Extended-Release Oxybutynin for the Treatment of Neurogenic Detrusor Overactivity: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Extended-Release Oxybutynin for the Treatment of Neurogenic Detrusor Overactivity (NCT01796548), a na phase 4 study. The primary outcome is Maximal Detrusor Pressure.

2. Clinical Question

3. Trial Design

The registry identifies this as a PHASE4 study of extended-release oxybutynin for neurogenic detrusor overactivity, with a planned enrollment of 17. It records the model as single group, allocation as NA, and masking as none. The listed intervention is oxybutynin extended-release, taken orally at a flexible daily dose of 10-30 mg using tablets containing 5, 10, or 15 milligram. No comparator is listed. As the registry notes, this is not a randomized comparison and any arms should not be treated as like-for-like control groups.

The stated study purpose includes evaluating effects and tolerability, with safety and quality-of-life assessment. The primary endpoint is maximal detrusor pressure at Week 12. Listed secondary outcomes include maximal cystometric capacity, detrusor leakpoint pressure, post-void residual urine volume, reflex volume, urge incontinence episodes, total incontinence episodes, the percentage of participants with no episodes of urge-urinary incontinence, and King Health Questionnaire score. These are outcome topics, not reported findings: numerical outcome analyses are not listed in the registry record.

The study start is recorded as 2008-12 and primary completion as 2010-12. Its status is terminated. The reason for termination, details of any changes to the study, and whether all planned assessments were completed are not reported in the registry record. The primary endpoint description specifies an intent-to-treat population, but the registry's single-group design information and its population wording do not explain how participants were assigned or how the analysis population was actually formed.

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: The Intent-to treat (ITT) population included all randomly assigned participants who received at least 1 dose of study medication and fulfilled all eligibility criteria.

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 Maximal Detrusor Pressure, measured over Week 12.

Maximal detrusor pressure is the primary endpoint, measured at Week 12 in centimeter of water. The registry describes it as the peak pressure in the bladder during the first involuntary contraction of the bladder muscle. It defines detrusor pressure as the portion of intravesical pressure generated by forces in the bladder wall, both passive and active, and says it was estimated by subtracting abdominal pressure from intravesical pressure.

This measure gives a pressure-based description of bladder muscle activity during an involuntary contraction. In general, a continuous endpoint such as pressure can be summarized by a mean and a measure of variability, as the registry's stated mean and standard-deviation format indicates. Such summaries can describe the observed distribution, but interpretation also depends on the number of observations, missing measurements, and the analysis method. Those details and the actual endpoint values are not reported in the registry record.

The endpoint is specified at a defined follow-up time, which identifies when the measurement was intended to be assessed. Without reported baseline and Week 12 values, a change estimate, or an uncertainty interval, the registry record does not establish the magnitude or precision of any difference over time.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary endpoint as a continuous measure and states that it is summarized using a mean and standard deviation. In general, a mean represents the arithmetic center of a set of measurements. A standard deviation describes how spread out individual measurements are around that mean. The mean alone does not show how variable participants' measurements were, and the standard deviation alone does not show the precision of the estimated mean. That precision also depends on how many observations contribute and on the analysis method. The registry record does not report the endpoint's mean, standard deviation, or analysis sample size.

What does a continuous endpoint summary tell the reader?

A summary of a continuous outcome can be useful for describing a group, but it does not by itself specify the treatment effect. For a single-group study, a mean at follow-up would describe measurements at that time. A comparison with baseline would require baseline data and a stated method for calculating change. A comparison against a control group would require an appropriate comparator and a between-group estimate. The registry record reports none of these numerical results for maximal detrusor pressure.

A confidence interval is, in general, an uncertainty summary around an estimated quantity. Its range reflects both the data and the statistical method used. A narrow interval indicates greater statistical precision than a wide interval, while neither width nor a p-value alone determines whether a difference matters clinically. No confidence interval is reported for the primary endpoint, and the registry does not list an inferential analysis.

Why does the single-group design matter?

With a single-group design, there is no listed concurrent control group against which to estimate a randomized treatment contrast. A change from an earlier measurement, if available, can be affected by factors other than the intervention, including natural variation, measurement conditions, and changes over time. These are general design considerations, not claims about what happened in this study. Because no baseline or follow-up result is reported, the registry does not permit an assessment of within-group change either.

The record gives allocation as NA and describes the model as single group. At the same time, its definition of the intent-to-treat population refers to randomly assigned participants who received at least one dose and met eligibility criteria. These statements do not explain how assignment operated in this study. The actual analysis population and participant flow are not reported in the registry record, so the population definition cannot be used to infer how many participants contributed to any endpoint analysis.

How should variability and over-dispersion be understood?

For a continuous measure, the standard deviation is one way to describe variation among observations. For event counts, variation can be greater than a simple statistical model expects; in general, this is called over-dispersion. If present, over-dispersion can make standard errors from an unsuitable model too small and uncertainty appear overstated in precision. This is a general statistical issue for count outcomes, not a finding about this study. The registry does not report event-count models, model diagnostics, or an analysis plan, so there is no basis for saying whether over-dispersion was assessed or relevant to any analysis.

The secondary outcomes include episode counts and a percentage-based outcome, as well as pressure, volume, capacity, and questionnaire measures. Different outcome types may require different summaries and models. In general, repeated observations, counts, percentages, and continuous measurements have distinct distributional features; methods should match the outcome and the way observations were collected. The registry names these outcomes but does not report their numerical distributions, analysis methods, or results. It is therefore not possible to evaluate whether the methods matched the observed data.

What do the planning assumptions mean?

The registry describes a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is expressed as a stated fraction of the observed effect. This is a planning framework, not evidence that the study was designed using those assumptions. The record also specifies that time-to-event planning values use total events, while other planning values use participants per arm. No trial-specific sample-size justification, target effect, or statistical plan is reported in the registry record. Since the study is recorded as single group and is not a randomized comparison, an equal-allocation two-arm illustration should not be read as a description of its actual design.

Planning sample sizes are conditional on assumptions about the effect and variability. In general, they are not observed power, and they do not establish that an observed result is reliable. A planning illustration based on an observed effect can also be difficult to interpret when the underlying outcome estimate is unavailable. The registry does not report the numerical primary endpoint result needed to assess such an effect in this case.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Oxybutynin")
n   <- c(15)
m   <- c(42.8)
sp  <- c(29.7)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Oxybutynin  15  42.800  29.700  26.353  59.247

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and multiple secondary outcomes, including pressure and volume measures, incontinence episode outcomes, a no-episode percentage, and a questionnaire score. Testing or estimating many outcomes raises a general multiplicity issue: the more questions examined, the greater the chance that at least one apparently noteworthy result may arise by chance when formal tests are used. Common approaches include identifying a primary analysis in advance, adjusting inferential thresholds, or interpreting secondary findings as exploratory. The registry record does not report a multiplicity strategy, a hierarchy among secondary outcomes, or an analysis plan, so it is not possible to determine how multiple outcomes were to be handled.

Missing-data methods are also not reported. The registry does not state how missing Week 12 pressure measurements, incomplete questionnaires, or unavailable episode records were handled. It does not report the number of observations available for any outcome, reasons for missingness, or sensitivity analyses. In general, excluding participants with missing measurements can change the population represented by an estimate; methods that account for missing data depend on assumptions that should be stated and examined. No such information is available in the registry record.

The primary endpoint description defines an intent-to-treat population as all randomly assigned participants who received at least one dose and fulfilled eligibility criteria. The study is also recorded as a single-group model with allocation NA. The record does not reconcile these descriptions or report the actual analysis population. It gives planned enrollment of 17, but does not state how many met the endpoint population definition or contributed primary endpoint measurements. The registry lists no analyses, so neither adherence to the stated population definition nor the treatment of missing observations can be assessed.

12. 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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: urinary tract infection (6.7%).

The adverse-event record lists Oxybutynin with 15 participants at risk for serious adverse events and 1 affected. For other adverse events, it lists 15 at risk and 12 affected. These are the registry's reported counts; they are not estimates of comparative risk because no control group is listed. The record also identifies urinary tract infection as the top serious adverse-event term, with 6.7% reported. This term-level figure should be read as the registry's entry, not as a comparison with another treatment or as evidence of causation.

Adverse-event counts describe what was recorded under the listed categories. They do not, on their own, establish that an event was caused by the intervention. The registry does not report event definitions, collection procedures, timing, severity details beyond the serious-event categorization, or an analysis relating events to dose or exposure. It also does not provide a comparator that could contextualize the counts.

Deaths are not reported in the registry record. The adverse-event entries should be interpreted alongside the study's planned enrollment of 17, but the reason that the adverse-event denominator is 15 is not reported. These safety entries do not fill the gap in the missing primary endpoint analyses and cannot establish a benefit-risk balance.

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

The registry record establishes the study's stated question and design features: a single-group, unmasked study of flexible-dose extended-release oxybutynin in participants with neurogenic detrusor overactivity, with maximal detrusor pressure at Week 12 identified as the primary endpoint. It also records a terminated status and limited adverse-event counts. These details describe what was registered, not an analyzed estimate of the treatment's effect.

No primary endpoint result is reported in the registry record. Without observed pressure values, a change estimate, a measure of uncertainty, or an inferential analysis, the magnitude and precision of any endpoint change cannot be described. The secondary outcome names likewise do not establish what was observed. The absence of reported analyses is not evidence that there was no change, no effect, or no safety concern; it means the registry record does not provide the outcome analyses needed to evaluate those questions.

The single-group design also limits interpretation. In general, a within-group observation cannot provide the same causal contrast as a well-conducted randomized comparison with a control group. Since no comparator is listed and no numerical outcome results are reported, the record cannot distinguish an intervention-related change from other explanations for a change over time.

The safety counts indicate that adverse events were recorded among participants at risk, including the serious event count and the listed urinary tract infection term. They do not show comparative risk or establish causation. The registry does not report the reason for termination, details of missing data, or an analysis plan that would resolve these uncertainties. The appropriate reading is therefore limited: the record describes a planned clinical question and study structure, but does not provide enough outcome information to determine the observed primary endpoint result or its statistical precision.

14. Why This Trial Matters Statistically

This trial is statistically instructive because its registry record distinguishes a clearly named clinical endpoint from an available numerical result. Maximal detrusor pressure at Week 12 is defined in measurement terms, and the intended summary format is specified as a mean and standard deviation. Yet no outcome analyses are listed. This illustrates why a protocol question and endpoint definition are not substitutes for the estimates needed to interpret a study.

It also illustrates the importance of design when interpreting treatment effects. The registry records a single-group model, no masking, and allocation as NA; it does not list a comparator. A treatment effect is usually most directly interpreted through an appropriate contrast. Without a comparator, any observed change would require careful qualification, and no numerical change is reported at all.

The record also highlights the need for clear population accounting. Planned enrollment is 17, while safety reporting lists 15 at risk in each event grouping. The registry does not explain the relationship between these entries, provide outcome-specific denominators, or show participant flow. In addition, the primary endpoint population description refers to random assignment even though the overall design is recorded as single group. These details matter because readers need to know which participants contributed to each estimate and how missing measurements were handled.

Finally, the presence of several secondary outcomes makes a stated analysis plan important. Multiplicity, missing data, and endpoint-specific methods affect how results should be read. Those methods are not reported in the registry record. The case therefore demonstrates that design labels, endpoint definitions, and adverse-event counts can inform a statistical reading, while the absence of analyzed outcomes prevents conclusions about endpoint magnitude or precision.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several trial-specific limitations restrict interpretation. The registry reports a single-group design and no comparator, so there is no listed control group for a randomized comparison. Masking is recorded as none. These design features affect how an observed change could be interpreted, although the registry does not report numerical outcome changes to assess.

The study status is terminated, but the reason for termination is not reported in the registry record. It is also not reported whether termination affected planned follow-up, endpoint collection, or analysis. The recorded planned enrollment is 17, while the safety entries list 15 participants at risk; the registry does not explain that difference or provide a participant flow account. Outcome-specific denominators are not reported.

The primary endpoint is described, but its numerical results and analyses are absent. The registry does not report baseline or Week 12 values, change estimates, standard deviations, confidence intervals, or inferential results. Secondary outcome results are also not reported. Without these data, neither effect magnitude nor statistical precision can be evaluated.

The registry's population description refers to randomly assigned eligible participants who received at least one dose, but the overall design is recorded as single group and allocation as NA. How this definition was applied is not reported. Missing-data procedures, analysis populations, protocol deviations, and multiplicity handling are also not reported in the registry record. These gaps prevent assessment of whether the analyzed population, if any, followed the stated definition or whether the outcome methods were appropriate.

The adverse-event entries offer limited counts but no comparator, timing, event-collection details, or causal assessment. The reason for termination and the deaths entry are not reported. Taken together, these limitations mean the registry record can describe the trial's stated aims and selected safety entries, but cannot support a detailed statistical evaluation of the primary endpoint or a comparative benefit-risk interpretation.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Extended-Release Oxybutynin for the Treatment of Neurogenic Detrusor Overactivity — NCT01796548.
• Registry record last updated 2013-11-26; status last verified 2013-10.
• Results first posted 2013-07-31.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT01796548 is a PHASE4, single-group study of flexible-dose extended-release oxybutynin for neurogenic detrusor overactivity. The registry lists planned enrollment of 17, no masking, and a terminated status. The study start is recorded as 2008-12, with primary completion at 2010-12.

Maximal detrusor pressure at Week 12 is the primary endpoint. The registry record lists secondary pressure, volume, incontinence, and quality-of-life outcomes, but no outcome analyses. The primary endpoint's numerical result and its precision are not reported in the registry record. Safety entries list 1 serious adverse-event-affected participant among 15 at risk, 12 affected by other adverse events among 15 at risk, and urinary tract infection at 6.7% among the top serious terms. No comparator is listed, and the reason for termination is not reported.