InterStim Micro Post Market Clinical Follow-up Study (ELITE): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for InterStim Micro Post Market Clinical Follow-up Study (ELITE) (NCT04506866), a non-randomized na study. The primary outcome is Change From Baseline for HRQL Total Score.

2. Clinical Question

3. Trial Design

ELITE is a post-market clinical follow-up study of the InterStim Micro System. Its stated purpose was continued assessment of safety and performance to confirm long-term outcomes. The registry lists the design as non-randomized, unmasked, and parallel. Participants were assigned to condition-based cohorts: overactive bladder, fecal incontinence, and non-obstructive urinary retention. Each cohort description says participants would receive InterStim Micro therapy and be followed for symptoms related to that condition.

The registry lists enrollment as 148, the study start as 2020-08-25, and primary completion as 2022-12-19. The study status is terminated. The phase is listed as NA, and MedtronicNeuro is listed as sponsor. The registry record does not report the reason for termination. The primary endpoint’s stated timeframe is 3 months; that timeframe should not be treated as the duration of all follow-up, which is not reported in the registry record.

The parallel designation means the registry represents separate cohorts rather than a single group crossing through multiple interventions. However, the cohorts have different conditions and the descriptions do not identify an untreated or alternative-treatment control group. Because allocation was non-randomized, the study is not a randomized comparison. Differences between the cohorts cannot be interpreted as treatment effects against one another: their underlying conditions and outcome measures differ, and the record does not establish that the groups are comparable.

The registry lists three outcome measures and no statistical analyses. It does not report the allocation procedures, eligibility criteria, detailed follow-up schedule, or a statistical analysis plan. Those omissions limit how fully the study’s conduct and intended analyses can be reconstructed from the registry record.

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: This score is applicable only for the OAB cohort.

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 Change From Baseline for HRQL Total Score, measured over 3 months.

The primary endpoint is change from baseline in the health-related quality-of-life total score for participants in the overactive bladder cohort, measured at 3 months. It uses the Overactive Bladder Quality of Life Questionnaire, or OAB-q, a validated questionnaire intended to assess symptom bother and the effect of overactive bladder on health-related quality of life.

The questionnaire has 33 items: an 8-item symptom-bother scale and a 25-item health-related quality-of-life scale. The latter covers coping, concern or worry, sleep, and social interaction. Domain scores are summed and transformed to a scale from zero to 100. The endpoint concerns the health-related quality-of-life total score, not the symptom-bother score. The registry defines a positive change from baseline as better quality of life, with a larger positive change indicating a greater improvement on that scale.

Change from baseline is used to describe how the score at follow-up differs from the participant’s starting score. In general, a baseline-referenced measure can make the direction of change easier to interpret than a follow-up score alone. It does not, by itself, establish that a change was caused by the intervention. The record does not report the observed mean change, standard deviation, confidence interval, or other inferential result for this endpoint. It also does not report a threshold for interpreting the size of a change as clinically important.

The endpoint is applicable only to the overactive bladder cohort. It should not be extended to the fecal incontinence or non-obstructive urinary retention cohorts, whose condition-specific symptoms are described separately.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a continuous measure summarized as a mean change from baseline, with standard deviation specified as the dispersion measure. The registry record identifies the instrument, score direction, target cohort, and assessment timeframe, but does not report the numerical endpoint result or a detailed statistical analysis plan.

What does a mean change describe?

In general, a mean change is the arithmetic average of participants’ follow-up scores minus their baseline scores, calculated according to the analysis definition. It describes the average direction and size of change for the observations included in that calculation. Here, the registry defines positive change as better quality of life. The actual mean change is not reported in the registry record, and the exact rules for calculating or summarizing change are not reported either.

A group mean is not a description of every participant. Participants can have different changes, including changes in opposite directions, while the average summarizes them in one value. The standard deviation describes the spread of observed values around the mean; it is not the uncertainty of the mean itself. The registry specifies standard deviation but does not report its observed value for the primary endpoint.

How does a confidence interval help?

In general, a confidence interval presents a range of values compatible with the data and the statistical method used, and indicates the precision of an estimate. A narrower interval generally indicates greater precision than a wider interval, under the assumptions of the method. A confidence interval does not remove possible bias from a non-randomized design, and it does not show that the measured change was caused by treatment. The registry information does not report a confidence interval for the primary endpoint.

A p-value, when reported, describes how compatible the observed data are with a specified null hypothesis under the chosen model and its assumptions. It is not a measure of effect size, clinical importance, or the probability that the treatment works. No primary-endpoint p-value or analysis result is reported in the registry record. Statistical significance therefore cannot be assessed from the record information.

What does non-randomized allocation mean for interpretation?

In general, random allocation is used to help balance prognostic characteristics between comparison groups. In a non-randomized study, group membership may be related to participant or clinical characteristics. That can make observed differences difficult to attribute to the intervention. ELITE’s cohorts are based on different conditions, and the registry does not describe a control cohort receiving a different intervention or no intervention. The condition-based groups should not be treated as interchangeable comparison arms.

A within-cohort change from baseline can describe the observed course of scores over time, but it does not separate treatment effects from other explanations for change. General influences can include natural fluctuation, other care, changes in circumstances, and measurement variability. These are general considerations for uncontrolled before-and-after measurements, not claims about what occurred in this study.

Why does over-dispersion matter?

Over-dispersion is a general statistical concern when outcome variability is greater than a model assumes. If a model understates variability, its standard errors and uncertainty intervals can be too small, making estimates appear more precise than they are. The primary endpoint is continuous and the registry specifies a mean and standard deviation; the record does not identify a model or report diagnostics for over-dispersion. This concept is therefore general background rather than a documented feature of the analysis.

How should planning calculations be read?

In general, sample-size planning calculations ask how many participants might be needed under specified assumptions to detect a target effect with a chosen error rate and power. The planning assumptions described for this study use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the target effect is expressed as a stated fraction of the observed effect. These are planning assumptions, not observed results and not observed power. They do not establish that the study used this design for enrollment, nor do they show that the enrolled cohort had a particular power. The registry record does not report a sample-size justification from the study’s own design.

Planning calculations based on an observed effect can be especially difficult to interpret when the underlying effect estimate and its uncertainty are unavailable. A planning illustration is conditional on its assumptions and does not replace an analysis of the trial data. No sample-size result should be read as evidence about the primary endpoint itself.

What can the registry analysis information establish?

The record lists no statistical analyses. It does not report how participants with missing baseline or follow-up scores were handled, whether the mean was adjusted for other characteristics, which analysis population was used, or whether any interim analyses occurred. The statistical plan is not reported in the registry record. These gaps prevent assessment of model choice, assumptions, multiplicity procedures, and robustness of the primary result. No recalculated estimate is available in the record information; consequently, there is no recalculation to compare with a sponsor analysis.

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("Overactive Bladder Cohort")
n   <- c(67)
m   <- c(33)
sp  <- c(24.2)
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  Overactive Bladder Cohort  67  33.000  24.200  27.097  38.903

11. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures and no analyses. It does not report a multiplicity procedure, such as whether the primary endpoint was tested separately from other outcomes or whether any adjustment was planned for multiple statistical tests. Without that information, the handling of the chance of false-positive findings across multiple outcomes or analyses is not reported in the registry record. The presence of multiple outcome measures alone does not establish that all were tested in the same way or that any particular adjustment was necessary.

Missing-data handling is also not reported in the registry record. The record information does not describe how many participants had an available baseline score, a 3-month score, or a calculable change, nor does it specify whether incomplete observations were excluded, imputed, or addressed by another method. No assumption about why observations might be missing or how missingness was handled can be made from the endpoint definition.

The analysis population is not reported in the registry record. It is therefore unclear whether the primary analysis was based on all enrolled participants, participants who received therapy, participants with available endpoint data, or another defined group. The enrollment figure alone does not establish the denominator used for the primary endpoint.

These items matter because missing observations and analysis-population choices can affect both the estimate and its uncertainty. Multiplicity procedures can affect how evidence across several outcomes is interpreted. In the absence of those details, the registry record does not support a full assessment of the statistical analysis or its sensitivity to alternative assumptions.

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: abdominal pain (3.8%), sepsis (3.7%), superinfection (3.7%), cystitis (3.7%), urinary tract infection (3.7%).

The registry reports serious and other adverse-event counts separately for each condition cohort. For the overactive bladder cohort, 68 were at risk for serious events and 3 were affected; 68 were at risk for other events and 5 were affected. For the fecal incontinence cohort, the corresponding figures were 53 and 8 for serious events, and 53 and 8 for other events. For the non-obstructive urinary retention cohort, they were 27 and 4 for serious events, and 27 and 14 for other events.

These figures describe the registry’s affected counts within each cohort. They should not be added together to create an overall count, and they do not constitute a comparison with a control group. The registry does not report whether events were judged related to the device or therapy, how events were defined for counting, or whether the count refers to participants with at least one event or event occurrences. The detailed event timing and severity information are not reported in the registry record.

The record lists deaths as 1 in the overactive bladder cohort and 0 in each of the other cohorts. A relationship between these deaths and treatment is not reported in the registry record. The listed adverse-event terms include abdominal pain at 3.8%, sepsis at 3.7%, superinfection at 3.7%, cystitis at 3.7%, urinary tract infection at 3.7%, and vascular pseudoaneurysm at 1.9%. The denominator and counting method for these term percentages are not reported, so they should not be interpreted as comparable cohort-level risks.

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

The registry record defines a primary quality-of-life endpoint for the overactive bladder cohort: mean change from baseline in OAB-q health-related quality-of-life total score at 3 months. It also states that a positive change represents better quality of life. However, the endpoint’s observed mean change and standard deviation are not reported in the registry record. There is therefore no numerical primary result from which to judge the direction, size, variability, or precision of the observed change.

Even a reported positive mean change would describe an observed before-and-after pattern, not establish that InterStim Micro caused the change. The study was non-randomized and the registry does not describe a like-for-like control group. General influences other than the intervention can contribute to changes over time. The design also does not support comparison of the three condition cohorts as if they were competing treatment groups.

The safety counts provide descriptive information about serious and other adverse events within the cohorts. They do not, on their own, establish causation or allow a controlled risk comparison. The record does not report event attribution, and the death counts are not linked to treatment in the information available. The adverse-event term percentages also lack a reported denominator and counting method, which limits their interpretation.

The registry’s terminated status is a status designation, not an explanation. The reason for termination is not reported in the registry record, and it should not be inferred from the endpoint or safety listings. Likewise, the study title’s reference to long-term outcomes does not establish the duration or completeness of follow-up for every participant; the primary endpoint timeframe is 3 months, and the broader follow-up schedule is not reported.

Overall, the record describes what the study set out to assess and provides cohort-level safety counts, but it does not report the primary outcome estimate or a statistical analysis. It cannot establish treatment effectiveness, lack of effectiveness, or a causal safety effect. Interpretation is limited by the absent outcome results, absent analysis details, and non-randomized cohort design.

14. Why This Trial Matters Statistically

Post-market follow-up can contribute information about how a device is evaluated after it is on the market. ELITE is registered as a continued assessment of safety and performance, with cohorts reflecting three clinical conditions. Statistically, the study illustrates why a clearly defined endpoint and a clearly described comparison are both important. The primary endpoint is specified as a mean change in a condition-specific quality-of-life score, but the registry record does not report the numerical result needed to assess that change.

The design also matters to the question that can be answered. A non-randomized, parallel study organized by condition can describe outcomes within cohorts, but it does not create a like-for-like control comparison. The distinction is important: a measured change over time and an effect attributable to treatment are not the same estimand. The registry description supports the former as a study objective, while the absence of a control group limits causal interpretation.

Safety reporting also benefits from careful statistical reading. Counts within cohorts describe events or affected participants according to the registry’s reporting, but causal attribution and comparisons require additional information. The record lists at-risk counts and affected counts, yet does not specify the detailed definitions or attribution needed to interpret these as treatment-related risks.

Finally, the record makes visible a broader reporting issue: endpoint definitions do not substitute for analysis results. Statistical conclusions depend on the estimate, its uncertainty, the population analyzed, missing-data handling, and analysis plan. Those details are not reported in the registry record. This makes it important to separate the study’s intended question from conclusions that the posted statistical information can support. ELITE is therefore informative as a description of a post-market follow-up design, but the recorded information is insufficient for numerical evaluation of its primary outcome.

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.

Several limitations specific to this study affect interpretation. First, the registry describes non-randomized allocation and does not identify a like-for-like control group. The condition cohorts differ by clinical problem and are not suitable substitutes for one another as controls. Observed changes within a cohort cannot isolate intervention effects from other changes over time.

Second, the primary endpoint is limited to the overactive bladder cohort. Its OAB-q total score does not represent outcomes for the fecal incontinence or non-obstructive urinary retention cohorts. The registry describes follow-up of condition-specific symptoms in those cohorts, but the primary endpoint cannot be generalized across them.

Third, the primary endpoint results and statistical analyses are not reported in the registry record. The observed mean change and standard deviation, uncertainty estimates, analysis population, missing-data handling, and statistical plan are unavailable. This prevents evaluation of the result’s magnitude, precision, and robustness. The registry also does not report a threshold for a clinically important change on the score.

Fourth, the listed safety information is not accompanied by details on event definitions, timing, attribution, or the basis for the adverse-event term percentages. The figures can be read descriptively, but not as evidence of causation or as controlled comparisons. The reason for the terminated status is not reported in the registry record, so the status cannot be interpreted as evidence for a particular outcome or safety concern.

Finally, the stated 3-month endpoint timeframe does not establish the duration or completeness of broader follow-up. The registry’s post-market and long-term aims do not provide participant-level follow-up details. These limitations arise from the recorded design and reporting information and should remain distinct from conclusions about unreported study results.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: InterStim Micro Post Market Clinical Follow-up Study (ELITE) — NCT04506866.
• Registry record last updated 2024-12-27; status last verified 2024-12.
• Results first posted 2024-01-05.
• 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

ELITE is a post-market clinical follow-up study of InterStim Micro, registered as non-randomized, unmasked, and parallel. The registry describes condition-based cohorts for overactive bladder, fecal incontinence, and non-obstructive urinary retention, with enrollment of 148. The study status is terminated; the reason is not reported in the registry record.

The primary endpoint is mean change from baseline at 3 months in the OAB-q health-related quality-of-life total score for the overactive bladder cohort. Positive change is defined as better quality of life. The registry record does not report the endpoint result or statistical analyses. Cohort-level serious and other adverse-event counts and death counts are listed, but attribution and detailed event methods are not reported. Because allocation was non-randomized and no like-for-like control group is described, the record does not support a causal treatment comparison.