EPAD Monitoring of Patients Undergoing Robotic Assisted Laparoscopic Genitourinary Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for EPAD Monitoring of Patients Undergoing Robotic Assisted Laparoscopic Genitourinary Surgery (NCT03319407), a na na study. The primary outcome is Somatosensory Evoked Potential Monitoring.

2. Clinical Question

The clinical rationale in the registry is that positioning during genitourinary surgery may put peripheral nerves at risk. SSEP devices are described as commonly used to detect pending peripheral nerve injury. Against that background, the study sought to characterize monitoring findings and relate them to neurologic status, rather than compare outcomes between an EPAD group and a control group.

The primary outcome timeframe was the first 24 hours of the postoperative period. However, the registry states that the study was terminated prematurely and that data were not collected. The record therefore does not answer whether significant waveform changes occurred, what caused any such changes, or how waveform findings related to neurologic status.

3. Trial Design

This was an interventional device study with a single-group model. The listed intervention was the EPAD monitoring system, and the observation arm description states that all participants would be monitored with that system. The registry records allocation as NA and masking as none. With no separate control group, the design does not support a like-for-like comparison between monitored and unmonitored participants.

The study concerned patients scheduled for laparoscopic genitourinary surgery, with EPAD monitoring described as part of intraoperative clinical care. Its stated purpose was to use SSEP monitoring to examine significant waveform changes, potential causes, and the relationship between changes and brachial plexus neurologic status after robotic surgery. The primary outcome was SSEP recording in patients undergoing genitourinary surgery, with a timeframe in the first 24 hours of the postoperative period.

The registry lists enrollment of 21. It also records the study status as terminated and states under the primary outcome that the study was terminated prematurely and data were not collected. The record lists a start date of 2017-10-05 and a primary completion date of 2018-12-30. These dates do not establish when recruitment stopped or explain the reason for termination; that information is not reported in the registry record.

The phase is listed as NA. The record names Mayo Clinic as sponsor and lists one outcome measure, but no analyses. The protocol’s planned sample-size justification, stopping rules, recruitment procedures, and detailed statistical analysis plan are not reported in the registry record. There is also no description of a separate control condition or a prespecified comparison between different monitoring strategies.

These design features matter when interpreting the intended question. A single-group monitoring study can describe monitoring recordings and clinical observations if they are collected, but a controlled comparison is needed to estimate how outcomes differ between monitoring strategies. In this case, the primary-outcome data were not collected, so the registry record supplies neither descriptive outcome findings nor a comparative estimate.

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: Study terminated prematurely. Data was not collected.

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 Somatosensory Evoked Potential Monitoring, measured over in the first 24 hours of postoperative period.

The primary endpoint is titled Somatosensory Evoked Potential Monitoring. Its description is the recording of somatosensory evoked potential in patients undergoing genitourinary surgery, and its timeframe is the first 24 hours of the postoperative period. The registry’s study summary explains that SSEP monitoring was intended to identify significant changes in waveforms, consider possible causes of changes, and relate those findings to brachial plexus neurologic status after robotic surgery.

SSEP recordings are used in this study context because the registry describes them as a way to detect pending injury to peripheral nerves. A waveform change could therefore be relevant to the study’s concern about nerve injury associated with intraoperative positioning. In general, an endpoint turns a broad clinical question into an observation to be collected and evaluated; here, the stated endpoint centers on SSEP recordings and their clinical interpretation.

The registry does not report a numerical definition of a significant waveform change, the recording protocol, criteria for determining potential causes, or the method for assessing postoperative neurologic status. Those details are not reported in the registry record. Most importantly, the endpoint’s population field states that the study was terminated prematurely and data were not collected. There are consequently no posted endpoint measurements with which to describe the occurrence or magnitude of waveform changes, or their association with neurologic status.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies a single-group study with no masking and allocation recorded as NA. These are design descriptions, not evidence of a completed statistical analysis. A single-group design observes participants under one study condition; it does not create a like-for-like control group. The record’s observation arm says all participants would be monitored with the EPAD system. Thus, any intended outcome description would concern that monitored group rather than a randomized contrast between monitoring strategies.

What would an endpoint measurement represent?

The listed primary outcome is SSEP monitoring, described as recording somatosensory evoked potentials in patients undergoing genitourinary surgery. Its timeframe is the first 24 hours of the postoperative period. The study summary says the aim was to identify significant waveform changes, consider potential causes, and correlate changes with brachial plexus neurologic status. To analyze such an endpoint, investigators would need operational definitions of the waveform features and change thresholds, a plan for neurologic assessment, and a way to link assessments over time. These details are not reported in the registry record.

In general, a prespecified endpoint definition helps ensure that measurements are interpreted consistently. If a study has several possible waveform features or definitions of a clinically meaningful change, selecting among them after seeing results can make findings harder to interpret. The registry does not report a threshold for a significant SSEP change or a detailed endpoint scoring method. More importantly, it states that the study was terminated prematurely and data were not collected, so no endpoint analysis can be evaluated.

What can a single-group analysis establish?

In general, a single-group study can report the observed distribution of outcomes among monitored participants, provided the measurements are collected and the analysis population is defined. It cannot, by itself, estimate how outcomes would have differed under a separate monitoring approach. An observed waveform change could be described, but attributing it to monitoring, surgery, positioning, or another factor would require additional evidence and a suitable analytic design. The record does not report an outcome dataset or an analysis of potential causes.

Random allocation, when used, can support comparison by reducing systematic differences between groups on average. Here, allocation is NA, the model is single group, and the record indicates that the arms are not a like-for-like control comparison. No randomized contrast is available. Masking is recorded as none. The registry does not describe a masking procedure for waveform interpretation or neurologic assessment; such procedures are not reported in the registry record.

How should statistical uncertainty be understood?

In general, an estimate summarizes an observed quantity, and a confidence interval expresses uncertainty around that estimate under the assumptions of the analysis. A wider interval usually indicates less precision than a narrower one. A p-value assesses how compatible data are with a specified null hypothesis under a model; it does not measure clinical importance or prove that a hypothesis is true. These concepts require observed data and a defined analysis. No primary-outcome estimate, confidence interval, or p-value is reported for this study.

For repeated or clustered observations, measurements from the same participant may be related rather than independent. General statistical methods account for such dependence when appropriate. For count outcomes with extra variation beyond a simple model’s assumptions, over-dispersion can make standard errors too small if it is ignored. These are general considerations only: the registry does not report a repeated-measures model, count analysis, assessment of over-dispersion, or any other primary-outcome method. Since primary endpoint data were not collected, it is not possible to determine whether those methods would have been relevant to the actual results.

What do the planning assumptions mean?

The sample-size assumptions describe a planning illustration using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; they state that the effect to detect is a fraction of the observed effect. The same note distinguishes total events for time-to-event calculations from participants per arm for other calculations. These are calculation assumptions, not evidence that the trial used that design or analysis. The actual study is listed as single group, not a two-arm comparison, and the record reports no collected primary outcome. Consequently, planning figures cannot be interpreted as results, actual power, or evidence that a particular effect was detectable in this trial. Sample-size planning illustrations are not observed power.

The registry does not report the trial’s own sample-size justification, target effect, primary-outcome hypothesis test, model specification, handling of missing observations, or analysis population. No analysis is listed. The absence of those details means that the methods used or intended for an eventual primary-outcome analysis cannot be reconstructed from the record. The most direct statistical conclusion is that the study’s intended outcome analysis is unavailable because the primary data were not collected.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and no analyses. It does not report a statistical analysis plan describing how the primary endpoint would be analyzed, whether there were planned secondary outcomes, or how multiple endpoints or comparisons would be handled. Multiplicity methods address the increased chance of misleading positive findings when several hypotheses are tested; in general, a prespecified plan helps readers understand which findings were primary and how additional tests were interpreted. There is no reported testing framework to assess in this record.

The outcome population field states that the study was terminated prematurely and data were not collected. The record does not specify missing-data procedures, reasons for missingness, whether any participants had partial measurements, or how incomplete postoperative assessments would have been handled. Since the primary endpoint was not collected, there is no basis for evaluating imputation, complete-case analysis, or sensitivity analyses. These approaches and decisions are not reported in the registry record.

The analysis population is also not described. The record lists enrollment of 21 and lists 21 at risk for adverse-event reporting, but it does not define an intention-to-treat, per-protocol, or other analytic population for the SSEP endpoint. No analysis set can be inferred from the safety counts. The reason for termination and whether any interim analysis occurred are not reported in the registry record. The available information therefore does not permit assessment of multiplicity control, missing-data bias, or the relationship between enrollment and outcome analysis.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry’s safety fields list 21 participants at risk for serious adverse events, with 0 affected, and 21 at risk for other adverse events, also with 0 affected. Deaths are listed as 0. These are the posted safety counts for the observation group. The record lists no serious adverse-event terms.

These counts should be read narrowly. They describe what the registry reports for the safety categories; they are not SSEP outcome measurements and do not indicate whether waveform changes occurred. They also do not establish that there were no events in every clinical context, or explain how adverse events were collected and assessed. The safety reporting timeframe, event definitions, and detailed ascertainment procedures are not reported in the registry record.

In general, a count of zero is different from proof that an event cannot occur. Interpretation depends on complete follow-up, definitions, and ascertainment. The registry’s separate statement that primary-outcome data were not collected should not be extended to the safety fields, which have their own reported counts. Conversely, the listed safety counts cannot be used to fill in the absent primary endpoint results or to establish effects of EPAD monitoring.

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

The record documents a planned single-group study of EPAD monitoring during genitourinary surgery. Its primary outcome concerned SSEP recordings during the first 24 hours of the postoperative period, and its stated aims included examining significant waveform changes, their potential causes, and their relationship to brachial plexus neurologic status. The study status is terminated, and the registry explicitly says that the primary outcome data were not collected. The principal result is therefore the absence of primary endpoint results in the record.

This does not show that SSEP waveforms remained unchanged, nor does it show that changes occurred. It does not establish whether EPAD monitoring identified a pending nerve injury, whether a waveform change predicted neurologic status, or whether any changes had a particular cause. Those conclusions require collected outcome observations and analyses, neither of which is reported. The record also does not explain why the study was terminated.

The study’s single-group design is another limit on interpretation. Even with outcome data, a monitored group without a separate control condition would not provide a randomized estimate of how outcomes differed under another monitoring strategy. The registry lists allocation as NA and masking as none. It does not report an alternative comparator or a controlled effect estimate.

The safety counts are separate: the registry lists 0 serious adverse events affected, 0 other adverse events affected, and 0 deaths. These counts do not answer the primary SSEP question, and their collection procedures and timeframe are not reported in the registry record. The record’s enrollment field lists 21, but that figure cannot substitute for missing primary measurements.

Accordingly, the record supports a description of the study’s intended purpose, design, status, and reported safety counts. It does not support a conclusion about the frequency or significance of SSEP changes, the association between monitoring findings and neurologic status, or the clinical effect of EPAD monitoring. Planning illustrations, if considered, are not observed power and do not overcome the absence of outcome data.

13. Why This Trial Matters Statistically

This study is a useful example of why study objectives and study results must be distinguished. The registry describes a clinically motivated question: whether SSEP monitoring during genitourinary surgery can identify significant waveform changes and how those changes relate to brachial plexus neurologic status. But the record also states that the study ended prematurely and that primary-outcome data were not collected. A clear objective is not itself evidence that the question was answered.

Its design illustrates a second statistical distinction. A single-group study may be suitable for describing observations under one monitoring condition, but it does not provide a randomized comparison with an alternative condition. Allocation is listed as NA, masking as none, and the study model as single group. Those features limit any comparative or causal interpretation, even if descriptive endpoint results had been available.

The record also highlights that enrollment and analysis are different concepts. It lists enrollment of 21, but the primary endpoint has no collected data and no analyses are listed. Enrollment alone cannot establish that an endpoint was measured, that follow-up was complete, or that an outcome estimate is precise. Safety counts are reported separately and should not be treated as evidence about the primary endpoint.

Finally, statistical planning assumptions need to match the design and available evidence. The planning note describes a two-arm equal-allocation illustration, while the registry identifies a single-group study and reports no primary-outcome data. Any such illustration is not observed power and cannot stand in for a completed analysis. The record matters statistically because it makes visible where intended measurement, study design, and reported evidence diverge.

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 consequential trial-specific limitation is that the primary endpoint was not collected. The registry states that the study was terminated prematurely, but gives no reason for termination. It is not possible to evaluate SSEP recordings, quantify waveform changes, identify their causes, or assess their relationship to neurologic status from the posted record.

The outcome definition is also limited in detail. Although the registry names SSEP monitoring and describes recording in patients undergoing genitourinary surgery, it does not report the threshold for a significant waveform change, recording procedures, criteria for potential causes, or the neurologic assessment method. The timeframe is specified as the first 24 hours of the postoperative period, but no endpoint observations are available for that period.

The design is single group, with allocation listed as NA and masking as none. No like-for-like control comparison is reported. As a result, the design would not support a randomized comparison of outcomes between EPAD monitoring and an alternative, even if descriptive outcome data had been available. The record does not report whether waveform reviewers or neurologic assessors were blinded.

The registry does not report recruitment details, eligibility criteria beyond the described surgical population, follow-up completeness, the reason for termination, an analysis population, or a detailed statistical analysis plan. It lists enrollment of 21 and safety counts, but those entries do not resolve the absence of the primary endpoint. The record also does not state whether interim analyses occurred or how missing data would have been handled. These omissions limit reconstruction of the study’s conduct and prevent assessment of its intended endpoint analysis.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: EPAD Monitoring of Patients Undergoing Robotic Assisted Laparoscopic Genitourinary Surgery — NCT03319407.
• Registry record last updated 2023-04-12; status last verified 2023-04.
• Results first posted 2019-10-30.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT03319407 is a Mayo Clinic study titled EPAD Monitoring of Patients Undergoing Robotic Assisted Laparoscopic Genitourinary Surgery. It is listed as an interventional device study with a single-group model, no masking, and allocation recorded as NA. The listed intervention is the EPAD monitoring system, and the observation arm describes all participants as monitored with it.

The registry lists enrollment of 21, a start date of 2017-10-05, a primary completion date of 2018-12-30, and status as terminated. The primary outcome is SSEP monitoring in the first 24 hours of the postoperative period. The record states that the study was terminated prematurely and primary-outcome data were not collected. No analyses are listed.

Safety fields list 21 at risk for serious and other adverse events, 0 affected in each category, and 0 deaths. The record does not report the reason for termination, a detailed statistical plan, or an outcome analysis.