A Safety and Efficacy Study of a Dexamethasone Drug Delivery System for Postoperative Inflammation and Pain After Cataract Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Safety and Efficacy Study of a Dexamethasone Drug Delivery System for Postoperative Inflammation and Pain After Cataract Surgery (NCT01605942), a randomized phase 1 study. The primary outcome is Number of Patients With Clearance of Anterior Chamber Inflammation.

2. Clinical Question

The record identifies the primary outcome as the number of patients with clearance of anterior chamber inflammation. It defines the anterior chamber as the area in front of the iris and says inflammation is measured on a scale from 0 (best) to 8 (worst). The record does not define the score or change that qualifies as “clearance,” so the clinical threshold behind the outcome cannot be determined from the registry record.

The results list 4.0 patients in the dexamethasone group and 1.0 patient in the placebo group as having clearance. These are counts, not a reported statistical comparison. The groups contain 6.0 and 2.0 patients, respectively, in the primary outcome results. The record does not report a confidence interval, a hypothesis test, or an adjusted comparison to describe the uncertainty around the group difference.

The study also lists plasma levels of dexamethasone as a secondary outcome. The registry record does not give a result for that outcome. Thus, the primary question is narrow: it concerns the recorded count of patients meeting an undefined clearance criterion, not a fully described estimate of the comparative treatment effect.

3. Trial Design

This was a randomized, triple-masked, parallel-group PHASE1 study of a dexamethasone drug delivery system after cataract surgery. The comparator was a placebo drug delivery system. Both treatments were administered into the study eye at the conclusion of cataract surgery on Day 1. The registry lists Allergan as the sponsor and cataract as the condition.

The registry reports enrollment of 8 and lists 6.0 patients in the dexamethasone arm and 2.0 in the placebo arm for the primary outcome. The study status is TERMINATED. Its recorded start was 2012-06, and primary completion was 2012-09. The reason for termination is not reported in the registry record, so the status alone does not explain why the study ended.

“Parallel” means the two treatment groups are compared as separate groups rather than as successive treatment periods for the same participants. Randomization indicates assignment to study groups by a random process, but the registry record does not describe the allocation procedure or its implementation. The record says masking was triple; it does not identify which roles or individuals were masked, or describe how masking was maintained.

The primary outcome timeframe extends up to Day 71. The stated outcome population is the safety population of all patients who received study treatment at randomization/surgery on Day 1. The registry does not report more detail on follow-up visits, analysis-population definitions, protocol deviations, or the handling of participants who did not complete follow-up. Those omissions limit how fully the design and conduct can be reconstructed from the 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.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Safety: all patients who received study treatment at randomization/surgery (day 1)

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 Number of Patients With Clearance of Anterior Chamber Inflammation, measured over Up to Day 71.

The primary endpoint is the number of patients with clearance of anterior chamber inflammation, assessed up to Day 71. The anterior chamber is the space in front of the iris. The registry describes inflammation as measured on a scale from 0 (best) to 8 (worst), but it does not state the score threshold, timing rule, or other criterion used to classify a patient as having “clearance.” The meaning of the endpoint is therefore only partly specified.

A patient count is a binary-outcome summary: each patient is classified as meeting or not meeting the endpoint, and the result is expressed as the count meeting it. Such an endpoint can provide a clinically interpretable description when the event definition and assessment rules are clear. Without the clearance definition, however, readers cannot establish precisely which inflammation scores or patterns of change correspond to the reported count.

The endpoint is recorded for the safety population, defined in the registry as all patients who received study treatment at randomization/surgery on Day 1. That population description does not establish whether every treated participant had an evaluable outcome at each assessment through Day 71. Missing endpoint data and the rule used to handle them are not reported in the registry record.

The registry reports 4.0 patients with clearance in the dexamethasone group and 1.0 in the placebo group. These counts describe the recorded outcomes, but by themselves do not express the precision of a treatment comparison. The record includes no confidence interval or test for this primary endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry reports counts for a binary primary outcome and does not list any analyses. The interpretation therefore depends mainly on understanding what a count can describe, what it leaves uncertain, and why the absence of an inferential comparison matters. General statistical explanations below are not claims about analyses that were performed in this study.

What does a binary endpoint count represent?

A binary endpoint assigns each participant to one of two categories, such as meeting or not meeting a stated criterion. The primary outcome is presented as the number of patients with clearance of anterior chamber inflammation. A count tells the reader how many patients in a group were classified as having the event. It does not, by itself, summarize the uncertainty in the underlying event frequency or estimate the comparative effect between groups.

For a binary endpoint, the event definition is central to interpretation. Here, the registry says inflammation was measured on a scale from 0 (best) to 8 (worst), but the record does not specify how “clearance” was determined from that scale. That missing rule prevents a full assessment of whether the endpoint reflects a particular score, a change over time, or another criterion. No such definition should be inferred.

Why are counts not a complete comparison?

A comparison between randomized groups usually aims to estimate how outcomes differ between the assigned treatments, while also describing uncertainty. Statistical methods can express that uncertainty with a confidence interval or assess compatibility with a specified null hypothesis using a test. The registry lists 0 analyses and does not provide a confidence interval or test for the primary endpoint. It reports the counts only.

In general, a confidence interval gives a range of values compatible with the data and the method’s assumptions. It can show whether the available data estimate an effect precisely or leave substantial uncertainty. A hypothesis test addresses a different question: how compatible the observed data are with a specified null model. Neither method resolves a poorly defined endpoint, and neither can be recreated as a reported sponsor analysis when the registry does not post one.

The registry says values were missing or not estimable for a two-arm comparison of this binary endpoint. This makes a comparative result unavailable in the posted analysis. The absence of an estimable test is not proof of no effect, nor is it evidence that a difference is statistically significant. It means that the record does not give a usable inferential comparison.

How does group size affect precision?

In general, smaller groups provide less information about event frequencies and make estimates more vulnerable to the outcome of an individual participant. That concern is especially relevant when one group is much smaller than the other, as in the primary results. A count from a small group can be stated exactly, but its underlying event frequency may still be uncertain. Because no interval is reported, the reader cannot use the registry results to quantify that uncertainty.

Random allocation can support a fair comparison by reducing systematic differences in expectation, but it does not guarantee that groups with very small enrollment will be similar on all relevant characteristics. The registry does not provide baseline characteristics or a detailed account of allocation, so the balance of prognostic factors cannot be assessed from this record.

What do the planning illustrations mean?

Planning calculations are not observed trial outcomes and are not a measure of the study’s observed power. The registry’s planning assumptions describe an illustration based on the observed effect, using 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. These assumptions describe a hypothetical future design exercise, not the original trial’s documented design rationale.

In general, a sample-size illustration asks how many participants might be needed under specified assumptions to detect a chosen effect with a chosen probability. Its answer depends on the assumed effect, variability or event frequency, error threshold, allocation, and method. When the observed effect comes from a very small study, it can be unstable; using it as a planning input does not make it a reliable estimate of the effect a future study should expect. The record does not report the original sample-size justification or protocol-level planning assumptions.

For a binary outcome, planning depends on the event probabilities assumed for the groups and on the effect targeted. The registry’s record does not provide a complete comparative analysis from which readers could evaluate the stability of those assumptions. Any such planning output should therefore be understood as conditional illustration rather than evidence that the original trial had a particular power or that its result is conclusive.

What can be inferred from the design labels?

“Randomized” describes how assignment was intended to occur; it does not state the exact sequence-generation or concealment method. “Triple” masking indicates a masking designation in the registry, but the identities of the masked roles are not specified. A parallel model means separate groups receive their assigned study treatments. These labels help characterize the design, but they do not replace details about implementation, adherence, missing outcomes, or analysis methods.

The registry identifies the primary analysis population as all patients who received study treatment at randomization/surgery on Day 1. It does not say how any missing endpoint observations were treated, whether participants were analyzed according to assigned group, or whether any sensitivity analyses were planned or conducted. Without those details and an inferential result, interpretation should remain descriptive.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Dexamethasone Drug Delivery System", "Placebo Drug Delivery System")
n      <- c(6, 2)
events <- c(4, 1)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Dexamethasone Drug Delivery System  6  4  66.7  22.3  95.7  30.0  90.3  29.0  90.1
ARM  Placebo Drug Delivery System  2  1  50.0  1.3  98.7  9.5  90.5  9.4  90.6

11. Multiplicity, Missing Data and Analysis Populations

The registry lists the primary outcome as the number of patients with clearance of anterior chamber inflammation and lists plasma levels of dexamethasone as a secondary outcome. It reports 2 outcome measures, but only one secondary outcome is named in the record. It lists 0 analyses. No testing strategy for multiple outcomes, adjustment method, hierarchy, or prespecified priority among analyses is reported in the registry record.

In general, testing several outcomes can increase the chance of finding at least one apparently notable result by chance. A prespecified multiplicity strategy can address that issue, but no such strategy is described. Since no comparative tests are posted, the record does not support conclusions about adjusted or unadjusted statistical significance.

The primary outcome population is described as all patients who received study treatment at randomization/surgery on Day 1. That identifies the stated population but does not explain how missing endpoint measurements or withdrawals were handled. The registry does not report the amount, timing, or reasons for missing outcome data, nor does it describe imputation, exclusions, or sensitivity analyses. The endpoint timeframe is up to Day 71, but the record does not establish whether all patients had outcome assessments through that timeframe.

The record also does not report whether analyses followed randomized assignment, how protocol deviations were handled, or whether any additional analysis populations were used. These details matter because different rules for inclusion and missing data can affect a comparative estimate. With no reported comparative estimate and no missing-data methods, the posted counts should be read as descriptive results for the stated population, not as a complete account of the analysis plan.

12. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: corneal oedema (33.3%), retinal tear (16.7%).

The safety results list serious adverse events for the two treatment groups. In the dexamethasone group, 2 of 6 patients at risk had a serious adverse event; in the placebo group, 0 of 2 patients at risk had one. The registry also lists other adverse events in 6 of 6 patients in the dexamethasone group and 2 of 2 patients in the placebo group. These are counts within the enrolled study groups, not comparative risk estimates.

The serious-event terms listed are Corneal Oedema at 33.3% and Retinal Tear at 16.7%. The record does not give an arm-specific breakdown for these terms, so they should not be attributed to a particular treatment group based on the listed percentages. The registry does not report a death count; deaths are not reported in the registry record.

With these small groups, the event counts provide limited information about the frequency or comparative safety of adverse events. The record does not report a statistical comparison, confidence interval, event timing, or detailed severity and relatedness assessments. The figures describe what was recorded in this study and should not be generalized as precise safety estimates.

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

The registry record establishes that this randomized, triple-masked parallel study compared a dexamethasone drug delivery system with a placebo drug delivery system after cataract surgery. It reports 4.0 patients with clearance of anterior chamber inflammation in the dexamethasone group and 1.0 in the placebo group, with group sizes of 6.0 and 2.0 in the primary outcome results. It also reports limited adverse-event counts.

Those observations do not establish the size or precision of a treatment effect. No confidence interval or hypothesis test for the primary comparison is reported, and the registry indicates that values were missing or not estimable for a two-arm comparison of this binary endpoint. A numerical difference in the observed counts should not be treated as a statistically established difference or as evidence that the groups are equivalent.

The meaning of “clearance” is not fully defined, even though the inflammation scale is described. The registry also does not report the reason the study was terminated, the handling of missing outcome data, or results for the listed secondary outcome of plasma levels of dexamethasone. These gaps prevent a complete assessment of the outcome definition, analysis, and study conduct.

The safety observations likewise do not establish a comparative safety profile. They are counts from small groups, without a reported comparative analysis or precision estimate. The serious adverse-event terms are listed with percentages but without a treatment-arm breakdown. No deaths are reported in the record.

The appropriate statistical reading is therefore limited and descriptive: the registry records outcome counts and safety events in this study, but does not provide enough comparative or methodological information to support a definitive conclusion about efficacy or safety. The study result should not be extended beyond the specific participants and outcome information recorded.

14. Why This Trial Matters Statistically

This study is statistically instructive because it illustrates the gap between a randomized design and an informative comparative result. Randomization and masking are important design features, but they do not by themselves ensure that a registry record will contain a precise estimate, a complete endpoint definition, or a reported analysis. Those elements are necessary for readers to judge what the observed data can support.

The primary outcome is a patient count, which is straightforward to understand at first glance. Yet the word “clearance” is not operationally defined in the registry record. A scale from 0 (best) to 8 (worst) is described, but the decision rule that connects scale measurements to the binary outcome is absent. This highlights why an endpoint’s measurement and classification rules are part of the statistical evidence, not merely technical details.

The study also shows why group size and balance matter when reading descriptive counts. The reported primary-outcome groups contain 6.0 and 2.0 patients. Such limited information makes it difficult to characterize uncertainty, particularly when no confidence interval or test is reported. The counts are factual summaries of the enrolled groups, but they should not be mistaken for precise estimates of a broader treatment effect.

Finally, the registry’s indication that a two-arm binary comparison was not estimable, together with the absence of analysis results, is an important reporting limitation. It leaves readers without an inferential comparison and without a stated account of missing-data or multiplicity methods. The statistical lesson is not that the observed counts have no value; it is that descriptive results, study design labels, and planning calculations answer different questions. Keeping those distinctions clear prevents the strength of the evidence from being overstated.

15. 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 registry record has several limitations that affect interpretation of this specific study. The primary endpoint is described as clearance of anterior chamber inflammation, but the criterion for clearance is not reported. Although the inflammation scale ranges from 0 (best) to 8 (worst), the record does not state which values, change, or assessment rule qualified a patient as having clearance. This makes the outcome difficult to reproduce or clinically characterize.

The primary results are counts from groups of 6.0 and 2.0 patients. No confidence interval or test is reported, and the registry notes that values were missing or not estimable for a two-arm comparison of this binary endpoint. The reason for that non-estimability is not explained. The status is TERMINATED, but the reason for termination is not reported in the registry record.

Details needed to assess outcome completeness and analysis conduct are absent. The record does not report how missing endpoint data were handled, whether all participants were followed through the stated timeframe, or how protocol deviations and analysis populations were addressed. It does not report the allocation procedure beyond labeling the study randomized, and it does not identify who was masked despite the triple-masked designation.

The registry lists a secondary outcome of plasma levels of dexamethasone but does not report its result. It also does not provide a multiplicity strategy, an original sample-size justification, or a detailed statistical plan. Safety findings are descriptive, with no comparative analysis; the listed serious-event terms do not have an arm-specific breakdown. These limitations restrict conclusions to the recorded counts and prevent a fuller assessment of efficacy, safety, and study conduct.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Safety and Efficacy Study of a Dexamethasone Drug Delivery System for Postoperative Inflammation and Pain After Cataract Surgery — NCT01605942.
• Registry record last updated 2015-07-01; status last verified 2015-06.
• Results first posted 2015-07-01.
• 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.

19. Record Summary

This registry record describes a randomized, triple-masked, parallel PHASE1 study of a dexamethasone drug delivery system versus a placebo drug delivery system administered into the study eye after cataract surgery. Enrollment was 8. The study is listed as TERMINATED; its start was 2012-06 and primary completion was 2012-09. The reason for termination is not reported in the registry record.

The primary outcome was the number of patients with clearance of anterior chamber inflammation, assessed up to Day 71. The registry reports 4.0 patients in the dexamethasone group and 1.0 in the placebo group, with no reported comparative analysis. Plasma levels of dexamethasone is the listed secondary outcome, but its result is not reported.

Safety counts include serious adverse events in 2 of 6 dexamethasone-group patients and 0 of 2 placebo-group patients. Other adverse events are recorded in both groups. Overall, the posted results are descriptive and do not include a confidence interval or hypothesis test for the primary comparison.