Two Devices for Reflex Voiding Following Spinal Cord Injury: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Two Devices for Reflex Voiding Following Spinal Cord Injury (NCT00662207), a na phase 1 study. The primary outcome is Number of Participants With a Change in Bladder Pressure.

2. Clinical Question

3. Trial Design

The registry identifies this as a Phase 1, completed, single-group study. Enrollment is listed as 3. Allocation is recorded as not applicable, and masking is listed as none. The record does not describe random assignment, a parallel control group, or a blinded assessment. It is not a randomized comparison, so results should not be interpreted as a contrast between assigned treatment arms.

The interventions are a vibrator, classified as a device, and an anal dilator, classified as a procedure. The single arm description names both: use of a vibrator on the participant’s bottom to assess whether it induces a bladder contraction, and use of an anal dilator to assess whether urethral relaxation occurs. The record does not report whether every participant received both interventions, the order of use, or whether one intervention was assessed separately from the other.

The study start is listed as 2008-10 and primary completion as 2009-10; status is completed. The record lists four outcome measures, but the primary outcome is the only one characterized in the available study details. Details about the other outcome measures are not reported in the registry record. No analyses are listed. The protocol, recruitment process, participant flow, and any prespecified analysis plan are not reported in the registry record.

This design can document observations made during the study, but without a separate comparison group it cannot establish whether any observed change is attributable to either intervention rather than other influences. In addition, the registry record does not post the primary outcome result, so it does not permit a numerical description of the observed pressure changes.

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.

Population: baseline anal pressure

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With a Change in Bladder Pressure, measured over 3 hour recording session.

The primary endpoint is the number of participants with a change in bladder pressure during a 3 hour recording session. The record says pressure was measured using a catheter in the bladder with a pressure transducer. It does not specify a threshold for what counted as a change, how changes were classified, or whether the count included any particular direction or magnitude of pressure change.

The endpoint is relevant to the stated purpose because the study description proposes evaluating methods intended to improve reflex urination. The arm description says the vibrator was assessed for inducing a bladder contraction, while the anal dilator was assessed for urethral relaxation. Pressure recorded in the bladder can describe a physiological response during observation. However, a count of participants with a pressure change is not, by itself, a measure of how completely the bladder emptied, whether urination was sustained, or whether urinary incontinence changed.

General statistical explanation: a binary participant-level endpoint reduces each participant’s observation to a category, such as whether a defined change occurred or did not occur. The count can be easy to interpret, but it leaves out details about the size, timing, and pattern of pressure changes unless those are reported separately. The registry record does not give the operational definition used to classify a change or the observed count, so the endpoint’s result and its precision cannot be assessed from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies the primary outcome as a participant count: the number of participants with a change in bladder pressure. It does not report an analysis of that endpoint. The record lists no analyses, and the outcome result, effect estimate, uncertainty interval, and p-value are not reported in the registry record. Accordingly, the posted information supports a description of the intended measurement and study structure, but not a reanalysis of the primary outcome.

What does a participant count represent?

General statistical explanation: a count for a binary outcome records how many participants meet a defined criterion. To interpret it, the criterion needs to be clear, and the reader needs both the count and the relevant denominator. A proportion can make a count easier to compare across groups, but it is meaningful only when the denominator and outcome definition are known. Here, the outcome is described as a change in bladder pressure, but the threshold or classification rule for a change is not reported in the registry record. The primary endpoint result is also not reported.

The count is a participant-level summary rather than a detailed description of a pressure trace. It does not convey the size or duration of a pressure change unless additional measures are reported. The record identifies a 3 hour recording session and a bladder pressure catheter with a pressure transducer, but does not describe how measurements were summarized into the participant-level outcome.

Why does the design affect statistical interpretation?

The study is listed as single group, with allocation not applicable and masking none. General statistical explanation: a single-group study can describe observations in its participants, but it does not provide a concurrent control group for estimating a between-group contrast. Without that contrast, observed changes cannot be separated from other factors using a randomized comparison. The record does not report a comparator condition, randomization, or a blinded assessment process.

The two named interventions are a vibrator and an anal dilator, and the arm description refers to both. The record does not specify how exposure to each was structured or whether outcomes were linked separately to each intervention. This means the available description does not establish an intervention-specific statistical contrast. No additional causal interpretation should be inferred from the intervention names or study purpose.

What do estimates and intervals usually add?

General statistical explanation: an effect estimate gives a numerical summary of the outcome under a defined comparison or measurement scheme. A confidence interval describes uncertainty around an estimate under the statistical model and assumptions used. With a small study, estimates can be especially sensitive to individual observations; intervals, if available, help communicate that imprecision. They do not correct for a missing control group, unclear endpoint definitions, or incomplete outcome reporting. Neither an estimate nor a confidence interval for the primary outcome is reported in the registry record.

A p-value, when used, summarizes how compatible observed data are with a specified null hypothesis under a chosen statistical model. It does not measure the size or clinical importance of an effect and does not substitute for an estimate with an uncertainty interval. The registry record does not report a p-value or a test for the primary outcome. The statistical methods or model used for outcome analysis are not reported in the registry record.

How should the planning assumptions be read?

The registry’s sample-size assumptions describe planning illustrations based on the observed effect, rather than the study’s own design. They specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. The record details do not include the resulting sample-size values. These assumptions do not change the recorded single-group design, and any sample-size figures in planning material should be read as hypothetical participants per arm for a specified power, not as observed power or as evidence about the study’s findings.

General statistical explanation: a sample-size calculation depends on assumptions about the target effect, variability or event frequency, significance level, allocation, and analysis. Changing those assumptions can change the planning result. A calculation based on an observed effect is particularly dependent on that effect estimate, and it cannot establish that a small completed study had adequate precision. The registry record does not report the protocol’s sample-size justification, the effect used for its own design, or an analysis plan.

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("Experimental Group")
n      <- c(3)
events <- c(0)
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  Experimental Group  3  0  0.0  0.0  70.8  0.0  56.1  0.6  60.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures and names the number of participants with a change in bladder pressure as the primary outcome. The details and results for the other measures are not reported in the registry record. No analyses are listed. The registry record does not report whether multiple outcomes were tested, whether a multiplicity adjustment was planned, or how any outcome hierarchy was handled.

General statistical explanation: when several outcomes or hypotheses are examined, the chance of a seemingly notable result can depend on how many analyses were performed and how they were selected. Prespecifying a primary outcome and an analysis approach can help readers distinguish confirmatory questions from exploratory ones. The record identifies a primary outcome, but does not provide the analysis plan needed to determine how multiplicity was addressed.

Missing-data methods and the extent of missing outcome data are not reported in the registry record. The registry does not state whether all enrolled participants completed the recording session or had an evaluable primary outcome. The primary outcome population is not described. No analysis population, such as a defined set of enrolled or evaluable participants, is reported in the registry record.

These omissions limit assessment of how participants were included in any outcome summary and whether missing observations could affect the interpretation. Since no primary endpoint result is posted, the record does not permit an assessment of the impact of missing data or multiplicity on a numerical finding.

12. Safety Results

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

Other (non-serious) adverse events

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

The adverse-event listing identifies an experimental group with 3 participants at risk for serious events and 0 participants affected. It also lists 3 participants at risk for other adverse events and 0 affected. No serious adverse-event terms are listed. These figures describe the registry’s recorded counts; they should not be read as proof that no adverse events of any kind occurred beyond the categories and reporting represented in the record.

The deaths value is not reported in the registry record. A missing death count should not be interpreted as a count of zero. The record does not provide further detail about the event collection period, event definitions, severity grading, or whether the listed categories include all events observed during the study. It also does not give participant-level safety information.

General statistical explanation: when the number of participants is small, a zero count in a category does not establish that the underlying risk is zero. It means only that no affected participants are recorded in that category for the listed group. The safety counts should be read alongside the limited enrollment and the registry’s incomplete detail, without drawing broader conclusions about safety.

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

The record establishes that a completed Phase 1 study of a vibrator and an anal dilator was registered as a single-group evaluation in people with spinal cord injury. It identifies a primary endpoint based on whether participants had a change in bladder pressure during a 3 hour recording session. The stated measurement used a pressure catheter in the bladder and a pressure transducer. Enrollment is listed as 3.

The record does not report the primary endpoint result. It therefore does not show how many participants had a pressure change, how large any change was, or how precisely an outcome was estimated. It also does not report a result for bladder emptying, sustained urination, or urinary incontinence. The absence of these posted findings cannot be treated as evidence that the interventions did or did not produce a particular outcome.

The study has no separate comparator identified in the registry record. Its single-group structure means the record does not provide a randomized contrast for estimating differences attributable to the interventions. The description names both interventions but does not report how their use was separated or how an outcome would be attributed to one rather than the other.

General statistical explanation: an endpoint measures a defined feature of participants’ observations. It is important not to extend a result beyond that feature. A measured pressure change, if reported, would not automatically answer broader questions about emptying or other clinical outcomes. In this case, even the pressure-change count is not reported, so no effect magnitude or precision can be interpreted.

The safety listing records 0 participants affected by serious adverse events among 3 at risk and 0 affected by other adverse events among 3 at risk; the death count is not reported. These entries are limited registry counts, not a comprehensive characterization of safety. Taken together, the record describes the study’s purpose, design, and selected measurements, but does not provide results sufficient to determine the observed primary outcome.

14. Why This Trial Matters Statistically

This study is statistically notable for the gap between a clearly stated physiological question and the limited outcome information available in the registry record. The aim describes assessing methods intended to improve reflex urination, while the named primary endpoint is a count of participants with a bladder-pressure change during a 3 hour session. Those are related concepts, but the endpoint does not itself report the degree of bladder emptying or a broader urinary outcome.

The single-group design also defines what kinds of conclusions the study could support. It can be framed as an evaluation of observations in a small enrolled group, but the registry does not identify a control condition or randomized contrast. The record names two interventions, yet does not explain how each was evaluated independently. These features make it important to distinguish a measurement taken during an intervention from a comparative estimate of intervention effect.

For biostatisticians and clinical researchers, the record illustrates why endpoint definitions, denominators, analysis plans, and results all matter. A count is interpretable only when the outcome rule and result are available. An analysis plan helps clarify how several outcomes are handled, while reporting the number analyzed and the uncertainty around an estimate supports transparent interpretation. These details are not reported in the registry record.

The record lists four outcome measures but no analyses and does not post the primary result. That limits evaluation of outcome reporting, missing data, and statistical precision. The planning assumptions refer to hypothetical two-arm calculations, while the study itself is registered as single group; planning illustrations should not be mistaken for evidence about observed performance or for a description of the study’s actual analysis.

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 central limitation of the registry record is that it does not report the primary endpoint result. No participant count for bladder-pressure change, effect estimate, confidence interval, or p-value is available in the record. The primary outcome’s rule for defining a change is also not reported, making it difficult to assess exactly what was counted.

Enrollment is listed as 3, and the design is single group with no separate comparator identified. The record does not describe randomization or masking. It does not state how participants were selected, provide participant characteristics, or define the population included in the primary endpoint analysis. The record’s arm description refers to both the vibrator and anal dilator, but intervention order, exposure details, and intervention-specific results are not reported.

The registry lists four outcome measures, but details of the other measures and their results are not reported in the registry record. No analyses are listed. The statistical analysis plan, handling of multiplicity, missing-data methods, and number of participants with evaluable outcome data are not reported. The trial’s sample-size justification is not reported; the separate planning assumptions do not describe the study’s own design.

The safety listing provides counts for serious and other adverse events, but the event collection period, definitions, and broader safety methods are not reported. The death count is not reported in the registry record. These limitations restrict interpretation of both the outcome and safety entries and prevent a full assessment of precision or completeness.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Two Devices for Reflex Voiding Following Spinal Cord Injury — NCT00662207.
• Registry record last updated 2014-11-05; status last verified 2014-11.
• Results first posted 2014-11-05.
• 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

NCT00662207 is a completed Phase 1, single-group study titled “Two Devices for Reflex Voiding Following Spinal Cord Injury.” The registry lists enrollment of 3, no masking, and allocation as not applicable. The interventions are a vibrator and an anal dilator.

The primary endpoint is the number of participants with a change in bladder pressure during a 3 hour recording session, measured with a bladder pressure catheter and pressure transducer. The record lists four outcome measures and no analyses. The primary endpoint result and details of the statistical analysis plan are not reported in the registry record.

The adverse-event listing records 0 serious events among 3 participants at risk and 0 other adverse events among 3 at risk. The death count is not reported in the registry record. The single-group design does not provide a like-for-like control comparison.