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 Microscopic Fluorescence-guided Vestibular Schwannoma Resection Using Fluorescein Sodium and YELLOW 560 (NCT04351373), a na phase 2 study. The primary outcome is Surgeon Predicted Use of Fluorescein Sodium in Future Cases.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04351373 |
| Phase | Phase 2 |
| Condition | Vestibular Schwannoma |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 12 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Mayo Clinic |
| Results posted | Yes |
2. Clinical Question
Population
The registry record lists vestibular schwannoma as the condition and describes surgery for vestibular schwannoma, meningioma, head and neck paraganglioma, or head and neck schwannoma. The recorded enrollment was 12. The registry record does not report how many participants had each tumor type.
Intervention
During surgery, the study used fluorescein sodium administered intravenously and a YELLOW 560 microscope filter. The registry describes the contrast agent being administered after tumor exposure. It does not report further procedural details in the available record.
Comparator
This was a single-group study, with allocation listed as not applicable and no masking. The registry record does not describe a concurrent control group or a like-for-like comparison. Accordingly, the recorded design does not establish a randomized comparison between use and non-use of the interventions.
Primary question
Approximately 3 months after surgery, the study asked the surgeon how likely they were to use fluorescein sodium in future cases involving the tumor, based on its use and performance in that case alone. Responses used a Likert-style scale from 0 to 4, ranging from unsure to plans to use it in all cases. The registry record does not report the observed responses.
3. Trial Design
This was a Phase 2, completed, single-group study with an enrollment of 12. The registry lists the study start as 2021-10-06 and primary completion as 2022-05-25. Allocation is listed as not applicable, and masking as none. Those design details describe an observational experience within a group receiving the study procedures, rather than a randomized, masked comparison.
The interventions were fluorescein sodium, listed as a drug, and the YELLOW560 filter, listed as a device. The registry describes intravenous fluorescein sodium administration after tumor exposure and use of the microscope filter during surgery. The surgical procedures named in the arm description include resection of vestibular schwannoma, meningioma, head and neck paraganglioma, or head and neck schwannoma. Although vestibular schwannoma is the listed condition and the study title focuses on it, the registry record does not report the number of enrolled participants in each tumor category.
The primary measure concerned the surgeon’s stated likelihood of using fluorescein sodium in future cases, assessed approximately 3 months postoperatively. Secondary outcomes are listed as time to differential visualization, average dose of sodium fluorescein administration, and total resection rate. The record lists six outcome measures overall, but it does not report numerical results for the primary or secondary outcomes. Detailed eligibility criteria, the number analyzed for each outcome, and further protocol details are not reported in the registry record.
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 | Fluorescein Sodium (FS) and YELLOW 560 nm Microscope Filter (YE560) During Surgery |
|---|---|
| STARTED | 12 |
| COMPLETED | 11 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | Fluorescein Sodium (FS) and YELLOW 560 nm Microscope Filter (YE560) During Surgery |
|---|---|
| Intraoperative diagnosis of facial nerve schwannoma | 1 |
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 | Fluorescein Sodium (FS) and YELLOW 560 nm Microscope Filter (YE560) During Surgery |
|---|---|---|
| Participants analysed | 12 | |
| Age, Continuous | years | 48 (SD 15.7) |
| Sex: Female, Male: Female | Participants | 9 |
| Sex: Female, Male: Male | Participants | 3 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 12 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 12 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 12 |
6. Primary Endpoint
The registry lists the primary outcome as Surgeon Predicted Use of Fluorescein Sodium in Future Cases, measured over Approximately 3 months postoperatively.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint records the surgeon’s response to a question about the likelihood of using fluorescein sodium in future cases involving the tumor, based on its use and performance in the current case alone. The assessment was scheduled approximately 3 months postoperatively. The response options formed a Likert-style rating from 0 to 4: unsure; plans not to use it in any cases; plans to use it in select cases; plans to use it in the majority of cases; or plans to use it in all cases.
This measure captures stated future-use intention, which can describe a surgeon’s perception of the procedure and its practical acceptability. It is not itself a direct measure of tumor removal, visualization quality, or a patient health outcome. A response also describes intention rather than later behavior; the registry record does not report whether surgeons subsequently used fluorescein sodium in other cases.
The endpoint is listed as a number of participants, but the observed response distribution and the number of participants with recorded responses are not reported in the registry record. No summary score, uncertainty interval, or statistical test result for this endpoint is reported there. Without those results, the registry entry does not show how surgeons rated future use or how consistent their responses were.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the design and planned measures, but it does not provide numerical outcome results for the primary endpoint. Although the primary measure asks surgeons to rate the likelihood of future fluorescein sodium use, no response counts, response distribution, or summary statistic are reported. Consequently, the record does not establish whether ratings tended toward uncertainty, selective use, broader use, or non-use.
The record also lists secondary outcomes for time to differential visualization, average dose of sodium fluorescein administration, and total resection rate. Numerical findings for these outcomes are not reported in the registry record. The record lists six outcome measures, but does not report results for the remaining measures in the information. It also lists no analysis records. In the absence of outcome estimates, there is no reported effect estimate or confidence interval to assess for magnitude or precision.
The design is single-group, with allocation listed as not applicable and masking listed as none. There is no concurrent control group described. As a result, even if an outcome value were available, this design would not by itself separate the experience of using the interventions from other influences, such as the surgical case or the surgeon’s judgment. This is a general limitation of interpreting uncontrolled observations, not a finding about a particular outcome in this study.
The safety record reports 0 participants affected by serious adverse events among 12 at risk, 1 affected by other adverse events among 12 at risk, and 0 deaths. These counts describe the registry’s recorded categories. The type and timing of the other adverse event are not reported in the registry record, and the absence of a reported serious event does not provide a detailed account of how events were collected or classified.
Overall, the posted record supports a description of a small, completed, single-group study and its intended assessments. It does not provide the outcome data needed to judge the observed visualization, resection, surgeon-response, or safety patterns in detail. No treatment conclusion follows from the information reported.
9. Statistical Methods Explained
The record identifies this as a Phase 2 study with a single-group model, allocation not applicable, and no masking. These labels describe how participants were grouped and whether treatment assignment or assessment was masked. In a single-group study, outcomes are recorded within the study group rather than contrasted with a concurrent control group. General statistical interpretation therefore focuses on describing the observed group and its uncertainty; causal comparisons require additional design or assumptions. The registry record does not report a randomized comparison.
What does the primary rating represent?
The primary endpoint is a surgeon’s stated likelihood of future use, on a Likert-style scale running from 0 to 4. The response options have ordered meanings, from unsure through plans for use in select, most, or all cases, with an option for plans not to use the approach. As a general statistical concept, an ordered rating conveys rank-like information: some responses indicate more intended use than others, but the gaps between neighboring categories are not necessarily equal. An analysis that treats such ratings as numeric would make assumptions about those gaps. The registry record does not report the analysis approach or the observed category counts, so it is not possible to determine how the endpoint was summarized or modeled.
The endpoint is recorded as a participant count, but that description alone does not show how the rating was analyzed. The record does not report whether a summary category, an average, or another measure was used. It also does not report a confidence interval or a test result. A confidence interval, as a general concept, expresses the precision of an estimate under the assumptions of the chosen method. Without an estimate and interval, the precision of the primary result cannot be assessed from the registry record.
How should a single-group design be read?
For a single-group study, descriptive estimates can summarize what was recorded among enrolled participants. They do not automatically show what would have happened under an alternative approach. A control group can offer a basis for a comparative estimate, but this study is not described as having one. The registry record does not report an adjusted comparison, an unadjusted comparison, or a treatment-effect estimate. General statistical reasoning therefore cautions against interpreting any unreported outcome as a comparative effect.
The enrollment is 12. In general, estimates based on small groups can be imprecise, especially when outcomes are uncommon or spread across several categories. Precision depends on the observed data and the statistical method; it cannot be quantified from enrollment alone. No confidence intervals, standard errors, or outcome-specific analysis counts are reported in the registry record.
What does a count of affected participants mean?
The safety information gives participants at risk and participants affected in serious and other adverse-event categories. These are descriptive counts. A count does not, by itself, give information about event type, severity within a category, timing, duration, or attribution. The registry record does not report the terms for serious adverse events, and the type of the other adverse event is not reported in the registry record. General statistical methods may use event rates or uncertainty intervals to characterize safety counts, but those measures are not reported.
What can planning assumptions tell a reader?
The registry record includes general assumptions for planning illustrations: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect specified as a fraction of the observed effect. It states that these illustrations are planning calculations, not the study’s own design. The trial itself is recorded as single-group, so the hypothetical equal-allocation assumption should not be read as evidence that participants were assigned to two arms. No planning sample-size values or study-specific sample-size justification are reported in the registry record.
In general, a planning calculation asks what sample size might be needed under a chosen statistical model and assumed effect. It is not an observed result, and it does not establish the probability that a completed study has detected a true effect. The registry record does not report an interim-analysis plan, a detailed statistical analysis plan, or the methods used for outcome-level analyses. Those details cannot be inferred from the listed planning assumptions.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists six outcome measures, including the surgeon’s future-use rating and secondary measures for time to differential visualization, average dose, and total resection rate. It does not report numerical results for these measures in the registry record. The record lists 0 analysis records, so no analysis-specific estimates, tests, or uncertainty intervals are available to describe.
When several outcomes are assessed, multiplicity is a general statistical concern: repeated testing can increase the chance of at least one apparently notable result under a specified testing framework. Researchers may address this through prespecified outcome hierarchies, adjustments, or a primarily descriptive approach. The registry record does not report whether any multiplicity strategy was planned or used. It also does not report the statistical analysis plan, prespecified analysis populations, or whether analyses were adjusted for other variables.
Missing-data handling is not reported in the registry record. The record does not give outcome-specific denominators, the number of participants with a completed primary survey, or the reasons for any missing observations. It therefore cannot establish whether all enrolled participants contributed data to each outcome, or how missing values were treated. These omissions matter because outcome summaries can depend on which participants have recorded measurements and on the analysis population used.
The registry record does not report an intention-to-treat, per-protocol, or other named analysis population. For a single-group study, the choice of who is included in each outcome analysis still affects how results should be interpreted. No assumptions about missingness or analysis populations can be inferred from the overall enrollment count alone.
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 |
|---|---|---|---|
| Fluorescein Sodium (FS) and YELLOW 560 nm Microscope Filter (YE560) During Surgery | 0 | 12 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Fluorescein Sodium (FS) and YELLOW 560 nm Microscope Filter (YE560) During Surgery | 0 of 12 |
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 |
|---|---|
| Fluorescein Sodium (FS) and YELLOW 560 nm Microscope Filter (YE560) During Surgery | 1 of 12 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Fluorescein Sodium (FS) and YELLOW 560 nm Microscope Filter (YE560) During Surgery |
|---|---|---|
| Fever | General disorders | 1 of 12 |
For the group receiving fluorescein sodium and the YELLOW 560 filter during surgery, the registry records 0 participants affected by serious adverse events among 12 at risk. For other adverse events, it records 1 participant affected among 12 at risk. Deaths are recorded as 0.
These figures are counts of affected participants in the registry categories, not a detailed event narrative. The registry record does not list serious adverse-event terms, and it does not identify the type, timing, duration, or attribution of the other adverse event. It also does not report further details about event monitoring or classification. A zero recorded count for a category describes the entry in the record; it does not provide detailed evidence about the range of possible events beyond what was recorded.
Because the study has one group and no concurrent comparator described, these counts do not provide a comparative safety estimate. They should be read as the reported safety observations for this group, not as a comparison between approaches.
12. What the Result Does, and Does Not, Mean
The record shows that a completed Phase 2, single-group study enrolled 12 participants and evaluated fluorescein sodium with a YELLOW 560 microscope filter during surgery. Its primary question concerned surgeons’ stated likelihood of using fluorescein sodium in future cases, assessed approximately 3 months after surgery. The registry also lists outcomes concerning differential visualization, administered dose, and total resection rate.
Those design and outcome descriptions do not reveal the observed results. The primary response distribution and numerical findings for the secondary outcomes are not reported in the registry record. There is therefore no reported estimate with which to assess the direction, size, or precision of an outcome pattern. The record does not establish whether surgeons intended future use, how visualization was rated, or what resection outcomes were observed.
The safety entries report 0 participants affected by serious adverse events among 12 at risk, 1 affected by other adverse events among 12 at risk, and 0 deaths. The available record does not describe the other adverse event or provide further event-level detail. These descriptive counts are not a comparison against another group.
More generally, a single-group study can document observations in the treated group, but without a concurrent comparator it cannot directly estimate how outcomes would differ under an alternative approach. This is a design-level caution, not a claim about the unreported results. The registry entry also does not report analysis methods, confidence intervals, or outcome-specific denominators, limiting assessment of precision and missing data.
Accordingly, the record supports a concise account of the study’s design, interventions, endpoints, and recorded safety counts. It does not support a conclusion about clinical benefit, effectiveness, or comparative safety. Those questions require outcome data and an appropriate basis for comparison, neither of which is reported in the registry record.
13. Why This Trial Matters Statistically
This study raises a useful statistical distinction between an intervention’s technical evaluation and the endpoint used to assess it. The primary endpoint is a surgeon’s stated intention to use fluorescein sodium in future cases, not a direct patient outcome or a measure of tumor removal. That intention may describe acceptability or anticipated uptake, but it cannot be treated as evidence of later behavior or clinical effect.
The single-group design also makes the interpretive role of comparison important. Without a concurrent control group, the recorded experience cannot, on its own, distinguish the intervention’s contribution from other influences on surgical observations. This is a general design consideration. The registry record does not report comparative estimates or a randomized allocation.
The registry entry is also a reminder that an endpoint description and a result are different kinds of information. It describes the primary rating scale and lists secondary outcomes, but numerical results are not reported in the registry record. Without response distributions, outcome estimates, or uncertainty intervals, readers cannot assess the magnitude or precision of the findings. The listed enrollment alone cannot fill that gap.
Finally, safety counts are most informative when accompanied by event descriptions and methods for collection and classification. The registry records affected-participant counts, but the type of the other adverse event and further event-level detail are not reported. Statistically, the study is useful to consider as an example of how design, endpoint choice, reporting completeness, and uncertainty shape what can be concluded from a clinical trial record.
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 numerical results for the primary and secondary outcomes are not reported in the registry record. The primary endpoint is described, but its response counts and summary are absent. The registry record does not report values for time to differential visualization, average dose, or total resection rate either. This prevents assessment of the observed outcomes and their precision.
The study is listed as single-group, with allocation not applicable and no masking. No concurrent control group is described, so the record does not provide a like-for-like comparison. Enrollment was 12, but the registry record does not report how many participants had each tumor type, whether all participants contributed data to each outcome, or the outcome-specific denominators.
The condition is listed as vestibular schwannoma, while the arm description includes surgery for vestibular schwannoma, meningioma, head and neck paraganglioma, or head and neck schwannoma. The composition of the enrolled group across these tumor types is not reported in the registry record. The primary assessment depends on a surgeon’s stated intention, and the registry record does not report later use in future cases.
Detailed statistical methods, missing-data handling, analysis populations, and any multiplicity strategy are not reported in the registry record. Safety reporting is limited to affected-participant counts; the other adverse event’s type and additional event details are not reported. These limits constrain interpretation of both benefit-related outcomes and safety observations.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Microscopic Fluorescence-guided Vestibular Schwannoma Resection Using Fluorescein Sodium and YELLOW 560 — NCT04351373.
- Registry record last updated 2023-08-01; status last verified 2023-07.
- Results first posted 2023-08-01.
- 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
The registry record describes NCT04351373, a completed Phase 2, single-group study sponsored by Mayo Clinic. Enrollment was 12. The recorded study start was 2021-10-06, and primary completion was 2022-05-25. Allocation is listed as not applicable and masking as none.
The interventions were intravenous fluorescein sodium and a YELLOW560 microscope filter during surgery. The primary measure was the surgeon’s stated likelihood of future fluorescein sodium use, assessed approximately 3 months postoperatively on a Likert-style rating from 0 to 4. Secondary outcomes included time to differential visualization, average dose, and total resection rate.
The registry record does not report numerical results for the primary or secondary outcomes. It records 0 participants affected by serious adverse events, 1 affected by other adverse events, and 0 deaths. The type of the other adverse event and detailed analysis methods are not reported in the registry record.