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 A Study of Ketorolac for the Treatment of Inflammation and Pain Associated With Cataract Surgery (NCT00521456), a randomized phase 3 study. The primary outcome is Resolution of Post Operative Inflammation.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00521456 |
| Phase | Phase 3 |
| Condition | Cataract Extraction |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 263 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Allergan |
| Results posted | Yes |
2. Clinical Question
Population
Participants in the Modified Intent-to-Treat Population undergoing cataract surgery. The registry lists Cataract Extraction as the condition. It does not report further eligibility details or define the modified analysis population.
Intervention
Ketorolac Solution, described in the record as ketorolac eye drops.
Comparator
Vehicle Solution. The registry identifies this as the control arm.
Primary question
At Day 14, what percentage of participants had a score of 0 for resolution of postoperative inflammation, based on anterior chamber cell and flare?
The registry describes a 16 day study evaluating the safety and efficacy of ketorolac eye drops for inflammation and pain associated with cataract surgery. Its primary outcome is framed as the percentage of participants reaching a specified score, rather than as an average score across the full scale. The outcome is therefore a responder-style measure: the result concerns the proportion meeting the zero-score criterion at the stated assessment time.
The posted primary results give the percentage and analysis-population count for each arm. They do not include an inferential comparison, such as a confidence interval or p-value, for this endpoint. That limits how precisely the between-arm contrast can be evaluated from the record. The registry also lists Ocular Pain and Mean Pupil Area as secondary outcomes; the available numerical secondary result concerns Mean Pupil Area. The record does not provide a numerical Ocular Pain result.
3. Trial Design
The registry classifies this as a Phase 3, randomized, double-masked, parallel-group study. It lists an enrollment of 263 and names Allergan as the sponsor. The record gives a start date of 2007-10, a primary completion date of 2008-03, and a status of Completed. These details describe the registered study; they do not, by themselves, establish how enrollment was divided across the reported outcome analyses.
The two posted arms are Ketorolac Solution and Vehicle Solution. The primary outcome is reported for the Modified Intent-to-Treat Population, with 169 participants in the ketorolac arm and 77 in the vehicle arm. The secondary Mean Pupil Area result is reported with 173 participants in the ketorolac arm and 81 in the vehicle arm. These are outcome-specific analysis counts. The registry does not explain why the counts differ between outcomes, and the enrollment figure should not be treated as a substitute for the denominator in a particular result.
The brief study summary describes a 16 day evaluation of safety and efficacy for inflammation and pain associated with cataract surgery. The registry does not provide the arm descriptions beyond the treatment names, details of the masking procedures, a randomization method, or a fuller schedule of assessments. Those elements are not reported in the registry record and should not be inferred from the broad design labels.
The record lists Ocular Pain and Mean Pupil Area as secondary outcomes, and identifies four outcome measures, but the posted numerical results include a Mean Pupil Area result. There are no reported formal analyses listed in the record. The design classification and outcome descriptions can therefore be summarized, but they do not supply a complete protocol or 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.
Overall Study
| Stage | Ketorolac Solution | Vehicle Solution |
|---|---|---|
| STARTED | 176 | 87 |
| COMPLETED | 163 | 59 |
| NOT COMPLETED | 13 | 28 |
Analysis population for the primary outcome, as defined in the registry: Modified 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 | Ketorolac Solution | Vehicle Solution | Total |
|---|---|---|---|---|
| Participants analysed | 176 | 87 | 263 | |
| Age, Customized: <45 years | participants | 4 | 3 | 7 |
| Age, Customized: Between 45 and 65 years | participants | 56 | 32 | 88 |
| Age, Customized: >65 years | participants | 116 | 52 | 168 |
| Sex: Female, Male: Female | Participants | 101 | 51 | 152 |
| Sex: Female, Male: Male | Participants | 75 | 36 | 111 |
6. Primary Endpoint
The registry lists the primary outcome as Resolution of Post Operative Inflammation, measured over Day 14.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | % of participants with a score of 0 |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is Resolution of Post Operative Inflammation, expressed as the percentage of participants with a score of 0 at Day 14. The registry defines anterior chamber inflammation as the sum of biomicroscopic cell and flare. Each component is measured on a scale from 0 to 4: zero indicates no flare or no cells, while the upper scale descriptions indicate intense flare and more than 50 cells. A combined score of zero corresponds to neither cells nor flare being observed under those component definitions.
This endpoint turns the underlying assessment into a binary classification for each participant: the person either meets the zero-score definition at the assessment or does not. Reporting the percentage meeting the criterion gives a direct description of how often complete resolution, as operationalized by the registry, was recorded in each arm. It does not describe the distribution of nonzero scores, the amount of change from an earlier assessment, or the degree of inflammation among participants who did not reach zero.
As a general statistical consideration, a threshold-based endpoint can be straightforward to interpret, but it discards distinctions among values on the same side of the threshold. The registry's posted primary result reports the percentages by arm, but does not report a confidence interval or formal between-arm test for this outcome. The degree of uncertainty around the percentages and their contrast is therefore not quantified in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
For the primary endpoint at Day 14, the registry reports that 58.0% of the Ketorolac Solution group and 27.3% of the Vehicle Solution group had a score of 0. The corresponding analysis counts are 169 and 77. These are descriptive arm-level results for the Modified Intent-to-Treat Population. They indicate the observed frequency of meeting the registry's zero-score definition in each group; by themselves, they do not establish the precision of the between-arm contrast.
No confidence interval, p-value, or other formal comparison is reported for this primary result. Consequently, the registry record does not quantify sampling uncertainty around the difference between the groups. No difference or ratio should be inferred from the percentages without an explicitly reported analysis. The record also does not explain whether an adjusted analysis was planned or performed for this endpoint.
The secondary Mean Pupil Area result is reported at Day 0 as a mean of 37.9 mm² for Ketorolac Solution and 36.5 mm² for Vehicle Solution. The posted mean difference is 1.4 mm², with a 95% confidence interval from -2.041 to 4.841 and an unadjusted p-value of 0.425. The interval spans zero, so the posted estimate is compatible with values on either side of zero under the analysis used. This is a secondary result and is not a substitute for the primary Day 14 inflammation outcome.
The Mean Pupil Area comparison is accompanied by standard deviations of 12.0 and 13.5. These describe variability among participants in each arm; they are not confidence intervals for the means. The record also reports no adjusted secondary analyses. An unadjusted p-value describes the particular comparison without accounting for the possibility of examining multiple outcomes or analyses. The registry does not report a multiplicity plan, so the weight to give this secondary result cannot be calibrated against a prespecified family of tests.
Safety information is limited in the posted fields. One serious adverse event is listed for Ketorolac Solution and zero for Vehicle Solution. Other adverse events are listed as 68 and 57, respectively. The record does not report the number at risk for these categories, so rates cannot be interpreted from these counts. Death counts are not reported. Post procedural haemorrhage is listed among the top serious terms with a value of 0.6%; the registry record does not provide further context for that entry.
The sample-size illustrations are planning calculations based on a fraction of the observed secondary effect, under stated assumptions. They are not evidence of the trial's original design rationale and are not observed power. The registry does not report the original sample-size justification. Overall, the posted results support a description of observed arm-specific outcomes, but the missing primary comparison and incomplete analysis details limit inferential conclusions.
9. Statistical Methods Explained
The registry labels the study randomized, double-masked, and parallel-group. In general, random allocation is intended to make treatment groups comparable with respect to both measured and unmeasured characteristics on average. Masking is intended to reduce the influence of treatment knowledge on care, assessment, or reporting. A parallel-group design assigns participants to a group that remains the basis of comparison. These are general descriptions of design concepts, not additional details about how this particular study implemented them. The randomization procedure and masking procedures are not reported in the registry record.
What does the primary percentage represent?
The primary outcome is a binary response defined by the zero score at Day 14. A participant's underlying assessment uses cell and flare components, each scored from 0 to 4, and the registry defines the inflammation score as their sum. The reported percentage is the proportion in an arm who meet the zero-score criterion in the specified analysis population. It is not a mean score, a change score, or a measure of the full distribution of inflammation scores.
For a binary endpoint, uncertainty around an arm-specific percentage is commonly expressed with a confidence interval, and a group comparison may be expressed as a difference in proportions, a ratio, or a model-based effect. Such methods require an explicit analysis choice. The registry reports none of these inferential results for the primary outcome. Therefore, the reported percentages can be described, but a precision estimate or formal contrast cannot be attributed to the record.
How should the secondary mean comparison be read?
Mean Pupil Area is a continuous outcome reported in square millimeters, with a mean and standard deviation for each arm. The posted comparison reports a mean difference of 1.4 mm², a confidence interval from -2.041 to 4.841, and an unadjusted p-value of 0.425. A confidence interval gives a range of values compatible with the estimate under the statistical model and its assumptions. It communicates uncertainty; it is not a range containing a stated proportion of individual participant measurements.
The interval includes zero and extends to both negative and positive values. Thus, the reported data do not pin down the direction of the underlying mean contrast with precision. The p-value is unadjusted, meaning the posted value does not account for a broader set of outcome tests. General statistical interpretation treats a p-value as a measure of how unusual data at least as incompatible with a specified null hypothesis would be if that hypothesis and the model assumptions held. It is not the probability that the null hypothesis is true, and it does not measure clinical importance. The record does not state a decision threshold or report an adjusted analysis.
Standard deviations describe the spread of observed measurements within each arm. They are different from standard errors, which describe uncertainty in an estimated mean. The reported standard deviations are 12.0 and 13.5. The registry also gives a pooled standard deviation of 12.5 for the comparison, but does not report a detailed analysis method beyond the comparison fields. These summaries should not be treated as individual-level data or as proof that the underlying measurement distributions meet any particular model assumption.
What do the planning illustrations mean?
The planning illustrations use the observed Mean Pupil Area effect as a reference and consider stated fractions of that observed effect. The registry specifies a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. The displayed quantities are participants per arm for 80% power or 90% power under those planning assumptions. They are hypothetical planning scenarios, not the sample size actually recruited, not the trial's original design calculation, and not observed power.
Power is a design-stage probability of detecting an effect under a specified model and set of assumptions if that effect is present. A planning calculation based on an observed effect does not demonstrate that the completed trial had that power. Observed effects can be uncertain, especially when estimated from a study, and changing the effect assumed for planning changes the resulting sample-size illustration. The original sample-size justification and protocol assumptions are not reported in the registry record.
Why can over-dispersion matter?
General explanation: for count outcomes, a simple model may assume that variability follows a particular relationship to the mean. Over-dispersion means the observed variation is greater than that assumption allows. If it is ignored, standard errors can be too small and confidence intervals or tests may appear more precise than warranted. The primary endpoint is presented as a percentage meeting a score criterion, not as a count-model analysis, and the record does not report an over-dispersion assessment. This concept should therefore not be interpreted as a claim about the analysis used in this trial.
More broadly, each method depends on its endpoint definition, analysis population, handling of missing measurements, and modeling choices. The registry identifies the primary population label and outcome time, but it does not define the modified intent-to-treat set, give missing-data rules, or describe a full statistical analysis plan. Without those details, readers should keep the interpretation close to the posted summaries and avoid assuming unreported modeling or adjustment decisions.
10. Multiplicity, Missing Data and Analysis Populations
The registry record does not report a multiplicity adjustment, a hierarchy of hypotheses, or a prespecified testing sequence. This matters because multiple outcomes or analyses can create multiple opportunities for apparently notable results. An unadjusted p-value is calculated for an individual comparison without accounting for that broader testing context. Without a reported strategy, the evidential status of secondary tests cannot be judged as though a particular correction or gatekeeping plan had been applied.
Missing-data handling is also not reported in the registry record. The record identifies the primary analysis population as Modified Intent-to-Treat Population, but does not define which participants qualified for that set, how missing Day 14 assessments were treated, or whether any imputation or sensitivity analysis was used. The reported primary counts are 169 and 77, while the secondary Mean Pupil Area counts are 173 and 81. The record does not explain these outcome-specific counts. They should be understood as the denominators attached to the respective results, not as evidence of a particular missingness rule.
The registry does not report a full statistical analysis plan, a prespecified handling of protocol deviations, or details of any interim analyses. Those items are not reported in the registry record; no particular procedure should be assumed. It also lists no formal reported analyses beyond the available posted result summaries. This absence of detail makes it difficult to assess whether the analysis populations, outcome definitions, and tests followed a plan established before results were examined.
These omissions do not change the numerical summaries that are posted, but they constrain interpretation. They leave uncertainty about how missing outcome data, multiple outcomes, and analysis choices were handled. The primary endpoint lacks an inferential comparison in the registry, while the secondary comparison is explicitly unadjusted. As a result, readers should distinguish the descriptive findings from stronger claims about precision or confirmatory evidence.
11. What the Result Does, and Does Not, Mean
The primary result describes the observed percentage of participants in each reported analysis group who met the registry's definition of a zero inflammation score at Day 14. It is a statement about the posted results, not a guarantee about what would be observed in another study or setting. The registry does not provide a confidence interval or formal test for this primary comparison, so the precision of the between-arm contrast is not reported.
The secondary Mean Pupil Area result is a separate measurement, collected at Day 0, and its reported comparison has an interval that includes zero. It should not be treated as interchangeable with the primary endpoint. Nor does an unadjusted secondary result, on its own, establish a broader conclusion about inflammation, pain, or safety. The registry's listed Ocular Pain outcome has no numerical result reported in the registry record.
These results do not establish a mechanism, explain why any observed group patterns occurred, or show how effects vary across participant subgroups. The record does not provide subgroup analyses, a detailed protocol, or the full analytic plan. The safety counts also lack reported numbers at risk, which prevents calculation or interpretation of event rates from those counts alone. The adverse-event listing should not be read as a complete safety profile.
General statistical interpretation distinguishes the estimate from its uncertainty and from its practical importance. A group-level estimate does not describe every participant, and a p-value does not measure the size or importance of an effect. Here, the primary endpoint is reported descriptively, and the secondary comparison is reported with uncertainty but without an adjustment for multiple testing. Conclusions should remain within those limits.
The record identifies a completed randomized, double-masked, parallel-group Phase 3 study, but those design labels do not fill in missing details about randomization, masking implementation, missing data, or analysis decisions. The posted information supports a focused account of registered outcomes and available summaries. It does not support medical advice or a general claim that a treatment does or does not work.
12. Why This Trial Matters Statistically
This record illustrates a common distinction in trial reporting: an outcome can have an interpretable clinical definition while still lacking the inferential information needed to judge its precision. The primary endpoint is clearly framed as the percentage reaching a zero-score criterion at a specified time, but the registry does not report a confidence interval or formal group comparison for it. Readers can describe the observed percentages without overstating what they establish.
It also shows why denominators must be read outcome by outcome. The primary endpoint and secondary Mean Pupil Area result use different reported analysis counts. The registry does not explain the difference, so neither the overall enrollment figure nor one outcome's count should be substituted for another outcome's denominator. Clear reporting of analysis populations and missing-data procedures would help readers understand such differences.
The secondary comparison demonstrates the importance of separating an effect estimate from its uncertainty and from multiplicity. Its confidence interval communicates a range of compatible values, while its unadjusted p-value does not account for other outcomes or tests. With no reported testing strategy, a secondary result should not carry the same weight as a clearly prespecified and appropriately interpreted primary analysis.
Finally, the planning illustrations are useful only as conditional scenarios. They rely on a stated observed effect and assumptions about allocation, significance level, and approximation. They are not the trial's original design rationale or a measure of achieved power. Taken together, these features make the record a useful example of how design labels, outcome definitions, descriptive results, uncertainty, and reporting gaps each contribute distinct information.
13. 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.
A central limitation of the available record is the lack of inferential statistics for the primary endpoint. The arm-specific percentages are reported, but uncertainty around them and a formal between-arm comparison are not. This prevents a direct assessment of how precisely the primary contrast is estimated from the posted information.
The Modified Intent-to-Treat Population is named but not defined. The registry does not describe how participants entered that population, how missing Day 14 outcomes were handled, or why primary and secondary outcome counts differ. Without those details, it is not possible to assess the impact of exclusions or missing observations on the reported summaries.
The registry provides limited secondary outcome reporting. Ocular Pain is listed but has no numerical result in the registry record. The available Mean Pupil Area comparison is unadjusted, and no multiplicity plan is reported. The record also does not provide a complete statistical analysis plan, details of subgroup analyses, or information about interim analyses. None of these methods should be assumed.
Safety reporting is similarly limited: counts are listed without numbers at risk, and death counts are not reported. The record does not provide sufficient context to interpret the listed adverse-event counts as rates. The listed serious-term percentage is not accompanied by further detail in the available information.
Finally, the registry describes the broad trial design but does not report the randomization procedure, the implementation of masking, or a sample-size justification for the trial itself. The sample-size illustrations are based on the observed secondary effect and stated assumptions, so they do not resolve that limitation. These gaps make the record more suitable for a qualified description of posted results than for a complete appraisal of the study methods.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: A Study of Ketorolac for the Treatment of Inflammation and Pain Associated With Cataract Surgery — NCT00521456.
- Registry record last updated 2009-10-01; status last verified 2009-08.
- Results first posted 2009-10-01.
- 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
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
17. Record Summary
The registry record describes a completed Phase 3, randomized, double-masked, parallel-group study sponsored by Allergan. It lists ketorolac eye drops and Vehicle Solution as the arms, with an enrollment of 263. The study summary describes a 16 day evaluation related to inflammation and pain associated with cataract surgery.
The primary outcome is the percentage with a score of 0 for postoperative inflammation at Day 14 in the Modified Intent-to-Treat Population. The registry reports arm-specific percentages and analysis counts but no confidence interval or formal primary comparison. A secondary Mean Pupil Area result is reported at Day 0 with a mean difference, confidence interval, and unadjusted p-value. Ocular Pain is listed as a secondary outcome, but its numerical result is not reported in the registry record.
Important details—including the full analysis plan, missing-data methods, multiplicity strategy, and primary sample-size justification—are not reported in the registry record. The posted results therefore support descriptive interpretation, with important limits on inference.