Clinical Study of Safety and Efficacy for the Relieva Stratus With Elution of Triamcinolone Acetonide: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Study of Safety and Efficacy for the Relieva Stratus With Elution of Triamcinolone Acetonide (NCT00791934), a na na study. The primary outcome is Mean Intrapatient Change in Ethmoid Lund-MacKay CT Score (Ethmoid Score Only) at 10 Weeks Post-procedure Compared to Baseline..

2. Clinical Question

This is a question about change over time in a group receiving the intervention, not about a treatment effect relative to an untreated or alternative-treatment group. Without a concurrent comparator, a change in scores could not by itself distinguish an effect of the intervention from other explanations, such as the natural course of symptoms or changes in care during follow-up. The registry record describes the study as non-randomized, multicenter, and prospective, and lists no masking. It does not report detailed information about the participating centers, participant characteristics, or eligibility criteria. The clinical question is therefore narrow: it concerns a radiographic measure of ethmoid sinus opacification before and after the procedure, rather than a direct comparison of patient outcomes between treatment strategies.

3. Trial Design

The registry record describes a non-randomized, multicenter, prospective clinical study of the Stratus Microflow Ethmoid Spacer for local delivery of triamcinolone acetonide. It lists the study model as single-group and masking as none. The allocation field is recorded as NA, and the phase is also recorded as NA. Enrollment was 63, and the study status is completed. The recorded start was 2008-08 and primary completion was 2011-11.

The intervention description is temporary implantation of an ethmoid spacer with triamcinolone acetonide for 28 days. The study summary says that the approach was intended to evaluate safety and efficacy of treating the ethmoid sinuses over a period of 28 days. The primary endpoint, however, is specified at 10 weeks post-procedure, comparing the ethmoid Lund-MacKay CT score with baseline. The record does not explain the relationship between the intervention period and any other follow-up schedule beyond the time points listed for outcomes.

Because there was one study group and no separate comparator, the design supports describing observed changes and adverse event counts among participants in that group. It does not support a randomized, between-group comparison. The registry record does not report a protocol-level statistical plan, a sample-size justification, or a rationale for the design. The sample-size assumptions described for planning illustrations are not identified as the trial’s own design assumptions. The registry record also does not report whether any interim analyses were planned or conducted, or details of recruitment, withdrawals, or treatment adherence.

The primary endpoint analysis population is described as 58 of the 63 subjects with paired baseline and 10 week post-procedure CT scans available for analysis. The record does not report why paired scans were unavailable for other subjects, how missing observations were handled, or whether any additional analysis populations were defined. Five outcome measures are recorded, while the analysis count is zero. This means the posted registry information does not give a numerical result for the primary endpoint or analyses for the listed 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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: A total of 58 of the 63 subjects had paired baseline and 10 week post-procedure CT scans available for analysis.

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 Mean Intrapatient Change in Ethmoid Lund-MacKay CT Score (Ethmoid Score Only) at 10 Weeks Post-procedure Compared to Baseline., measured over 10 weeks post-procedure.

The primary endpoint is the mean within-participant change in ethmoid Lund-MacKay CT score at 10 weeks post-procedure compared with baseline. The Lund-MacKay system rates radiographic opacification in sinus regions. For this endpoint, only the left and right anterior and posterior ethmoid sinuses contribute to the total. The score ranges from a minimum of 0 to a maximum of 8, with higher scores representing greater sinus disease burden.

A CT score is a radiographic measure, not a direct measure of symptoms, daily functioning, or quality of life. It is used to describe sinus opacification at two time points. Comparing a participant’s follow-up score with that participant’s baseline score focuses on change within the same person. Averaging those individual changes gives a group-level description of the direction and typical magnitude of change, though the mean alone does not show how variable individual changes were.

The registry record reports that 58 of the 63 subjects had paired baseline and 10 week post-procedure CT scans available for analysis. It does not report the mean change, its standard deviation, or a confidence interval. The subtraction order used to define change is also not reported in the registry record, so the sign convention cannot be confirmed from the posted information. Consequently, the endpoint definition explains what was intended to be measured, but the posted results do not establish the observed direction, magnitude, or precision of change.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean within-participant change describe?

For a continuous measure such as the ethmoid CT score, an individual change is obtained by comparing a participant’s follow-up score with their baseline score. The mean of those individual changes describes the average change among participants included in that analysis. This differs from comparing two unrelated group means because the two observations belong to the same participants. The paired structure can be useful because stable differences between people are not treated as if they were changes over time.

The registry record identifies the endpoint as a mean intrapatient change and gives the standard deviation as the planned measure of dispersion. A standard deviation describes how spread out individual values are around their mean. For a change endpoint, it would help show whether individual changes were relatively similar or varied substantially. Neither the mean change nor its standard deviation is reported in the registry record, so the endpoint’s magnitude and spread cannot be described.

Why does pairing matter?

In a paired analysis, the relevant data are the two measurements from each participant who has both baseline and follow-up observations. The registry record says that 58 of the 63 subjects had paired CT scans available. Pairing preserves the within-person relationship between measurements. In general, the uncertainty of a mean change depends on the variation in individual changes, not merely on the variation of baseline scores and follow-up scores considered separately. The record does not state which estimator or statistical test was used, or whether any adjustment was made.

Missing paired observations matter because a participant without both measurements cannot contribute an observed within-participant change in the usual paired calculation. The registry record does not explain why scans were unavailable, whether missingness was related to participant condition or follow-up, or whether any method was used to address missing outcomes. These omissions prevent assessment of whether the analyzed participants might differ systematically from those without paired scans.

What would a confidence interval add?

As a general statistical concept, a confidence interval communicates uncertainty around an estimated quantity, such as a mean change. A narrower interval indicates greater precision under the assumptions of the method; a wider interval indicates more uncertainty. The interval is not a guarantee that the true value lies within its bounds, and it does not establish that a change is important to patients. No confidence interval for the primary endpoint is reported in the registry record. The posted information therefore does not allow an assessment of statistical precision.

What can a one-group design establish?

A single-group before-and-after design can describe how measurements changed among participants who received the intervention. It does not provide the same basis for estimating a treatment contrast as a concurrent comparison group. In general, a comparison group helps account for changes that could occur over time even without the intervention. Without one, observed change can reflect multiple influences, including the intervention, natural fluctuation, other care, or measurement variability. Randomization and masking can address some sources of bias in comparative studies, but the registry record identifies this study as non-randomized and unmasked and does not describe additional safeguards.

How should the planning assumptions be understood?

The registry record includes assumptions for planning illustrations based on the observed effect: a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect, and that planning values for non-time-to-event outcomes are participants per arm. These are general planning assumptions, not evidence that the original single-group study used a two-arm design. The record does not give the numerical planning results in the registry record for this explanation. Such sample-size illustrations describe hypothetical future-study planning, not the power actually achieved by this trial. They are not observed power.

In general, planning sample size depends on the effect a study is intended to detect, the assumed variability, the chosen significance level, the desired power, and the design. A planning calculation is conditional on its assumptions. It does not demonstrate that an effect exists, nor does it repair the absence of a concurrent comparator in the study being described. The registry record does not report the trial’s own sample-size justification or statistical design rationale.

What does over-dispersion mean in general?

Over-dispersion is a general issue for count outcomes when observed variation exceeds what a selected statistical model assumes. When that occurs, standard errors based on the narrower variance assumption can be too small, making results appear more precise than warranted. The primary outcome in this study is a continuous score change, and the record does not report a model or analysis requiring an over-dispersion assessment. No claim about over-dispersion in this study can be made from the registry record.

More broadly, statistical methods should match the outcome type and study design. A continuous paired score, a count of participants with an event, and a time-to-event outcome have different data structures and may require different methods. The record lists multiple outcome types but reports no analyses. It does not identify model specifications, handling of repeated measurements, covariate adjustment, or methods for multiplicity. Those elements are not reported in the registry record, so no more detailed account of the analysis can be justified.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Stratus Microflow Ethmoid Spacer")
n   <- c(58)
m   <- c(-1.91)
sp  <- c(1.94)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Stratus Microflow Ethmoid Spacer  58  -1.910  1.940  -2.420  -1.400

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists five outcome measures and zero analyses. The primary endpoint is the mean within-participant change in ethmoid Lund-MacKay CT score at 10 weeks compared with baseline. Secondary outcomes include vision decrease of more than 2 lines on the Snellen chart, specified intraocular pressure changes, and SNOT-20 change. The SNOT-20 outcome is listed twice using the same wording. Numerical results for these endpoints are not reported in the registry record.

When a study evaluates multiple outcomes or performs multiple statistical tests, the chance of at least one apparently unusual result can increase. This is a general statistical issue called multiplicity. A prespecified hierarchy, adjustment method, or clear distinction between primary and exploratory analyses can help readers interpret multiple results. The registry record does not report a multiplicity strategy, an endpoint hierarchy beyond identifying the primary endpoint, or a statistical analysis plan. It is therefore not possible to determine how multiple outcomes were handled or whether any adjustment was intended.

The primary endpoint analysis population is described as 58 of the 63 subjects with paired baseline and 10 week post-procedure CT scans. The record does not report reasons for missing scans, follow-up completeness for the other outcomes, or any imputation or sensitivity analysis. In general, missing data can affect both the number of observations informing an estimate and the representativeness of those observations. The implications depend on why data are missing, which is not reported.

The registry record does not report whether the analysis followed an intention-to-treat principle, whether participants were excluded for protocol deviations, or whether any other analysis populations were specified. These details, as well as the handling of missing data and multiplicity, are not reported in the registry record. Without them and without endpoint estimates, the robustness of the analyses cannot be assessed.

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 3% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: wing detachment from device (3.2%).

The safety record lists 63 at risk for both the serious-event and other adverse-event categories. It reports 2 participants affected in the serious-event category and 19 in the other adverse-event category. These are counts in the study group; they do not compare the intervention with a control group. The registry record also identifies wing detachment from device as a serious adverse event term at 3.2%.

The figures should be read as registry-reported safety summaries, not as proof that an event was caused by the device or drug. The record does not provide the event-level details needed to assess timing, duration, severity, recurrence, or attribution. It also does not give a comparison rate from another treatment group. The listed serious-event term does not, by itself, establish how many events occurred or whether the event was considered related to the intervention beyond its placement in the serious adverse event listing.

Deaths are not reported in the registry record. The record does not report additional context that would explain how adverse events were collected or classified. Accordingly, the counts describe what is recorded for this single group, while causal interpretation and comparative safety assessment remain unavailable from the posted information.

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

The record establishes that a prospective, multicenter, non-randomized, single-group study evaluated a temporary ethmoid sinus spacer with triamcinolone acetonide. Its primary endpoint was a radiographic score change measured at 10 weeks compared with baseline. The endpoint is relevant to the study’s focus on ethmoid sinus opacification, and its scale and direction of disease burden are described: scores range from 0 to 8, with higher scores indicating greater burden.

However, the registry record does not report the mean endpoint change, its standard deviation, a confidence interval, or a p-value. That means the posted information cannot establish whether the average score changed, in which direction it changed, or how precisely the change was estimated. Naming an endpoint is not the same as reporting its result. The analysis population is reported as 58 of the 63 subjects with paired scans, but the reasons for unavailable scans are not given.

Even if the numerical before-and-after result were available, a one-group design would describe change among participants who received the intervention rather than a causal difference relative to another treatment or no treatment. Other influences on measurements over time cannot be separated from the intervention by this design alone. The record identifies no masking and no randomization, and it does not report further methods to address possible bias.

The listed safety counts are similarly descriptive. They show recorded serious and other adverse events in the study group, along with a serious-event term for wing detachment from device. They do not establish comparative safety or causation. The record does not report deaths or enough detail to evaluate the circumstances of the events.

Thus, the available registry information is useful for understanding the intended design, endpoint, analysis population, and recorded safety summaries. It is not sufficient to judge the magnitude or precision of the primary result, to compare the intervention with an alternative, or to determine whether the intervention caused any observed change or adverse event.

14. Why This Trial Matters Statistically

This study illustrates why the definition of an endpoint and the report of its result are both essential. The primary measure is specified as a mean within-participant change in ethmoid Lund-MacKay CT score, with a clear score range and interpretation. The registry record also identifies how many subjects had paired scans available. Those details help readers understand what was intended to be measured and which observations could contribute to the paired endpoint.

At the same time, the absence of the mean change and its uncertainty prevents the central statistical question from being answered. A defined outcome without its estimate does not tell readers whether there was a change or how variable that change was. Reporting the estimate together with a measure of precision would be necessary for a quantitative interpretation. The record’s zero reported analyses emphasizes the difference between listing outcomes and reporting analyses of them.

The design also demonstrates the distinction between change over time and a treatment comparison. A single-group study can document outcomes among participants receiving an intervention, but it lacks a concurrent control group for estimating what might have happened under another condition. This distinction is important when interpreting both potential benefit and safety. The listed adverse event counts have no comparator and do not establish causality.

Finally, the paired-scan population and unreported reasons for missing scans highlight the role of analysis populations and missing-data transparency. Readers need to understand who contributed outcome data and whether missingness could affect interpretation. The record does not provide those explanations, a statistical analysis plan, or a multiplicity strategy. These gaps limit reproducibility and the strength of inferences that can be drawn, regardless of how clearly the endpoint itself is defined.

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 most direct limitation is that the registry record does not report the numerical result for the primary endpoint. It gives the endpoint definition and states that 58 of the 63 subjects had paired baseline and 10 week post-procedure CT scans, but it does not report the mean change, standard deviation, confidence interval, or p-value. The subtraction order for change is not reported either. Therefore the direction, magnitude, and precision of the primary result cannot be determined from the posted information.

The study has a single-group, non-randomized design with no separate comparator. The record lists masking as none. As a result, any observed change over time would not by itself isolate an intervention effect from other possible influences. The registry record does not report design features or analysis methods that might address these concerns.

Information about missing observations is limited. The record identifies the paired-scan analysis population but does not explain why scans were unavailable for some subjects, describe missingness in other outcomes, or report imputation or sensitivity analyses. It also does not report participant characteristics, detailed eligibility criteria, adherence, withdrawals, or protocol deviations.

The registry record lists five outcome measures and zero analyses, and it duplicates the SNOT-20 outcome wording. It does not describe an analysis plan, multiplicity handling, or the planned analysis populations. The safety summaries lack event-level context and a comparison group; deaths are not reported in the registry record. Taken together, these omissions constrain assessment of both the endpoint findings and the safety information.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Clinical Study of Safety and Efficacy for the Relieva Stratus With Elution of Triamcinolone Acetonide — NCT00791934.
• Registry record last updated 2024-08-06; status last verified 2024-07.
• Results first posted 2014-07-14.
• 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

NCT00791934 is a completed, prospective, multicenter, non-randomized, single-group study of the Stratus Microflow Ethmoid Spacer with triamcinolone acetonide for local treatment of the ethmoid sinuses. Enrollment was 63. The recorded study start was 2008-08, and primary completion was 2011-11. The intervention description specifies temporary implantation with the drug for 28 days.

The primary endpoint was mean within-participant change in ethmoid Lund-MacKay CT score at 10 weeks compared with baseline. The score ranges from 0 to 8, with higher values indicating greater sinus disease burden. Paired scans were available for 58 of the 63 subjects. The numerical primary outcome and its statistical uncertainty are not reported in the registry record.

The record lists five outcome measures and zero analyses. It reports 2 participants affected in the serious-event category and 19 in the other adverse-event category, each with 63 at risk, and lists wing detachment from device at 3.2% among serious adverse event terms. Deaths are not reported in the registry record.