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 A Feasibility Study of a Modular Video Augmentation System for Image-Guided Skull Base Surgery (NCT01591954), a na na study. The primary outcome is Qualitative Assessment of Video Augmentation Software by Post-operative Survey of Neurosurgeon and Otolaryngologist.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01591954 |
| Phase | NA |
| Condition | Feasibility of Video Augmentation System, Value of Video Augmentation Navigation |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 1 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins |
| Results posted | Yes |
2. Clinical Question
Population
Patients undergoing image-guided endoscopic skull base surgery were the intended population. The registry reports that the study was terminated following accrual of one participant. It does not report further participant characteristics in the primary outcome description.
Intervention
The intervention was a video-augmentation device intended to overlay preoperative data on endoscopic video. The registry describes the study as a clinical pilot assessing feasibility and gathering qualitative assessment of the system.
Comparator
There was no comparator group. The design is listed as single group, with allocation marked NA and masking listed as none. The record therefore does not describe a randomized or controlled comparison.
Primary question
The primary question was how neurosurgeons and otolaryngologists assessed the software after surgery, including its effect on surgical confidence, procedure, approach and visualization. The registry also describes safety assessment through information about additional time, personnel and possible contamination. The system encountered basic software incompatibility and would not function reliably, and the study was terminated. A primary outcome result is not reported in the registry record.
3. Trial Design
This was a single-group feasibility and pilot study of a modular video-augmentation system for image-guided endoscopic skull base surgery. The intervention is named Video Augmentation and classified as a device. The registry lists the study phase as NA, allocation as NA, masking as none, and the model as single group. These entries describe a study without a parallel control arm or masking; they do not support a treatment comparison.
The planned work focused on basic feasibility and qualitative assessment in a small number of patients at Johns Hopkins Hospital. The registry’s enrollment is one. Its primary outcome description states that the study was terminated following accrual of one participant because of basic software incompatibility. The system would not function reliably, and the problem could not be resolved despite extensive technical troubleshooting. The study status is terminated.
The sponsor is Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins. The listed start is 2012-01, and primary completion is 2013-01. The registry lists one primary outcome and a secondary outcome titled Data Recording for Retrospective Analysis. It lists two outcome measures overall and zero analyses. Detailed results for the secondary measure are not reported in the registry record.
The design can address whether the system was usable enough to proceed with the intended assessment, and it can describe feedback if that feedback is available. It cannot estimate a comparative effect against usual navigation or another system because no comparator group is recorded. The registry record does not report a protocol, a sample-size justification, or a planned statistical analysis. The absence of those details should not be filled in by assuming standard procedures for feasibility studies.
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 | Video Augmentation |
|---|---|
| STARTED | 1 |
| COMPLETED | 1 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: The study was terminated following 1 subject accrual. The system encountered basic software incompatibility and would not function reliably. The problem could not be resolved even with extensive technical troubleshooting, so the study was terminated. Data was collected for one participant but could not be analyzed due to software incompatibility.
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 | Video Augmentation |
|---|---|---|
| Participants analysed | 1 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 1 |
| Sex: Female, Male: Male | Participants | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Qualitative Assessment of Video Augmentation Software by Post-operative Survey of Neurosurgeon and Otolaryngologist, measured over Assessment is immediate, following operation..
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is a qualitative post-operative survey of neurosurgeon and otolaryngologist assessments of the video-augmentation software. Its stated timeframe is immediate, following operation. The description says the survey concerned the effect of the overlay on overall surgical confidence, procedure, approach and visualization. It also describes safety assessment through collection of information about additional time, personnel and possible contamination.
The rating scale assigns meanings from 1, “Significant hindrance / Negative effect,” through 3, “Not helpful / No benefit or hindrance,” to 5, “Very helpful / Major benefit.” The descriptions for 2 and 4 are “Minor hindrance / Slightly negative effect” and “Somewhat helpful / Slight benefit.” These ordered response categories make the measure qualitative and ordinal: they express an ordering of views, but do not establish that the distance between adjacent categories is equal.
A post-operative survey is used in this pilot to capture clinicians’ immediate perceptions of the system, rather than a numerical measure of surgical performance. This is a general explanation of the measure’s role, not evidence that the system improved an outcome. The registry does not report completed ratings, a summary of responses, or a primary endpoint analysis. It also does not report how individual survey responses were combined or whether every intended assessor completed a survey. Consequently, the endpoint’s definition is available, but its observed result and precision are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central result in the registry record is about feasibility and study conduct: the system encountered basic software incompatibility, did not function reliably, and the study was terminated after one participant was accrued. The registry states that extensive technical troubleshooting did not resolve the problem. These registry entries explain why the planned clinical assessment did not proceed as intended. They are not a numerical estimate of the system’s effect on surgical confidence, procedure, approach or visualization.
The primary outcome was defined as a qualitative post-operative survey, with ordered response options ranging from a negative assessment to a positive assessment. However, no response values or outcome summary are reported. The registry also lists zero analyses. Thus, no observed rating distribution, average, median, treatment effect, confidence interval or statistical test result is available in the record. An outcome definition tells readers what investigators intended to measure; it does not establish what participants or clinicians reported.
The enrollment of one is important for interpreting the scope of the evidence. Even if a survey result had been available, information from one participant would describe only a very limited experience and would not establish how the system would perform across a broader clinical population. In this record, the more immediate limitation is that the primary outcome data are not reported, so even a descriptive account of that one participant’s survey cannot be made.
The registry’s background summary describes technical work on automatic camera calibration, run time and phantom registration accuracy. It also describes the planned clinical pilot as a way to assess basic feasibility and obtain qualitative feedback. Those statements provide context for why the study was undertaken, but they are not clinical outcome findings from the terminated participant’s assessment. In particular, phantom work and clinical use are distinct settings, and the record does not report a clinical comparison that would connect them.
No comparator arm was included, and the record lists no masking. Accordingly, the study cannot estimate a difference between the video-augmentation system and another approach. It also cannot support a causal interpretation based on a controlled comparison. These are design constraints, separate from the software incompatibility that led to termination.
The posted safety counts list one participant at risk for serious adverse events and zero serious events; one participant at risk for other adverse events and zero other events. The death count is not reported. The zero event counts are the posted counts for this very small group, not proof that the intervention has no safety risks. The record’s clinical outcome and adverse-event information should therefore be read as limited registry reporting from a terminated feasibility study, rather than as a completed efficacy or safety evaluation.
9. Statistical Methods Explained
The registry describes a single-group study and reports zero analyses. It does not report a statistical analysis plan, a sample-size justification, or methods for handling missing outcome data. The following concepts explain how the recorded design and endpoint would generally be understood; they are not claims about procedures that investigators used.
What a single-group design can describe
In a single-group study, observations come from participants exposed to the intervention, without a concurrent control group in the recorded design. Such a study can describe whether an intervention could be delivered and can summarize observed feedback or events. It does not directly estimate how outcomes would have differed under a comparator, because the record contains no comparator observations. Without that comparison, changes or impressions cannot be attributed to the intervention by contrasting groups.
Feasibility is often a practical question: whether the planned system can be used and whether study procedures can be carried out. Here, the registry reports a concrete feasibility problem: software incompatibility prevented reliable function and could not be resolved through extensive troubleshooting. That report is a study-conduct finding. It is distinct from a survey score, and it does not substitute for an unreported primary endpoint result.
How to interpret the survey scale
The primary endpoint uses ordered response categories. In general, an ordinal scale indicates which response is more positive or negative in rank, but it does not guarantee equal spacing between neighboring labels. A rating of 4 therefore represents a more favorable category than a rating of 3 according to the wording, but an analysis should not automatically treat the difference between those categories as numerically identical to the difference between 3 and 2.
With adequate data, ordinal responses could be described by showing how many assessments fell into each category, or by reporting an appropriate summary that respects the ordered nature of the scale. A confidence interval, in general, expresses uncertainty around an estimated quantity under the assumptions of the method used. It would not eliminate limitations from a small or incomplete set of observations. No category counts, statistical summaries or confidence intervals for the primary endpoint are reported in the registry record, so no such interpretation is available.
Why no inferential result is available
Inferential statistics use observed data and a specified model or test to quantify uncertainty or assess a defined comparison. The registry reports zero analyses and does not report a numerical survey outcome. Therefore, there is no posted estimate to interpret, and a p-value or confidence interval cannot be inferred from the endpoint definition alone. General statistical methods cannot recover results that are not reported.
For outcomes that count events, analysts may distinguish the number of events from the number of participants who experienced at least one event. Those quantities can differ when an individual has more than one event. The adverse-event record presents event-related counts, including participants at risk and affected counts. It does not supply a detailed event list or a fuller analysis. Given the single participant, the counts are descriptive and provide little information about the range of possible event frequencies in a larger population.
Over-dispersion and modeling
Over-dispersion is a general concern for count data when observed variability exceeds what a chosen statistical model expects. It can make standard errors and confidence intervals too small if the model does not account for the extra variability. This concept is not evidence that over-dispersion occurred in this study. The registry does not report a count-data model, an estimate of dispersion, or an analysis of adverse events. With no reported event analysis, there is no basis for claiming that a particular model or adjustment was used.
Likewise, a sample-size calculation is a planning exercise, not an observed result. A planning illustration based on an observed effect would depend on an effect estimate and assumptions such as significance level, allocation and a target power. The registry does not report the trial’s own sample-size justification or a numerical primary outcome effect. Any planning illustration should not be called observed power, and it cannot turn this terminated study into a powered comparison.
Overall, the appropriate statistical reading is descriptive and limited: the design, endpoint definition, enrollment, termination reason and posted event counts are available. A primary outcome estimate, its uncertainty and a planned inferential analysis are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two outcome measures: the primary qualitative survey assessment and the secondary measure Data Recording for Retrospective Analysis. It does not report an analysis for either measure, and the analysis count is zero. The record does not describe a multiplicity plan, such as a hierarchy of outcomes, an adjustment to account for multiple statistical tests, or a rule for selecting which outcomes to emphasize. It would therefore be inappropriate to assume that any such procedure was used.
Multiplicity is a general statistical issue that arises when several hypotheses or outcomes are tested. As the number of tests grows, the chance of at least one apparently notable finding can increase unless the analysis plan accounts for the testing strategy. That general concern does not establish that this study conducted multiple tests; no analyses are reported. With no outcome results and no stated testing plan, there is no basis for evaluating multiplicity adjustments or interpreting a collection of p-values.
The record says data were collected for one participant, but the primary outcome description ends without specifying the extent or completeness of those data. It does not report whether a survey was completed, whether any responses were missing, or how missing values would have been handled. The secondary measure’s details are also not reported in the registry record. Missing-data methods should not be inferred from the fact that data collection began.
The registry does not define analysis populations, such as an intention-to-treat or per-protocol population, nor does it report exclusions or a participant flow beyond the single accrual and termination statement. In general, an analysis population specifies which enrolled participants or observations contribute to a particular analysis. Without a reported analysis or population definition, no population-based estimate can be reconstructed. The available record supports a description of study status and conduct, but not a completed outcome analysis.
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 |
|---|---|---|---|
| Video Augmentation | 0 | 1 | 0.0% |
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 |
|---|---|
| Video Augmentation | 0 of 1 |
The registry lists one participant at risk for serious adverse events and zero serious adverse events. It also lists one participant at risk for other adverse events and zero other adverse events. No serious adverse event terms are listed. The death count is not reported in the registry record; it should not be read as a reported zero.
These are counts recorded for a study that enrolled one participant and was terminated. They indicate that the registry’s posted counts show no serious or other adverse events in the listed group. They do not establish that the system is free of safety risks or that event rates would be low in a larger group. With so few participants and a terminated study, the observation has limited ability to characterize uncommon events or the range of possible safety outcomes.
The primary outcome description says safety assessment was to involve information about additional time, personnel and possible contamination. No results for those items are reported. The adverse-event counts should not be treated as a substitute for those assessments: the record does not provide measurements of added time, personnel requirements or contamination. The counts describe the posted event reporting, not a complete evaluation of every safety question named in the endpoint description.
12. What the Result Does, and Does Not, Mean
This record documents a clinical feasibility pilot that did not proceed as intended. The system encountered basic software incompatibility, did not function reliably, and the issue remained unresolved despite extensive technical troubleshooting. The study was terminated after accrual of one participant. Those details are the clearest findings available from the registry record.
The study’s primary outcome was designed to capture clinicians’ qualitative assessments after surgery. Its response scale and assessment topics are described, but no completed ratings or outcome summary are reported. As a result, the record does not show whether the software was judged helpful, neutral or hindering by the assessors. It does not report an estimate of effect, a confidence interval or a statistical test for the primary outcome.
The intended application was to augment endoscopic video with preoperative data in image-guided skull base surgery. The registry’s background describes the rationale as supporting navigation around critical structures and target resection, and notes that conventional CT/MRI data are not registered with video endoscopy. Those statements describe the motivation for development. They are not evidence from a comparative clinical trial that the system achieved those aims.
The record also cannot establish comparative effectiveness or safety. It has no control group, reports no outcome analysis, and includes only one accrued participant. The posted adverse-event counts are zero for serious and other adverse events, but a zero count in this limited record does not demonstrate absence of risk. The death count and the planned additional-time, personnel and contamination assessments are not reported.
The result should therefore be understood as a feasibility interruption and incomplete clinical evaluation, not as evidence for or against the system’s performance in broader clinical use. The registry record identifies a technical obstacle and records termination; it does not provide enough clinical outcome data to quantify benefit, harm or uncertainty.
13. Why This Trial Matters Statistically
This study illustrates why feasibility findings and clinical outcome findings are different forms of evidence. A system may be intended to address a clinically relevant technical gap, but a clinical assessment depends first on the system functioning reliably enough for the planned observations to be made. In this record, software incompatibility prevented reliable function and led to termination. That is important information about the conduct of this pilot even though it is not a measured effect on the primary survey outcome.
The record also highlights the importance of separating a clearly described endpoint from a reported endpoint result. The survey has a stated timing, topics and ordered response scale. Those details make the intended measurement understandable. But without posted responses or an analysis, the endpoint definition cannot answer whether assessors viewed the overlay favorably or how uncertain any estimate would be.
Statistically, a single-group study with one participant cannot provide a comparative estimate. The absence of a comparator is not repaired by the detail of a rating scale, and the absence of outcome values is not repaired by a statistical method. These distinctions help prevent descriptive study status, technical background and clinical outcome evidence from being conflated.
The record is also a reminder that zero reported adverse events should be read in the context of the number of participants and the scope of reporting. The counts describe what is posted for this group; they cannot characterize the frequency of events across a broader population. The planned safety questions about time, personnel and possible contamination remain without reported results.
For biostatisticians and clinical researchers, the practical lesson is to distinguish what the registry establishes—design, enrollment, termination reason and posted event counts—from what remains unavailable, including survey results, analysis methods and uncertainty estimates. That separation supports transparent interpretation without overclaiming from a very limited pilot 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 most direct limitation is that the study was terminated after one participant was accrued because the system encountered basic software incompatibility and would not function reliably. The registry says the problem could not be resolved despite extensive technical troubleshooting. The intended clinical assessment therefore has no reported primary outcome result.
The design was single group, with no comparator and no masking. It cannot provide a controlled estimate of how outcomes differed from another navigation approach. Enrollment of one participant also sharply limits the descriptive scope of any observations. Participant characteristics beyond what is stated in the primary outcome description are not reported in the registry record.
The survey outcome is described, including its ordinal response categories and the domains it was intended to assess, but no survey responses, response counts or summary statistics are reported. The registry does not state how responses from the surgeons were to be combined, whether the intended assessors completed the survey, or how missing responses would be handled. The secondary measure is named, but its results and analytic details are not reported.
The record lists zero analyses and does not report a statistical analysis plan, sample-size justification, analysis populations or multiplicity procedures. It also does not report uncertainty estimates for the primary endpoint. The adverse-event listing shows zero serious and zero other events for one participant at risk in each category, but the death count is not reported. The record does not give results for the additional-time, personnel or possible-contamination assessments named in the primary outcome description.
These limitations mean the registry supports a narrow conclusion about technical feasibility and termination, rather than a conclusion about clinical performance or safety. Background statements about calibration and phantom studies do not replace clinical outcome evidence from this pilot.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Feasibility Study of a Modular Video Augmentation System for Image-Guided Skull Base Surgery — NCT01591954.
- Registry record last updated 2016-12-01; status last verified 2016-10.
- Results first posted 2016-12-01.
- 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 describes a feasibility/pilot study of a modular video-augmentation system for image-guided endoscopic skull base surgery. It was a single-group device study with no masking and no comparator. Enrollment was one, and the study status is terminated.
The primary endpoint was an immediate post-operative qualitative survey of neurosurgeon and otolaryngologist assessments. The study was terminated because software incompatibility prevented reliable function and could not be resolved through extensive troubleshooting. The registry lists two outcome measures and zero analyses. Primary survey results and detailed secondary outcome results are not reported in the registry record.
The posted adverse-event counts are zero serious and zero other events, with one participant at risk in each category. The death count is not reported. The record does not provide a comparative estimate, primary outcome analysis or uncertainty interval.