• Results first posted 2014-09-25.
• 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.

18. Record Summary

NCT02138461 is a completed study sponsored by MDbackline, LLC, with 211 participants and glaucoma listed as the condition. The record gives a study start of 2013-10 and primary completion in 2014-09. It describes patients already taking bimatoprost 0.01% or latanoprost and an immediate enrollment-time assessment using a modified COMTOL questionnaire focused on tolerability of the current medication.

The registry lists one outcome measure and zero analyses. It does not report primary questionnaire results, group comparisons, or uncertainty estimates. Allocation is not stated, and the record cautions that the medication groups are not a like-for-like control comparison. The adverse-event record lists zero serious and zero other adverse events in groups of 101 and 110 participants at risk; death counts are not reported in the registry record.