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 Loteprednol Etabonate Ophthalmic Ointment vs. Vehicle in the Treatment of Inflammation Following Cataract Surgery (NCT00645671), a randomized phase 3 study. The primary outcome is Subjects With Complete Resolution of Anterior Chamber Cells and Flare. Grade=0..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00645671 |
| Phase | Phase 3 |
| Condition | Ocular Inflammation |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 400 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Bausch & Lomb Incorporated |
| Results posted | Yes |
2. Clinical Question
Population
People undergoing cataract surgery, with the trial focused on inflammation following surgery. The registry identifies ocular inflammation as the condition and lists an intent-to-treat population for the primary outcome.
Intervention
Loteprednol etabonate 0.5% ophthalmic ointment.
Comparator
Vehicle of loteprednol etabonate ointment.
Primary question
At Postoperative Day 8 (Visit 5), how many participants had complete resolution of anterior chamber cells and flare, with a grade of 0?
The trial set out to evaluate clinical safety and efficacy of the ointment compared with vehicle for inflammation following cataract surgery. The primary endpoint is a participant count for complete resolution, rather than a reported estimate of the size of a treatment difference. Although the registry identifies the endpoint and its assessment time, it does not report the group counts or a statistical comparison for that endpoint. The efficacy question is therefore identifiable, but its answer cannot be determined from the results in the registry record.
3. Trial Design
The study is registered as a randomized, multicenter, double-masked, parallel-group phase 3 clinical trial. It compares loteprednol etabonate 0.5% ophthalmic ointment with the ointment vehicle. The registry lists enrollment of 400 and a completed status. The recorded start is 2008-03, and primary completion is recorded as 2009-03. Bausch & Lomb Incorporated is identified as the sponsor.
In a randomized design, assignment to the study groups is determined by a random process; this is intended to support a fair comparison by limiting systematic differences at assignment. A parallel-group design means the groups receive their assigned study interventions alongside one another during the trial, rather than participants crossing from one intervention to the other. Double masking indicates that the study is recorded as double-masked, but the registry record does not specify which people were masked or how masking was maintained. It also does not report the randomization procedure, the number of centers, or the planned allocation ratio.
The named arms are Loteprednol Etabonate and Vehicle. The primary outcome is described for the intent-to-treat population and is assessed at Postoperative Day 8 (Visit 5). Secondary outcomes include participants with complete resolution of anterior chamber cells and flare at each follow-up visit, and change from baseline in those measures at each follow-up visit. The registry lists 4 outcome measures, but no analysis entries. Enrollment is not the same as a reported number analyzed for each endpoint; the endpoint-specific analysis counts 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.
Before assignment: Following cataract surgery at visit 3 (post operative day 1), subjects were assessed for eligibility. 201 subjects were randomized to receive loteprednol etabonate ointment and 199 to receive its vehicle.
Overall Study
| Stage | Loteprednol Etabonate | Vehicle |
|---|---|---|
| STARTED | 201 | 199 |
| COMPLETED | 200 | 193 |
| NOT COMPLETED | 1 | 6 |
Reasons for not completing this period:
| Reason | Loteprednol Etabonate | Vehicle |
|---|---|---|
| Protocol Violation | 1 | 0 |
| Withdrawal by Subject | 0 | 4 |
| Adverse Event | 0 | 1 |
| Physician Decision | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: Intent to treat population
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 | Loteprednol Etabonate | Vehicle | Total |
|---|---|---|---|---|
| Participants analysed | 201 | 199 | 400 | |
| Age, Continuous | years | 69.2 (SD 9.39) | 69.2 (SD 8.77) | 69.2 (SD 9.08) |
| Sex: Female, Male: Female | Participants | 118 | 119 | 237 |
| Sex: Female, Male: Male | Participants | 83 | 80 | 163 |
| Race/Ethnicity, Customized: Asian | participants | 1 | 6 | 7 |
| Race/Ethnicity, Customized: Black or African American | participants | 17 | 12 | 29 |
| Race/Ethnicity, Customized: White | participants | 183 | 179 | 362 |
| Race/Ethnicity, Customized: Other | participants | 0 | 2 | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Subjects With Complete Resolution of Anterior Chamber Cells and Flare. Grade=0., measured over Postoperative Day 8 (Visit 5).
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint counts participants with complete resolution of anterior chamber cells and flare, defined as Grade=0 at Postoperative Day 8 (Visit 5). Anterior chamber cells refer to white blood cells in the aqueous. The registry description grades cells from 0, no cells seen, through 4, more than 30 cells. Flare refers to scattering of a slit-lamp light beam in the anterior chamber, described as the Tyndall effect; its scale runs from 0, none, to 4, very severe.
The endpoint combines these two clinical signs into a complete-resolution outcome. A binary endpoint distinguishes participants who meet the specified condition from those who do not. That can make the result easier to interpret as a count of participants reaching a defined state at a particular visit. It also loses detail compared with reporting each grade or the amount of change across grades. The registry record does not specify the rule used to combine the cell and flare grades beyond identifying the primary outcome as complete resolution with Grade=0.
Such a sign-based endpoint is used to assess whether the observed inflammatory findings have resolved at the chosen follow-up. That is a general description of the role of a clinical endpoint, not evidence that the outcome was met. The registry record does not report the number of participants meeting the endpoint in either group, so the extent of resolution and the comparison between groups cannot be assessed from the posted results.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The primary outcome is clearly identified: participants with complete resolution of anterior chamber cells and flare at Postoperative Day 8 (Visit 5). However, the registry record does not report the primary endpoint counts by group or a treatment-effect estimate. It also lists 0 analyses. Consequently, the posted results do not establish the direction or magnitude of the primary comparison, and do not show how precisely that comparison was estimated.
For a binary endpoint, a useful comparison would ordinarily describe the number meeting the endpoint in each group, alongside an effect estimate and an indication of its uncertainty. Those quantities help distinguish the observed group results from the uncertainty around an estimate. No such primary comparison is reported in the registry record. There is therefore no basis in these results for describing the outcome as favoring either intervention or for judging whether any apparent difference might be compatible with chance variation.
The registry lists enrollment of 400, but does not state how many participants contributed data to the primary endpoint analysis. The adverse-event record gives separate numbers at risk for the safety groups, but those safety counts are not substitutes for efficacy endpoint results. The reported safety figures are discussed separately because they describe participants affected by adverse events, not complete resolution of cells and flare.
The secondary outcomes include complete resolution at each follow-up visit and change from baseline in cells and flare at each follow-up visit. These outcomes could provide information about the pattern of findings over follow-up, but the registry record does not report their results or analyses. The record also does not report estimates, confidence intervals, or p-values for the primary or secondary outcomes.
Sample-size illustrations based on an observed effect are planning calculations, not observed trial results. The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation, with the effect to detect set as a stated fraction of the observed effect. The registry record does not give the trial's own sample-size justification or the resulting planning estimates. Such illustrations cannot replace the missing endpoint counts and cannot be read as evidence that the trial did or did not detect an effect.
9. Statistical Methods Explained
What does a binary endpoint represent?
A binary endpoint places each participant into one of two outcome categories according to a defined criterion. For this trial, the criterion is complete resolution of anterior chamber cells and flare, identified as Grade=0 at Postoperative Day 8 (Visit 5). The endpoint is reported as a number of participants. A group count is easy to understand, but by itself it does not show the uncertainty of the result or how the groups compare.
A comparison of binary outcomes can be described in different ways. An absolute difference describes the separation between the groups' proportions meeting the criterion. A relative measure describes their ratio. These approaches answer different questions and can give complementary context. The registry record does not report either type of estimate for the primary outcome, so no treatment comparison can be reconstructed from the endpoint description alone.
What would an uncertainty interval add?
A confidence interval is a range of values compatible with the observed data under a specified statistical method. It communicates precision: a narrower interval indicates less uncertainty about the estimated effect, while a wider interval indicates more. An interval also helps readers assess whether the data are consistent with effects that differ meaningfully in size or direction. These are general properties of confidence intervals. The registry record does not report a confidence interval for the primary comparison.
A p-value, when used, describes how compatible the observed data are with a specified null model, under the assumptions of the test. It does not measure the probability that the null hypothesis is true, nor does it describe the size or practical importance of an effect. The registry record does not report a p-value or identify a test for the primary endpoint. Without counts and an analysis, there is no reported statistical significance result to interpret.
What can be inferred from the design?
Random assignment is intended to reduce systematic differences between groups at the point of assignment. Masking can reduce the influence of knowledge of treatment assignment on care, assessment, or reporting, depending on who is masked and how masking is maintained. These are general reasons for using randomized and masked designs. The registry describes this trial as randomized and double-masked, but does not report the assignment method, the people masked, or masking procedures. Those details should not be inferred from the design labels.
A parallel-group trial compares assigned groups during the same trial period. The registry identifies this model and lists two interventions: loteprednol etabonate 0.5% ophthalmic ointment and vehicle. Although the record lists enrollment of 400, it does not state the number analyzed for the primary endpoint or how missing endpoint observations were handled. Enrollment alone cannot establish the amount of information available for an endpoint analysis.
How should the planning illustration be understood?
The stated sample-size assumptions describe a planning illustration based on the observed effect, not the trial's own design. They specify a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation. The target effect is expressed as a stated fraction of the observed effect. Such calculations ask what sample size might be needed under those assumptions to detect a chosen effect with a chosen power. They do not report how many participants actually experienced the endpoint, and they are not observed power.
A planning calculation based on an observed effect depends on that effect estimate and the assumptions used. If the underlying estimate is uncertain, the resulting planning exercise also inherits that uncertainty. Planning for a fraction of an observed effect can illustrate how required sample size changes when the target effect is smaller, but it does not demonstrate that the trial was designed around that target or that the target is clinically important. The registry record does not report its own sample-size justification, nor does it identify a prespecified effect used to plan enrollment.
Why does outcome structure matter?
The registry identifies secondary outcomes at each follow-up visit, as well as changes from baseline. Repeated measurements can describe how findings evolve over time, but analyses of multiple visits raise questions about which visit is primary, how repeated observations are handled, and how the chance of false-positive findings is controlled across comparisons. These are general statistical considerations. The registry record does not report an analysis plan for these outcomes or a multiplicity procedure.
The record notes that the primary outcome has several categories or time points and is not reduced to one comparison. Accordingly, there is no single reduced comparison to interpret from that note. A method such as an overall test or a prespecified visit-specific comparison could be considered in general, but the registry record does not say which, if any, was used. No test, model, adjustment, or confidence-interval method should be attributed to the trial without a report of it.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary outcome at Postoperative Day 8 (Visit 5), along with secondary outcomes assessed at each follow-up visit. Looking across multiple outcomes or visits can increase the chance of finding an apparently notable result by chance when many comparisons are examined. Statistical methods may address that issue by defining a testing hierarchy, selecting a primary comparison in advance, or adjusting for multiple comparisons. These are general approaches; the registry record does not report a multiplicity plan or state whether any adjustment was used.
The record identifies an intent-to-treat population for the primary outcome. In general, an intent-to-treat analysis aims to retain participants in the groups to which they were assigned, regardless of later treatment use. That principle does not by itself explain how missing endpoint data are handled or which participants were included in an actual analysis. The registry record does not report the analysis population counts, missing-data methods, or the number with an observed primary endpoint in each group.
The endpoint definition gives a visit and a resolution criterion, but the available record does not describe how incomplete assessments, deviations, or missing visits were treated. These details matter because the analysis can depend on whether missing outcomes are excluded, imputed, or handled by another method. None of those approaches can be assumed. With 0 analyses listed and no endpoint-specific comparison reported, it is not possible to evaluate multiplicity control, missing-data handling, or adherence to a prespecified analysis population from the registry 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 |
|---|---|---|---|
| Loteprednol Etabonate | 3 | 201 | 1.5% |
| Vehicle | 2 | 199 | 1.0% |
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 |
|---|---|
| Loteprednol Etabonate | 110 of 201 |
| Vehicle | 161 of 199 |
Most frequent serious adverse event terms
| Event term | Organ system | Loteprednol Etabonate | Vehicle |
|---|---|---|---|
| Endophthalmitis | Eye disorders | 1 of 201 | 1 of 199 |
| Fracture | Musculoskeletal and connective tissue disorders | 1 of 201 | 1 of 199 |
| Myocardial Infarction | Cardiac disorders | 1 of 201 | 1 of 199 |
| Post-operative inflammation | Eye disorders | 1 of 201 | 1 of 199 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Loteprednol Etabonate | Vehicle |
|---|---|---|---|
| Anterior chamber inflammation | Eye disorders | 61 of 201 | 106 of 199 |
| Photophobia | Eye disorders | 17 of 201 | 19 of 199 |
| Eye pain | Eye disorders | 8 of 201 | 26 of 199 |
| Iritis | Eye disorders | 11 of 201 | 19 of 199 |
| Conjunctival hyperemia | Eye disorders | 10 of 201 | 15 of 199 |
| Ocular pruritis | Eye disorders | 5 of 201 | 16 of 199 |
| Lacrimation increased | Eye disorders | 6 of 201 | 14 of 199 |
| Corneal edema | Eye disorders | 8 of 201 | 11 of 199 |
| Anterior chamber cell | Eye disorders | 5 of 201 | 10 of 199 |
| Ciliary hyperemia | Eye disorders | 5 of 201 | 10 of 199 |
Serious events with the highest arm-level rate: endophthalmitis (0.5%), fracture (0.5%), myocardial infarction (0.5%), post-operative inflammation (0.5%).
For serious adverse events, the registry reports 3 affected participants among 201 at risk in the Loteprednol Etabonate group, and 2 among 199 at risk in the Vehicle group. For other adverse events, it reports 110 affected among 201 at risk in the Loteprednol Etabonate group, and 161 among 199 at risk in the Vehicle group. These are counts within the recorded safety groups; they are not the primary efficacy outcome.
The serious-event terms listed are Endophthalmitis, Fracture, Myocardial Infarction, and Post-operative inflammation, each with a reported value of 0.5%. The registry record does not provide further context for those term-level values in this entry. Death counts are not reported in the registry record.
Adverse-event counts describe events recorded during the trial; by themselves, they do not establish that an intervention caused an event. The registry record does not provide event timing, duration, severity details beyond the serious-event classification, or a comparative statistical analysis. The counts should therefore be read descriptively, without treating them as proof of a causal difference between groups.
12. What the Result Does, and Does Not, Mean
The registry record establishes the trial's question and design, and gives safety counts for the two groups. It does not report the primary efficacy counts or a statistical analysis of the primary outcome. As a result, the posted results cannot show whether participants receiving loteprednol etabonate 0.5% ointment had more, fewer, or a similar number of complete resolutions than participants receiving vehicle at Postoperative Day 8 (Visit 5).
That absence is not evidence that the groups were the same. A conclusion of similarity would require results and an analysis designed to assess similarity or equivalence; neither is reported. Nor can the missing comparison be interpreted as proof of benefit or lack of benefit. The record gives no effect estimate, confidence interval, or p-value for the endpoint, so neither the direction nor precision of a primary treatment comparison can be assessed.
The safety counts offer descriptive information about participants recorded as affected by serious and other adverse events. They do not answer the efficacy question, and event counts alone do not determine whether a treatment caused an event. The registry also does not provide the details needed to evaluate the severity, timing, or statistical uncertainty of those comparisons.
In general, the meaning of a trial result depends on the endpoint definition, the observed group data, the analysis, and the uncertainty around the estimate. Here, the endpoint definition and design labels are available, but the efficacy results and analysis are not. The responsible interpretation is therefore limited to what the record documents: a completed randomized comparison with a specified primary endpoint and recorded safety counts, without a reported primary efficacy result.
13. Why This Trial Matters Statistically
This trial illustrates why a registry entry's design description and outcome definition should be separated from its evidence about comparative efficacy. Randomization, masking, and a defined assessment visit describe how a study was organized. They do not, on their own, reveal the size or direction of an outcome difference. For that, readers need the group-level endpoint results and an analysis that quantifies uncertainty.
The primary endpoint is a participant count based on complete resolution of anterior chamber cells and flare. This makes the intended clinical state explicit, but the registry record does not provide the counts needed to compare groups. Without those values, the outcome cannot be converted into a treatment-effect estimate or assessed for precision. This is a useful statistical distinction: a well-specified question is not the same thing as a reported answer.
The entry also names secondary outcomes across follow-up visits. Repeated assessments can add detail, but they create analytic choices about the primary time point, repeated observations, and multiplicity. When those choices and results are not reported, readers cannot determine how the multiple outcome opportunities were handled. The registry record lists 0 analyses, leaving these questions unresolved.
Finally, the safety record demonstrates why counts need context. The number affected and the number at risk are both important for describing recorded events, while neither alone establishes causation. Separating descriptive safety information from the absent efficacy comparison avoids overinterpreting a set of counts. In this record, the central statistical lesson is the boundary between what the study was designed to ask and what its posted results allow readers to conclude.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The main trial-specific limitation of the registry record is that it does not report group counts or an effect estimate for the primary endpoint. Although the primary outcome, population label, and assessment visit are identified, the efficacy comparison cannot be evaluated without the observed endpoint data. The record lists 0 analyses and does not report confidence intervals or p-values.
Important analysis details are also not reported in the registry record. These include the number analyzed for the primary endpoint, the handling of missing observations, the method used for the primary comparison, and whether any covariate adjustment was used. The intent-to-treat population is named, but the record does not give analysis counts or explain how that population was implemented.
The registry describes the study as randomized, multicenter, double-masked, and parallel-group, but does not report the randomization procedure, the centers, the people masked, or how masking was maintained. It also does not report a multiplicity approach for outcomes assessed at each follow-up visit. These omissions limit appraisal of the methods; they do not establish that a particular method was or was not used outside the registry entry.
The listed safety counts are descriptive, and the record does not provide fuller event details or a comparative analysis. The listed serious-event terms each have a value of 0.5%, but the entry provides no further context for interpreting those term-level values. The registry record does not report the trial's sample-size justification. Planning assumptions based on an observed effect are not a substitute for that justification or for the missing efficacy results.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Loteprednol Etabonate Ophthalmic Ointment vs. Vehicle in the Treatment of Inflammation Following Cataract Surgery — NCT00645671.
- Registry record last updated 2015-03-24; status last verified 2015-03.
- Results first posted 2010-09-23.
- 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.
Continue through the Clinical Biostats statistical pathway
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18. Record Summary
NCT00645671 is a completed, randomized, double-masked, parallel-group phase 3 trial sponsored by Bausch & Lomb Incorporated. It compares loteprednol etabonate 0.5% ophthalmic ointment with vehicle for inflammation following cataract surgery. The registry lists enrollment of 400, a start of 2008-03, and primary completion of 2009-03.
The primary endpoint is the number of participants with complete resolution of anterior chamber cells and flare, Grade=0, at Postoperative Day 8 (Visit 5), in the intent-to-treat population. Secondary outcomes concern resolution and change from baseline at follow-up visits. The registry record does not report the primary efficacy counts, a treatment-effect estimate, or an analysis; it lists 0 analyses.
Safety counts are reported for serious and other adverse events, but they do not replace the missing efficacy comparison. Details of the statistical analysis, missing-data handling, multiplicity approach, and sample-size justification are not reported in the registry record.