Study of Botulinum Toxin Type A for the Treatment of Patients With Idiopathic Overactive Bladder With Urinary Incontinence: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Botulinum Toxin Type A for the Treatment of Patients With Idiopathic Overactive Bladder With Urinary Incontinence (NCT00910845), a randomized phase 3 study. The primary outcome is Change From Baseline in Number of Daily Episodes of Urinary Incontinence.

2. Clinical Question

3. Trial Design

This was a randomized, quadruple-masked, parallel-group Phase 3 study sponsored by Allergan. The registry record gives an enrollment of 557 and lists overactive bladder as the condition. The study began in 2009-09, reached primary completion in 2011-07, and is marked completed. The record’s brief description says the study assessed the safety and effectiveness of onabotulinumtoxinA in patients with idiopathic overactive bladder with urinary incontinence.

The treatment descriptions specify detrusor injections. The onabotulinumtoxinA arm received 100 U at Day 1, with a repeat injection of 100 U after a minimum of 12 weeks if applicable. The placebo/onabotulinumtoxinA arm received normal saline at Day 1, followed by onabotulinumtoxinA 100 U after a minimum of 12 weeks if applicable. These descriptions establish the recorded treatment sequence, but do not explain which patients received a subsequent injection or the criteria for doing so. Those details are not reported in the registry record.

Random allocation is intended to create groups that are comparable on average at the start of a trial, while masking is intended to limit influences of treatment knowledge on care, reporting, or assessment. Those are general purposes of these design features; the registry record does not describe how masking was maintained or assessed. The parallel-group designation means the record characterizes the trial as comparing groups followed under their assigned treatment strategies, rather than as a crossover design.

The enrollment figure is the recorded study enrollment and should not be assumed to equal the number included in every outcome analysis. For the primary outcome, the registry record defines the population as all randomized patients, but does not give the number with evaluable Week 12 diary data or the number included in a numerical result. The record also does not report a sample-size justification, allocation ratio, or details of randomization beyond the randomized designation.

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.

Treatment Cycle 1

Treatment Cycle 2

Analysis population for the primary outcome, as defined in the registry: Intent-to-treat population included all randomized patients.

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 in Number of Daily Episodes of Urinary Incontinence, measured over Baseline, Week 12.

The primary endpoint is change from baseline in the number of daily episodes of urinary incontinence, measured at Baseline and Week 12. A urinary incontinence episode is defined as involuntary loss of urine recorded in a patient bladder diary during the 3 days before each of those study visits. The outcome is expressed as a mean, with standard deviation identified as the measure of dispersion.

Change from baseline compares a participant’s recorded episode frequency at follow-up with that participant’s own baseline frequency. The registry record explicitly states that a negative change indicates a reduction in episodes and describes that direction as improvement. This makes the sign of the change important when reading any group result: a negative mean change represents a decline in recorded episodes, while a positive mean change represents an increase. That interpretation describes the endpoint scale and does not establish whether a treatment effect is present.

Daily episode frequency is a direct measure of the symptom targeted by the study’s stated purpose. A bladder diary allows the outcome to be based on repeated participant records over the specified three-day periods rather than on a single recollection at the visit. In general, diary-based endpoints can characterize frequency during the recorded days, but their interpretation depends on diary completion and the analysis rules. Those rules, including how incomplete diaries were handled, are not reported in the registry record.

The registry record identifies the intent-to-treat population as all randomized patients. It does not provide the group means, standard deviations, estimated between-group contrast, confidence interval, or p-value for the primary endpoint. It also notes that the primary outcome has several categories or time points and was not reduced to one comparison. As a result, the outcome definition is available, but the numerical treatment comparison cannot be reconstructed from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a continuous measure: change from baseline in the number of daily urinary incontinence episodes. The registry record specifies the mean as the outcome parameter and standard deviation as the dispersion measure. A mean gives the arithmetic average on the recorded scale; a standard deviation describes how spread out individual measurements are around that average. These statistics have different roles. The mean describes the group’s central outcome, while the standard deviation describes variability among participants. The record contains no primary-outcome means or standard deviations, so neither can be interpreted numerically for this trial.

What does change from baseline represent?

For each participant, change from baseline represents the follow-up measurement relative to the baseline measurement. The endpoint uses diary records from the 3 days before Baseline and the 3 days before Week 12. As stated in the registry record, a negative number change indicates a reduction in episodes. When group averages are reported, their signs should be interpreted using that definition. The difference between group means would then describe the contrast in average change, but no such contrast is reported in the registry outcome information.

In general, analyzing change from baseline can account for participants’ starting levels by focusing on how their measurements move over follow-up. The statistical interpretation still depends on the chosen model, the handling of missing measurements, and the population included. The registry record does not report the primary-outcome model or give sufficient outcome statistics to determine how the comparison was estimated.

What would an interval estimate add?

In general, a confidence interval conveys uncertainty around an estimated effect by giving a range of values compatible with the data and the assumptions of the analysis. A narrow interval indicates greater precision than a wide interval, although precision alone does not establish clinical importance. A confidence interval for a difference in mean change would be interpreted on the same scale as the endpoint. No such interval is reported for the primary outcome in the registry record.

A p-value is a measure of how unusual the observed data, or data more extreme, would be under a specified null model. It does not express the probability that the null hypothesis is true, and it does not measure the size or importance of an effect. The registry record does not report a p-value for the primary outcome or list a primary statistical analysis. The record reports zero analyses in its outcome analysis information, so there is no posted analysis result to interpret.

Why can variability matter?

In general, variability affects how precisely a group mean or between-group contrast can be estimated. If participant outcomes vary considerably, an estimate may be less precise than one based on outcomes that are more tightly clustered, all else being equal. The standard deviation is one way to describe that variation for a continuous outcome. It is not itself an estimate of treatment effect, and it should not be confused with a standard error, which describes uncertainty in an estimated statistic. The registry record names standard deviation as the dispersion measure but gives no numerical value.

Some count outcomes can show greater variability than a simple statistical model assumes. In general, over-dispersion means the observed variability exceeds the model’s expectation; ignoring it can make uncertainty estimates too small. Whether over-dispersion was assessed or whether a count-specific model was used is not reported in the registry record. The endpoint is described as a mean of a continuous measure, and no model details are available to determine how the count-like episode data were analyzed.

How should the design be considered?

Randomization is generally used to reduce systematic baseline differences between assigned groups. Masking can reduce bias related to knowledge of assignment, and parallel-group designs compare groups followed under their assigned strategies. The record identifies the study as randomized, quadruple-masked, and parallel. It does not describe the randomization procedure, what roles were masked, or whether masking was successful. These design labels should therefore be treated as recorded characteristics, not as proof that every potential source of bias was eliminated.

The treatment descriptions also matter to the estimand, meaning the exact treatment contrast that an analysis aims to estimate. The onabotulinumtoxinA group is described as receiving an initial injection and a repeat injection if applicable; the placebo/onabotulinumtoxinA group is described as receiving placebo initially and onabotulinumtoxinA later if applicable. The record does not explain the conditions for later injections or specify whether the primary comparison reflects assignment at the initial injection, treatment received over time, or another analysis strategy. The intended statistical estimand is not reported in the registry record.

How do planning calculations differ from observed results?

In general, sample-size planning uses assumptions about the effect to detect, variability, significance level, allocation, and analysis method. A planning calculation is prospective or illustrative; it is not evidence that a study had a particular probability of detecting an effect after its results were observed. The registry record describes a planning illustration based on a fraction of the observed effect, with a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It states that non-time-to-event planning results are expressed as participants per arm. The numerical planning estimates and the observed effect needed to interpret them are not reported in the registry record.

Accordingly, the methods information supports general explanation of how an analysis of a continuous change outcome could be read, but not an account of the analysis actually conducted. The primary comparison, its uncertainty, its p-value, and details of the model and missing-data approach are not reported in the registry record. General statistical principles should not be mistaken for trial-specific methods or results.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists three outcome measures: the primary change in daily urinary incontinence episodes, change in daily micturition episodes, and change in volume voided per micturition. It also indicates that the primary outcome has several categories or time points and was not reduced to one comparison. The record does not identify a single primary contrast for interpretation or report an analysis result. A count of listed outcomes is not itself evidence of a multiplicity adjustment.

In general, testing multiple outcomes, time points, or comparisons can increase the chance of at least one apparently notable result if each is assessed independently. Statistical plans may address this by defining a hierarchy, adjusting significance thresholds, or treating some analyses as exploratory. Which approach was planned or used is not reported in the registry record. No adjustment method, testing hierarchy, or prespecified analysis sequence is described in the available information.

The primary endpoint population is defined as the intent-to-treat population, including all randomized patients. This definition identifies the intended population, but it does not state how participants without Week 12 diary measurements were handled. The number with observed endpoint data, reasons for missing data, imputation procedures, sensitivity analyses, and assumptions about missingness are not reported in the registry record. These details matter because missing outcomes can affect both the estimate and its uncertainty, depending on why data are absent and how the analysis handles them.

The registry record reports zero outcome analyses. Consequently, no analysis population beyond the stated intent-to-treat definition, missing-data procedure, or multiplicity strategy can be inferred from a posted primary result. The absence of these details limits the ability to assess how robust any numerical comparison would be, but does not establish that a particular method was or was not used outside the registry record.

11. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: osteoarthritis (1.1%), dehydration (0.7%), pneumonia (0.7%), depression (0.7%), coronary artery disease (0.4%).

The registry record reports serious adverse events for 18 of 278 participants at risk in the onabotulinumtoxinA group and 16 of 272 at risk in the placebo/onabotulinumtoxinA group. It reports other adverse events for 155 of 278 and 79 of 272, respectively. These are recorded counts with their stated denominators. They are not estimates of a causal treatment effect, and the registry information does not provide a statistical comparison or uncertainty interval for these counts.

The serious adverse event terms listed with percentages are osteoarthritis, 1.1%; dehydration, 0.7%; pneumonia, 0.7%; depression, 0.7%; coronary artery disease, 0.4%; and angina pectoris, 0.4%. The record does not provide enough detail in the available information to establish whether these terms were judged related to treatment, how event severity was classified, or whether participants could contribute more than one event. The listed percentages should be read as reported, not recalculated or treated as mutually exclusive categories.

Deaths are not reported in the registry record. The safety summaries do not establish that an event was caused by an assigned treatment, and differences in raw counts alone do not account for follow-up, event recurrence, or other relevant factors. The treatment descriptions include a possible later injection, but the record does not state how exposure over time relates to these safety summaries. These figures describe the posted safety information without establishing comparative safety.

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

The registry record establishes that this was a randomized, quadruple-masked, parallel-group Phase 3 study of onabotulinumtoxinA in patients with idiopathic overactive bladder with urinary incontinence. It describes an initial onabotulinumtoxinA injection in one group and an initial normal-saline placebo injection in the other, with later onabotulinumtoxinA injections described as applicable. The stated primary endpoint is change in daily urinary incontinence episodes from baseline to Week 12, measured through bladder diary records.

What the record does not establish is the size or direction of the primary treatment comparison. The primary means, standard deviations, between-group estimate, confidence interval, and p-value are not reported. The record notes that the primary outcome involved several categories or time points and was not reduced to one comparison. Therefore, the endpoint definition and design description cannot be used to infer a numerical effect or its precision.

In general, a randomized design can support a comparison between assigned groups when the analysis is appropriately conducted, but randomization does not make the outcome estimate known in the absence of reported results. Masking may reduce some biases, but the registry record does not describe how it was implemented or maintained. The design labels are not substitutes for details about the analysis population, missing data, model, or treatment contrast.

The record also lists two secondary outcomes and provides adverse-event counts and serious-event terms. Those entries describe which outcomes and safety information were recorded, but do not answer the primary efficacy question. The adverse-event figures are counts with denominators, not adjusted comparisons or proof of treatment causation. Deaths are not reported in the registry record. No conclusion about the balance of benefit and harm can be drawn from the listed information alone.

The practical statistical meaning is therefore bounded: the registry record documents a trial design and defines an outcome that could be used to compare changes in symptom frequency. It does not provide the numerical outcome analysis needed to judge the magnitude, uncertainty, or statistical compatibility of a treatment difference. The missing analysis information should not be filled in by assumptions about what the protocol might have specified or what results might have been observed.

13. Why This Trial Matters Statistically

This trial is statistically notable for the gap between a detailed outcome definition and the absence of a posted numerical primary comparison. The registry record identifies a diary-based continuous endpoint, its measurement windows, its summary parameter, and the direction that represents a reduction in episodes. Those details establish what the primary outcome was intended to represent. Without group summaries and an estimated contrast, however, they do not show how the groups differed.

The design information is also relevant to statistical interpretation. Randomization, quadruple masking, and a parallel-group structure are features intended to support a credible comparison. Yet interpretation still requires knowing which participants contributed endpoint data, how missing diary records were treated, and which treatment contrast was estimated. The registry record defines the intent-to-treat population but does not report the outcome analysis or these supporting details.

The record’s note that the primary outcome has several categories or time points and was not reduced to one comparison highlights why a clearly identified estimand matters. If there is more than one plausible time point or comparison, readers need to know which one answers the primary question and how other comparisons were handled. The registry record does not report that selection or a multiplicity strategy.

Safety reporting presents a separate statistical issue. Serious and other adverse-event counts are available with at-risk denominators, along with selected serious-event terms and percentages. These figures are descriptive. Without information on event definitions, exposure over time, attribution, and comparative analysis, they do not establish causal differences. The endpoint and safety summaries therefore illustrate distinct evidence needs: efficacy requires a defined and quantified outcome contrast, while safety interpretation requires context for event ascertainment and exposure.

The central statistical lesson is that design labels and outcome definitions are necessary but insufficient for evaluating a trial’s findings. Estimates, uncertainty, analysis populations, and transparent handling of missing outcomes are needed to understand what the data show and how precisely. In this record, those elements are not reported for the primary endpoint, so the appropriate interpretation remains limited to the documented design and measures.

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.

A trial-specific limitation of the registry information is that it describes the primary endpoint without reporting its numerical results. There are no group means or standard deviations for change in daily urinary incontinence episodes, and no estimated between-group comparison, confidence interval, or p-value. The registry record also states that the outcome has several categories or time points and was not reduced to one comparison, leaving the intended primary contrast unclear from the posted outcome information.

The endpoint depends on patient bladder diary entries for the 3 days before Baseline and Week 12. The record defines an episode and the relevant windows, but does not report diary completion, the number of participants with usable records, or procedures for incomplete diaries. The missing-data strategy and sensitivity analyses are not reported in the registry record. These omissions limit assessment of how representative the analyzed outcomes may be.

The treatment descriptions include a later injection if applicable in each group, with onabotulinumtoxinA specified for the later injection in both. The conditions governing that injection, the number receiving it, and the analysis strategy for treatment received over time are not reported in the registry record. This makes it difficult to identify from the registry information alone the exact treatment contrast represented by an eventual outcome analysis.

Although the study is identified as randomized and quadruple-masked, the randomization procedure and masking details are not reported. The statistical model, multiplicity handling, sample-size justification, and primary analysis plan are also not reported in the registry record. Safety information is descriptive and does not include a posted comparative analysis; deaths are not reported. These record-specific gaps constrain interpretation without establishing that the unreported procedures were absent from the full study documentation.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Study of Botulinum Toxin Type A for the Treatment of Patients With Idiopathic Overactive Bladder With Urinary Incontinence — NCT00910845.
• Registry record last updated 2013-03-05; status last verified 2013-01.
• Results first posted 2013-03-05.
• 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.

18. Record Summary

NCT00910845 is a completed Phase 3 randomized, quadruple-masked, parallel-group study sponsored by Allergan. The record gives enrollment as 557, a start of 2009-09, and primary completion in 2011-07. The study concerned idiopathic overactive bladder with urinary incontinence.

The primary endpoint was change from baseline in daily urinary incontinence episodes at Week 12, measured using bladder diaries. A negative change indicates a reduction. The record defines the primary population as all randomized patients but does not report a numerical primary comparison, confidence interval, or p-value. It lists change in daily micturition episodes and change in volume voided per micturition as secondary outcomes.

Safety entries include serious and other adverse-event counts by group and selected serious-event terms. Deaths are not reported in the registry record. The analysis model, missing-data approach, multiplicity strategy, and sample-size justification are not reported in the registry record.