Safety Study of MRI-guided Transurethral Ultrasound Ablation of Prostate Tissue to Treat Localized Prostate Cancer: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety Study of MRI-guided Transurethral Ultrasound Ablation of Prostate Tissue to Treat Localized Prostate Cancer (NCT01686958), a na na study. The primary outcome is Safety - Evaluate the Frequency of Treatment Related Adverse Events.

2. Clinical Question

The primary question is descriptive and focused on safety. It asks how many participants experienced a treatment- or device-related adverse event, rather than whether ablation produces better outcomes than another treatment. The registry defines the safety population by treatment delivery, so the endpoint concerns participants who received the investigational procedure.

The study also listed a feasibility outcome concerning whether the system thermally coagulated prostate tissue in conformity with the target volume, with a high degree of accuracy and precision. That objective is distinct from the primary safety question: it concerns delivery of the intended tissue effect, while the primary outcome concerns adverse events. Results for that feasibility outcome are not reported in the registry record.

Because the study has no concurrent control group, its adverse-event counts describe what was recorded in this study population and follow-up period. They do not estimate how those participants’ outcomes would have differed under another treatment or without treatment. The record identifies 30 enrolled participants, but the primary outcome population is defined by treatment delivery; the posted information does not give additional detail about whether every enrolled participant entered that safety population.

3. Trial Design

The registry describes a prospective, multi-center, single-arm study evaluating the safety and feasibility of MRI-guided transurethral ultrasound therapy to ablate prostate tissue in men with localized prostate cancer. Its official title calls it a Phase 1 study, while the registry phase classification is NA. The listed intervention is a device: MR-guided transurethral ultrasound ablation of prostate tissue.

The enrollment was 30. The study began on 2013-03-13, reached primary completion on 2015-03-23, and has a COMPLETED status. The primary endpoint’s timeframe is 12 months from the treatment date. No additional description of recruitment criteria, the participating centers, or the timing of individual assessments is reported in the registry record.

With a single group and no allocation to a control condition, the design supports a descriptive account of safety events observed after treatment. It does not provide a randomized or concurrent comparison. As a result, observed events cannot be separated statistically into those attributable to the procedure and those that might also have occurred without it. The registry’s endpoint description identifies events as treatment- or device-related, but it does not report the process or criteria used to determine that relationship.

The posted primary outcome is a participant count, not a time-to-event outcome or a measure of change from baseline. The registry lists 8 outcome measures and 1 analysis. Further detail about the analysis, such as an inferential model or a prespecified method for handling uncertainty, is not reported in the registry record. The sample-size assumptions associated with planning illustrations describe a separate calculation framework; they are not evidence that the trial was designed around those assumptions or that a particular sample-size justification was used.

The study therefore answers a limited but clinically relevant research question: what safety events were recorded in the defined follow-up after participants received this investigational procedure? The design does not establish comparative effectiveness, and the listed feasibility aim cannot be assessed from the posted outcome information.

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 safety population consists of all subjects who underwent treatment delivery with PAD-105, the investigational medical device.

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: Baseline measures were only done for the patients who passed screening and eligibility criteria

6. Primary Endpoint

The registry lists the primary outcome as Safety - Evaluate the Frequency of Treatment Related Adverse Events, measured over 12 months from the Treatment Date.

The primary endpoint measures the frequency of participants who experienced a treatment- or device-related adverse event after receiving PAD-105 treatment delivery. The unit is participants, and the outcome is expressed as a count of people with an event. The stated observation window is 12 months from the treatment date. The registry says all reported adverse events were recorded and defines the safety population as subjects who underwent treatment delivery.

A participant count is a straightforward way to describe how many people in the safety population had an event. In general, this kind of endpoint can communicate the observed burden of adverse events without requiring an assumption about how event times are distributed. It is important, however, to distinguish the count of affected participants from the total number of events: a participant may experience more than one event, and a count of people does not by itself convey event recurrence or duration.

The endpoint is useful for a safety-focused study because it summarizes whether treatment-related events were reported during a defined follow-up period. The registry does not report event severity grading criteria, attribution procedures, or whether a participant with multiple events was counted once for this endpoint. Those details are not reported in the registry record. Nor does the record provide a comparison group against which the observed frequency could be contrasted.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of outcome is this?

The primary endpoint is binary at the participant level: each participant either experienced a qualifying treatment- or device-related adverse event during the specified follow-up or did not. The registry reports the outcome as a count of participants, rather than as a continuous measurement. In general, a count of affected participants is often accompanied by the number at risk so readers can understand the group in which the events were observed. The posted record gives those counts for serious and other adverse events.

This participant-level count is not the same as a count of all adverse-event episodes. A participant who experiences repeated events may still contribute as an affected participant, while an event-level summary could count episodes separately. The registry’s primary endpoint specifies participants, but it does not state how recurrent events or multiple qualifying events in one participant were handled beyond this participant-count framing.

What does a confidence interval add?

As a general statistical explanation, a confidence interval describes the uncertainty around an estimate under a specified analysis method. It helps distinguish the observed result in a study from the range of values that may be compatible with the data and method. A count alone gives the observed number of affected participants, but it does not convey that sampling uncertainty. No confidence interval for the primary outcome is reported in the registry record, and no interval method is specified there.

For a binary endpoint, analysts may estimate a proportion and attach an interval, but the registry outcome is described as a participant count. No proportion should be inferred beyond the figures expressly reported. In general, interval estimates can also depend on the sample size and on the method used, especially when event counts are limited. Readers should not treat an unreported interval as if it were zero-width or as if the observed count were known without uncertainty.

Why does the single-group design matter?

In general, a randomized comparison can help balance measured and unmeasured prognostic factors between treatment groups, while a single-group study has no such concurrent contrast. This study is listed as single-group, with no allocation to a comparator. The adverse-event counts can describe events after treatment, but they cannot estimate a treatment-versus-control difference. Events may be related to the intervention, underlying disease, other care, or other causes; the registry does not report a method that separates these possibilities.

The endpoint labels events as treatment- or device-related, but attribution is not the same as a randomized comparison. The record does not describe how attribution was assessed, whether an independent committee reviewed it, or whether assessors were blinded. The masking field is NONE. These features matter when interpreting safety classification, because judgments about relatedness can involve clinical assessment.

What do the planning assumptions mean?

As a general explanation, a sample-size calculation asks how many participants might be needed under chosen assumptions to detect a specified effect with a chosen error rate and power. The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; they also define the effect to detect as a stated fraction of the observed effect. The registry notes that these are planning illustrations computed from the observed effect, not the trial’s own design. They should not be interpreted as observed power or as a justification for the enrollment in this single-group study. The record does not report a trial-specific sample-size justification.

In general, assumptions about the effect size are consequential: a smaller target effect usually requires more information to detect than a larger one, all else being equal. A planning calculation is conditional on its assumptions and does not establish that a study actually had a particular probability of detecting an effect after results are known. The record’s stated framework also assumes equal allocation between two arms, unlike the single-group design described for this study. The planning illustrations therefore do not constitute a direct description of the study’s design.

How should the analysis be read?

The registry lists 1 analysis, but the statistical procedure, estimate, and uncertainty measure are not reported in the registry record. A reader can interpret the displayed adverse-event information as descriptive counts, but cannot determine from the record whether inferential testing was conducted, whether adjustment was used, or how potential missing observations were handled. General statistical guidance about models or tests should not be mistaken for a description of the analysis actually used.

For count outcomes, over-dispersion is a concern in some settings when event counts vary more than a chosen model expects. That issue is most relevant to models of event counts or rates; it is not automatically a feature of a participant-level yes-or-no endpoint. The registry does not report a model that would make an over-dispersion assessment applicable to the primary endpoint. No model assumptions beyond those stated for the planning illustrations should be attributed to the trial analysis.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("MR-Guided Transurethral Ultrasound Ablation of Pro")
n      <- c(30)
events <- c(30)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  MR-Guided Transurethral Ultrasound Ablation of Pro  30  30  100.0  88.4  100.0  88.6  100.0  88.8  99.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 8 outcome measures and 1 analysis. The available primary outcome description identifies a safety measure, and a secondary outcome describes feasibility of thermal coagulation relative to the target volume. A complete account of all outcome definitions, their analysis hierarchy, and any prespecified distinction between confirmatory and exploratory outcomes is not reported in the registry record.

When a study examines multiple outcomes, multiplicity can arise because several statistical tests create more opportunities for a chance finding. As a general statistical principle, investigators may specify a hierarchy or adjust inference to address that issue. The registry does not report a multiplicity strategy, an adjustment method, or a testing hierarchy. No claim about whether multiplicity was addressed can therefore be made from the posted information.

The registry defines the safety population as all subjects who underwent treatment delivery with PAD-105. The number enrolled was 30, and the serious and other adverse-event counts each list 30 participants at risk. The record does not provide further details on participant flow, treatment receipt by every enrolled participant, withdrawals, incomplete follow-up, or exclusions from the safety analysis. It also does not describe a missing-data method, imputation, or sensitivity analysis. These procedures are not reported in the registry record.

In general, missing outcome information can affect interpretation if participants with incomplete follow-up differ in their event experience from those with observed data. A participant count and at-risk count do not explain why any data might be missing or whether follow-up was complete. The posted record does not give enough detail to assess that possibility. The scope of interpretation should therefore remain limited to the reported safety counts and the registry’s stated safety-population definition.

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: epididymitis (3.3%), urinary retention (3.3%).

For serious adverse events, the registry lists 30 participants at risk and 2 affected. For other adverse events, it lists 30 at risk and 30 affected. These figures count participants, not necessarily every event episode. The registry also lists epididymitis and urinary retention as serious adverse event terms, each at 3.3%. The record does not report whether those terms occurred in the same participant or in different participants, so the categories should not be added or treated as independent people.

The primary safety timeframe is 12 months from the treatment date, and the endpoint description says all reported adverse events were recorded. It does not give event-level timing, duration, severity criteria, or the method used to determine treatment or device relatedness. Deaths are not reported in the registry record.

These counts describe the safety observations in a single-group study. They do not provide a comparative estimate of risk, and they do not establish that an event was caused by the procedure. The absence of a concurrent comparator and the lack of reported attribution details constrain causal interpretation.

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

The registry record describes a completed, prospective, multi-center, single-group evaluation of MRI-guided transurethral ultrasound ablation in men with localized prostate cancer. Its primary safety outcome concerns participants with treatment- or device-related adverse events within 12 months from treatment. The posted counts show that serious and other adverse events were recorded in the study population, with the specific counts described in the safety outcome.

Those observations are useful as a descriptive record of what was reported after treatment delivery. They may help readers understand which adverse-event categories appeared in the registry and how the endpoint was defined. The report also identifies a technical feasibility objective concerning thermal coagulation within the target volume, although a result for that objective is not reported in the registry record.

The findings do not show how the safety experience compares with an alternative treatment, because there was no concurrent comparator group. They do not establish that the procedure caused each event classified as treatment- or device-related, since attribution procedures are not reported. They also do not establish effectiveness for cancer outcomes: the primary endpoint is safety, and the available information does not report a cancer-control result.

The counts should not be read as exact estimates of event frequency in all people who might receive the procedure. The record does not provide a confidence interval for the primary outcome, details on missing follow-up, or a complete description of the analysis. The enrolled population and follow-up context also define the scope of what was observed. General statistical interpretation therefore calls for a distinction between observed study counts and conclusions about broader populations or comparative effects.

In short, the posted information documents adverse events within a specified follow-up in a single-group study and records the stated feasibility aim. It does not supply the comparative evidence, uncertainty estimates, or detailed analysis information needed to draw broader conclusions about relative safety, efficacy, or technical performance.

14. Why This Trial Matters Statistically

This study matters statistically because it illustrates the role and limits of a single-group safety evaluation. A study can document adverse events after a procedure and make the outcome definition explicit, but without a concurrent comparator it cannot estimate how the same participants would have fared under another approach. Descriptive safety evidence and comparative treatment evidence answer different questions.

The endpoint is a participant count within a defined follow-up period. That is easy to interpret at a basic level, but it does not convey event recurrence, timing, severity grading, or uncertainty unless those features are reported separately. The registry identifies a 12-month timeframe and distinguishes serious from other adverse events, while details about event attribution and participant-level overlap are not reported.

The record also makes the safety population definition important: it consists of subjects who underwent treatment delivery. That definition is not automatically interchangeable with enrollment. Reporting a clear analysis population helps readers understand whose outcomes the results describe, while participant flow and missingness details are needed to assess whether follow-up could have influenced the observed counts.

Finally, planning calculations and trial design should not be conflated. The stated planning framework uses assumptions for a two-arm comparison, whereas the registered study is single-group. Such illustrations can be useful for planning future research, but they do not establish the design rationale or observed power of this study. The registry does not report a trial-specific sample-size justification or detailed inferential analysis. These distinctions help keep descriptive evidence, planning assumptions, and comparative conclusions separate.

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.

The design is single-group, so there is no concurrent control against which to compare adverse-event counts. This limits interpretation of whether events occurred more often than they would under another treatment or in the absence of the intervention. The endpoint labels events as treatment- or device-related, but the criteria and process for determining relatedness are not reported in the registry record.

The primary outcome is a count of participants with qualifying events during 12 months from the treatment date. The record does not report event timing, duration, severity grading, recurrence handling, or overlap between serious event terms. It lists epididymitis and urinary retention at 3.3% each, but does not indicate whether the terms apply to the same participants. Deaths are not reported in the registry record.

The analysis description is limited. Although the registry lists 1 analysis and 8 outcome measures, it does not report the statistical method, an uncertainty interval for the primary endpoint, a multiplicity approach, or a missing-data method. Details about withdrawals, incomplete follow-up, and exclusions from the safety population are also not reported. The feasibility objective is described, but its result is not reported in the registry record.

The study enrolled 30 participants, and the safety population is defined by treatment delivery. The record does not provide enough participant-flow information to establish how enrollment relates to the analyzed safety population beyond the listed at-risk counts. Generalization beyond this study population is also limited by the available information: recruitment criteria and further details of the participating centers are not reported. These limitations favor a descriptive reading of the posted safety information rather than broad or comparative conclusions.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety Study of MRI-guided Transurethral Ultrasound Ablation of Prostate Tissue to Treat Localized Prostate Cancer — NCT01686958.
• Registry record last updated 2020-02-11; status last verified 2020-01.
• Results first posted 2018-10-25.
• 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

The registry record describes a completed, prospective, multi-center, single-arm study of MR-guided transurethral ultrasound ablation of prostate tissue for men with localized prostate cancer. Its official title identifies it as a Phase 1 study, while the registry phase classification is NA. Enrollment was 30; the study began on 2013-03-13 and reached primary completion on 2015-03-23.

The primary outcome counts participants with treatment- or device-related adverse events after treatment delivery, within 12 months from the treatment date. The registry lists 2 participants affected by serious adverse events and 30 affected by other adverse events, with 30 at risk in each category. Epididymitis and urinary retention are each listed at 3.3% among serious adverse event terms. Deaths are not reported in the registry record.

The registry also describes a feasibility objective concerning thermal coagulation relative to the target volume. Its result, detailed statistical methods, missing-data handling, and multiplicity strategy are not reported in the registry record. The single-group design supports descriptive safety interpretation, not a concurrent treatment comparison.