Prophylactic Antibiotic Administration for Bladder OnabotulinumtoxinA Injection: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Prophylactic Antibiotic Administration for Bladder OnabotulinumtoxinA Injection (NCT05719285), a randomized phase 4 study. The primary outcome is Establish Noninferiority of the Single Dose Antibiotic Administration to the Multi-dose Antibiotic Administration..

2. Clinical Question

The study addresses whether the duration of antibiotic prophylaxis is associated with postoperative UTI incidence after bladder onabotulinumtoxinA injection. The registry describes a noninferiority objective, rather than merely asking whether a conventional test detects a difference. That distinction matters: a non-significant difference by itself does not establish noninferiority. The stated noninferiority criterion depends on both the observed contrast and its uncertainty in relation to the prespecified margin.

The margin's numerical value and the details of its justification are not reported in the registry record. Consequently, the primary counts and comparison can be described, but the registry record does not allow the noninferiority criterion to be checked against a numerical threshold. The question is about these prophylaxis regimens in the registered procedural context; it does not address other antibiotic strategies or other clinical settings.

3. Trial Design

This is a completed phase 4 randomized, parallel-group trial with no masking. The registry lists The Cleveland Clinic as sponsor. The start date is 2022-12-06, and the primary completion date is 2023-06-08. Enrollment is listed as 100. The primary outcome records 50 participants in each antibiotic group.

Participants were assigned to single-dose or multi-dose antibiotic prophylaxis with bladder onabotulinumtoxinA injection. In the single-dose group, participants were to receive one antibiotic dose before the procedure. In the multi-dose group, participants were to receive one dose before the procedure and continue the same antibiotic for 3 days of total administration, with additional doses prescribed to the pharmacy. The antibiotic itself is not named in the registry record.

The study was open label, so masking is listed as none. The registry does not report whether outcome assessors were masked or provide further details about how randomization was generated or concealed. Allocation is described as randomized, and the model is parallel; other operational details of assignment are not reported in the registry record.

The primary outcome is the number of participants with postoperative UTI within 4 weeks. The registry also lists antibiotic adverse events and symptomatic urinary retention as secondary outcomes. Numerical secondary results are posted for symptomatic urinary retention; a numerical result for the listed antibiotic adverse events outcome is not reported in the registry record. The record does not include detailed participant characteristics, the exact antibiotic, or further procedural eligibility criteria. These omissions limit how fully the enrolled population and treatment implementation can be characterized.

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

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 Establish Noninferiority of the Single Dose Antibiotic Administration to the Multi-dose Antibiotic Administration., measured over 4 weeks.

The primary endpoint counts participants with a postoperative urinary tract infection within 4 weeks after bladder onabotulinumtoxinA injection. It is a binary outcome at the participant level: each participant either had a recorded UTI during the specified follow-up window or did not. The registry presents the event count and the number of participants assessed in each group.

This endpoint directly addresses the trial's stated comparison of prophylaxis duration. Because the trial aims to establish noninferiority, the relevant question is not simply whether the groups have identical observed counts. The comparison must be interpreted with uncertainty, and the interval around the estimated between-group difference must be assessed against the prespecified noninferiority margin. A numerical margin is not reported in the registry record.

The posted primary results record 1 participant with UTI among 50 in the single-dose group and 1 among 50 in the multi-dose group. The posted risk difference is 0.0, with a confidence interval that extends in both directions around zero. Equal observed event counts are a straightforward description of the sample; they do not, on their own, establish equal underlying risks or satisfy a noninferiority criterion. The endpoint is limited to the stated 4-week window, so it does not describe UTI incidence outside that period.

Definitions for diagnosing or confirming UTI, handling events occurring at different times within follow-up, and treatment of incomplete follow-up are not reported in the registry record. Those details would help assess consistency of endpoint ascertainment and interpretation.

7. Results Posted in the Registry

• 2: Multi-Dose Antibiotic Prophylaxis: 2.0% (1/50) versus 2.0% (1/50) on control; risk difference 0.0 percentage points (95% CI -5.5 to 5.5), risk ratio 1.00 (0.06–15.55); unadjusted two-proportion z-test p = 1.000.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Symptomatic Urinary Retention

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • 2: Multi-Dose Antibiotic Prophylaxis: 2.0% (1/50) versus 0.0% (0/50) on control; risk difference 2.0 percentage points (95% CI -1.9 to 5.9); unadjusted two-proportion z-test p = 0.315.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between 2: Multi-Dose Antibiotic Prophylaxis and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes add context but do not change the central reading of the primary UTI comparison. Symptomatic urinary retention is the secondary outcome with posted group counts and a comparison. Its event count differs by one participant between groups, while the interval includes zero and the unadjusted p value is 0.315. This is an uncertain estimate, not clear evidence of a group difference.

Antibiotic adverse events are listed among the secondary outcomes, but numerical outcome results for that endpoint are not reported in the registry record. Adverse-event counts are posted separately in the safety information, but the record does not establish that these counts correspond to a defined secondary endpoint analysis. They should not be substituted for a missing endpoint result or treated as a complete analysis of antibiotic-related effects.

In general, secondary outcomes often address additional questions and can help describe a trial's broader result pattern. They usually carry less evidential weight than a prespecified primary outcome, particularly when there are several outcomes and no stated adjustment for multiple comparisons. Testing multiple outcomes can increase the chance that at least one result appears notable by chance. The registry record does not report a multiplicity strategy for the secondary outcomes.

Secondary outcomes also differ in their definitions, event frequencies, and relevance to the primary objective. Their results should be interpreted on their own terms and with their own uncertainty, rather than combined informally into a single overall conclusion. Here, the secondary information is limited: one comparison is posted for symptomatic urinary retention, while a numerical endpoint analysis for antibiotic adverse events is not reported in the registry record. These limitations make the secondary pattern supportive context at most, not independent confirmation of noninferiority for the primary endpoint.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Antibiotic Adverse Events
• Symptomatic Urinary Retention

9. Statistical Interpretation

10. Statistical Methods Explained

The posted comparison for the primary endpoint is a risk difference. This is an absolute contrast between the event proportions in the groups, expressed on the probability scale. A value of 0.0 means that the observed proportions are equal in the posted data. Positive or negative values would indicate a difference in one direction or the other according to the comparison's coding. Here, the posted point estimate is zero because the registry records the same event count and group size in both arms.

What does a confidence interval add?

In general, a confidence interval describes the range of effect values reasonably compatible with the data under the interval's statistical method. It conveys uncertainty around an estimate; it is not a statement that a particular range contains the true effect with a specified probability after the data have been observed. The primary risk-difference interval extends to both negative and positive values and includes zero. Thus, the observed equality of counts does not rule out a difference in either direction. The interval method itself is not reported in the registry record.

How should the p value be read?

In general, a p value describes how unusual the observed data, or data more extreme, would be under a specified null hypothesis and the assumptions of the test. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of an effect. The posted primary unadjusted p value is 1.0. It is consistent with the equal observed counts, but it does not establish equality or noninferiority. The test method and any adjustment beyond the unadjusted result are not reported in the registry record.

Why is noninferiority a separate question?

In general, a noninferiority analysis asks whether the results rule out an unacceptable loss relative to a comparator. The acceptable loss is defined by a prespecified margin, and the direction of the comparison matters. A point estimate close to zero is not enough: uncertainty must be sufficiently constrained relative to that margin. The registry describes a prespecified margin but does not report its numerical value. It also does not post an explicit primary noninferiority analysis result. The stated objective therefore cannot be independently evaluated from a conventional p value alone.

What do sparse binary outcomes imply?

For binary outcomes, the count of participants with events is central to interpretation. When counts are low, estimates may be sensitive to a small number of additional or differently classified events. In general, sparse data can produce wide uncertainty even when the observed arm counts match. The equal primary counts should therefore be read alongside the interval, not as a guarantee that the underlying risks are equal. The record does not report the statistical method used to calculate the risk difference interval, or whether any special method was used for sparse events.

Over-dispersion is a concern mainly for outcomes modeled as counts or rates when observed variability exceeds what a chosen model expects. It is not a feature that can be inferred from these posted participant-level binary event counts. The registry record does not describe a model-based adjustment for over-dispersion, and none should be assumed.

The comparison is described as unadjusted. The registry record does not report a covariate-adjusted primary model, stratification variables, or subgroup analysis. Without those details, the posted contrast should be interpreted as the unadjusted comparison represented in the results, rather than as an adjusted estimate controlling for participant or procedural characteristics.

The record includes a sample-size planning illustration based on the observed effect, with two-sided significance level 0.05, equal allocation, and a normal approximation. It is explicitly described as an illustration rather than the trial's own design calculation. Such planning values are not observed power and cannot establish how likely the trial was to detect a difference. The original sample-size justification and any target power for the registered trial are not reported in the registry record.

These distinctions matter because several ideas can be confused: an observed difference, a test of a null hypothesis, an interval estimate, and a noninferiority conclusion each answer a different statistical question. The registry provides event counts and an unadjusted comparison, but the numerical margin, interval method, and full primary analysis plan are not reported. Interpretation should remain within those limits.

11. Confidence Intervals and Precision

The primary risk difference is 0.0, with a posted confidence interval extending approximately from -0.055 to 0.055. This interval includes zero and permits differences on either side of the point estimate. The observed equality of event counts is therefore precise as a description of the recorded sample, but the estimate is not precise enough to rule out every potentially meaningful difference. Whether the interval is narrow enough for the trial's noninferiority objective cannot be determined without the numerical margin.

For the secondary symptomatic urinary retention comparison, the posted risk difference is 0.02 and its interval extends approximately from -0.019 to 0.059. This interval also includes zero. It indicates uncertainty around the secondary estimate, rather than a conclusive difference between groups. The methods used to calculate either interval are not reported in the registry record.

In general, confidence intervals are useful because they show both the direction and the range of uncertainty in an estimate. A point estimate alone can obscure how much the data leave unresolved. With sparse events, intervals may remain broad even when the observed counts are very similar. Conversely, inclusion of zero does not prove no effect; it indicates that zero is among the values compatible with the interval method and data.

Precision and statistical significance are related but not interchangeable with clinical importance. A confidence interval must be compared with a clinically and statistically justified threshold to evaluate noninferiority. The registry record states that a prespecified margin was used but does not report its value or justification. Thus, the interval can be described, but a threshold-based conclusion cannot be checked from the registry record alone.

12. Multiplicity, Missing Data and Analysis Populations

The registry record does not report whether the trial used a formal multiplicity adjustment or a hierarchical testing strategy across outcomes. The primary endpoint is identified, and secondary outcomes are listed, but the analysis plan for controlling the chance of false-positive findings across those outcomes is not reported in the registry record. The secondary p value should therefore be read as unadjusted, as posted, rather than as evidence that a family of outcomes was evaluated under a stated multiplicity procedure.

Missing-data procedures and the handling of participants without a complete 4-week outcome assessment are not reported in the registry record. The record does not say whether all randomized participants were included in the primary analysis, whether an intention-to-treat or per-protocol population was used, or how incomplete follow-up was treated. These details are particularly relevant to a noninferiority assessment, where analysis populations and missing outcomes can affect interpretation. No assumptions about those procedures can be made from the posted counts alone.

The registry record also does not report a numerical noninferiority margin, its justification, or a detailed statistical analysis plan. It states that the margin was prespecified, but the absence of its value prevents comparison of the primary interval with the decision threshold. Details of the randomization method, allocation concealment, and endpoint adjudication are also not reported. Masking is listed as none, but assessor masking is not separately described.

Finally, the registry lists 3 outcome measures and reports 0 analyses in its analysis count, while posting a primary comparison and a secondary comparison in the results data. This presentation does not supply a full account of analysis methods or analysis populations. It is most appropriate to distinguish the posted numerical comparisons from an undocumented inferential plan, rather than infer that unreported methods were or were not used.

13. 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% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cellulitis (2.0%).

The serious adverse event information records 0 participants affected in the single-dose group and 1 in the multi-dose group. No deaths are recorded in either group. The record lists cellulitis at 2.0% among the top serious adverse event terms. It does not provide enough detail to assign that term to a particular group from the listed term alone.

Other adverse events are recorded for 4 participants in the single-dose group and 5 in the multi-dose group. These are counts, not a complete account of event severity, duration, attribution, or treatment. The registry record does not define the relationship between the adverse-event figures and the listed secondary outcome of antibiotic adverse events.

These figures are descriptive. A difference in small event counts is not, by itself, evidence of a dependable safety difference, and the absence of a recorded event does not establish that an event cannot occur. The record does not report a formal comparative safety analysis or detailed event narratives. Safety interpretation should therefore remain limited to the adverse events and deaths recorded in the registry.

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

The posted primary results show equal observed UTI counts in the two groups: 1 participant in each, with 50 recorded in each group. The estimated risk difference is 0.0, and the unadjusted p value is 1.0. These results describe the trial's recorded sample and show no observed difference in the primary event proportions.

They do not prove that the regimens have identical underlying risks. The confidence interval includes zero and extends in both directions, leaving uncertainty about the size and direction of a possible difference. Nor does a p value of 1.0 establish equivalence or noninferiority. The trial's stated noninferiority question requires comparison with a prespecified margin, whose numerical value is not reported in the registry record. The registry record also does not post an explicit conclusion from a noninferiority analysis.

The results apply to the registered comparison of prophylaxis durations around bladder onabotulinumtoxinA injection in the described refractory overactive bladder population, and to the specified 4-week primary outcome window. They do not establish results for other antibiotics, other durations, other procedures, or outcomes beyond the recorded follow-up. The exact antibiotic and additional eligibility or participant characteristics are not reported in the registry record.

The secondary and safety findings are also limited by low event counts and incomplete analysis detail. Symptomatic urinary retention has a posted comparison with an interval that includes zero, while a numerical result for the listed antibiotic adverse events endpoint is not reported. Serious adverse event and death counts can be described, but they do not establish comparative safety. The most defensible conclusion is therefore descriptive: the observed primary event counts match, while the available registry information does not resolve the noninferiority threshold or remove uncertainty about underlying differences.

15. Why This Trial Matters Statistically

This trial illustrates why noninferiority questions require more than a comparison of observed event counts. When the recorded counts are equal, the point estimate can be zero, yet uncertainty may still permit meaningful effects in either direction. The relevant decision depends on the confidence interval and a prespecified margin, not on equal counts alone or on whether a conventional test detects a difference.

The primary results also demonstrate the interpretive limits of sparse binary outcomes. With 1 recorded event in each group, the point estimate is simple to describe, but the evidence is constrained by the small number of observed events. Confidence intervals make that uncertainty visible. In general, reporting both counts and an interval helps readers distinguish the observed data from the range of effect values that remain compatible with them.

For clinical researchers, the record highlights the importance of transparent reporting of the noninferiority margin, its rationale, analysis populations, missing-data procedures, and the statistical method used for interval estimation. These elements are not reported in the registry record, making it difficult to verify how the stated objective maps onto a formal decision. A non-significant result and a noninferiority conclusion are not interchangeable.

The trial also shows why secondary results and safety counts should be read as supporting context rather than as a substitute for the primary analysis. Unadjusted comparisons across multiple outcomes may be exploratory, and a small difference in event counts can be highly uncertain. Clear separation of primary, secondary, and safety findings supports more disciplined interpretation without overstating what the posted evidence establishes.

16. 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 primary outcome has only 1 recorded event in each group, limiting the information available about the between-group difference. The interval extends around zero in both directions. This is a specific constraint of the posted result, not simply a general concern about trial size. The record gives the group sizes but does not provide a numerical noninferiority margin, so the adequacy of precision for the stated aim cannot be assessed.

The intervention is described by dose schedule, but the antibiotic is not named. The registry record does not provide further detail about procedure technique, diagnostic criteria for UTI, adherence to the multi-dose regimen, or how outcomes were confirmed. These omissions make it harder to assess how consistently treatment and endpoint definitions were applied.

Although the trial is described as randomized, the record does not report the random sequence method or allocation concealment. It is open label, and masking of outcome assessors is not separately reported. Participant characteristics, further eligibility criteria, and the analysis population are not reported. The record also does not describe missing-outcome handling, the primary interval method, or any adjustment for covariates or multiple comparisons.

Secondary reporting is incomplete: a numerical result for the listed antibiotic adverse events outcome is not reported in the registry record. Safety counts are descriptive, with limited detail on event attribution and timing. These specific reporting gaps constrain interpretation of both the primary noninferiority question and the broader benefit-risk pattern, without implying that unreported procedures were necessarily absent.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Prophylactic Antibiotic Administration for Bladder OnabotulinumtoxinA Injection — NCT05719285.
• Registry record last updated 2024-01-02; status last verified 2023-09.
• Results first posted 2024-01-02.
• 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.

20. Record Summary

The registry record describes a completed, randomized, open-label, parallel-group phase 4 trial sponsored by The Cleveland Clinic. It compares a single antibiotic dose before bladder onabotulinumtoxinA injection with a regimen that continues the same antibiotic for 3 days of total administration. Enrollment is listed as 100, with 50 participants recorded in each primary-outcome group.

The primary endpoint is postoperative UTI within 4 weeks. The record reports 1 event in each group, a risk difference of 0.0, and an unadjusted p value of 1.0. The stated objective is noninferiority, but the numerical margin and an explicit noninferiority analysis conclusion are not reported in the registry record. A symptomatic urinary retention comparison is also posted; numerical endpoint results for the listed antibiotic adverse events outcome are not reported.

The available findings describe the recorded outcomes but do not establish equivalence, noninferiority, or a comparative safety conclusion. The confidence interval, event counts, and missing analysis details should remain central to interpretation.