Sling vs Botox for Mixed Incontinence: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Sling vs Botox for Mixed Incontinence (NCT04171531), a randomized phase 3 study. The primary outcome is UDI-LF Total Score Change From Baseline.

2. Clinical Question

The trial’s stated aim was to compare treatment for mixed urinary incontinence, with the brief summary emphasizing symptom change 6 months after treatment. The primary outcome timeframe in the registry lists 3, 6, 9, and 12 Months. Its outcome description specifies score differences at 3, 6, or 12 months, so the handling of the 9-month assessment is not clear from the registry record.

The clinical question is about comparative change in reported distress, not simply whether either treatment was followed by a change within its own group. A comparison requires outcome estimates for both groups at the relevant time points and an estimate of the difference between those changes, with uncertainty. Those primary outcome estimates and comparisons are not reported in the registry record. The registry therefore identifies the question and outcome but does not establish the direction, size, or precision of any comparative effect.

3. Trial Design

NCT04171531 is a completed Phase 3 randomized trial with parallel groups. The registry reports enrollment of 150 and identifies the sponsor as NICHD Pelvic Floor Disorders Network. The study started on 2020-06-08, and primary completion was 2024-02-12. Masking is listed as none, meaning the registry does not describe a masked trial.

The comparison was between Botox® injection and mid-urethral sling. The Botox A arm description specifies an injection of 100 units of Botulinum toxin A into the bladder. The sling arm included retropubic as well as transobturator full-length slings. Follow-up visits were described at 2 weeks, 3 and 6 months, to collect clinical and patient-reported outcomes. These descriptions identify the interventions and follow-up schedule; they do not give further procedural details or explain how clinical decisions during follow-up were handled.

The registry identifies UDI-LF Total Score Change From Baseline as the primary outcome and UDI-LF Stress Score Change From Baseline and UDI-LF Irritative Score Change From Baseline as secondary outcomes. It lists 55 outcome measures, but no analysis results are listed. The primary outcome estimates are not reported in the registry record, and the number of analyses reported is 0. Consequently, the available record supports describing the design and intended measurement, but not estimating the comparative outcome from the trial results.

The registry labels the analysis population as intent-to-treat, while specifying that eligible randomized participants had to provide outcome data after baseline. It also states that data collected after retreatment for urinary incontinence were excluded. These conditions are important when interpreting what the registry calls intent-to-treat; further detail about participant flow and the handling of missing outcome data is 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: An intent-to-treat (ITT) analysis which included all eligible participants who were randomized and who provided outcome data after baseline was performed. Data that was collected after a participant was retreated for urinary incontinence was excluded from the analysis.

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 analysis is limited to those participants that were randomized, received treatment, and provided at least one post-baseline measurement.

6. Primary Endpoint

The registry lists the primary outcome as UDI-LF Total Score Change From Baseline, measured over 3, 6, 9, and 12 Months.

The primary outcome is UDI-LF Total Score Change From Baseline, measured in units on a scale. The registry describes the Urogenital Distress Inventory as a standardized measure of overactive bladder symptoms and health-related quality of life. The scale ranges from 0 to 300, with higher scores indicating greater distress. A change score expresses how a participant’s score at follow-up differs from that participant’s baseline score.

Change from baseline is used to describe symptom status after treatment in relation to the starting measurement. In a randomized comparison, the relevant question is how the changes compare between the treatment groups, not merely whether one group’s average changed. The registry gives a mean as the summary measure and a 95% Confidence Interval as the dispersion measure. A confidence interval communicates the statistical uncertainty around an estimate; it does not itself show whether an effect is clinically important.

The brief summary emphasizes change 6 months following treatment, while the primary outcome timeframe lists 3, 6, 9, and 12 Months. The outcome description says the difference is calculated at 3, 6, or 12 months and does not explain the 9-month assessment. The group means, comparative estimates, and confidence intervals are not reported in the registry record, so the size and precision of change cannot be assessed from the recorded outcome information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: it is a score with a numerical scale, and the registry specifies the mean as its summary measure. Statistical methods for continuous outcomes generally estimate a group average and then compare averages or changes between groups. The registry identifies the outcome and a 95% Confidence Interval, but does not report the actual means or comparative estimate.

What does a mean change describe?

A change score is calculated by comparing a follow-up score with the same participant’s baseline score. The mean change summarizes those individual changes across the analyzed participants. It is distinct from a follow-up average alone: two groups can have different starting scores, and baseline-relative change describes movement from the starting measurement. For the UDI scale, the registry states that higher scores correspond to greater distress. Thus, a negative change would represent a decrease in distress and a positive change an increase, if such estimates were reported. The registry does not give the observed mean changes.

In a randomized trial, the main comparative quantity is usually the difference in outcome between assigned groups, with the exact definition depending on the analysis plan. The registry does not report the comparative estimate or enough analysis detail to establish how it was calculated. It would be inappropriate to infer that estimate from the intervention descriptions or from adverse-event counts.

How should a confidence interval be read?

In general, a confidence interval expresses the uncertainty around an estimated quantity under the statistical method’s assumptions. It provides a range of values that are compatible with the data and method, rather than a guarantee that the true effect lies within that particular interval. A confidence interval is most useful alongside the point estimate: the estimate indicates the observed direction and size, while the interval indicates its precision. Because no primary outcome interval is reported in the registry record, neither the precision nor the range of compatible effects can be assessed.

The registry names a 95% Confidence Interval as the dispersion measure. It does not describe the interval calculation, any adjustment for baseline values, or any modeling assumptions. Those analysis details are not reported in the registry record. General explanations of confidence intervals cannot substitute for the missing estimate and its trial-specific calculation.

Why do time points matter?

Repeated outcome assessments can describe how scores evolve over follow-up, but each time point can answer a different question. A comparison at 3 months is not automatically interchangeable with one at 6 or 12 months. The registry’s primary outcome timeframe lists 3, 6, 9, and 12 Months, while the outcome description specifies differences at 3, 6, or 12 months. The brief summary emphasizes 6 months. The record does not clarify the role of the 9-month assessment or identify which time point should be treated as the primary comparative estimate for interpretation.

When outcomes are measured repeatedly, statistical analysis may account for correlation among measurements from the same participant. General methods can model repeated measurements or analyze selected time points separately. The registry does not report which approach was used. Without that information and the corresponding estimates, readers cannot assess how the analyses treated the repeated observations.

What does randomization contribute?

Random allocation is intended to make treatment groups comparable at the point of assignment, on average, with respect to both measured and unmeasured characteristics. This supports interpreting a properly conducted between-group comparison as an estimate of the effect of assignment to the treatment strategies. Randomization does not guarantee identical groups in every realized trial, and it does not remove concerns about missing outcome data, exclusions, measurement, or analysis choices.

Masking is listed as none. In general, lack of masking can matter when outcomes depend on participant reports or judgments, because knowledge of treatment assignment may influence reporting or assessment. The primary measure is a patient-reported distress and quality-of-life scale as described by the registry. The registry does not provide information about measures used to reduce or assess potential influence of treatment awareness, so the extent of any such influence cannot be determined from the record.

What can planning calculations tell readers?

Sample-size calculations are planning tools used to illustrate how many participants may be needed under specified assumptions about an effect, variability, allocation, and statistical testing. They are not observed power, and a planning illustration based on an observed effect does not establish that the trial was originally designed around that effect. The record says that planning illustrations use a two-sided significance level 0.05, equal allocation between the two arms, and a normal approximation, with the effect to detect stated as a fraction of the observed effect. It also specifies that participant counts per arm apply to non-time-to-event outcomes.

The registry record does not report the trial’s sample-size justification or design assumptions. The primary outcome is not reduced to one comparison because it has several categories or time points. Thus, there is no single primary contrast in the reported outcome information from which to judge the precision of the planned or observed comparison. Planning illustrations should be read as conditional scenarios, not as evidence that a treatment effect was detected or as a substitute for the missing outcome estimates.

What does the analysis population mean?

The registry describes an intent-to-treat analysis including eligible randomized participants who provided outcome data after baseline. It also says data collected after retreatment for urinary incontinence were excluded. In general, an intent-to-treat approach aims to preserve the comparison created by random assignment. The registry’s stated eligibility and outcome-data conditions qualify how that label was applied in this analysis. The record does not report participant flow, the amount or pattern of missing data, or the method used to address missing measurements.

These methodological details matter because a result depends on both the outcome definition and the analysis set. Without the reported primary estimates and fuller analytic details, readers can describe the planned comparison but cannot independently evaluate its numerical result, robustness, or precision.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 55 outcome measures, including the primary UDI-LF Total Score Change From Baseline and secondary UDI-LF Stress Score Change From Baseline and UDI-LF Irritative Score Change From Baseline. The primary outcome timeframe spans 3, 6, 9, and 12 Months, while the outcome description specifies changes at 3, 6, or 12 months. The brief summary emphasizes 6 months. The record does not explain how these time points relate to the primary analysis or how the 9-month assessment was handled.

When many outcomes, time points, or comparisons are examined, the chance of observing an apparently notable result by chance can increase. General approaches to multiplicity include identifying a primary comparison in advance, adjusting inference across selected tests, or treating secondary analyses as exploratory. The registry does not report a multiplicity plan, a hierarchy among comparisons, or whether any adjustment was used. With 0 analyses reported, readers cannot assess how the listed outcomes were analyzed or prioritized.

The stated analysis population includes eligible randomized participants who provided outcome data after baseline, and excludes data collected after retreatment for urinary incontinence. The registry does not report how many participants lacked outcome data, why measurements were missing, or whether missingness differed between groups. It also does not describe imputation, sensitivity analyses, or other missing-data methods. These details are not reported in the registry record.

The stated analysis set is therefore important context: the registry uses the intent-to-treat label, but its description includes an outcome-data requirement and an exclusion after retreatment. Without further detail, the effects of these conditions on the analysis cannot be evaluated. Missing-data and multiplicity information would be needed to judge how secure any reported comparative conclusion was; those conclusions cannot be assessed when primary outcome estimates are absent.

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 0.00% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cardiac failure (1.4%), myocardial infarction (1.4%), pyelonephritis (1.4%), obesity (1.4%), arthralgia (1.4%).

The registry reports serious adverse events for Botox A and Mid-Urethral Sling separately. For Botox A, 71 were at risk for serious adverse events and 3 were affected. For Mid-Urethral Sling, 69 were at risk and 8 were affected. These are recorded counts, not a comparison adjusted for differences in follow-up or other factors. The registry also reports other adverse events: 40 were affected in the Botox A group and 41 in the Mid-Urethral Sling group, with 71 and 69 at risk, respectively. Deaths are reported as 0 in each group.

The listed serious adverse-event terms include Cardiac failure, Myocardial infarction, Pyelonephritis, Obesity, Arthralgia, and Osteoarthritis, each reported as 1.4%. The registry does not assign these listed terms to a treatment group in the information recorded for those terms. Nor does it explain whether an individual could contribute more than one event or term. The percentages should therefore be read as recorded event information, not as a basis for calculating a group-specific comparative risk.

Adverse-event counts describe safety observations in the registry, but they do not establish causation or replace a fuller clinical assessment. The registry does not report additional detail about event severity, timing, relatedness, or duration. These details are not reported in the registry record.

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

The registry record identifies a randomized trial comparing Botox A injection with mid-urethral sling for mixed urinary incontinence. It gives the primary symptom measure, its scale direction, the intended follow-up timeframe, and the analysis population description. It also records serious and other adverse-event counts by group. These registry entries describe the study’s purpose and some of its recorded outcomes.

What the record does not give is the primary outcome result: there are no group mean changes, comparative estimates, confidence intervals, or reported analyses for UDI-LF Total Score Change From Baseline. Without them, the relative change in distress cannot be quantified or judged for precision. The absence of reported estimates is not evidence that the groups had identical results, and it is not evidence that either treatment did or did not produce a particular effect.

Even when estimates are available, statistical evidence and clinical importance are different questions. An estimate describes the observed effect, and its confidence interval describes uncertainty under the analysis assumptions. Clinical interpretation also depends on whether the magnitude matters to patients and whether benefits and harms are balanced. The registry does not report a clinically meaningful threshold for the UDI-LF Total Score or the primary outcome estimates needed for such an assessment.

The recorded adverse-event counts are also limited. They do not establish that an event was caused by the intervention, and they do not provide the event detail needed for a comprehensive safety comparison. The registry’s listing of zero deaths in both groups is a specific recorded observation, not a statement about every possible safety outcome.

Accordingly, the record can support a description of design and outcome definitions, but it cannot support a conclusion about which intervention produced greater symptom improvement or about the comparative precision of that effect. Those conclusions require reported primary outcome results and sufficient analysis detail.

13. Why This Trial Matters Statistically

This trial matters statistically because it compares two different treatment strategies using a patient-reported measure of distress and health-related quality of life. The primary outcome is a change from baseline on a scale with an explicit direction: higher UDI scores indicate greater distress. A properly reported between-group estimate could therefore help readers understand not only whether scores changed, but how the changes compared under randomized assignment.

The outcome is assessed at several follow-up times. Repeated measurements can provide a broader view of the course of symptoms, but they also create choices about which time point is primary and how comparisons across time are handled. The record’s timeframe lists 3, 6, 9, and 12 Months, while the outcome description specifies 3, 6, or 12 months and the brief summary emphasizes 6 months. This makes clear reporting of the chosen contrast and its uncertainty especially important.

The trial also illustrates why a registry’s design information should be distinguished from its results. Randomization and a defined outcome are important features, but they cannot stand in for estimates. The registry lists 55 outcome measures and 0 analyses, leaving the primary comparative result unavailable in the record. Without those results, readers cannot evaluate effect size, precision, or the consistency of findings across outcomes and time points.

Finally, the described analysis population is relevant to interpretation. The intent-to-treat description requires post-baseline outcome data and excludes observations after retreatment. Understanding how these conditions affected analyzed data would help readers assess the consequences of missingness and retreatment. The registry does not report those details. Clear reporting of outcome estimates, analysis choices, and participant flow would be needed to make the statistical evidence interpretable.

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.

The most consequential limitation of the registry record is that it does not report primary outcome estimates or analyses. The design and outcome definitions are available, but the comparative change in UDI-LF Total Score cannot be evaluated without group estimates and their uncertainty. This also prevents assessment of whether observed changes were precise or clinically important.

There is ambiguity in the stated primary outcome timing. The timeframe lists 3, 6, 9, and 12 Months; the outcome description names changes at 3, 6, or 12 months; and the brief summary emphasizes 6 months. The registry does not explain the status of the 9-month assessment or specify which time point forms the principal comparative analysis.

The registry lists 55 outcome measures and 0 analyses, but does not report a multiplicity strategy or explain how outcome comparisons were prioritized. It also does not describe the sample-size justification, missing-data methods, participant flow, or sensitivity analyses. The analysis population description includes only eligible randomized participants with post-baseline outcome data and excludes measurements after retreatment. The consequences of those conditions cannot be assessed from the information recorded.

Masking is listed as none. Since the primary measure concerns reported distress and quality of life, treatment awareness may be relevant in general, but the registry does not describe any procedures to address or evaluate its influence. The adverse-event information is also limited: the record does not supply further detail on timing, severity, relatedness, or group assignment for the listed serious terms. These limitations concern the available registry record and do not, on their own, establish the quality of the full trial report.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Sling vs Botox for Mixed Incontinence — NCT04171531.
• Registry record last updated 2025-06-03; status last verified 2025-05.
• Results first posted 2025-03-20.
• 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

NCT04171531 is a completed Phase 3 randomized parallel-group trial sponsored by NICHD Pelvic Floor Disorders Network. Enrollment was 150. The study compared Botox® injection, described as 100 units of Botulinum toxin A injected into the bladder, with mid-urethral sling, including retropubic and transobturator full-length slings. Masking is listed as none.

The primary outcome was UDI-LF Total Score Change From Baseline, with higher scores indicating greater distress. The registry describes a mean and a 95% Confidence Interval, but primary outcome estimates and analyses are not reported. The analysis population description requires outcome data after baseline and excludes data collected after retreatment for urinary incontinence.

The record lists 55 outcome measures and 0 analyses. It reports serious and other adverse-event counts by group and deaths as 0 in each group. The primary comparative symptom result cannot be determined from the registry record.