Safety and Efficacy of the Propel Mini and Propel Nova Steroid-Eluting Sinus Implant in Frontal Sinus: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy of the Propel Mini and Propel Nova Steroid-Eluting Sinus Implant in Frontal Sinus (NCT02266810), a randomized phase 3 study. The primary outcome is Percent of Sinuses That Require Post-operative Interventions (Propel Mini Cohort).

2. Clinical Question

The primary endpoint is specific to the Mini cohort; the registry record does not identify the Nova cohort as part of that primary comparison. The posted endpoint is a percentage of sinuses, while the registry also reports arm counts. These are different units, so the arm counts should not be read as counts of sinuses requiring intervention.

3. Trial Design

The registry describes PROGRESS as a randomized, double-blind, controlled, parallel-group Phase 3 study. The record lists an enrollment of 160 and describes the study as completed. It gives a start date of 2014-09 and a primary completion date of 2016-04. The sponsor is Intersect ENT.

The study addresses use of the PROPEL Mini and PROPEL Nova steroid-eluting sinus implants following surgery to open the frontal sinus in patients with chronic sinusitis. The Mini and Nova comparisons are organized into separate cohorts. In each, the implant was placed in the frontal sinus opening following endoscopic sinus surgery, and the comparator received surgery alone with standard post-operative care. The record does not report the allocation ratio, details of sequence generation, or how the double masking was implemented.

The primary outcome concerns the Mini cohort and is assessed at Day 30. The arm counts posted for that endpoint are 67 for the PROPEL Mini group and 67 for the surgery-only cohort. Other posted measures include Day 30 inflammation ratings in both the Mini and Nova cohorts, and secondary outcome categories concerning post-operative interventions, surgical interventions, inflammation, and occlusion or restenosis.

The registry lists 10 outcome measures and no reported analyses. It does not report the planned statistical model, the sample-size justification, a prespecified analysis plan, or whether any interim analyses were planned or conducted. The record also does not explain how participants were assigned to the Mini and Nova cohorts. Those omissions limit what can be established about the study's design and analysis beyond the information explicitly recorded.

4. Participant Flow and Accounting

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

Overall Study

Analysis population for the primary outcome, as defined in the registry: ITT population

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: This is an intra-patient design where one sinus side of the patient is randomized to receive the treatment while the contralateral sinus side acts as the control.

6. Primary Endpoint

The registry lists the primary outcome as Percent of Sinuses That Require Post-operative Interventions (Propel Mini Cohort), measured over Day 30.

The primary endpoint is the percent of sinuses requiring post-operative interventions in the PROPEL Mini cohort at Day 30. An independent blinded sinus surgeon assessed the need for intervention using video-endoscopy reviews. The endpoint is a composite: it counts a need for surgical treatment to clear obstructive adhesions or scar tissue in the frontal sinus opening, defined as grade 2 or 3 on the adhesion/scarring scale, and/or a need for oral steroids to resolve recurrent inflammation and polypoid edema in the frontal recess or frontal sinus opening.

A composite endpoint can capture more than one clinically relevant route to additional care. Here, the components include a procedure for obstruction or scarring and medication for recurrent inflammatory changes. A single percentage therefore summarizes whether either qualifying type of intervention was needed; it does not show, by itself, how much each component contributed. The registry record does not report component-specific primary results.

The assessment at Day 30 gives the outcome a defined time point after surgery. Video review by an independent blinded sinus surgeon is intended to make assessment less dependent on knowledge of treatment assignment. The record does not report further details about adjudication or how disagreements were resolved.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a randomized, double-blind, parallel-group design, but does not report the statistical analysis plan. The primary result is posted as a percentage with a 95% confidence interval for each arm. The registry does not provide a formal contrast, p-value, or adjusted estimate for the primary comparison. The separate secondary inflammation comparisons are recalculated from posted group summaries and are not listed as reported analyses.

What does a confidence interval convey?

In general, a confidence interval describes the uncertainty associated with an estimate under a statistical procedure. It gives a range of values compatible with the observed data and the method used to form the interval. It is not a guarantee that the true value lies in the interval, nor does it express the probability that a particular value is true. For the primary endpoint, the intervals apply to the group percentages; they are not an interval for the difference between groups. A direct interval for that difference is not reported in the registry record.

How should the primary endpoint be understood?

The primary measure is a percentage of sinuses requiring intervention, not a continuous score. Its composite definition includes surgical treatment for adhesions or scarring and/or oral steroid treatment for recurrent inflammatory changes. A composite can be useful when more than one kind of event represents the outcome of interest, but its overall value may conceal different patterns among its components. The record does not post separate component estimates, so the contribution of each component cannot be assessed from the primary result.

The primary outcome is assessed at Day 30 by an independent blinded sinus surgeon reviewing video-endoscopy. Blinding can reduce the risk that knowledge of treatment assignment affects outcome assessment. The registry record does not state how masking was maintained, how reviewers were selected, or what procedures were used to resolve uncertain classifications.

What do the secondary recalculations represent?

The secondary inflammation measures are means and standard deviations on a 100-mm VAS. The recalculated comparisons estimate the difference between the surgery-only cohort mean and the implant cohort mean within each cohort. Their confidence intervals and p-values are unadjusted calculations from the posted summary statistics. The registry does not list these as sponsor-reported analyses, and the record does not say that this exact calculation was prespecified.

For general context, a mean difference expresses the separation between group averages in the outcome's measurement units. A confidence interval for a mean difference conveys uncertainty about that estimated separation. A p-value describes how surprising data at least as incompatible with a null comparison would be under the assumptions of the test; it does not measure the size or practical importance of an effect. The recalculated results rely on summary-statistic assumptions and do not adjust for other variables or for the number of outcomes examined.

Why does multiplicity matter?

When many outcomes or comparisons are examined, the chance of obtaining at least one small p-value by chance can increase. Statistical procedures can account for multiple testing, but the registry record does not report a multiplicity strategy. The secondary p-values should therefore be treated as exploratory evidence rather than as independently confirmatory findings. The absence of reported analyses also means it is not possible to establish which outcomes were designated in advance for formal testing.

What do planning illustrations mean?

The posted planning illustrations apply to the recalculated secondary inflammation comparisons, not to the primary endpoint. They use the observed effect or specified fractions of it, a two-sided significance level of 0.05, equal allocation, and a normal approximation. They estimate participants per arm for 80% or 90% power under those assumptions. Such illustrations are conditional planning calculations, not observed power and not evidence that the trial was designed using those assumptions. The trial's own sample-size justification is not reported in the registry record.

In general, planning based on an observed effect is sensitive to the uncertainty and possible overstatement of that estimate. Considering smaller fractions of an observed effect illustrates that detecting a more modest effect can require more participants per arm under otherwise similar assumptions. This is a general statistical relationship, not a reconstruction of the PROGRESS design. The record does not report a protocol-based target effect, a recruitment allowance, or the statistical model used for the trial's primary analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 10 outcome measures, including the primary intervention endpoint and secondary categories concerning post-operative interventions, surgical interventions, inflammation, and occlusion or restenosis. It reports no analyses. Although numerical Day 30 inflammation results are posted for the Mini and Nova cohorts, the registry record does not report sponsor analyses for those outcomes, a hierarchy for testing outcomes, or a multiplicity adjustment.

Multiplicity matters because testing several outcomes can make a chance finding more likely. Without a reported strategy, the unadjusted secondary p-values cannot be interpreted as if they came from a single isolated, prespecified test. The primary outcome has group estimates and confidence intervals, but no reported test or interval for the between-group contrast. The record does not report whether the primary endpoint analysis was adjusted, which model was used, or how any covariates were handled.

The primary endpoint identifies the ITT population. The registry record does not give further detail about the analysis population, the handling of missing endpoint assessments, or whether all randomized participants were included in the posted estimates. It also does not report missing-data methods, imputation, sensitivity analyses, or reasons for missing observations. The listed arm counts for the primary endpoint and the different counts attached to other posted outcomes should not be treated as interchangeable without further documentation.

It is therefore not possible to assess whether missing data or outcome availability could have affected the estimates, or whether the analyses followed a prespecified plan. The record does not report interim analyses, stopping rules, or a sample-size justification. These are reporting gaps; they do not establish that such procedures were or were not used. A protocol or statistical analysis plan would be needed to clarify them.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cerebrovascular accident (1.2%), diverticulitis (1.2%), respiratory tract infection fungal (1.2%), deep vein thrombosis (1.2%).

The registry lists serious adverse events among groups at risk of 80 participants: 3 affected in the PROPEL Mini group and 1 affected in the PROPEL Nova group. It lists other adverse events among groups at risk of 80: 43 affected in the Mini group and 36 in the Nova group. These are group-level registry figures; they should not be interpreted as evidence that an implant caused an event or that a difference between groups is statistically established.

The record lists Cerebrovascular Accident, Diverticulitis, Respiratory tract infection fungal, and deep vein thrombosis among the top serious adverse event terms, each at 1.2%. The posted information does not give event-level narratives, timing, severity details beyond the serious-event classification, or a causal assessment. The deaths field is not populated, so deaths are not reported in the registry record.

Safety counts need context, including how events were defined, collected, and attributed, and whether participants could experience more than one event. Those details are not reported in the registry record. The figures therefore describe the posted counts and listed terms, not comparative safety conclusions.

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

The primary result describes the observed percentage of sinuses requiring post-operative intervention by Day 30 in the PROPEL Mini group and in its surgery-only cohort. The group estimates are lower in the implant group, and their confidence intervals show that each estimate is uncertain. The registry does not report a formal between-group primary analysis, so the posted values do not establish a prespecified statistical test or quantify uncertainty in the group difference.

The result applies to a defined endpoint: a blinded review of video-endoscopy, with intervention based on surgical treatment for qualifying adhesions or scarring and/or oral steroid treatment for recurrent inflammation and polypoid edema. It does not separately quantify those components, describe outcomes beyond Day 30, or establish the experience of every patient with chronic sinusitis. The record does not provide enough detail to assess the representativeness of the enrolled population.

The secondary inflammation results are related measurements, but they are not substitutes for the primary composite. Their p-values are unadjusted recalculations, and no multiplicity plan is reported. They should not be treated as a confirmatory set of findings. Likewise, safety counts describe events recorded in the groups; they do not establish causation or a comparative safety profile.

In general, randomized comparisons can help distinguish treatment-group patterns from some forms of confounding, but interpretation also depends on allocation procedures, outcome measurement, missing data, and the analysis plan. The registry record does not report enough detail to evaluate all of these elements. The posted results support a careful description of the recorded group estimates, not medical advice or a conclusion about treatment for an individual.

13. Why This Trial Matters Statistically

This trial is statistically interesting because its primary endpoint is a percentage based on a composite intervention outcome, while the registry posts group estimates rather than a formal between-group analysis. That distinction matters: two arm-specific estimates can describe the observed data, but they do not by themselves supply a test or confidence interval for the contrast that answers the comparative question.

The outcome also combines different clinical actions. A composite can capture more of the post-operative burden than a single component, but interpretation depends on knowing which components occurred. Since the registry does not post component-specific primary results, the overall percentage cannot explain the source of the observed pattern.

The secondary inflammation outcomes illustrate a separate statistical issue. They are continuous measures with recalculated comparisons, while the primary outcome is a percentage. The secondary calculations are unadjusted, and the registry does not report a multiplicity strategy or sponsor analyses. Their results can be informative as context, but should not be elevated to the same confirmatory status as a clearly specified primary contrast.

Finally, a completed randomized study can still have reporting gaps that constrain statistical interpretation. Here, the analysis plan, sample-size justification, missing-data approach, and interim-analysis information are not reported in the registry record. Recognizing the distinction between observed estimates, recalculated comparisons, and unreported design details helps readers avoid treating descriptive data as stronger evidence than the record supports.

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 primary registry result is limited to the Mini cohort at Day 30. The Nova cohort is described in the record, but no Nova result for the primary endpoint is posted. The primary endpoint is a composite, and component-specific estimates are not reported. This prevents assessment of whether surgical interventions, oral steroid interventions, or both account for the overall percentage.

The registry gives arm-specific primary percentages and confidence intervals but does not report a primary between-group estimate, p-value, or analysis method. It also does not report the statistical analysis plan, the sample-size justification, or the allocation ratio. Although the study is described as randomized and double-blind, the record does not explain sequence generation, concealment, or masking procedures.

Numerical results are absent for several listed secondary outcome categories. The inflammation comparisons are recalculated and unadjusted, and no approach to multiplicity is reported. The record does not report missing-data methods, sensitivity analyses, or detailed participant flow. These omissions limit assessment of robustness and of whether the posted estimates reflect the planned analyses.

The posted safety figures do not include detailed event definitions, timing, causal assessment, or participant-level context. The deaths field is not populated. The record also does not report details that would permit a fuller assessment of generalizability, such as participant characteristics or eligibility criteria. These limitations concern what can be interpreted from the registry record; they do not establish that unreported procedures or information were absent from the full study record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Efficacy of the Propel Mini and Propel Nova Steroid-Eluting Sinus Implant in Frontal Sinus — NCT02266810.
• Registry record last updated 2018-08-15; status last verified 2017-10.
• Results first posted 2017-10-06.
• 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 PROGRESS Study is recorded as a completed Phase 3 randomized, double-blind, parallel controlled study of PROPEL Mini and PROPEL Nova implants after frontal sinus surgery for chronic sinusitis. The registry lists enrollment of 160, with a start date of 2014-09 and primary completion in 2016-04.

The primary posted outcome is the percentage of sinuses requiring post-operative intervention by Day 30 in the Mini cohort. The registry provides arm-specific estimates and 95% confidence intervals, but no formal primary between-group analysis. Day 30 inflammation means are also posted for the Mini and Nova cohorts; their comparisons are unadjusted recalculations. Several other secondary results and important analysis details are not reported in the registry record.