Safety and Efficacy Study of Transdermal Oxybutynin to Treat Overactive Bladder With a Neurological Condition: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy Study of Transdermal Oxybutynin to Treat Overactive Bladder With a Neurological Condition (NCT00224016), a randomized phase 4 study. The primary outcome is Average Catheterization Urine Volume.

2. Clinical Question

The clinical question concerns a measurable aspect of bladder function in children with detrusor overactivity and a neurological condition. Catheterization yields a volume measurement, so the primary endpoint is continuous rather than a count or a time-to-event outcome. The planned comparison concerns two routes of administration for oxybutynin. Because both arms received oxybutynin, the trial can address their comparative outcomes as recorded, but it does not establish how either arm compares with an untreated or placebo group.

The record reports 57 participants enrolled and labels the allocation randomized. It does not report the number analyzed in each arm for the primary endpoint, the baseline and follow-up means, or the estimated difference between arms. Consequently, the clinical question can be described from the registered design and endpoint, but the size and precision of the observed comparison cannot be assessed from the registry results recorded.

3. Trial Design

This was a Phase 4, randomized, parallel-group, open-label, active-controlled study sponsored by Watson Pharmaceuticals. The official title describes a multicenter study evaluating safety, efficacy, and pharmacokinetics of oxybutynin transdermal systems in pediatric patients. The registry lists detrusor hyperreflexia as the condition. The brief summary describes children with a neurological condition contributing to overactive bladder.

One group received oxybutynin through a transdermal system at 1.3 mg/day, 2.6 mg/day, or 3.9 mg/day. The other received oral oxybutynin at 5 to 15 mg/day, as immediate-release or extended-release tablets or syrup. The official title refers to dose titration, but the registry record does not report the titration schedule or how doses were selected. It also does not report details of the randomization procedure, allocation concealment, or the planned group sizes.

The study is described as open-label, meaning masking was not used. That design feature matters when interpreting outcomes that involve judgment or participant reporting, and it can also shape study conduct. The primary endpoint is a measured urine volume, but the record does not provide further details about measurement procedures or whether outcome assessment was masked.

The registry lists an enrollment of 57 and a completed status. The study start is recorded as 2004-12 and primary completion as 2007-04. Those dates describe the registry record; they do not by themselves establish when results were analyzed or posted. The registry record does not report the duration of follow-up beyond the primary endpoint timeframe, details of study sites, or reasons for any participant withdrawals.

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.

Titration Period

Reasons for not completing this period:

Maintenance Period

Reasons for not completing this period:

Follow-Up Period

Analysis population for the primary outcome, as defined in the registry: Modified intent-to-treat (mITT) population, Last Observation Carried Forward (LOCF) imputation

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 Average Catheterization Urine Volume, measured over 14 weeks.

The primary endpoint is change from baseline in average volume of urine collected by catheterization, measured in mL, with a 14 weeks timeframe. It is described as a mean with standard deviation. The specified analysis population is modified intent-to-treat, using last observation carried forward imputation.

A continuous volume measure can describe the amount collected rather than reducing the outcome to a simple yes-or-no event. Comparing change from baseline can account for where participants started, while the average gives a group-level summary. In general, the standard deviation describes the spread of individual measurements around the group mean; it is not the uncertainty of the estimated mean or of a comparison between groups.

Catheterization urine volume is used in this trial as a measure related to bladder function in the studied population. The registry record does not explain the clinical interpretation of particular changes, specify a threshold considered important, or report the numerical change in either arm. It also does not report a between-group estimate or confidence interval. Thus, the endpoint and its intended timeframe are clear, but the size and precision of the observed result cannot be determined from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of endpoint is this? The primary outcome is continuous: it measures urine volume in mL. Its summary measure is a mean, with standard deviation as the measure of variability. In general, a mean describes the average observed value in a group, while a standard deviation describes how dispersed individual values are around that mean. These quantities answer different questions from a confidence interval, which expresses uncertainty around an estimate.

What does change from baseline mean? The endpoint is defined as change from baseline in average catheterization urine volume over 14 weeks. In general, analyzing change focuses on how a measure differs from its starting value, rather than reporting only a later measurement. To interpret such an analysis, readers need to know how the change was calculated and how it was compared between groups. The registry record supplies the endpoint definition but does not report the group-level values, the between-group estimate, or its uncertainty.

Why does the comparison matter? The two study arms received active oxybutynin regimens: a transdermal system and oral formulations. A comparison between active arms addresses the contrast between those assigned regimens, not the effect of oxybutynin compared with no treatment. Random allocation can help make groups comparable at the start, on average, but it does not remove the need to examine participant flow, baseline characteristics, outcome measurement, and the analysis actually used. Those details are not reported in the registry record.

What does open-label mean for interpretation? Open-label means the trial did not use masking, as reflected by the masking status of none. In general, lack of masking can influence expectations, reporting, care decisions, or assessment. The extent of any influence depends on the outcome and trial procedures. A measured volume may be less dependent on subjective judgment than a symptom rating, but collection and recording procedures still matter. The registry record does not report whether outcome assessors were masked or provide detailed measurement procedures, so the role of masking cannot be assessed further.

How should the standard deviation be read? In general, a standard deviation describes participant-to-participant spread in observed values. It is not a measure of the precision of a treatment contrast. The precision of a group comparison is usually conveyed by a standard error or confidence interval, together with the estimate itself. Neither the primary endpoint’s group-level standard deviations nor a comparison confidence interval is reported in the registry record, so variability and precision cannot be judged from the available primary results.

What is a confidence interval? General statistical explanation: a confidence interval gives a range of values compatible with the data and the method used to calculate it. A narrower interval indicates greater precision under that method; a wider interval indicates greater uncertainty. It is not reported in the registry record for the primary comparison. Without an estimate and interval, a reader cannot determine whether the result is precise enough to distinguish among materially different possible effects.

Why can over-dispersion matter? General statistical explanation: over-dispersion occurs when the variability in data is greater than a model assumes. It can make standard errors too small if the model does not account for the extra variability, leading to overly narrow confidence intervals or misleading tests. This concern is especially relevant to some count outcomes. The primary outcome in this trial is a continuous volume measure, and the registry record does not report a model or a finding of over-dispersion. No claim about its presence or handling is warranted.

What do the planning assumptions mean? The record describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. The target effect is specified as a fraction of the observed effect. In general, such calculations estimate the number of participants per arm that would be required for a chosen power under the assumed effect and method. They are planning illustrations, not observed power and not evidence that the original trial was designed with those assumptions. The registry record does not report the resulting planning values or the original sample-size justification.

What analysis details remain unknown? The primary outcome population is described as modified intent-to-treat, and the record specifies last observation carried forward imputation. It does not define which participants qualified for that population, report the number analyzed, or describe other analytic choices. The registry record reports zero analyses. It does not report the statistical model, handling of repeated observations, covariate adjustment, hypothesis-testing procedure, or confidence-interval method. These omissions limit the reproducibility and interpretation of any quantitative comparison.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is identified as change from baseline in average catheterization urine volume, and two secondary outcomes are named: catheterizations without leakage and urine volume after first awakening. The registry record does not report a multiplicity plan, such as how inference across outcomes or repeated assessments was controlled. It also does not report a hierarchy of hypotheses or which outcomes were considered confirmatory. Without those details, the chance of false-positive findings across multiple tests cannot be assessed.

The primary endpoint uses a modified intent-to-treat population and last observation carried forward imputation. In general, an analysis population definition determines which randomized participants contribute to an estimate, while an imputation method determines how missing measurements are represented in the analysis. Last observation carried forward carries an earlier measurement forward when a later one is missing. This relies on assumptions about what missing values would have been; it does not recover the unobserved measurement itself. Its suitability depends on the pattern and reasons for missingness and on how outcomes evolve over time.

The registry record does not report how many participants had missing primary measurements, why data were missing, whether missingness differed between arms, or whether sensitivity analyses were conducted. It also does not report an alternative analysis population or how deviations from assigned treatment were handled. These details are needed to judge the robustness of a result to missing data and analysis choices. The record describes the population and imputation approach, but the actual primary outcome analysis and its numerical results are not reported in 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: allergic reaction (6.2%), worsening abdominal pain (6.2%), thrombophlebitis (6.2%), vp shunt malfunction (6.2%), knee wound dehiscence (2.6%).

The registry lists serious adverse events for two groups. For Oxybutynin TDS, 6 of 39 participants at risk were affected; for oral oxybutynin, 3 of 16 were affected. The figures describe the recorded participants with serious adverse events, not the total number of distinct event episodes. The registry also reports other adverse events affecting 33 of 39 participants in the transdermal group and 12 of 16 in the oral group.

The listed serious-event terms and registry percentages are allergic reaction (6.2%), worsening abdominal pain (6.2%), thrombophlebitis (6.2%), VP shunt malfunction (6.2%), knee wound dehiscence (2.6%), and worsening dehydration (2.6%). The registry record does not identify the corresponding arm for each term in the information, nor does it clarify whether participants could contribute to more than one term. The listed percentages should therefore be read as event-term figures, not as a direct comparison of treatment groups.

These safety counts are descriptive. They do not by themselves establish that an event was caused by a treatment or that a difference between arms is meaningful. The deaths field is not reported in the registry record. Information about event timing, severity definitions, relatedness assessments, withdrawals due to events, and statistical comparisons is also not reported in the registry record.

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

The registry record establishes that a Phase 4 randomized, parallel-group, open-label study compared transdermal oxybutynin with oral oxybutynin in pediatric patients with detrusor overactivity. It identifies a continuous primary endpoint, the change from baseline in average catheterization urine volume, measured in mL over 14 weeks, in a modified intent-to-treat population with last observation carried forward imputation. This information describes what the study set out to assess and how its primary outcome was defined.

It does not establish the numerical outcome of that comparison. The primary means, standard deviations, change estimates, between-group estimate, confidence interval, and p-value are not reported in the registry record. Therefore, the direction, magnitude, and precision of the primary result cannot be judged. No conclusion about the comparative outcome should be inferred from the study’s completed status, enrollment, or stated objective alone.

The registry does report safety counts and serious-event terms. Those are descriptive observations in the recorded groups. They do not establish causation, and the information recorded does not support a complete comparison of event types by arm. Similarly, a randomized design can support comparative interpretation when implemented and analyzed appropriately, but the registry record does not supply enough methodological detail or primary results to assess the comparison quantitatively.

In general, a result’s meaning depends on its estimate, uncertainty, analysis population, missing-data handling, and clinical context. Here, the registry specifies an analysis population and imputation approach but does not report the outcome estimate or enough information to assess the sensitivity of the result to those choices. The record supports a description of the trial design and endpoint; it does not support a numerical conclusion about the primary comparison or a claim about the clinical importance of any change.

13. Why This Trial Matters Statistically

This trial illustrates why a registry entry needs to be read in two layers: the design description and the reported results. Design details can identify the population, assigned treatments, comparison, endpoint, and analysis population. They cannot replace the endpoint estimates needed to understand what the study observed. Here, the registry identifies a randomized active-control comparison in pediatric patients and defines a continuous urine-volume outcome, but the numerical primary results are not reported.

The distinction between within-group change and between-group comparison is especially important. In general, a change within one arm does not by itself establish how that arm compares with another. A comparative estimate, together with its uncertainty, is needed to characterize the difference between assigned regimens. The registry record does not report that estimate or its precision, so the trial’s main statistical contrast remains unevaluable from the recorded results.

The entry also makes visible questions that matter for interpretation: an open-label design, a modified intent-to-treat population, last observation carried forward imputation, and an active comparator. Each feature has a statistical or interpretive role, but the registry record lacks details needed to assess their implementation and consequences. The listed safety counts add descriptive information, while not resolving the missing primary comparison.

Finally, planning calculations should not be confused with observed evidence. The record describes sample-size illustrations based on an observed effect and specified assumptions, but such illustrations are not observed power. The original sample-size justification is not reported in the registry record. Taken together, this study is a useful example of how a clearly named endpoint and trial design can coexist with insufficiently reported results for quantitative interpretation.

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 for interpreting this trial from the registry record is the absence of numerical primary outcome results. The endpoint is defined, but arm-specific summaries and the between-group estimate are not reported. Without those values, the direction, magnitude, and precision of the main comparison cannot be assessed. The record also does not report a confidence interval or p-value for that comparison.

The primary analysis is described as modified intent-to-treat with last observation carried forward, but the record does not define the analysis population or report its size. Missing-data counts, reasons for missingness, withdrawals, and sensitivity analyses are not reported. This prevents assessment of how much the primary result might depend on the population definition or imputation assumptions.

Other design details are also limited. The registry describes randomization but does not report the randomization method, allocation concealment, group enrollment counts for the primary analysis, or baseline characteristics. It identifies the study as open-label but does not report whether outcome assessors were masked or give detailed procedures for collecting catheterization volume. The dose-titration procedure is not reported in the registry record.

The registry names secondary outcomes but does not report their numerical results or a multiplicity plan. Safety information includes participant counts and event terms, but the record does not give the arm associated with each listed serious-event term in the information, event timing, or relatedness assessments. The deaths field is not reported in the registry record. The original sample-size justification and detailed statistical analysis plan are also not reported.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Efficacy Study of Transdermal Oxybutynin to Treat Overactive Bladder With a Neurological Condition — NCT00224016.
• Registry record last updated 2012-02-09; status last verified 2012-02.
• Results first posted 2009-12-23.
• 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

NCT00224016 is a completed Phase 4 randomized, parallel-group, open-label, active-controlled study sponsored by Watson Pharmaceuticals. It enrolled 57 pediatric patients with detrusor overactivity, comparing oxybutynin transdermal system doses of 1.3 mg/day, 2.6 mg/day, or 3.9 mg/day with oral oxybutynin at 5 to 15 mg/day. The registry records a study start of 2004-12 and primary completion of 2007-04.

The primary endpoint was change from baseline in average catheterization urine volume over 14 weeks, summarized as a mean with standard deviation in a modified intent-to-treat population using last observation carried forward. Numerical primary outcome results are not reported in the registry record. Safety counts and several serious-event terms are listed, but the recorded information does not permit a full arm-specific interpretation of those terms.