CorPath® GRX Neuro Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for CorPath® GRX Neuro Study (NCT04236856), a na na study. The primary outcome is Number of Participants With Procedural Technical Success..

2. Clinical Question

This is a descriptive, single-group question rather than a randomized comparison. It can characterize the recorded performance of the robotic procedure, but the design does not directly estimate how outcomes would differ for comparable participants assigned to manual procedures. The historical performance criteria offer a reference point in the stated study objective, but their details and the primary endpoint result are not reported in the registry record. Enrollment was 120; that figure alone does not establish how many participants were treated, assessed for the endpoint or included in an analysis.

3. Trial Design

The CorPath® GRX Neuro Study is a completed, single-group device study sponsored by Siemens Healthineers Endovascular Robotics, Inc. The registry lists enrollment of 120, a start date of 2020-08-21 and a primary completion date of 2022-04-23. Its phase is listed as NA. The intervention was a robotic endovascular procedure using the CorPath GRX System for cerebral aneurysm embolization.

The stated primary objective was to evaluate the effectiveness and safety of robotic-assisted endovascular embolization compared with objective performance criteria for traditional manual operation based on scientific literature. This comparison is not a randomized, concurrent comparison: allocation is listed as NA, masking as NONE and the model as SINGLE GROUP. There is no like-for-like manual-treatment arm in the record. The posted objective therefore describes a comparison with criteria, not a direct estimate of the difference between two groups enrolled and followed within the study.

The primary endpoint was procedural technical success, assessed over the procedure from start to end. Secondary outcomes listed in the record include robotic navigation to the target aneurysm, deployment of the therapeutic device, procedure and fluoroscopy time, radiation exposure, contrast volume, adverse events and thromboembolic events. The registry lists 13 outcome measures, but the record does not post statistical analyses for them.

Further details about recruitment, eligibility, follow-up, outcome adjudication, the performance criteria and the analysis populations are not reported in the registry record. The record marks the study completed, but that status does not itself provide evidence about the endpoint result. The accompanying tables and plots can be read as displays of posted data; they do not replace the absent primary outcome analysis.

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

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 Number of Participants With Procedural Technical Success., measured over Measured from the start of the procedure to the end of the procedure..

The primary endpoint counts participants with procedural technical success. Success is defined as completing the robotic-assisted endovascular procedure without an unplanned conversion to manual operation for guidewire or microcatheter navigation, deployment of embolization coils or intracranial stents, or an inability to navigate vessel anatomy. The timeframe runs from the start of the procedure to its end.

This endpoint captures whether the intended procedure was completed using the robotic approach for the specified tasks. It is a participant-level count, rather than a measure of time, radiation exposure or a continuous change in clinical status. Its definition also makes clear that conversion for the listed tasks, or inability to navigate vessel anatomy, prevents a participant from meeting the endpoint.

In general, a procedural success endpoint can summarize technical completion in a way that is straightforward to interpret. Its meaning depends on the operational definition, how conversions and navigation difficulties are recorded, and how many participants are assessed. Those details determine what the count represents and how precisely it can be estimated.

The registry record gives the endpoint definition but does not report the observed number of successful participants, the number assessed for this outcome, an estimated success proportion or a confidence interval. Enrollment of 120 should not be treated as the endpoint denominator without confirmation of the analyzed population. As a result, the posted record does not allow readers to quantify the primary endpoint or assess its precision.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The record identifies a participant count as the primary endpoint, but it does not report an analysis method, an endpoint estimate or a confidence interval. The discussion below separates the information in the registry record from general statistical context; it does not reconstruct an analysis that is absent from the posting.

What the endpoint count represents

The endpoint is a count of participants meeting a defined procedural success criterion. The definition focuses on completion of the robotic-assisted procedure without an unplanned manual conversion for the listed navigation or device-deployment tasks, and without inability to navigate vessel anatomy. The timeframe is the procedure itself. To interpret a count, a reader would ordinarily also need to know who was eligible for endpoint assessment, how many were assessed, and how missing or unevaluable procedures were handled. These details are not reported in the registry record.

In general, when a binary outcome is summarized as a count, the count can be presented alongside the number assessed and, where appropriate, a proportion. A proportion makes the scale of the outcome easier to compare across populations of different sizes, while the count retains the actual number of participants represented. Neither can be reliably interpreted without a clearly defined denominator. Here, enrollment is 120, while the posted adverse-event risk sets are 117; neither figure should be assumed to be the primary endpoint denominator.

Uncertainty and precision

In general, a confidence interval describes uncertainty around an estimated quantity under a specified statistical model. It is not a guarantee that the true value lies in a particular interval, nor does it remove concerns about study design or measurement. For a binary outcome, the interval depends on the observed count, denominator and method used. Since the registry record reports none of the primary endpoint estimate, denominator or interval, readers cannot assess its statistical precision.

A point estimate alone, if it were available, would not describe how much uncertainty surrounds the result. Conversely, a narrow interval would not resolve limitations such as absence of a concurrent comparison group, nonrepresentative recruitment or ambiguity in outcome assessment. Statistical precision and causal interpretation are distinct issues. The record does not provide enough information to evaluate the first for the primary outcome, and the single-group design limits the second.

Single-group evaluation and historical criteria

The stated objective refers to objective performance criteria for traditional manual operation based on scientific literature. In general, external criteria can provide a benchmark, but interpretation depends on how the benchmark was defined, whether it is comparable to the study population and procedures, and whether the comparison method was specified in advance. The criteria, literature details and statistical comparison are not reported in the registry record. No result against a benchmark can therefore be described from this posting.

A concurrent comparison group can help distinguish a treatment-group outcome from differences in participant characteristics, care settings or measurement practices. This study has no concurrent manual-procedure group in the registry record. That does not make its descriptive observations meaningless, but it means a direct between-group treatment effect is not available from this design as posted.

Planning illustrations are not results

The page includes a sample-size section with planning illustrations based on the observed effect, under assumptions that include a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation. The stated effect to detect is a fraction of the observed effect. These are planning illustrations, not the study’s own design justification and not observed power. The registry record does not report a sample-size justification, and the numeric planning outputs are not stated.

In general, sample-size planning asks how many participants might be needed to detect a specified effect under chosen assumptions. It does not show that an effect exists, nor does a planned sample size guarantee a conclusive result. Observed power is not a substitute for reporting an estimate with its uncertainty. The study itself is single-group; the two-arm assumptions in the planning description should not be mistaken for the clinical trial’s allocation design.

Over-dispersion and model choice

In general, over-dispersion means that observed variability exceeds what a chosen model expects. It matters when a model’s standard errors and confidence intervals rely on an assumption about the relationship between the mean and variance. A model that fails to account for extra variability can produce uncertainty estimates that are too small. This is general statistical context; the registry record does not report an over-dispersion assessment or a model for the primary endpoint.

For a simple participant-level success count, the analysis would need to respect the binary nature of the outcome and clearly identify the assessed population. More complex models might be relevant for clustered or repeated observations, but no such analysis is described in the registry record. It would be inappropriate to infer the model, adjustment variables, significance tests or interval method from the endpoint description alone.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Robotic Endovascular Procedure")
n      <- c(117)
events <- c(110)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Robotic Endovascular Procedure  117  110  94.0  88.1  97.6  88.2  97.1  88.2  97.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 13 outcome measures, including the primary technical success endpoint and secondary measures covering navigation, device deployment, procedure duration, radiation, contrast, adverse events and thromboembolic events. It lists 0 analyses. The record does not present a statistical analysis plan, outcome-level test results or an account of how multiple outcomes were handled. The presence of several listed outcomes does not show that each was formally tested, and the absence of posted analyses does not establish that no analyses were performed elsewhere.

In general, testing many outcomes can increase the chance of obtaining at least one apparently unusual result by chance. A prespecified hierarchy, adjustment procedure or clear separation of primary and exploratory outcomes can help readers understand the intended interpretation. Whether any such approach was planned or used is not reported in the registry record. The primary objective and named primary endpoint are stated, but this alone does not describe multiplicity handling for secondary outcomes.

The record does not report missing-data counts, reasons for missingness, imputation methods, or sensitivity analyses. It also does not specify the analysis population for the primary endpoint. These omissions matter because the number enrolled is not necessarily the number treated, assessed or included in an endpoint analysis. For safety, the posted risk sets are 117; how those participants relate to enrollment and the analysis populations is not explained.

In general, missing-data methods should be described alongside the population analyzed and the assumptions they require. Without those details, readers cannot judge whether the reported counts represent all relevant participants or how incomplete observations might affect estimates. Here, the primary endpoint estimate itself is not reported, so no assessment of missing-data impact or multiplicity-adjusted inference is possible from the registry record.

12. 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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: stroke (14.5%), vascular access site complication (3.4%), transient ischemic attack (2.6%), intraprocedural aneurysm rupture (1.7%), aphasia (0.9%).

The registry lists the Robotic Endovascular Procedure group with 117 participants at risk for serious adverse events and 40 affected. For other adverse events, it lists 117 at risk and 21 affected. It also reports 1 death. These are the posted group figures; the registry record does not explain how the risk sets relate to enrollment or to the population assessed for the primary endpoint.

Among the listed serious adverse-event terms, the record reports Stroke at 14.5%, Vascular Access Site Complication at 3.4%, Transient Ischemic Attack at 2.6%, Intraprocedural Aneurysm Rupture at 1.7%, Aphasia at 0.9% and Confusion Episode at 0.9%. These figures describe terms and percentages in the registry listing. The record does not state how the percentages were calculated or whether participants could contribute to more than one event category.

In general, safety counts and event terms are descriptive and should not be read as proof of causation. Without a concurrent comparison group and further detail about event definitions, follow-up and attribution, these figures do not estimate comparative risk or identify whether an event was caused by the device or procedure. The posted numbers should be interpreted as registry-reported safety observations, not as a complete causal analysis.

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

The record establishes what the study set out to evaluate: procedural technical success and safety during robotic-assisted endovascular embolization of cerebral aneurysms, with performance considered against objective criteria for traditional manual operation based on scientific literature. It also describes the operational definition of technical success and lists safety outcomes. These details clarify the question being asked.

However, the registry record does not report the primary endpoint result. There is no posted count of participants meeting the success definition, no primary endpoint denominator, no proportion and no confidence interval. Consequently, readers cannot determine from this record how often the procedure met the endpoint or how precisely that frequency was estimated. Enrollment of 120 is not a substitute for an outcome count or analyzed denominator.

The record also does not provide a concurrent manual-procedure group. Its design is single-group, and the criteria-based comparison is not accompanied by the criteria or a reported analysis. Thus, the posting does not establish a randomized comparison or quantify a difference between robotic and manual procedures. Any statement about comparative performance would go beyond what is reported.

The adverse-event data give a descriptive account for the named study group, including serious and other adverse-event figures and a death count. They do not, on their own, show that an event was caused by the intervention or establish comparative safety. Details on event attribution and analysis populations are not reported in the registry record.

In general, a registry entry documents selected study information and posted outcomes; it is not necessarily a full report of all methods or findings. Here, the study’s completed status should be distinguished from the availability of its results. The appropriate statistical reading is therefore limited: the design and endpoint can be described, and the safety figures can be quoted, but the primary effectiveness result and its precision cannot be evaluated from this record.

14. Why This Trial Matters Statistically

This study raises an important statistical issue for device evaluations: technical performance can be measured with an endpoint that is close to the procedure itself, but the endpoint’s interpretation depends on a transparent definition and complete reporting. Here, procedural technical success has a specific definition involving completion, conversion to manual operation for listed tasks and navigation of vessel anatomy. That definition helps identify what was intended to count as success.

The single-group design also makes the comparison question important. The study objective invokes performance criteria for traditional manual operation based on scientific literature, rather than a concurrent manual arm. In general, a historical benchmark may be useful, but readers need its source, population, definition and comparison method to judge whether it is a suitable reference. Those details and a result against the benchmark are not reported in the registry record.

Statistical reporting is as important as the endpoint definition. A primary count requires an analyzed denominator, and an estimate is more informative when accompanied by an uncertainty interval and a description of who was included. None of these primary outcome results is posted. The record’s status as completed does not resolve that reporting gap.

The safety figures illustrate another distinction: a registry can report event counts and terms without providing causal attribution or comparative risk estimates. Keeping descriptive counts separate from treatment-effect claims is essential, particularly when no like-for-like comparison group is listed.

For biostatisticians and clinical researchers, this record is a reminder to distinguish study objectives, design, planned measures and observed findings. The first three are described to some extent; the primary observed result and analysis are absent. That boundary is central to any statistically responsible interpretation of the posting.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The principal limitation for interpreting effectiveness is that the registry record does not report the primary technical-success count, its denominator, an estimated proportion or an uncertainty interval. Enrollment is listed as 120, but the number assessed for the endpoint is not stated. The posted record therefore cannot support a quantitative interpretation of the primary endpoint.

The single-group design has no concurrent manual-procedure arm. Although the stated objective refers to literature-based objective performance criteria, the criteria, their source and the comparison result are not reported in the registry record. This limits direct interpretation of performance relative to manual procedures and leaves uncertainty about comparability between the study population and the historical reference.

Further details needed to assess the endpoint are not reported, including eligibility criteria, the population analyzed, handling of missing or unevaluable procedures, and outcome assessment procedures. The registry lists 13 outcome measures and 0 analyses, but it does not describe the statistical methods used or how multiple outcomes were handled. These omissions preclude assessment of the primary analysis and the reliability of any unposted estimates.

For safety, the record gives risk sets and affected counts, but does not explain their relationship to enrollment or the primary analysis population. It also does not report event attribution, detailed follow-up or whether participants may appear in multiple serious-event categories. The listed percentages should therefore be read as registry-reported descriptors, not as comparative or causal estimates.

The record marks the study completed, but completion does not establish that all outcomes or analyses are available in the registry. These limitations are specific to the posted information and should not be taken as evidence about results that may exist outside the record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: CorPath® GRX Neuro Study — NCT04236856.
• Registry record last updated 2025-03-06; status last verified 2025-02.
• Results first posted 2025-03-06.
• 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.

19. Record Summary

The CorPath® GRX Neuro Study is a completed, single-group device study of robotic-assisted endovascular embolization procedures for cerebral aneurysms. Enrollment is listed as 120. The primary endpoint is the number of participants with procedural technical success, defined by completion without specified unplanned manual conversions or inability to navigate vessel anatomy.

The registry record does not report the primary endpoint result, its denominator, a confidence interval or statistical analyses. It lists 13 outcome measures and 0 analyses. The study objective refers to literature-based objective performance criteria for manual operation, but there is no concurrent manual arm and the criteria-based result is not reported.

For the Robotic Endovascular Procedure group, the record lists 117 at risk and 40 affected for serious adverse events, 117 at risk and 21 affected for other adverse events, and 1 death. These figures are descriptive and do not establish causation or comparative risk. Overall, the record describes the design and intended endpoint but does not provide enough primary outcome information to quantify technical success.