Effect of Ozurdex® 0.7 mg on Improvement of Efficacy of Bevacizumab for Central Retinal Vein Occlusion: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effect of Ozurdex® 0.7 mg on Improvement of Efficacy of Bevacizumab for Central Retinal Vein Occlusion (NCT01295112), a randomized phase 2, phase 3 study. The primary outcome is The Primary Efficacy Endpoint is the Total Number of PRN Bevacizumab Intravitreal Injections Through 24 Weeks.

2. Clinical Question

3. Trial Design

The registry lists this study as phase 2 and phase 3, randomized, single-masked, and parallel-group. Randomization means treatment assignment is made by chance rather than selected by the participant or clinician; in general, this is intended to reduce systematic differences between comparison groups. The registry does not report the randomization sequence method, allocation concealment procedures, or whether assignment used any stratification.

The parallel-group design assigned participants to one of two treatment combinations: active bevacizumab with sham Ozurdex®, or active bevacizumab with active Ozurdex®. A single-masked design indicates that masking was recorded, but the registry does not identify who was masked or describe how masking was maintained. It also does not report whether the sham was indistinguishable from the active intervention.

The recorded enrollment is 68. The registry lists Texas Retina Associates as the sponsor, a start date of 2011-05, a primary completion date of 2015-10, and a completed status. These administrative details do not supply the outcome findings or establish which participants contributed to a particular analysis. The adverse-event record gives risk-set counts of 35 for Group 1 and 33 for Group 2; these are reported in the safety record and should not be treated as a substitute for an outcome-specific analysis population.

The stated purpose was to determine whether adding Ozurdex® to bevacizumab reduced the need for repeat bevacizumab injections in non-ischemic central retinal vein occlusion. The primary endpoint covered 24 weeks. The registry also identifies best corrected visual acuity (BCVA) at Week 24 as a secondary efficacy endpoint. It does not report detailed visit schedules, treatment adherence, protocol deviations, or the exact procedures used to assess these outcomes.

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 The Primary Efficacy Endpoint is the Total Number of PRN Bevacizumab Intravitreal Injections Through 24 Weeks, measured over 24 weeks.

The primary efficacy endpoint is described as the total number of PRN bevacizumab intravitreal injections through 24 weeks. PRN means injections were given as needed. The endpoint therefore concerns the number of repeat injections over the stated follow-up period, rather than a single measurement of vision or a time-to-first-event outcome. The registry lists the unit as participants and the parameter as a count of participants, but it does not explain how that description maps to the total number of injections, or provide the outcome categories and values.

This endpoint matches the stated study objective: to assess whether adding Ozurdex® changes the need for repeat bevacizumab treatment. A count over a fixed period can reflect both how often additional treatment is required and the duration over which it is observed. Interpretation depends on a consistent rule for deciding when an injection is needed, as well as complete and comparable follow-up in both groups. The decision criteria and handling of incomplete follow-up are not reported in the registry record.

The primary result itself is not reported in the registry record. There is no posted group count, treatment contrast, uncertainty interval, or significance test to interpret. Consequently, the endpoint definition can be described, but the magnitude and precision of any group difference cannot be evaluated from the available record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a randomized, single-masked, parallel-group study. In general, random allocation helps make comparison groups similar on average with respect to measured and unmeasured characteristics, although it does not guarantee balance in any particular trial. A parallel-group design compares groups assigned to different treatment combinations during the same study period. Here, both listed groups received active bevacizumab, while one received sham Ozurdex® and the other active Ozurdex®. The record does not state who was masked, how masking was maintained, or how assignment was generated and concealed.

What would a treatment contrast represent?

For the primary question, a treatment contrast would compare the number of PRN bevacizumab intravitreal injections through 24 weeks between the two assigned groups. A contrast is useful because it expresses the comparison of interest, rather than describing each group in isolation. For a count outcome, a suitable summary might depend on how the outcome was recorded and distributed. The registry record does not report the group summaries, the form of the contrast, or the statistical model, so it is not possible to identify which analysis was used or interpret its assumptions.

The endpoint description combines a total number of injections with a unit and parameter description referring to participants and a count of participants. This leaves uncertainty about the exact data structure. For example, the record does not clarify whether the posted outcome was an injection count for each participant, a count of participants in injection categories, or another representation. These distinctions matter: an analysis of participant-level counts and an analysis of category frequencies may require different summaries and methods. The registry notes that the primary outcome has several categories or time points and was not reduced to one comparison. The full categories and corresponding results are not reported in the registry record.

Why can counts need special methods?

As a general statistical consideration, count outcomes are often nonnegative and may be unevenly distributed. Some participants may have no events while others have several, and the variability can be greater than a simple model assumes. Over-dispersion means that the observed variability exceeds what a particular count model expects. If it is present, standard errors and confidence intervals from an unsuitable model may be too narrow, making the results appear more precise than warranted. Whether the injection outcome showed over-dispersion, and whether any count model was used, are not reported in the registry record. The endpoint coding details are also unavailable, so no model choice can be inferred from its label alone.

What would uncertainty estimates tell readers?

In general, a confidence interval gives a range of estimates compatible with the data and the assumptions of the analysis. It communicates precision as well as the estimated direction and size of a contrast. A narrow interval indicates greater precision than a wide interval, while an interval spanning values that would imply different substantive interpretations leaves more uncertainty. No confidence interval for the primary endpoint is reported in the registry record. The estimate itself is also absent, so neither its magnitude nor its precision can be evaluated.

A p-value, in general, describes how unusual data at least as incompatible with a specified null model would be, if that model and the test assumptions held. It is not the probability that the null hypothesis is true, nor does it measure the clinical importance of a result. The record does not report a p-value for the primary outcome or name a test. The sample-size assumptions refer to a two-sided significance level of 0.05 for a planning illustration, but that detail does not establish the significance threshold used for the trial’s actual analysis.

What do the planning assumptions mean?

The registry text describes planning illustrations based on an observed effect, with two-sided significance level 0.05, equal allocation, and a normal approximation. It also says the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not evidence about the trial’s originally intended sample-size justification. Sample-size illustrations derived from an observed effect are not observed power, and they do not demonstrate that the trial had a particular probability of detecting a true effect. The original sample-size rationale, target effect, and any prespecified planning calculations are not reported in the registry record. No numeric planning result is available in the record.

More generally, sample-size calculations depend on the chosen outcome, the effect considered important, outcome variability, the analysis method, and the error-rate assumptions. A calculation based on an observed effect can be sensitive to sampling variation in that estimate. If the observed effect is imprecise, planning estimates that use it may also be unstable. For the injection endpoint, the record does not give the effect estimate or variability needed to assess such calculations. It also does not report whether any assumptions were revised during the study.

The record lists 2 outcome measures and 2 analyses, but does not describe the analyses in enough detail to identify model specifications or explain how results correspond to each endpoint. The primary outcome is flagged as having several categories or time points and not reduced to one comparison. Without the detailed outcome definitions and analysis results, readers cannot reconstruct the primary comparison or check the calculations independently. Any interpretation should therefore distinguish the stated endpoint and design from statistical findings that are not reported.

10. Multiplicity, Missing Data and Analysis Populations

The registry identifies the injection count through 24 weeks as the primary efficacy endpoint and BCVA at Week 24 as a secondary efficacy endpoint. It also records 2 outcome measures and 2 analyses, while noting that the primary outcome has several categories or time points and was not reduced to one comparison. The categories, time points, and corresponding analysis results are not reported in the registry record. This makes it difficult to determine how many statistical comparisons were made or which one was considered the main inferential test.

Multiplicity arises when several outcomes, time points, or comparisons are examined. In general, conducting multiple tests can increase the chance of at least one apparently unusual result under a null hypothesis. Prespecified priorities and statistical adjustments can help readers understand how such testing was handled. The registry record does not report a multiplicity strategy, any adjustment, or a hierarchy among outcome analyses. It is therefore not possible to determine whether the reported analyses, if any, accounted for multiple comparisons.

The record does not describe how missing outcome data were handled, whether follow-up differed between groups, or whether any sensitivity analyses were planned or conducted. Missingness can affect an estimate if the availability of observations is related to outcomes or treatment assignment. The registry also does not specify an intention-to-treat, per-protocol, or other analysis population, nor how participants with incomplete follow-up or protocol deviations were treated. Enrollment and safety risk-set counts do not identify the population included in the primary efficacy analysis.

These omissions limit assessment of the reliability and interpretation of any treatment comparison. They do not establish that particular problems occurred; they mean that the relevant methods are not reported in the registry record.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry safety record lists Group 1 with 35 participants at risk for serious adverse events and 0 affected; Group 2 has 33 participants at risk and 0 affected. For other adverse events, it lists 35 at risk and 0 affected in Group 1, and 33 at risk and 0 affected in Group 2. Deaths are recorded as 0 in each group. These are counts entered in the safety record, not estimates of comparative risk.

A count of zero means that no affected participants were recorded in that category in the registry entry. It does not establish that the true risk is zero, and it does not rule out events that were not captured, not reported, or classified differently. With no recorded events in either group, these figures cannot by themselves show that one treatment combination is safer than the other. A comparative safety assessment would need appropriate follow-up, event definitions, and uncertainty estimates.

The registry does not list serious adverse event terms, so the nature and timing of any reported events cannot be described; no serious events are recorded in the group counts. It also does not provide details about adverse-event ascertainment, severity classifications beyond the serious category, relatedness assessments, or participant withdrawals due to adverse events. The safety counts should be read narrowly as the registry’s recorded figures, not as a comprehensive account of safety.

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

The study’s stated objective was to test whether adding active Ozurdex® to active bevacizumab reduced the need for repeat bevacizumab injections in non-ischemic central retinal vein occlusion. Its primary endpoint was the total number of PRN bevacizumab intravitreal injections through 24 weeks, comparing active bevacizumab plus active Ozurdex® with active bevacizumab plus sham Ozurdex®. That description identifies the question and comparison, but does not supply the answer.

The primary outcome values and treatment contrast are not reported in the registry record. There is no effect estimate, interval expressing uncertainty, or significance test to establish the direction, magnitude, or precision of a difference. Consequently, the available information cannot support a conclusion that adding Ozurdex® reduced injections, increased them, or made no difference. This is a limitation of the recorded results, not a finding of equivalence or absence of effect.

The registry also names BCVA at Week 24 as a secondary efficacy endpoint, but its results are not reported. The record therefore does not establish whether the groups differed in visual acuity or how any such difference related to injection frequency. The safety record contains zero recorded serious adverse events, other adverse events, and deaths in the listed group counts, but those entries alone cannot establish that the interventions carry no risk or that their safety profiles are equivalent.

More broadly, registry design details do not replace outcome estimates and analysis methods. A randomized design can support a comparative interpretation when properly implemented and analyzed, but readers still need the actual outcome data, definitions, uncertainty estimates, and information on missingness and analysis populations. Those elements are not reported in the registry record. The record supports description of the intended comparison and the listed safety counts, but not a conclusion about efficacy, clinical importance, or treatment choice.

13. Why This Trial Matters Statistically

This study illustrates why a clearly stated clinical question and an interpretable statistical result are both necessary. The groups differ in whether active Ozurdex® or sham Ozurdex® was paired with active bevacizumab, and the stated primary outcome concerns repeat injections through 24 weeks. That design description makes the intended contrast understandable. However, without the group outcome values and an estimate of their difference, the central statistical question remains unanswered in the registry record.

The endpoint also highlights the importance of precise outcome definitions. A total number of injections is a count, while the registry’s unit and parameter description refers to participants and a count of participants. The record further notes multiple categories or time points without reducing them to one comparison. Such details are not merely technical: they determine what is being compared, which model may be appropriate, and how readers should interpret uncertainty. The categories and analysis details are not reported in the registry record.

Randomization, masking, and parallel-group allocation describe important design features, but they do not by themselves show how results were analyzed or whether outcome data were complete. The record does not state who was masked, how missing data were handled, or which participants were included in the efficacy analysis. These absences limit assessment of precision and robustness.

The safety entries likewise demonstrate the distinction between recorded counts and broad claims. Zero recorded events in a category is a useful factual description, but does not establish zero underlying risk or comparative safety. Overall, the trial record is a reminder that design, endpoint definition, analysis, uncertainty, and transparent reporting all contribute to statistical interpretation; the posted record does not contain enough efficacy results to complete that interpretation.

14. Limitations

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

Several limitations are specific to the information recorded for this study. The primary endpoint is described as the total number of PRN bevacizumab intravitreal injections through 24 weeks, but the registry also labels the unit as participants and the parameter as a count of participants. It does not explain the data structure or clarify how injection totals correspond to the participant counts. This ambiguity makes it difficult to know precisely what the primary comparison would summarize.

The registry notes that the primary outcome has several categories or time points and was not reduced to one comparison. It does not list those categories or time points, and the primary outcome results are not reported. The record therefore does not permit evaluation of group differences, uncertainty, or the analysis used to produce the outcome. BCVA at Week 24 is named as a secondary efficacy endpoint, but its result and measurement details are also absent.

Important design and analysis details are not reported in the registry record: who was masked, how randomization and allocation concealment were implemented, the criteria for PRN injections, the analysis population, handling of missing data, treatment adherence, protocol deviations, and the statistical plan. The record also does not provide a sample-size justification from the trial’s original design. The stated planning assumptions are illustrative and based on an observed effect, rather than a documented account of the original design rationale.

Finally, the safety record gives aggregate counts without adverse-event terms or details of ascertainment, timing, or relatedness. These limitations concern reporting in the registry record; they do not establish that the study procedures or analyses were inadequate, only that they cannot be assessed from the recorded information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Effect of Ozurdex® 0.7 mg on Improvement of Efficacy of Bevacizumab for Central Retinal Vein Occlusion — NCT01295112.
• Registry record last updated 2025-09-25; status last verified 2017-09.
• Results first posted 2017-10-18.
• 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

The registry describes NCT01295112, titled “Effect of Ozurdex® 0.7 mg on Improvement of Efficacy of Bevacizumab for Central Retinal Vein Occlusion.” The official title specifies non-ischemic central retinal vein occlusion. The study is listed as phase 2 and phase 3, randomized, single-masked, parallel-group, and completed. Texas Retina Associates is recorded as the sponsor; enrollment is 68, with start in 2011-05 and primary completion in 2015-10.

One group received active bevacizumab with sham Ozurdex®, and the other received active bevacizumab with active Ozurdex®. The primary efficacy endpoint was the total number of PRN bevacizumab intravitreal injections through 24 weeks. BCVA at Week 24 was identified as a secondary endpoint. The primary and secondary efficacy results are not reported in the registry record. Safety counts list zero serious adverse events, zero other adverse events, and zero deaths in each group.