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 Efficacy of an Intravitreal DEX Implant in Retinal Vein Occlusion Following Treatment With Anti-VEGF Injections. (NCT01449682), a randomized phase 3 study. The primary outcome is Macular Function Using Microperimetry.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01449682 |
| Phase | Phase 3 |
| Condition | Retinal Vein Occlusion, Macular Edema |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 10 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Retina Macula Institute |
| Results posted | Yes |
2. Clinical Question
Population
People with retinal vein occlusion and macular edema who had received 2 or more prior intravitreal anti-VEGF drug injections. The registry record lists an enrollment of 10, but further eligibility details and the characteristics of enrolled participants are not reported in the registry record.
Intervention
A 0.7 mg intravitreal dexamethasone implant at Visit 1, then PRN for the 48-week trial if evidence of fluid on OCT.
Comparator
A 0.7 mg intravitreal dexamethasone implant at Visit 1, then Q16 weeks. Both assigned regimens use Ozurdex; the comparison is between dosing schedules, not between different named drugs.
Primary question
Whether mean macular sensitivity measured by microperimetry changed from baseline to 48 weeks in each treatment group. The registry record does not report the observed changes or an estimated difference between the schedules.
The clinical question concerns macular function in people with retinal vein occlusion and recalcitrant macular edema after prior anti-VEGF treatment. The trial description frames the intervention as a dexamethasone implant following at least 2 previous anti-VEGF injections. It does not establish that every enrolled participant had the same prior treatment history or degree of disease; those participant-level details are not reported in the registry record.
The two arms differ in when additional implants are planned after the initial implant. In the PRN arm, further treatment is described as conditional on evidence of fluid on OCT. In the Q16 weeks arm, the description specifies administration every 16 weeks. The registry record does not report actual treatment received, the number of implants administered, or how often the PRN criterion was met.
The primary question is about change in mean macular sensitivity, not a direct comparison of vision-related outcomes in everyday life. Visual acuity and central foveal thickness at 48 weeks are listed as secondary outcomes. Their numerical results are not reported in the registry record. Accordingly, the clinical question can be described, but the comparative findings cannot be assessed from the registry results recorded.
3. Trial Design
The registry record identifies this as a randomized, double-masked, parallel phase 3 trial. The enrollment is 10. The study is marked completed; its start is listed as 2011-10, and primary completion as 2012-07. The sponsor is Retina Macula Institute. These registration details describe the planned and recorded study structure, but do not by themselves establish whether the trial achieved its intended enrollment or how many participants contributed data to each outcome.
Participants were assigned to one of two Ozurdex schedules. Both descriptions specify a 0.7 mg intravitreal dexamethasone implant at Visit 1. The PRN schedule calls for further implants during the 48-week trial if evidence of fluid on OCT; the other schedule specifies implants every 16 weeks. The registry record does not report the randomization sequence method, allocation concealment, or the people covered by double masking. It also does not report whether masking was maintained throughout follow-up.
A parallel design assigns participants to a treatment group and follows the groups over the study period, rather than having each participant receive both schedules in sequence. General statistical interpretation of such a design relies on comparing outcomes across the randomized groups while accounting for the baseline-to-follow-up structure when appropriate. The registry record does not describe the specific analysis used for this trial.
The primary outcome is mean macular sensitivity measured by microperimetry, with the stated timeframe from baseline to 48 weeks. The registry record also lists visual acuity in ETDRS letters and central foveal thickness measured by OCT as secondary outcomes at 48 weeks. Although four outcome measures are indicated, the registry record does not report their numerical results. It records zero analyses, so it does not supply an analysis population, estimated treatment effects, confidence intervals, or significance tests for the outcomes.
The record describes a small enrollment and two treatment schedules, but does not state the rationale for the planned enrollment or give a statistical analysis plan. It is therefore not possible to establish from the registry record whether the trial was designed to detect a particular difference, how missing measurements would be handled, or which analysis was designated for each outcome.
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 | Active Comparator: Ozurdex PRN | Active Comparator: Ozurdex q16 Weeks |
|---|---|---|
| STARTED | 5 | 5 |
| COMPLETED | 4 | 4 |
| NOT COMPLETED | 1 | 1 |
Reasons for not completing this period:
| Reason | Active Comparator: Ozurdex PRN | Active Comparator: Ozurdex q16 Weeks |
|---|---|---|
| Death | 0 | 1 |
| Adverse Event | 1 | 0 |
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 | Ozurdex PRN | Ozurdex q16 Weeks | Total |
|---|---|---|---|---|
| Participants analysed | 5 | 5 | 10 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 3 | 2 | 5 |
| Age, Categorical: >=65 years | Participants | 2 | 3 | 5 |
| Age, Continuous | years | 69.1 (SD 5.7) | 63.3 (SD 8.0) | 66.2 (SD 4.7) |
| Sex: Female, Male: Female | Participants | 2 | 1 | 3 |
| Sex: Female, Male: Male | Participants | 3 | 4 | 7 |
| Region of Enrollment: United States | participants | 5 | 5 | 10 |
6. Primary Endpoint
The registry lists the primary outcome as Macular Function Using Microperimetry, measured over baseline to 48 weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Error |
| Unit | dB |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is mean macular sensitivity measured using microperimetry, expressed in dB. The registry description asks whether this measure changes from baseline to 48 weeks in each of the PRN and Q16 weeks groups. The listed summary parameter is a mean, and the dispersion is identified as a standard error. The population field for this outcome is blank; a more specific analysis population is not reported in the registry record.
Microperimetry assesses retinal sensitivity at locations in the macula. As a general explanation, it can provide a functional measure of how sensitive macular locations are to visual stimuli, rather than describing retinal structure alone. A mean summarizes measurements across the observations included in an analysis. A standard error describes the precision of an estimated mean, conditional on the data and the analysis used; it is not the same thing as the spread of individual participant measurements.
Using a baseline-to-follow-up change can help frame whether the measure shifts during the study, while comparing randomized groups can address whether the observed changes differ between assigned schedules. These are general statistical interpretations, not findings about this trial. To interpret the endpoint empirically, readers would need group-level baseline and follow-up results or a reported change estimate, along with uncertainty and the analysis population. Those results are not reported in the registry record. The record therefore identifies what was intended to be measured, but does not show the magnitude, direction, or precision of any change.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies the central comparison as two schedules of the same intravitreal dexamethasone implant after prior anti-VEGF injections. One schedule allows further implants PRN when OCT shows evidence of fluid; the other specifies treatment every 16 weeks. This is a schedule comparison within the stated clinical context, rather than a comparison of dexamethasone with anti-VEGF treatment or with no implant.
The primary outcome is mean macular sensitivity by microperimetry from baseline to 48 weeks. However, the registry record does not report numerical baseline values, follow-up values, changes, or a between-group estimate. It also gives no confidence interval or p-value. Without these, readers cannot determine the direction or size of the observed primary outcome, how uncertain an estimate might be, or whether the groups differed statistically under a specified analysis. The title and objective state the question, not its answer.
The registry lists visual acuity measured in ETDRS letters and central foveal thickness measured on high resolution OCT as secondary outcomes at 48 weeks. Their results are not reported in the registry record either. The record indicates four outcome measures and zero analyses. Consequently, the available entry does not provide a results-based comparison across the listed functional and structural outcomes.
General statistical interpretation distinguishes an estimate from its uncertainty. A point estimate describes the size and direction of an observed effect, while a confidence interval indicates a range of values compatible with the data under the method's assumptions. A p-value, when reported, addresses compatibility with a specified null model; it does not describe the probability that a treatment works. None of these inferential quantities for the primary comparison is reported in the registry record, so no conclusion about statistical evidence can be drawn from them.
The enrollment of 10 indicates that the study was small in scale, but does not identify how many people had usable primary outcome measurements or how the analysis was conducted. Those details are not reported in the registry record. Small studies generally yield less precise estimates, especially when outcomes vary, but the actual precision in this trial cannot be evaluated without outcome data and an uncertainty estimate.
Safety information is recorded separately from the primary efficacy endpoint. The adverse event entry lists serious events, other events, and deaths by group, as well as a serious-event term with a percentage. These figures are descriptive counts in the record; they do not replace the missing primary outcome analysis. Taken together, the entry describes trial design, endpoints, and some safety counts, but does not report the outcome estimates needed to assess the comparative results.
9. Statistical Methods Explained
Randomization is a general method for assigning participants to groups by chance. Its purpose is to reduce systematic differences between groups at assignment, so that a comparison can be interpreted as a comparison of assigned strategies, subject to the study's conduct and analysis. This registry record identifies allocation as randomized. It does not report the sequence-generation method, allocation concealment, or further operational details, so those features cannot be assessed from the record.
What does double masking mean?
In general, masking is intended to limit the influence of knowledge about treatment assignment on behavior, outcome assessment, or reporting. The record calls the trial double-masked, but does not identify which parties were masked or describe how masking was maintained. This matters especially when outcomes involve measurement or judgment: a description of masking is not enough to determine whether participants, clinicians, assessors, or analysts were unaware of assignment.
What does the parallel design imply?
In a parallel-group study, participants remain in their assigned group during follow-up. The two groups in this trial are described as PRN Ozurdex and Ozurdex Q16 weeks, with a shared initial implant and different subsequent schedules. General analysis of a randomized parallel trial usually compares outcomes according to assigned group, but the registry record does not state whether this trial used an intention-to-treat approach, a per-protocol approach, or another analysis population. It also does not report adherence or treatment received after assignment.
How should a mean and standard error be read?
The primary outcome is a mean of a continuous measure: macular sensitivity in dB. A mean gives a central summary of measured values. A standard error describes the precision of an estimated mean under the analysis assumptions. It is not the same as a standard deviation, which describes variability among individual observations. For a treatment comparison, a reported difference in mean changes, paired with a confidence interval, would communicate both the estimated contrast and its precision. This is a general explanation; the registry record does not report those estimates for this trial.
Why can baseline-to-follow-up change be useful?
A change outcome compares a follow-up measurement with a baseline measurement for the same participant. In general, accounting for baseline can make the clinical question explicit: how did the measure move during follow-up, and did that movement differ between assigned groups? Methods vary, including analysis of change scores or models that adjust follow-up values for baseline. The record states that change from baseline to 48 weeks was the objective, but does not report which statistical method was used. It also does not give the baseline values needed to understand group comparability on the outcome.
What does a confidence interval contribute?
As a general concept, a confidence interval represents uncertainty around an estimate using a specified statistical procedure. A narrow interval indicates greater precision than a wide interval, all else equal. An interval around a between-group estimate can show which effect sizes remain compatible with the data and method. It should be read alongside the endpoint, direction of the contrast, and analysis population. No confidence interval for the primary outcome is reported in the registry record, so its precision cannot be described numerically.
Why can over-dispersion matter?
General statistical note: over-dispersion occurs when the observed variability in data is greater than a model assumes. When a model does not account for that extra variability, standard errors may be too small and inferential conclusions may appear more certain than warranted. The relevance depends on the outcome and model. The primary endpoint is described as a continuous mean, and the registry record does not report the analysis model or evidence of over-dispersion. It would therefore be inappropriate to claim that over-dispersion occurred or affected this trial.
What do planning assumptions tell readers?
The record describes a planning illustration based on the observed effect and states assumptions of a two-sided significance level of 0.05, equal allocation, and a normal approximation. It also says that the target effect is a stated fraction of the observed effect. These are assumptions for planning, not observed outcomes and not evidence of the trial's power. The registry record does not report the observed primary effect, a trial-specific sample-size justification, or the design rationale. No conclusion about whether the trial was adequately sized can be drawn from the assumptions alone.
What cannot be inferred from a missing analysis?
The registry record lists zero analyses and does not report the primary outcome estimate, its uncertainty, or a test. Missing inferential results are not evidence that an effect is absent, nor are they evidence that an effect is present. General statistical interpretation requires results linked to an endpoint and an analysis population, with enough detail to assess uncertainty and potential bias. Those details are not reported in the registry record, so the methods can be described only at the level of the registered design and outcome objective.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists a primary microperimetry outcome and secondary outcomes for visual acuity and central foveal thickness. It indicates four outcome measures, but does not report numerical results or analyses. It does not describe a plan for handling multiplicity, such as whether the primary outcome was the sole confirmatory test, whether secondary outcomes were adjusted, or how repeated assessments or multiple outcome measures were addressed. Such a plan is not reported in the registry record.
Multiplicity is a general statistical concern when many hypotheses or outcomes are assessed. Repeated testing can increase the chance of obtaining an apparently unusual result under a null model. Adjustments and prespecified outcome hierarchies are possible approaches, but the appropriate interpretation depends on the protocol and analysis plan. Because neither the results nor a multiplicity strategy is reported in the registry record, no adjustment can be reconstructed and no claim about multiplicity-controlled evidence is justified.
The primary outcome timeframe is baseline to 48 weeks, but the record does not report participant-level completion, missing measurements, reasons for missingness, or methods for handling missing data. It does not identify an analysis population or explain whether all randomized participants were included in any analysis. These omissions prevent assessment of attrition, the potential for missingness to bias estimates, and the extent to which the analyzed participants represent those randomized.
In general, missing-data methods rely on assumptions about why values are unavailable. The assumptions and method matter because results can differ depending on whether missingness is related to observed information, unobserved outcomes, or both. The record contains no such details, so no particular missing-data mechanism or remedy should be inferred. The listed enrollment is not a substitute for a reported analysis denominator.
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 |
|---|---|---|---|
| Ozurdex PRN | 1 | 5 | 20.0% |
| Ozurdex Q16 Weeks | 0 | 5 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Ozurdex PRN | 0 of 5 |
| Ozurdex Q16 Weeks | 1 of 5 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Ozurdex PRN | 0 of 5 |
| Ozurdex Q16 Weeks | 1 of 5 |
Most frequent serious adverse event terms
| Event term | Organ system | Ozurdex PRN | Ozurdex Q16 Weeks |
|---|---|---|---|
| Cataract Requiring Emergent Surgery | Eye disorders | 1 of 5 | 0 of 5 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Ozurdex PRN | Ozurdex Q16 Weeks |
|---|---|---|---|
| Elevated Intraocular Pressure | Eye disorders | 0 of 5 | 1 of 5 |
Serious events with the highest arm-level rate: cataract requiring emergent surgery (20.0%).
The registry record reports adverse-event figures separately for the Ozurdex PRN and Ozurdex Q16 Weeks groups. For serious events, the at-risk count is 5 in each group; the affected count is 1 in the PRN group and 0 in the Q16 Weeks group. For other events, the at-risk count is 5 in each group; the affected count is 0 in the PRN group and 1 in the Q16 Weeks group. The recorded death counts are 0 in the PRN group and 1 in the Q16 Weeks group.
The record also lists “Cataract Requiring Emergent Surgery” as a top serious-event term at 20.0%. It does not identify the group for this term in the posted adverse-event summary, so it should not be attributed to either schedule. The counts are descriptive registry entries, not adjusted comparisons of safety between groups. The record does not provide event timing, severity details beyond the serious-event classification, participant characteristics, exposure duration by group, or explanations of events.
General interpretation: event counts from a small study can be highly imprecise, and a count difference alone does not establish that a schedule caused an event or that the schedules differ in safety. No comparative safety estimate or uncertainty interval is reported in the registry record. These figures should therefore be read as recorded counts, not as a definitive assessment of relative risk.
12. What the Result Does, and Does Not, Mean
The registry record allows a clear description of the question the trial set out to examine: whether macular sensitivity from baseline to 48 weeks changed in people assigned to PRN or Q16 weeks dexamethasone implant schedules after prior anti-VEGF treatment. It also identifies the randomized, double-masked, parallel design and lists visual acuity and central foveal thickness as secondary outcomes. These details explain the intended comparison, but they do not answer it.
The primary outcome values and comparative analysis are not reported in the registry record. There is no reported direction or magnitude of change, no between-group estimate, and no uncertainty interval or p-value. The secondary outcome results are also not reported. As a result, the entry does not establish whether outcomes differed between assigned schedules, nor how precise any potential difference would be. It also cannot establish that the schedules produced equivalent outcomes; absence of reported results is not an equivalence finding.
The adverse-event counts offer limited descriptive safety information, including the recorded deaths and event counts by group. These should not be interpreted as causal comparisons or as a comprehensive safety assessment. The registry record does not report enough information about timing, exposure, or analysis to support stronger conclusions.
General statistical principle: a trial's design and objective are distinct from its findings. Randomization can support causal comparisons when allocation, follow-up, outcome measurement, and analysis are appropriately conducted, but the existence of randomization alone does not supply an estimated effect. Readers need the observed outcomes and a transparent account of the analysis to evaluate what the data indicate. For this trial, the registry record documents the design and objectives but does not report the outcome analysis required to judge the comparative result.
Accordingly, the record is informative about what was planned and which outcomes were registered, while leaving the main empirical question unresolved in the posted results. Any conclusion about effectiveness, lack of effect, or comparative benefit would go beyond the numerical outcome information reported in the registry record.
13. Why This Trial Matters Statistically
This trial is statistically notable because it frames a randomized comparison between two schedules of the same implant rather than a comparison between different drugs. The shared initial treatment and differing subsequent schedules make the central question one of dosing strategy in the registered population. Describing the comparison accurately is essential: the registry record does not compare Ozurdex with anti-VEGF injections, even though participants had prior anti-VEGF treatment.
The choice of outcome also illustrates why different measures answer different questions. Microperimetry is used for the registered primary measure of macular function, while visual acuity and central foveal thickness appear as secondary outcomes. General statistical interpretation treats these as related but non-interchangeable endpoints: a functional measurement, a visual acuity measure, and a structural OCT measure describe different aspects of outcome. A result for one cannot be assumed to determine the result for another. The registry record does not report numerical results for any of them.
The enrollment of 10 underscores the importance of reporting uncertainty and analysis details. In a small study, estimates may be imprecise, and the number enrolled alone does not tell readers how many outcome measurements were available or how they were analyzed. The registry record gives no confidence interval, analysis population, or missing-data account with which to evaluate precision and robustness.
Finally, the record illustrates the distinction between a registered objective and a reported result. It records the primary endpoint, treatment schedules, and selected safety figures, but lists zero analyses and does not report outcome estimates. Statistical transparency depends not only on naming an endpoint, but also on making the analysis and its uncertainty interpretable. Without those results, the trial's intended comparison can be understood, but its statistical answer cannot be evaluated from this registry entry.
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 limitation for interpretation is that the registry record does not report numerical results for the primary microperimetry outcome or the listed secondary outcomes. It therefore does not permit assessment of effect direction, magnitude, or precision. The record indicates zero analyses, and does not provide a confidence interval, p-value, or other inferential result. The clinical question is identifiable, but the comparative outcome answer is not.
The enrollment is 10, and the record does not report a trial-specific sample-size justification or the basis for the planned enrollment. It gives no analysis denominators, participant flow, baseline characteristics, or outcome completion information. Enrollment therefore cannot be treated as the number included in each outcome analysis. The record does not establish the extent of missing data or whether participants received the assigned schedules as planned.
Other design and analysis details are also absent. Although randomization and double masking are recorded, the sequence method, concealment procedures, masked roles, and maintenance of masking are not reported in the registry record. The statistical analysis plan, analysis populations, handling of repeated measurements, multiplicity strategy, and missing-data methods are not reported. These gaps limit evaluation of potential bias and of how the results would have been interpreted if estimates were available.
The safety entry gives event counts and a serious-event term, but does not report timing, exposure information, event narratives, or comparative uncertainty. Those counts are not enough to characterize relative safety. The record's planning-illustration assumptions do not replace the missing outcome estimates or a trial-specific design rationale. Together, these limitations mean that the registry entry supports a description of the study's intended comparison and selected safety counts, but not a reliable assessment of its comparative outcome findings.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Efficacy of an Intravitreal DEX Implant in Retinal Vein Occlusion Following Treatment With Anti-VEGF Injections. — NCT01449682.
- Registry record last updated 2017-05-31; status last verified 2017-04.
- Results first posted 2017-05-31.
- 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.
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18. Record Summary
NCT01449682 is a completed randomized, double-masked, parallel phase 3 trial sponsored by Retina Macula Institute. The registry lists enrollment of 10, a start of 2011-10, and primary completion in 2012-07. The study concerns retinal vein occlusion and macular edema after 2 or more prior intravitreal anti-VEGF drug injections.
Both groups received a 0.7 mg intravitreal dexamethasone implant at Visit 1. One schedule allowed further PRN treatment during the 48-week trial if OCT showed evidence of fluid; the other specified treatment every 16 weeks. The primary objective concerned change in mean macular sensitivity by microperimetry from baseline to 48 weeks. Visual acuity and central foveal thickness were listed as secondary outcomes.
The registry record does not report outcome analyses or numerical results. It lists adverse-event counts by group, including a recorded death count, but these figures do not establish comparative safety. The design and registered objectives are documented; the comparative outcome findings are not reported in the registry record.