A Study of a Sustained Release Fluocinolone Implant for Treatment of Central Retinal Vein Occlusion: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of a Sustained Release Fluocinolone Implant for Treatment of Central Retinal Vein Occlusion (NCT00952614), a na na study. The primary outcome is Change From Baseline in Visual Acuity Using Early Treatment Diabetic Retinopathy Study (ETDRS) Charts.

2. Clinical Question

The study summary frames the purpose as assessing whether the sustained drug-delivery implant is effective for central retinal vein occlusion that has caused persistent macular edema and decreased visual acuity. Statistically, the listed design can describe outcomes over time in the group receiving the study intervention, but it does not provide a concurrent untreated or alternative-treatment comparison. Any change from baseline would therefore be a within-group observation, not a randomized estimate of the difference attributable to the implant.

The primary outcome is titled as a change in visual acuity using Early Treatment Diabetic Retinopathy Study charts, with the unit expressed as letters read correctly. Its timeframe is baseline (preoperatively) to 3 years postoperatively. The outcome description also refers to eyes at time points with a 10-letter ETDRS score improvement. The registry does not report the numerical visual-acuity results, so the clinical question cannot be answered from the outcome entry alone.

3. Trial Design

The registry records this as a completed pilot study with a single-group model and enrollment of 29. Its official title identifies it as a pilot study of a sustained-release fluocinolone implant for central retinal vein occlusion. The listed intervention is a device: fluocinolone acetonide, identified as the Retisert implant. The arm description specifies 0.59 mg Fluocinolone Acetonide for retinal vein occlusion.

Allocation is marked NA, and masking is recorded as none. No separate comparison arm is listed. This structure is important for interpretation: outcomes can be described for the study group over time, but the registry does not define a parallel group against which to estimate a treatment contrast. Changes from baseline can also reflect factors other than the intervention, and the record does not describe a design feature that would separate those influences.

The recorded study start is 2002-10, primary completion is 2009-05, and status is completed. The condition listed is central retinal vein occlusion. The primary outcome concerns change in visual acuity from baseline before surgery to 3 years after surgery. A secondary outcome is listed as improvement in macular edema on optical coherence tomography and color photos.

The registry does not report a protocol-level statistical plan, a sample-size justification for the actual study, or a detailed account of the analysis population. It also lists no analyses. These gaps limit assessment of how the investigators intended to summarize repeated measurements, handle incomplete follow-up, or address the outcome-description wording about a 10-letter improvement.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: Twenty nine (29) participants were consented, 30 eyes. Of the 29 consented, there were 23 subjects included in the data pool of which one subject had both eyes included in the study.

Overall Study

Reasons for not completing this period:

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.

Population: Twenty nine participants were consented. Of the 29 consented (30 eyes; one subject consented twice), 23 participants were studied and 24 eyes. Both eyes of one participant were studied

6. Primary Endpoint

The registry lists the primary outcome as Change From Baseline in Visual Acuity Using Early Treatment Diabetic Retinopathy Study (ETDRS) Charts, measured over baseline (preoperatively) to 3 years postoperatively.

The primary endpoint is titled as change from baseline in visual acuity measured with Early Treatment Diabetic Retinopathy Study charts. The unit is letters read correctly, and the registry describes the summary parameter as a mean with full-range dispersion. The stated timeframe runs from baseline (preoperatively) to 3 years postoperatively. ETDRS letter scores provide a structured way to record visual-acuity performance, while a change score expresses how a measurement at follow-up differs from its baseline reference.

Using a baseline measure can make within-person change easier to interpret than a follow-up score alone, because it establishes the starting point for each observation. However, the registry record does not provide the mean change, the range, the number of observations at each time point, or a confidence interval. It also leaves the population entry blank and does not clarify the analysis unit or how multiple eyes, if applicable, were handled.

The endpoint description adds that it is based on eyes at time points with a 10-letter ETDRS score improvement. That wording does not fully explain how it relates to the title's mean change endpoint. The registry record does not report whether the 10-letter phrase defines a separate threshold, describes a subset, or specifies another aspect of the outcome. Without clarification and numerical results, the measure cannot be reconstructed or interpreted beyond its stated description.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends on what quantity an analysis estimates, how observations are summarized, and how uncertainty is represented. The registry describes a mean change in ETDRS letters with full-range dispersion, but it does not report the numerical estimate or uncertainty interval. General statistical explanations can clarify what those summaries would mean, but they cannot substitute for missing study results.

What does a mean change describe?

In general, a mean change summarizes the average difference between follow-up measurements and baseline measurements in the observations included in an analysis. A mean can provide a compact description of the group, but it does not show how individual observations are distributed. A similar mean can arise when most observations are close to the average or when individual values vary widely. The registry does not provide the actual mean change or the underlying measurements, so neither the average direction nor the variability can be assessed.

The endpoint uses ETDRS letters read correctly. In general, a change score needs a clearly specified subtraction order to determine how positive and negative values are interpreted. Although the outcome title says change from baseline, the record does not state the precise calculation convention. It also does not explain how observations at different time points were combined into the reported endpoint.

What does full-range dispersion convey?

In general, a full range describes the lowest and highest observed values in the analyzed set. It gives the span of observed data, but it does not indicate how frequently values occur within that span or how concentrated they are near the mean. A range can be sensitive to extreme observations, and it is not the same as a standard deviation or a confidence interval. Because the registry posts no range values, the extent of observed variation is unknown.

Why does the missing confidence interval matter?

In general, a confidence interval communicates uncertainty around an estimated quantity under the assumptions of the analysis. Its width reflects both the variability in the data and the amount of information available. An estimate without an interval can be difficult to distinguish from a value that is imprecisely estimated. The registry record does not report a confidence interval for the primary endpoint, so precision cannot be judged from the posted outcome description.

Statistical significance and clinical importance are also distinct concepts. In general, a significance test assesses compatibility between data and a specified null hypothesis under a statistical model; it does not by itself establish whether an effect is meaningful in practice. A clinically meaningful threshold would need to be stated and justified for the outcome. The registry does not report an inferential result or a threshold for interpreting mean change. The phrase about a 10-letter improvement appears in the outcome description, but its role is not defined clearly enough to treat it as an explicit decision threshold.

How does a single-group design affect inference?

In general, repeated measurements in one group can describe change over time, but they do not separate intervention effects from time trends, concurrent care, measurement variation, or other influences. A control group can provide a basis for estimating a between-group contrast when the design and analysis support that comparison. No comparator is listed in this record, and allocation is recorded as NA. It would therefore be inappropriate to interpret a within-group change as a controlled treatment effect.

The registry's sample-size assumptions refer to planning illustrations with a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a fraction of an observed effect. These are described as planning calculations rather than the actual trial design. The record does not provide the study's own design justification or report the observed primary effect needed to understand the basis of such illustrations. A planning sample size is a design aid, not an observed result or a measure of the study's actual power after completion.

What is not specified about the analysis?

The registry does not report the statistical model, the handling of measurements at multiple time points, or whether baseline adjustment was used. The primary outcome population is blank, and the record does not clarify the unit of analysis or how observations were selected when follow-up data were incomplete. It also does not describe missing-data methods, assumptions about distributions, or sensitivity analyses. Those choices can influence both the estimate and its uncertainty, so their absence limits independent assessment of the analysis.

No recalculated estimate is available in the record to compare with a sponsor analysis. More generally, recalculation from summary statistics can only assess a calculation under its stated assumptions; it cannot recover unreported individual-level data or replace a prespecified analysis. In this case, the registry reports no analysis results to recalculate. The appropriate statistical conclusion is therefore limited: the record describes the outcome and design, but does not permit a numerical evaluation of the primary endpoint.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary visual-acuity outcome and a secondary outcome concerning macular edema assessed on optical coherence tomography and color photos. It does not provide a statistical analysis plan describing how these outcomes were prioritized analytically, whether additional outcome measures were prespecified, or how multiple tests were to be interpreted. Although the record lists two outcome measures, the specific multiplicity strategy is not reported in the registry record.

In general, evaluating multiple outcomes or repeated time points can increase the chance of finding at least one apparently notable result by chance if each is tested without an appropriate plan. Methods for addressing multiplicity depend on the study question and analysis strategy. No correction, hierarchical testing procedure, or other multiplicity approach is reported, so it is not possible to determine whether or how this issue was handled.

The record does not report missing-data methods, the amount of missing data at follow-up, or the number of observations included at each time point. It does not describe whether analyses used all enrolled participants, only participants with available measurements, or another analysis population. The population entry for the primary outcome is blank. These details matter because incomplete follow-up can affect both the analyzed group and the interpretation of change from baseline.

General methods for incomplete data rely on assumptions about why observations are missing and how missingness relates to observed or unobserved outcomes. Without an account of the missingness pattern and analytic approach, those assumptions cannot be evaluated. The record also does not report sensitivity analyses that might assess whether conclusions change under alternative assumptions. As a result, the statistical consequences of missing outcome data cannot be assessed from the registry record.

11. 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 1% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: death (13.0%).

For the listed Retisert group, the safety entries report 29 at risk for serious adverse events and 3 affected. The entry for other adverse events reports 29 at risk and 1 affected. These are the counts recorded in the registry; they do not, by themselves, describe event timing, duration, severity beyond the serious classification, or whether investigators considered events related to the intervention.

The deaths value is null. Separately, the list of top serious terms includes Death with 13.0%. The record does not explain the denominator or basis for that percentage, and it does not reconcile the percentage with the null deaths count. It should not be read as a count of deaths or as a percentage of participants who died without that information.

In general, affected-participant counts and event counts are not interchangeable: one participant may experience more than one event, and a registry may report these quantities differently. The record does not clarify whether its affected figures represent people or events, nor does it provide a comparator group for safety contrasts. These entries are descriptive registry data, not a complete comparative safety analysis.

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

The record establishes that a completed, single-group pilot study evaluated a 0.59 mg fluocinolone acetonide Retisert implant in the setting of central retinal vein occlusion. It identifies change in ETDRS visual-acuity letters from preoperative baseline to 3 years postoperatively as the primary outcome and lists macular edema imaging as a secondary outcome. These details define the question the study was intended to address.

However, the registry record does not report numerical results for either outcome. Without an estimated mean change, a range, or an uncertainty interval, readers cannot judge the direction, magnitude, or precision of the visual-acuity outcome. The outcome description's reference to a 10-letter improvement is not accompanied by a clear operational explanation or numerical result. The listed secondary outcome also has no posted results.

Even if a within-group change were available, the single-group design would limit causal interpretation. Change over time can reflect multiple influences, and this design does not provide a listed concurrent comparison group to help distinguish them. The record therefore cannot support a randomized between-group treatment estimate.

The adverse-event counts should likewise be read as descriptive entries rather than as evidence of comparative risk. In particular, the serious-term entry for Death with 13.0% is not explained, while the deaths count is null. The registry's information is not sufficient to resolve that discrepancy or to characterize the context of the events.

Overall, the record supports a description of the study's purpose, intervention, design, and stated outcome framework. It does not support a numerical conclusion about visual-acuity change, the secondary imaging outcome, or a causal treatment effect. The missing statistical plan and analysis details further restrict interpretation of how results would have been generated and assessed.

13. Why This Trial Matters Statistically

This study is statistically notable because its stated clinical question concerns change in visual acuity over time, while the registry records a single-group design without a comparator. That design can be useful for describing a group's observed course, especially in a pilot setting, but it answers a different question from a controlled comparison. Keeping those estimands distinct prevents a within-group change from being treated as an isolated effect of the intervention.

The registry also illustrates why outcome definitions need to align across the endpoint title, unit, and description. The title refers to mean change in ETDRS letters; the unit is letters read correctly; and the description refers to eyes at time points with a 10-letter improvement. The relationship among those elements is not explained. Clear definitions are necessary for readers to know whether an outcome is a continuous change measure, a threshold-based response, or a combination of both.

Another important issue is completeness of results reporting. The record identifies a primary endpoint, a secondary imaging outcome, and safety entries, but does not post numerical efficacy results or an analysis plan. Without estimates and measures of uncertainty, it is not possible to assess precision. Without details on analysis populations and missing data, it is also difficult to understand which observations would contribute to an estimate.

Finally, the sample-size assumptions described for planning illustrations should not be mistaken for the completed study's design or evidence of its statistical performance. Their two-arm planning framework differs from the registered single-group model. This distinction is a useful reminder that planning calculations, observed results, and causal comparisons serve different purposes and should not be conflated.

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 registry record leaves several trial-specific details unresolved. The primary outcome population entry is blank, and the record does not state the analysis unit or explain how observations were handled across time points. Although the measure is described in terms of eyes, it does not specify how eye-level observations relate to participants or whether both eyes could contribute. These omissions make it difficult to understand the structure of the primary analysis.

The primary outcome wording is also not fully aligned. Its title describes mean change in ETDRS letters, while the description mentions eyes at time points with a 10-letter improvement. The registry does not clarify whether that phrase defines a responder outcome or serves another purpose. No numerical outcome result is posted to help resolve the ambiguity.

For the secondary outcome, the record names improvement in macular edema on optical coherence tomography and color photos but does not give a precise measurement scale, assessment schedule, result, or analysis. It also does not report how many observations were available at each follow-up point or how missing measurements were handled.

The study is recorded as single-group, with no comparator and no masking. The registry does not describe a statistical analysis plan, sample-size justification for the actual study, multiplicity approach, or analysis population. Safety reporting has its own incompleteness: the deaths value is null, while a top serious term lists Death with 13.0%, without an explanation of its denominator or relationship to the count. These limitations prevent a complete assessment of outcome estimation, precision, and event context from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Study of a Sustained Release Fluocinolone Implant for Treatment of Central Retinal Vein Occlusion — NCT00952614.
• Registry record last updated 2014-08-06; status last verified 2014-08.
• Results first posted 2014-06-30.
• 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 identifies a completed pilot study of a sustained-release fluocinolone acetonide Retisert implant for central retinal vein occlusion. It records a single-group model, allocation marked NA, no masking, and enrollment of 29. The listed intervention arm specifies a 0.59 mg implant.

The primary outcome is change from baseline in visual acuity using ETDRS charts, measured in letters read correctly, from baseline before surgery to 3 years after surgery. The secondary outcome concerns macular edema on optical coherence tomography and color photos. Numerical efficacy results and analysis details are not reported in the registry record.

Safety entries list 3 affected for serious adverse events and 1 affected for other adverse events, each with 29 at risk. The deaths count is null; a serious-term entry lists Death with 13.0%, without clarifying its basis. The record does not report a comparator or a statistical analysis plan.