Extension Study of Vibegron in Men With Overactive Bladder (OAB) Symptoms on Pharmacological Therapy for Benign Prostatic Hyperplasia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Extension Study of Vibegron in Men With Overactive Bladder (OAB) Symptoms on Pharmacological Therapy for Benign Prostatic Hyperplasia (NCT04103450), a na phase 3 study. The primary outcome is Number of Participants With Any Serious Adverse Event, and Treatment Emergent Adverse Event (>5%).

2. Clinical Question

The central statistical question is descriptive: what adverse events were recorded among participants receiving vibegron in this extension? The primary endpoint counts participants with qualifying safety events rather than measuring a treatment difference against a concurrent randomized control. The symptom outcomes extend the study’s description to changes from baseline at Week 52, but their numerical results are not reported in the registry record.

The study enrolled 276 participants. The safety figures are grouped by the registry’s 52-Week Vibegron Group and 28-Week Vibegron Group labels. Those labels do not make the groups exchangeable: the study was open label, allocation is listed as NA, and the registry explicitly cautions that this is not a randomized comparison. The results therefore address observed event counts in the listed groups, not whether vibegron caused more or fewer events than an alternative treatment.

3. Trial Design

This was a Phase 3, open-label extension study of vibegron in men with overactive bladder symptoms who were receiving pharmacological therapy for benign prostatic hyperplasia. Participants had previously completed treatment in Study URO-901-3005 (NCT03902080). The registry describes the extension as assessing long-term safety and efficacy, with vibegron dosed for up to 52 weeks.

The intervention was vibegron 75 milligrams orally once daily. The record lists a 52-Week Vibegron Group and a 28-Week Vibegron Group. It does not describe a randomized allocation process: allocation is NA, masking is NONE, and the model is SINGLE GROUP. The registry cautions that this is not a randomized comparison and that the arms are not a like-for-like control comparison. Accordingly, group differences in the posted counts should not be read as an estimate of a causal treatment effect.

The study began on 2019-09-19, reached primary completion on 2022-07-29, and has COMPLETED status. Enrollment was 276. The primary safety timeframe is up to Week 52. Adverse-event collection is described as starting when each participant provided informed consent in the parent study and continuing through the extension follow-up visit, approximately 5 days after the last dose of study drug. The record also specifies that, for the 28-Week Vibegron Group, adverse events recorded before starting vibegron, while receiving placebo in the parent study, were reported as adverse events in the parent study.

The record identifies the safety population as the SAF-Ext Population. It names secondary outcomes concerning changes from baseline at Week 52 in urinary symptoms and voided volume. Numerical results for those secondary outcomes are not reported in the registry record. A detailed protocol, rationale for the enrollment target, and further account of the study’s analysis plan are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: A total of 276 participants who completed Study URO-901-3005 (NCT03902080) were enrolled in Study URO-901-3006 (NCT04103450) and received at least 1 dose of open-label study drug (vibegron).

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: SAF-Ext Population.

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: Safety Analysis Set Extension (SAF-Ext) consists of all participants randomized in the parent study who: a. completed the 24-week treatment period in the parent study, and b. enrolled into, and received at least 1 dose of vibegron in, this extension study.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Any Serious Adverse Event, and Treatment Emergent Adverse Event (>5%), measured over Up to Week 52.

The primary endpoint counts participants with any serious adverse event and treatment-emergent adverse events occurring in more than 5% of participants. Its stated timeframe is up to Week 52, and the endpoint unit is participants. This is a safety endpoint: it describes how many participants experienced specified kinds of adverse events during the study’s observation period, rather than measuring a change in a symptom score or a difference in efficacy between treatment groups.

The registry defines a serious adverse event as an untoward medical occurrence that, at any dose, results in death, is life-threatening, requires inpatient hospitalization or prolongs existing hospitalization, results in persistent disability or incapacity, is a congenital anomaly or birth defect, is associated with liver injury and impaired liver function, or meets another situation based on medical or scientific judgment. A treatment-emergent adverse event is defined as an event occurring on or after the first dose of study drug and no more than 30 days after the last dose. The endpoint description states that treatment-emergent events occurring in more than 5% of participants are reported.

Counting participants is useful for describing how many people experienced an event, but the count alone does not describe severity beyond the endpoint’s classification, duration, or relationship to treatment. The registry’s safety counts are reported by group. Because the study is not a randomized comparison, the counts do not establish that vibegron caused an event or that one group had a higher treatment-related risk. The registry record does not report a statistical comparison or an adjusted estimate for this endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical information in the registry is primarily descriptive. The safety endpoint is expressed as counts of participants with events, and the adverse-event listing gives denominators for each group. A participant count answers how many people in the specified safety population had a recorded event. It is not the same as a count of all event episodes: one participant may experience more than one event, while the endpoint wording focuses on participants with any qualifying event.

What does a count of participants tell the reader?

A count is a direct description of the recorded events in the listed population. To interpret it, the denominator and the definition of the event matter. The registry lists 142 participants at risk in the 52-Week Vibegron Group and 134 in the 28-Week Vibegron Group for both serious and other adverse-event counts. The serious-event figures are 2 and 3, and the other-event figures are 17 and 3. These are observed counts, not model-based estimates. No confidence intervals, hypothesis tests, or adjusted comparisons are reported for the counts in the registry record.

A confidence interval, in general, expresses statistical uncertainty around an estimated quantity under the assumptions of the method used. It can help show that a point estimate is not exact, but it does not account automatically for bias, incomplete event capture, or a non-comparable study design. No confidence interval for the posted safety counts is reported in the registry record. No inferential claim should be substituted for the absent interval or analysis.

Why does the design constrain comparison?

In a randomized comparison, allocation is used to make treatment groups comparable in expectation, supporting an estimate of the difference attributable to treatment under the study assumptions. This study is open label, has allocation listed as NA, and is described as a single-group model. The registry includes two duration-labeled vibegron groups but explicitly states that they are not a randomized, like-for-like control comparison. As a result, a numerical contrast between their event counts would not isolate a treatment effect. There is no posted adjusted estimate to account for group differences.

General statistical principle: unequal or differing observation periods can affect the opportunity to record events. The labels 52-Week Vibegron Group and 28-Week Vibegron Group indicate different durations, while the primary endpoint timeframe is up to Week 52. The record does not give exposure-adjusted event rates or enough detail to quantify how observation time differs for each participant. The counts therefore should be read in the context of the study’s stated collection period, not as equivalent time-at-risk rates.

How should the event definitions be read?

The serious adverse-event definition includes outcomes such as death, life-threatening events, inpatient hospitalization or its prolongation, persistent disability or incapacity, congenital anomaly or birth defect, and events associated with liver injury and impaired liver function. It also allows other situations based on medical or scientific judgment. A treatment-emergent adverse event is defined by its timing relative to study drug: on or after the first dose and no more than 30 days after the last dose. The primary endpoint description reports treatment-emergent events occurring in more than 5% of participants. These are registry definitions; they do not by themselves establish whether an event was caused by treatment.

The registry’s collection description begins when each participant provided informed consent in the parent study and continues through the extension follow-up visit, approximately 5 days after the last dose. It separately notes that events before vibegron initiation in the 28-Week Vibegron Group, while receiving placebo in the parent study, were reported as parent-study events. This means timing and study attribution are relevant to how the safety record is understood. Further detail on event adjudication or coding is not reported in the registry record.

What are the planning illustrations?

Planning sample-size illustrations are not observed study results and are not observed power. The stated assumptions for such illustrations are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. Time-to-event illustrations use the total number of events; other illustrations use participants per arm. These assumptions describe the planning calculations, not the design of this extension study. The registry record does not report the trial’s own sample-size justification, and no numerical planning estimates are included in the registry record for this description.

General statistical principle: over-dispersion matters when count data vary more than an assumed statistical model expects. If a model assumes less variability than is present, uncertainty can be understated and inference can become too confident. The registry record does not report a count model, an over-dispersion assessment, or a model-based analysis for the safety endpoint. The posted event counts should therefore be treated as descriptive rather than as outputs of such a model.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 13 outcome measures and names secondary outcomes for changes from baseline at Week 52 in average micturition episodes per day, urgency episodes per day, nocturia episodes per night, urge urinary incontinence episodes per day among participants with incontinence, IPSS storage score, and volume voided per micturition. Numerical results for these secondary outcomes are not reported in the registry record. A multiplicity adjustment or strategy for interpreting several outcomes is also not reported in the registry record.

Multiplicity is a general statistical concern when many outcomes or comparisons are examined: the chance of finding an apparently unusual result can increase across repeated tests. The appropriate approach depends on the prespecified questions and analysis plan. The record does not report whether any outcomes were prioritized beyond identifying the primary safety endpoint, whether formal tests were planned for secondary outcomes, or how multiple tests would be handled. No interim analyses or stopping rules are reported in the registry record.

Missing-data methods are not reported in the registry record. The registry entries do not describe how missing symptom measurements, withdrawals, or incomplete follow-up were handled, nor do they provide outcome-specific analysis denominators for the Week 52 measures. Those omissions limit assessment of whether the reported or unreported outcomes would represent all enrolled participants or a subset with available measurements.

The primary endpoint identifies the SAF-Ext Population, but other analysis populations and their definitions are not reported in the registry record. The record lists no statistical analyses. It does not provide a detailed statistical analysis plan, a sample-size justification, or a method for handling missing safety or efficacy data. Without these details, the precision and analysis population for outcomes beyond the posted safety counts cannot be assessed.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: atrial fibrillation (0.7%), cervical vertebral fracture (0.7%), non-cardiac chest pain (0.7%), angina pectoris (0.7%), chest pain (0.7%).

For serious adverse events, the registry lists 2 participants among 142 in the 52-Week Vibegron Group and 3 among 134 in the 28-Week Vibegron Group. Deaths are listed as 0 in both groups. The other adverse-event counts are 17 among 142 and 3 among 134, respectively. These are counts of participants, not a comparative estimate of treatment effect.

The serious adverse-event terms listed are atrial fibrillation, cervical vertebral fracture, non-cardiac chest pain, angina pectoris, and chest pain; each is reported as 0.7%. The registry does not attach group-specific counts to that list in the record, so the terms cannot be allocated to either group from this information alone.

In general, safety counts depend on event definitions, follow-up, and the population being observed. The registry’s collection period starts at informed consent in the parent study and extends through follow-up after the last dose. The record also states that events before vibegron initiation in the 28-Week Vibegron Group, while receiving placebo in the parent study, were reported in the parent study. The counts should therefore be interpreted according to those recording conventions. Because the groups are not a randomized comparison, their counts do not show whether treatment caused an event or establish a relative safety difference.

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

The posted data describe adverse events recorded during an open-label extension in men with overactive bladder symptoms receiving pharmacological therapy for benign prostatic hyperplasia. They show the serious-event and other adverse-event participant counts for the two registry-listed groups, as well as zero deaths in each group. The record also lists several serious adverse-event terms, each reported as 0.7%.

These observations do not establish that vibegron caused or prevented any particular event. There is no randomized control group, and the registry explicitly cautions that the two groups are not a like-for-like control comparison. The counts do not account for possible differences between groups or provide an adjusted comparison. They also should not be interpreted as equivalent rates because the groups are identified by different treatment durations and the registry does not report exposure-adjusted estimates.

The study’s stated purpose includes long-term safety and efficacy assessment, and the registry names symptom outcomes at Week 52. However, numerical results for those symptom outcomes are not reported in the registry record. The registry entries therefore do not establish the extent of symptom change, its precision, or how it varied among participants. There are no posted confidence intervals or statistical comparisons for those outcomes in the record described.

General statistical principle: an observed count is evidence about what was recorded in a particular study population and observation period; it is not, by itself, a causal estimate. A causal interpretation requires suitable comparison and analysis assumptions, which cannot be inferred from the event counts alone. The registry record also does not report enough information to assess missing-data handling, outcome multiplicity, or the precision of unreported symptom estimates.

The appropriate reading is limited but useful: these counts characterize recorded safety events in the extension’s listed groups. They should not be translated into a claim that the treatment is effective or ineffective, or into a treatment recommendation. The registry record does not report a randomized efficacy comparison or sufficient statistical detail to support such conclusions.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of the difference between describing events and estimating a treatment effect. It records safety outcomes during an open-label extension, but the registry does not identify a randomized control group. The two listed groups therefore provide descriptive context, not a direct experiment comparing vibegron with an alternative treatment.

The distinction matters because event counts can appear directly comparable while the underlying groups, treatment durations, and observation histories are not established as equivalent. Here, the registry labels the groups by duration and explicitly warns against treating them as a like-for-like randomized comparison. Reporting the counts alongside that design information helps prevent an unsupported causal interpretation.

The endpoint definitions also shape what the counts mean. Serious adverse events include a range of specified outcomes, while treatment-emergent events are defined by their timing relative to study drug and the endpoint describes events occurring in more than 5% of participants. The registry’s account of event capture across the parent study and extension, including the handling of events before vibegron initiation in the 28-Week Vibegron Group, is relevant context for understanding the safety record.

Finally, the contrast between posted safety counts and unreported numerical results for the named symptom outcomes illustrates why readers need outcome-specific results, uncertainty estimates, and analysis details. The registry record does not report those details for the symptom measures, nor does it report a multiplicity approach or missing-data methods. Recognizing what the record does and does not establish is an essential part of interpreting clinical trial statistics.

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 principal limitation for comparative interpretation is the study design. It is open label, allocation is listed as NA, and the registry explicitly states that this is not a randomized comparison and that the arms are not a like-for-like control comparison. The safety counts can describe what was recorded in each group but cannot establish a causal difference between groups.

The group labels indicate 52-week and 28-week vibegron periods, while the primary safety timeframe is up to Week 52. The registry does not provide exposure-adjusted event rates or participant-level time at risk. It also explains that event collection spans the parent study and extension, with a specific attribution convention for events before vibegron initiation in the 28-Week Vibegron Group. These features require care when interpreting raw counts across groups.

Numerical results for the listed Week 52 symptom outcomes are not reported in the registry record. The record also does not report confidence intervals, statistical tests, adjusted analyses, missing-data methods, or a multiplicity strategy. The registry identifies the SAF-Ext Population for the primary safety endpoint, but further details on other analysis populations are not reported.

The record does not report the study’s sample-size justification, interim analyses, or a detailed statistical plan. The listed serious-event terms are not accompanied by group-specific counts. Consequently, the available information supports a limited descriptive account of safety events but does not permit a full assessment of precision, outcome completeness, or comparative efficacy.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Extension Study of Vibegron in Men With Overactive Bladder (OAB) Symptoms on Pharmacological Therapy for Benign Prostatic Hyperplasia — NCT04103450.
• Registry record last updated 2024-08-21; status last verified 2024-06.
• Results first posted 2024-08-21.
• 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

NCT04103450 is a completed Phase 3, open-label extension study sponsored by Urovant Sciences GmbH. It enrolled 276 men with overactive bladder symptoms receiving pharmacological therapy for benign prostatic hyperplasia who had previously completed treatment in Study URO-901-3005 (NCT03902080). Participants received vibegron 75 milligrams orally once daily. The study began on 2019-09-19 and reached primary completion on 2022-07-29.

The primary safety endpoint counts participants with any serious adverse event and treatment-emergent adverse events occurring in more than 5% of participants, with a timeframe up to Week 52. The registry lists serious-event counts of 2 among 142 in the 52-Week Vibegron Group and 3 among 134 in the 28-Week Vibegron Group; deaths are 0 in each group. The study is not a randomized comparison. Numerical results for the named secondary symptom outcomes, detailed analysis methods, and missing-data handling are not reported in the registry record.