Adjustable Continence Therapy (ACT) Device for the Treatment of Female Stress Urinary Incontinence: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Adjustable Continence Therapy (ACT) Device for the Treatment of Female Stress Urinary Incontinence (NCT00113555), a na na study. The primary outcome is Change of Stamey Grade From Baseline to 12 Months..

2. Clinical Question

The clinical question concerns change in the severity classification of stress urinary incontinence after ACT device implantation. The Stamey grade ranges from 0 to 3: grade 0 means no leaking, while higher grades describe leakage under progressively less exertion or without relation to activity or position. The study description identifies a reduction in grade as the basis for therapeutic success.

Because there is no reported control group, the central statistical comparison is within the study population: baseline status is compared with status at 12 months. This can describe how the measured outcome changed over time among participants included in the analysis. It cannot, by itself, distinguish a device-related effect from other explanations for change, including the natural course of symptoms, concurrent care, or changes in reporting. Those possibilities are not measured or addressed in the registry information.

The record lists enrollment of 221 and describes a study purpose involving up to 160 implanted female patients. These are different registry entries and should not be treated as interchangeable measures of the primary-outcome analysis population. The number of participants contributing to the reported primary endpoint is not reported in the registry record.

3. Trial Design

This is a completed, single-group, open-label device study sponsored by Uromedica. The intervention is ACT, an adjustable continence therapy device. The study description concerns an adjustable periurethral prosthetic system for female stress urinary incontinence, with or without hypermobility. The registry record lists enrollment of 221.

The record identifies no masking and gives allocation as NA. Its design is classified as single group, and there is no comparator group described. Accordingly, the results are not a randomized comparison between ACT and another treatment or a control condition. The study can describe observed outcomes and adverse events in the reported group, but the design does not provide a concurrent comparison for estimating what would have happened without ACT.

The study purpose describes evaluating the procedure's safety and effectiveness in up to 160 implanted female patients. The record separately lists enrollment of 221; it does not explain the relationship between this enrollment figure and the implanted population in the study description. The number actually implanted and the number included in each outcome analysis are not reported in the registry record.

The primary outcome timeframe is baseline to 12 months. The endpoint is the mean change in Stamey grade, with Intent to Treat named as the analysis population. A stated success criterion is a mean change of greater than or equal to -1. The registry record does not report a protocol-level account of follow-up visits, device adjustment procedures, treatment adherence, or how the Intent to Treat label was implemented.

The study is listed as completed, with a start date of 2001-12 and primary completion of 2008-07. Its phase is recorded as NA, which is consistent with a device investigation rather than a drug-phase description. The exact allocation procedure, a formal statistical analysis plan, and the rationale for the enrollment target are not reported in 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.

Before assignment: One patient was implanted and was considered a compassionate use patient that did not meet the enrollment criteria.This patient was not included in the efficacy and safety summaries and her adverse vents are recorded.Therefore the total number of implants for the analyses is 162.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Intent to Treat

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 of Stamey Grade From Baseline to 12 Months., measured over Baseline to 12 months.

The primary endpoint is the mean change in Stamey grade from baseline to 12 months, expressed in units on a scale. The grade classifies stress urinary incontinence from 0 to 3. Grade 0 denotes no leaking; grade 1 describes loss of urine with sudden increases in abdominal pressure; grade 2 describes loss with lesser degrees of stress; and grade 3 describes loss unrelated to physical activity or position.

The scale gives a structured way to record symptom severity at the stated assessment times. A mean change summarizes the average direction and magnitude of change across the participants included in the analysis. The stated endpoint criterion is a mean change of greater than or equal to -1. The study description also says therapeutic success is based on at least a one-grade mean reduction at 12 months.

Using a mean for an ordered grade scale is a summary choice: grades have an order, but the clinical distance between neighboring grades is not established as equal by the descriptions in the record. The mean can therefore be useful for a concise group-level summary while concealing differences in individual trajectories or in the distribution of grades. The registry record does not report the observed mean change or its 95% confidence interval, so the endpoint's result and precision cannot be assessed from the registry information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a continuous primary outcome summarized as a mean, with a 95% confidence interval. The following concepts explain how those methods are generally read; they do not fill in analysis details that the registry record does not report.

What does a mean change summarize?

A mean change is calculated by taking each analyzed participant's change from baseline to the follow-up assessment and summarizing those changes with an average. The record defines the timeframe as baseline to 12 months and the measurement as Stamey grade. A mean can capture the overall direction of change, but it does not show whether most individuals changed similarly or whether the average reflects a mixture of different responses. Individual-level changes and the distribution of grades are not reported in the registry record.

Stamey grade is an ordered scale: a higher grade represents a more severe description of leakage. Treating the grades numerically to calculate a mean makes the average straightforward to report, but it implicitly treats steps between grades as comparable for purposes of averaging. That assumption can matter when interpreting an average on an ordinal scale. A mean change does not describe the proportion of participants who improved, stayed the same, or worsened; those proportions are not reported in the registry record.

What does a confidence interval add?

A confidence interval expresses uncertainty around an estimate. In general, it gives a range of values that are reasonably compatible with the data and the statistical procedure used. A narrower interval conveys more precision than a wider interval, all else equal. It is not a range of individual participant outcomes, nor does it establish that the measured change was caused by the intervention. The primary endpoint is specified with a 95% confidence interval, but its limits are not reported in the registry record.

The relationship between the interval and the success criterion would be relevant to judging how the estimated mean compares with the threshold. The record's criterion is a mean change of greater than or equal to -1. Without the estimate and interval limits, readers cannot assess whether the data are clearly on one side of the criterion, whether uncertainty spans it, or how much precision supports the estimate. No additional inference should be substituted for the missing result.

Why does the design matter to interpretation?

This investigation is classified as single group, with no masking and no comparator reported. The outcome is therefore a change over time within the study group. In general, within-group change can reflect the intervention, but it can also reflect factors such as natural fluctuation, concurrent care, changes in expectations, or changes in how symptoms are recorded. Without a comparison group, those possibilities cannot be separated by a treatment-versus-control contrast. This is a design limitation, not a problem that can be corrected by interpreting the mean or confidence interval differently.

Open-label status means that masking is not reported as part of the study. For subjective or participant-reported outcomes, knowledge of treatment can potentially affect reporting or assessment; this is a general methodological consideration, not evidence that such influence occurred in this trial. The record does not describe blinded outcome assessment or other measures intended to reduce that possibility.

What is the role of sample-size planning?

Sample-size illustrations are planning calculations, not trial findings and not observed power. The stated illustration assumptions use 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. The illustrations are based on the observed effect and are not described as the trial's own design calculations.

Those assumptions describe a hypothetical two-arm planning setting, whereas this study is a single-group investigation. They should not be read as evidence that the study was designed with a comparator, or as proof that the observed estimate is reliable. Sample-size calculations depend on assumptions about the target effect, variability, significance level, allocation, and analysis. The registry record does not report the study's original sample-size justification or statistical plan. It also does not provide a primary endpoint result in the registry record for interpretation, so no planning figure should be treated as a substitute for an observed result.

Why does over-dispersion matter in general?

For count outcomes, such as daily incontinence episodes or pads changed, a simple model may assume that variation follows a particular relationship to the average count. Over-dispersion occurs when the observed variability is greater than that assumption allows. If ignored, uncertainty may be understated and tests may be too optimistic. This is a general consideration for count data, not a description of the trial's analysis: the registry record does not identify a count-data model, report an over-dispersion assessment, or provide results for those secondary outcomes.

More broadly, sound interpretation depends on both the estimate and the analysis choices behind it. The registry record names a mean and confidence interval for the primary outcome, but does not report the calculation method, assumptions, handling of missing observations, or a detailed model specification. Those omissions prevent independent appraisal of whether the reported analysis appropriately reflects the data structure.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists seven outcome measures and one analysis. It identifies the Stamey grade change as the primary endpoint and names six secondary measures: the Incontinence Quality of Life Questionnaire, the Incontinence Impact Questionnaire, the Urinary Distress Inventory, daily incontinence episodes, daily pads changed, and provocative pad weight. Considering several outcomes can broaden the clinical picture, but it also creates multiple opportunities to observe apparently notable findings by chance.

The registry record does not report whether the study used a multiplicity adjustment, a hierarchy of secondary endpoints, or another approach to control the interpretation of multiple analyses. It also does not provide results for the secondary outcomes. Consequently, the strength of evidence across the full set of measures cannot be assessed, and an isolated result should not be treated as confirmatory without knowing how the analyses were planned and interpreted.

The primary analysis population is labeled Intent to Treat. That label indicates the intended analysis population, but the record does not explain how it was implemented, identify the number analyzed for the primary endpoint, or describe whether all enrolled participants were included. Missing-data methods, reasons for missing observations, and sensitivity analyses are not reported in the registry record.

These omissions matter because follow-up data may be unavailable for some participants, and estimates can be affected if missingness is related to symptoms, treatment experience, or other factors. This is a general concern; the record does not establish that missing data occurred or explain their causes. Without the analysis denominator and missing-data approach, the completeness and robustness of the 12-month estimate cannot be judged.

11. 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 1% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: other (non-pelvic) (1.2%), port erosion (0.6%).

The safety information lists 163 at risk for serious adverse events and 2 affected. For other adverse events, the record lists 163 at risk and 155 affected. It reports 0 deaths. These are counts in the registry record; they are not a comparison with another treatment group, because no comparator group is reported.

The record also identifies “Other (non-pelvic)” at 1.2% and “port erosion” at 0.6% among the top serious adverse-event terms. The registry information does not give a fuller account of event timing, duration, severity grading, relatedness assessment, or the distribution of all event types. It is therefore important not to treat the listed terms as a complete description of the safety experience.

The serious and other adverse-event counts should be read as separate registry categories. The record does not say whether participants could appear in both categories, so they should not be combined. Likewise, the safety denominator is not the reported denominator for the primary endpoint. These figures describe reported safety events in the listed group; without a control group, they do not establish comparative safety or identify how many events would have occurred under another approach.

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

The registry record establishes that this was a completed, open-label, single-group study of ACT for female stress urinary incontinence. It identifies the primary measure as mean Stamey grade change from baseline to 12 months and defines a threshold for the mean change. It also records safety-event counts and names secondary measures. These details describe what the study set out to assess and what information the registry lists.

The registry information does not report the primary mean change or its 95% confidence interval. It therefore does not show whether the endpoint met its stated criterion, how precise the estimate was, or how outcomes varied among participants. The endpoint definition must not be mistaken for a result. The record also lacks secondary outcome results, so no claim about changes in quality of life, urinary distress, diary counts, or pad weight can be based on the listed outcome names alone.

Even if a within-group change were reported, a single-group study could not by itself establish that the device caused that change. The absence of a comparator leaves other possible influences on change unresolved. Open-label status adds a further consideration for outcomes involving symptom reporting or assessment, although the record does not establish that reporting was biased.

The safety counts indicate reported events in the study group, including serious and other adverse-event categories and no deaths in the recorded data. They do not quantify comparative risk, and the limited event detail prevents a complete characterization of the safety profile. The best-supported interpretation is therefore descriptive: the registry records the design, selected outcomes, and safety counts, but it does not provide enough primary efficacy results or analysis detail to evaluate the endpoint finding or its uncertainty.

13. Why This Trial Matters Statistically

This study illustrates why the design and the reported result both matter in clinical statistics. A registry can identify a clinically interpretable endpoint—in this case, mean change in an ordered symptom-severity grade over a defined follow-up period—without providing the estimate needed to judge the outcome. A stated success criterion is useful for understanding the question, but it cannot stand in for the observed change and its uncertainty.

The single-group structure also makes the limits of within-group evidence visible. A baseline-to-follow-up comparison can describe change, yet it does not provide the counterfactual comparison needed to isolate what would have happened without the intervention. This distinction is central when translating a statistical summary into a causal claim.

The trial also raises a measurement issue: an average is used for a scale made of ordered severity grades. That summary is compact, but it may conceal individual variation and relies on treating grade steps as suitable for averaging. Considering the distribution of changes alongside the mean would help readers understand the pattern, but those details are not reported in the registry record.

Finally, the record distinguishes enrollment, the study description's implanted population, and the safety denominator without explaining how they relate to the primary endpoint analysis. This underscores why analysis denominators, missing-data methods, and the statistical plan are important parts of transparent reporting. Their absence limits how confidently readers can evaluate precision, completeness, and the relation between a threshold and the observed data.

14. 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 trial-specific limitations constrain interpretation. The study is single group and open label, with no comparator described. It can document change over time and reported adverse events, but it cannot establish a comparative treatment effect from the registry information. The registry does not report masking of outcome assessment or procedures intended to address potential effects of treatment knowledge.

The primary endpoint is a mean change on the Stamey grade scale, which consists of ordered categories. A mean offers a concise summary, but the record does not report individual-level changes or the distribution of grades at follow-up. It therefore cannot show whether the average reflects a consistent pattern or varied experiences. The observed mean and its 95% confidence interval are not reported in the registry record.

Enrollment is listed as 221, while the study description refers to up to 160 implanted female patients and the safety information lists 163 at risk. The registry does not explain the relationship among these figures or give the primary endpoint analysis denominator. The number completing the 12-month assessment, if different from the analysis population, is not reported in the registry record.

The record does not report how missing data were handled, how the Intent to Treat population was defined in practice, or whether sensitivity analyses were conducted. It also does not give the detailed statistical plan, sample-size justification, multiplicity approach, or secondary outcome results. Safety information is limited to the listed counts and top serious-event terms, without detailed timing, relatedness, or event-level descriptions. These gaps limit independent assessment of the primary result, the completeness of follow-up, and the broader balance of outcomes.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Adjustable Continence Therapy (ACT) Device for the Treatment of Female Stress Urinary Incontinence — NCT00113555.
• Registry record last updated 2018-07-09; status last verified 2018-07.
• Results first posted 2018-06-04.
• 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.

18. Record Summary

NCT00113555 is a completed, open-label, single-group device study sponsored by Uromedica. It evaluates ACT for female stress urinary incontinence, with or without hypermobility. Enrollment is listed as 221, and the primary outcome is mean Stamey grade change from baseline to 12 months in an Intent to Treat population.

The endpoint description sets a mean-change criterion of greater than or equal to -1 and specifies a 95% confidence interval. The registry record does not report the observed primary estimate or interval limits, nor does it provide results for the listed secondary measures. Safety information lists serious and other adverse events, along with 0 deaths, but no comparator is available for relative safety interpretation.

The record supports a description of the study design and its planned outcome framework. Its missing primary results, analysis details, and explanation of participant denominators prevent a complete assessment of the endpoint finding or its precision.