Recovery of Cardiovascular Function With Epidural Stimulation After Human Spinal Cord Injury: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Recovery of Cardiovascular Function With Epidural Stimulation After Human Spinal Cord Injury (NCT02037620), a na na study. The primary outcome is Mean Arterial Blood Pressure in Response to Epidural Stimulation.

2. Clinical Question

3. Trial Design

The registry identifies this as a completed, single-group study sponsored by the University of Louisville. Its listed start is 2014-07, and its primary completion date is 2019-09-20. The phase is recorded as NA. Allocation is also NA, and masking is listed as none. These design details do not describe a randomized comparison between epidural stimulation and a control intervention.

Enrollment was 5. The intervention group is named Epidural Stimulation. Its description states that participants received 80 sessions of epidural spinal cord stimulation for cardiovascular function, voluntary movement, and standing. The record also lists a 5-6-5 Specify electrode and a Restore Advance Pulse Generator. It does not provide further detail about the sequence of sessions, how stimulation settings were selected, or how the different session aims related to the primary blood-pressure outcome.

The primary outcome is mean arterial blood pressure in response to epidural stimulation, measured in mmHg over 20 months. The description specifies a noninvasive continuous finger-cuff measurement calibrated to brachial blood pressure, with mean arterial pressure calculated from systolic and diastolic pressure. The registry lists one outcome measure and no statistical analyses. It does not report a numerical primary-outcome result, a measure of uncertainty, or the analysis population.

Because there is one study group and no control comparison, the design can describe observations made during the intervention but cannot by itself separate intervention-associated change from other explanations. The registry record does not report additional design details that would establish a causal comparison.

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 Mean Arterial Blood Pressure in Response to Epidural Stimulation, measured over 20 months.

The primary endpoint is mean arterial blood pressure in response to epidural stimulation, expressed in mmHg, with a stated timeframe of 20 months. Mean arterial pressure is a continuous measure of pressure averaged across the cardiac cycle. The registry describes noninvasive continuous measurement from a finger cuff using a plethysmographic technique, calibrated to brachial blood pressure. It states that mean arterial pressure was calculated as one-third of systolic blood pressure plus two-third of diastolic blood pressure.

As a general statistical point, a continuous endpoint retains information about the measured value rather than reducing observations to categories such as above or below a threshold. Mean arterial pressure is relevant to the stated cardiovascular-function aim because it represents blood pressure as a single summary measure. The measurement approach and calibration are part of how the endpoint is defined; they do not, by themselves, establish that the measure changed during the study.

The registry record does not report a mean value, standard deviation, change from baseline, or other numerical result for this endpoint. It also does not describe the timing or number of outcome assessments within the 20-month timeframe. Consequently, the endpoint’s measurement definition is available, but the observed level, change, and precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a continuous primary outcome summarized as a mean, with standard deviation specified as the dispersion measure. It lists no statistical analyses and does not report numerical outcome summaries. The following explains the relevant statistical ideas in general terms; it does not imply that any particular analysis was conducted in this study.

What does a mean describe?

In general, a mean is a measure of the central level of a continuous outcome. For this study, the outcome is mean arterial blood pressure in mmHg. A mean can provide a compact description of observed blood-pressure measurements, but it does not show how widely individual observations vary. The registry’s stated dispersion measure is the standard deviation, which describes variability among observations around a mean. Neither the outcome mean nor its standard deviation is reported in the registry record.

What does a standard deviation tell the reader?

As a general explanation, a standard deviation describes the spread of observed values in the units of the outcome. A larger spread means observations are more dispersed around their mean; a smaller spread means they are more closely clustered. It is not the same as the uncertainty in an estimated mean. The uncertainty of an estimate also depends on the amount of information available and on the analysis. Since the registry record does not report the primary outcome’s standard deviation or an estimate of uncertainty, the variability and precision of the blood-pressure result cannot be evaluated from this record.

How should a confidence interval be understood?

In general, a confidence interval gives a range of values compatible with an estimate under the assumptions of the statistical method. A narrow interval indicates greater precision than a wide interval, while an interval that spans values on either side of a reference point may leave the direction or magnitude uncertain. A confidence interval is not reported for the primary outcome in the registry record. No interval can therefore be interpreted as evidence about the size or precision of a blood-pressure response.

Why does the study structure matter?

In general, a single-group study describes outcomes within one group, while a controlled comparison estimates differences between groups. Without a like-for-like control group, changes in a continuous measure cannot automatically be attributed to the intervention. Natural changes over time, measurement variation, and other influences may also contribute to what is observed. The registry identifies a single-group model and allocation as NA, and its record does not report a control group or a comparative analysis. This limits causal interpretation regardless of which statistical summary might be used.

What can planning calculations show?

The planning assumptions describe an illustration using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a stated fraction of the observed effect. In general, such calculations can illustrate how a hypothetical future comparison might be planned under specified assumptions. They are not observed power, and they do not add evidence about the intervention’s effect in this single-group study. The record does not report the primary-outcome estimate needed to assess the connection between an observed effect and those planning scenarios. Any sample-size illustration should therefore be read as planning information, not as a result from the trial.

What do the listed safety counts represent?

In general, adverse-event counts describe reported events or affected participants according to the registry’s categories; they are not an efficacy analysis. Interpretation depends on the definitions, observation period, and completeness of reporting. The registry lists serious and other adverse events for the Epidural Stimulation group, as well as deaths and selected serious-event terms. Those entries do not create a control comparison. The record does not report further details needed to assess event timing, attribution, or how recurrent events were handled.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Epidural Stimulation")
n   <- c(4)
m   <- c(112.5)
sp  <- c(8.25)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Epidural Stimulation  4  112.500  8.250  99.372  125.628

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and no statistical analyses. Mean arterial blood pressure in response to epidural stimulation is identified as the primary endpoint, but the record does not report a numerical result or an inferential analysis for it. A multiplicity-adjustment plan, such as a plan for handling several statistical tests, is not reported in the registry record. With no analysis results listed, there is no reported set of p-values or confidence intervals to assess for multiplicity.

Missing-data methods are not reported in the registry record. It does not state whether outcome measurements were missing, how missing measurements were handled, or whether any sensitivity analysis was conducted. The analysis population is also not reported: the registry does not describe which participants or observations were included in an outcome analysis. Enrollment was 5, but enrollment alone does not establish how many contributed measurements at each assessment or to a particular analysis.

As a general statistical matter, missing outcome data can affect both the estimate and its precision, especially when the likelihood of missingness is related to participants’ outcomes or circumstances. Different analysis populations or assumptions about missing observations can also lead to different interpretations. Those are general concerns, not claims that missingness occurred in this study. The registry record does not report enough information to determine whether these issues arose or how they were addressed.

The registry’s lack of a reported analysis should not be interpreted as evidence that no analysis occurred outside the record; it means an analysis is not reported in the registry record. The available entry therefore does not support an assessment of multiplicity control, missing-data handling, or the population used for statistical inference.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: incision dehiscence (60.0%), urinary tract infection (20.0%).

For the Epidural Stimulation group, the registry lists serious adverse events affecting 3 of 5 participants and other adverse events affecting 1 of 5 participants. Deaths are listed as 0. The top serious-event terms are Incision Dehiscence at 60.0% and Urinary Tract Infection at 20.0%. These are the registry’s reported figures and should be read as safety descriptions for this group, not as evidence of a comparative treatment effect.

Serious and other adverse events are separate categories in the record. The entries do not explain whether a participant could appear in both categories, whether any participant had more than one event, or how the event percentages were calculated. The registry record also does not report event timing, duration, severity details beyond the serious-event classification, or an assessment of whether events were attributed to stimulation or a device.

Because the study is single-group and there is no like-for-like control comparison, these counts do not show how event occurrence compares with another group. They also do not establish that the intervention caused a listed event. The figures should be interpreted as reported observations, with the limited group size and absent comparative context in mind. Further event-level detail is not reported in the registry record.

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

The registry record establishes that the study was completed, enrolled 5, and evaluated epidural stimulation in a single group. It identifies mean arterial blood pressure in response to stimulation as the primary outcome, defines the measurement in mmHg, and gives a timeframe of 20 months. It also records the intervention devices and session aims. These details describe the study question and its conduct as recorded; they are not a numerical demonstration of an outcome.

The record does not report the primary endpoint’s mean, standard deviation, change, confidence interval, or statistical test. It therefore does not show the magnitude or direction of any observed blood-pressure response, or how precisely that response was estimated. No statistical analyses are listed. Without a numerical outcome estimate, readers cannot assess whether the observed data are consistent with a small or large response, or with no change.

The single-group design also constrains what could be concluded even if a within-group change were reported. In general, without a control group, a change over time cannot be separated confidently from other time-related or measurement influences. The registry record does not report a randomized comparison, a control group, or an adjusted comparison that could support a treatment-versus-control interpretation.

The safety entries report serious adverse events affecting 3 of 5 participants, other adverse events affecting 1 of 5 participants, and 0 deaths. These are useful descriptions of events recorded for the intervention group, but they do not establish comparative safety or causation. The record does not report event-level details that would resolve those questions.

Thus, the record supports a description of the study design, endpoint definition, and listed safety experience. It does not support a conclusion about the size, precision, or causal meaning of a primary blood-pressure result, because that result and its analysis are not reported in the registry record.

14. Why This Trial Matters Statistically

This study is statistically notable because its stated primary question concerns a continuous cardiovascular measure, yet the registry record does not report a numerical result or an analysis. That distinction matters: defining an outcome and collecting it are not the same as presenting an estimate that readers can evaluate. Without the mean, variability, or uncertainty, the primary endpoint cannot be interpreted quantitatively from the registry record.

The single-group structure is also central to statistical interpretation. A one-group study can document measurements made during an intervention, but it does not provide the direct concurrent comparison needed to distinguish intervention-associated change from other influences. This limitation is about the design, not simply the choice of a statistical test. A more elaborate analysis cannot create a control group that the record does not describe.

The enrollment of 5 also places the safety counts in a small-study context. As a general principle, estimates based on limited observations can be imprecise, and event percentages can be sensitive to a small number of observations. The registry’s adverse-event counts should therefore be read as descriptions of the recorded group, not as stable estimates of risk or comparisons with another treatment.

Finally, planning illustrations and trial results answer different questions. The record’s planning assumptions refer to hypothetical future comparisons and an observed effect, but the primary estimate is not reported in the registry record. Such illustrations do not substitute for the missing efficacy estimate and should not be read as evidence of observed power or proof of an intervention effect. The statistical importance of this record lies in recognizing what the design and reporting can establish, and where the information needed for stronger inference is absent.

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 registry record reports a single-group model and no like-for-like control comparison. This means the study design, as recorded, does not support a direct estimate of the difference between epidural stimulation and a control condition. Any claim that a change was caused by stimulation would require evidence beyond a description of observations within the intervention group.

Enrollment was 5, and the record does not report participant characteristics, eligibility criteria, baseline blood pressure, or injury details beyond the condition of spinal cord injury. That limits assessment of whom the findings might describe and whether participants had similar starting characteristics. It also does not report the number of outcome observations at different time points.

The primary outcome is defined and its measurement method is described, but a numerical result, standard deviation, confidence interval, and analysis are not reported in the registry record. The timing and frequency of blood-pressure assessments within the 20-month timeframe are not described. Missing-data handling, analysis populations, and the statistical plan are also not reported in the registry record.

For safety, the record provides group-level counts and selected serious-event terms but not event timing, participant-level detail, attribution, or the handling of recurrent events. With no comparator, the counts cannot establish relative risk. The registry lists the study as completed, but completion status does not fill the gaps in outcome reporting or establish that every planned measure was reported.

These limitations are specific to the information and design recorded. They do not show that an unreported procedure was or was not used; they identify what cannot be evaluated from the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Recovery of Cardiovascular Function With Epidural Stimulation After Human Spinal Cord Injury — NCT02037620.
• Registry record last updated 2022-03-28; status last verified 2022-03.
• Results first posted 2022-03-28.
• 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 registry describes a completed, single-group study sponsored by the University of Louisville, with enrollment of 5 and no masking. The listed intervention is epidural stimulation, with a 5-6-5 Specify electrode and a Restore Advance Pulse Generator. The group description specifies 80 sessions addressing cardiovascular function, voluntary movement, and standing.

The primary outcome is mean arterial blood pressure in response to epidural stimulation, measured in mmHg over 20 months. The registry record gives a measurement description but no numerical primary-outcome result or statistical analysis. It lists serious adverse events affecting 3 of 5 participants, other adverse events affecting 1 of 5 participants, and 0 deaths. The single-group design and absent outcome analysis limit conclusions about efficacy, precision, and comparative safety.