Clinical Feasibility Study, Implantable Tibial Nerve Stimulator (ITNS): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Feasibility Study, Implantable Tibial Nerve Stimulator (ITNS) (NCT04115228), a na na study. The primary outcome is Percent Change of Urinary Incontinence Frequency From Baseline to 13 Weeks.

2. Clinical Question

The study objectives were to report feasibility data for device safety and effectiveness. Its single-group design is suited to describing what occurred among enrolled participants, but it does not establish how outcomes would have differed under an alternative treatment or without implantation. The record describes enrollment of 10 participants and follow-up for 26 weeks. The primary endpoint was assessed at 13 weeks; the additional outcomes included a threshold measure, change in an Overactive Bladder Questionnaire Short-form symptom-bother score, and a Global Response Assessment at 13 weeks. Results for those outcomes are not reported in the registry record.

3. Trial Design

This was a completed clinical feasibility study of an implantable tibial nerve stimulator for overactive bladder. The registry lists 10 participants enrolled, a single-group longitudinal design, one study site in the United States, and no masking. Allocation and phase are each recorded as NA. The intervention was implantation and neuromodulation therapy using the Nine Continents Medical device model 9C-680 with programmer model 9C-580.

The study description states that participants who provided informed consent, met all inclusion criteria, and met no exclusion criterion would have a device implanted and be followed closely for 26 weeks. It describes an intended study duration of one year, comprising six months for enrollment and implantation of 10 participants and 26 weeks of follow-up. The record lists a start date of 2019-10-09, a primary completion date of 2021-01-31, and a status of COMPLETED.

A single-group design has no concurrent control arm. Outcomes can therefore describe the enrolled group over the stated follow-up, but changes from baseline cannot by themselves distinguish an intervention-associated change from other explanations, such as natural variation, changes in behavior, or measurement effects. Those are general limitations of uncontrolled before-and-after comparisons, not findings about what occurred in this study.

The registry record does not report a statistical analysis plan, a sample-size justification, interim analyses, or further details of the analysis populations. Completion status indicates that the study is listed as completed; it does not supply the missing endpoint results or establish that every planned analysis was reported.

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: Subjects who met the inclusion criterion for incontinence

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 Percent Change of Urinary Incontinence Frequency From Baseline to 13 Weeks, measured over Baseline to 13 weeks.

The primary endpoint is the percent change in urinary incontinence frequency from baseline to 13 weeks. Frequency is based on the average number of voids with leakage per 24 hours, calculated from the first 72 hours of the baseline diary and the first 72 hours of the 13-week diary. For each analyzed participant, the registry defines percent change as 100 * (x1 - x0) / x0, where x0 is the baseline average and x1 is the 13-week average. The endpoint is summarized as a mean with standard deviation.

Using a change relative to baseline expresses the follow-up frequency in relation to each participant’s starting frequency. Under the stated formula, a negative value corresponds to a lower follow-up frequency than baseline, while a positive value corresponds to a higher frequency. The percentage-change scale can be easier to interpret across participants with different baseline frequencies, although it depends on the baseline value and does not replace inspection of the underlying diary counts.

The outcome was selected to quantify change in a symptom relevant to the stated study objective. The record specifies the time window, diary measure, calculation, and population criterion, but does not report the group mean, standard deviation, analyzed sample size, or an uncertainty interval for this endpoint. Consequently, the size and precision of the primary endpoint estimate cannot be evaluated from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is a continuous measure: each analyzed participant has a percent-change value, and the registry specifies a mean and standard deviation as its summary. A mean describes the arithmetic average of participant-level values. The standard deviation describes how dispersed those individual values are around the mean. It is not a measure of uncertainty in the mean itself; a confidence interval is commonly used to express uncertainty about an estimated mean. No confidence interval for the primary endpoint is reported in the registry record.

What does percent change express?

The endpoint compares the diary-based frequency at 13 weeks with the baseline diary-based frequency. The registry formula divides the change by the baseline frequency and expresses the result as a percentage. This makes the change relative to each participant’s own baseline rather than simply a difference in leakage-associated voids per day. As a general statistical consideration, relative change may be sensitive to the baseline value, particularly when baseline values vary across participants. The record defines the measure but does not report the baseline distribution or the observed endpoint values, so those features cannot be evaluated.

The endpoint uses the first 72 hours of each diary period to estimate average daily frequency. Diary-based measurements can capture repeated observations over a short window, but they remain subject to ordinary measurement variability and participant recording. This is a general consideration for diary outcomes, not evidence of a particular recording problem in this study. The registry record does not report diary completion rates or how incomplete diaries were handled.

What does the single-group design allow?

In a longitudinal single-group study, measurements are collected in the same group over time. A baseline-to-follow-up summary describes the observed within-group change. Without a concurrent control group, that change cannot separate effects associated with the device from other influences that also change over time. Examples in general include natural fluctuation in symptoms, regression toward a participant’s usual level after an unusually high or low baseline, and changes in measurement or behavior. These are possible interpretive considerations, not claims that any one of them affected this study.

Random allocation is not applicable in the registry description, and masking is listed as none. The record therefore does not describe a blinded randomized comparison. Knowledge of receiving an implant or of study participation could, in general, influence reporting or assessment of subjective outcomes. The record does not report procedures intended to reduce such influences, so no further detail should be inferred.

How should uncertainty and sample-size planning be read?

Uncertainty intervals, when reported, show a range of values compatible with the data under the assumptions of the statistical model. A wider interval indicates less precise estimation than a narrower interval. Statistical significance and clinical importance are distinct ideas: a p-value addresses compatibility with a specified null model, whereas clinical importance requires context about the outcome and a meaningful difference. Neither a p-value nor a confidence interval for the primary endpoint is reported in the registry record.

The registry description of planning illustrations specifies 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 stated fraction of the observed effect. These assumptions describe a planning exercise, not the design of this single-group study. The record does not report the trial’s own sample-size justification, and the planning assumptions do not turn the enrollment of 10 into an observed-power calculation. Sample-size illustrations are prospective planning tools; they do not determine whether a study’s result is reliable after data have been collected. No particular planning count or target can be inferred from the information reported for the primary endpoint.

Why can variation matter?

The mean and standard deviation are useful summaries when a continuous outcome is reasonably represented by its average and spread. If participant-level changes are highly skewed or include extreme values, the mean can be strongly influenced by a few observations. Small samples also make distributional features difficult to assess. These are general statistical considerations. The record does not provide participant-level values, a distribution plot, or a stated diagnostic assessment, so it is not possible to judge the shape of the endpoint data or whether a particular model was appropriate.

Over-dispersion is a general concern for count outcomes when observed variability exceeds what a simple count model assumes. It can lead to uncertainty estimates that are too small if the model fails to account for the extra variability. The primary outcome in this record is analyzed as percent change, not as a posted count-model result, and no count-model specification is reported. This concept therefore explains a possible issue for count data generally; it does not describe an analysis documented for this study.

What analysis details remain unavailable?

The registry record does not report the exact number analyzed for the primary endpoint, how missing diary data were treated, whether any adjustment was made, which inferential test was used, or whether the analysis followed a prespecified statistical plan. The primary endpoint’s population is defined as subjects who met the inclusion criterion for incontinence, but the record does not provide further analysis-population rules. Without those details and the outcome estimate, readers cannot reproduce the primary analysis or assess sensitivity to alternative assumptions.

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("Study Device")
n   <- c(7)
m   <- c(-89)
sp  <- c(14)
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  Study Device  7  -89.000  14.000  -101.948  -76.052

11. Multiplicity, Missing Data and Analysis Populations

The registry lists seven outcome measures, including the primary endpoint and secondary outcomes such as threshold at 13 weeks, change in the Overactive Bladder Questionnaire Short-form symptom-bother subscale from baseline to 13 weeks, and a Global Response Assessment at 13 weeks. It does not report a multiplicity procedure, such as an adjustment to account for testing several outcomes, or a hierarchy specifying which outcomes would be tested first. The registry record therefore does not establish how any family of statistical tests was handled. This matters generally because conducting multiple tests can increase the chance of at least one apparently unusual result under a null model.

The primary endpoint description defines its measure and population criterion, but the registry record does not report the number included in the analysis or how missing observations were handled. It does not say whether participants with incomplete diaries were excluded, whether any values were imputed, or whether another method was used. Those details should not be guessed. Missing-data methods can affect estimates when the availability of an outcome is related to participants’ outcomes or characteristics; the direction and size of any such effect depend on the circumstances.

The record also does not describe an intention-to-treat, per-protocol, or other named analysis population. The primary outcome population is stated to include subjects who met the inclusion criterion for incontinence, but no further rules or analyzed count are reported. The number enrolled is 10, which should not automatically be taken as the number contributing data to every outcome.

No interim analyses or statistical analysis plan are reported in the registry record. The record lists no analysis entries. This does not establish what work may have been conducted outside the registry; it means that analysis details, missing-data handling, and multiplicity decisions are not available in the registry information.

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 non-serious adverse event terms

For the Study Device group, the registry lists 10 participants at risk for serious adverse events and zero affected. It lists 10 at risk for other adverse events and 8 affected. Deaths are listed as zero. These are participant counts in the reported categories, not rates calculated. The record does not identify the types of other adverse events, their timing, or their severity beyond the distinction between serious and other adverse events.

The denominator matters: the counts describe a group of 10 participants. In a group this small, a count of zero serious adverse events does not precisely establish the frequency of uncommon harms in a broader population. It means that none were reported among the listed participants during the registry’s reported observation. The record does not supply event-level descriptions or a comparator group, so it is not possible to assess relative safety or attribute an event pattern to the device by comparison.

The registry lists no top serious adverse-event terms. That does not provide detail about the eight participants affected by other adverse events. Safety counts should be read as descriptive registry information, alongside the limited group size and lack of a control arm.

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

The registry record establishes that a single-group feasibility study of the implantable tibial nerve stimulator was completed, with 10 participants enrolled. It defines a primary endpoint based on percent change in urinary incontinence frequency from baseline to 13 weeks and reports selected safety counts. Those details describe the study’s scope and the information available for review.

The record does not report the primary endpoint result. It therefore does not show whether the mean percent change was positive, negative, or near zero, and it does not provide a measure of precision. There is no reported estimate on which to base a conclusion about the size of symptom change in the enrolled group. Results for the listed secondary outcomes are also not reported in the registry record.

Even if a within-group change were available, this design would not show what would have happened to comparable participants without the device or under another treatment. A single-arm before-and-after result can describe change over time, but it cannot isolate a comparative effect. The absence of random allocation and a control group is therefore central to interpretation, not a minor technical detail.

The safety information reports zero serious adverse events and zero deaths among 10 participants, while 8 of 10 were affected by other adverse events. These descriptive counts do not establish that serious events are impossible or quantify comparative safety. The record lacks event details and a control group, and enrollment was limited.

Accordingly, the posted record can be read as a description of a completed feasibility study’s design and reported safety counts. It does not provide enough outcome information to judge the primary endpoint’s observed change or precision, and it cannot establish a treatment effect. These limits do not negate the study’s descriptive role; they specify what conclusions the available record can support.

14. Why This Trial Matters Statistically

This study is statistically useful as an example of how feasibility research differs from a comparative efficacy trial. Its stated objective was to report feasibility data for safety and effectiveness, and it used a single-group longitudinal design with 10 enrolled participants. Such a design can organize early observations around a defined intervention, a symptom-focused endpoint, and a follow-up schedule. It does not, by itself, provide a controlled estimate of what would have happened in the absence of the intervention.

The primary endpoint is explicitly defined: it uses diary-derived urinary incontinence frequency at baseline and 13 weeks, calculates percent change for each analyzed participant, and summarizes the measure with a mean and standard deviation. Clear definitions are important because they let readers understand what the intended outcome represents. Yet a defined endpoint is not the same as a reported result. The registry record does not include the primary endpoint estimate or its uncertainty, so a reader cannot assess the observed magnitude or precision.

The record also illustrates why denominators and outcome categories matter in safety reporting. It distinguishes serious adverse events from other adverse events and reports the number of participants at risk and affected. Those counts are interpretable as descriptive observations in the enrolled group, but their reach is constrained by the small sample and absence of a comparator.

Finally, the registry lists multiple outcome measures without reporting analysis-level results or multiplicity procedures. This highlights the value of complete reporting: outcome definitions, analysis populations, missing-data handling, uncertainty estimates, and planned approaches to multiple outcomes all affect how readers judge evidence. The limitations are especially important when a study’s purpose is feasibility and the posted record does not contain the primary result.

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 most direct limitation of the registry information is that it does not report the primary endpoint estimate, standard deviation, analyzed sample size, or confidence interval. The endpoint’s definition is available, but its observed value and precision are not. Results for the listed secondary outcomes are also not reported in the registry record. As a result, this record cannot support an assessment of the magnitude or direction of symptom change.

The study enrolled 10 participants and had a single group. Its size limits the precision and generalizability of descriptive findings, while the lack of a concurrent control group prevents a like-for-like comparison. Because masking is listed as none, subjective reporting outcomes may also be open to expectation or assessment influences in general; the record does not describe procedures that would address these concerns.

The primary endpoint applies to subjects who met the inclusion criterion for incontinence, but the registry does not state how many participants met that criterion or contributed endpoint data. It does not report missing diary handling, analysis-population definitions beyond the stated criterion, or the analysis method. The registry lists seven outcome measures but does not report a multiplicity approach or analysis entries.

For safety, the record reports counts but does not give descriptions of the eight participants affected by other adverse events, event timing, or further severity information. The small group and lack of a comparator limit what those counts can establish about risks relative to another approach. The record also does not report the trial’s own sample-size justification, interim analyses, or statistical analysis plan. These are limitations of the information reported and should not be filled in by assumption.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Clinical Feasibility Study, Implantable Tibial Nerve Stimulator (ITNS) — NCT04115228.
• Registry record last updated 2022-04-12; status last verified 2022-03.
• Results first posted 2022-04-12.
• 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

NCT04115228 is a completed, single-group longitudinal feasibility study of implantation and neuromodulation therapy using the Nine Continents Medical implantable tibial nerve stimulator. The registry lists 10 participants enrolled, no masking, one United States study site, and 26 weeks of follow-up. The primary endpoint was mean percent change in urinary incontinence frequency from baseline to 13 weeks among subjects meeting the incontinence inclusion criterion.

The primary endpoint result and the listed secondary outcome results are not reported in the registry record. For the Study Device group, zero of 10 participants were affected by serious adverse events, 8 of 10 were affected by other adverse events, and zero deaths were listed. The single-group design supports description rather than a randomized comparison, and the registry information does not provide enough outcome detail to assess the primary endpoint’s magnitude or precision.