Safety and Efficacy Study of HET Bipolar System for Treatment of Stage I and Stage II Hemorrhoids: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy Study of HET Bipolar System for Treatment of Stage I and Stage II Hemorrhoids (NCT01841970), a na na study. The primary outcome is Number of Participants With Resolution of Symptoms.

2. Clinical Question

The clinical question is therefore whether symptoms were recorded as resolved following a single HET procedure in the treated group, and what safety events were recorded during the study. Because the study has no comparator arm, its design cannot directly estimate how outcomes would differ under another treatment or without the device. The registry describes the study objective as determining safety and efficacy, but an objective is not itself evidence of an outcome. Interpretation depends on the outcome values, follow-up completeness, and analysis details; the primary outcome values and several of those details are not reported in the registry record.

3. Trial Design

This was a prospective, multicenter study of the HET Bipolar System for Stage I and Stage II hemorrhoids. The registry records the condition as internal hemorrhoids, the study model as single group, masking as none, and allocation as not applicable. The active arm is called the HET Arm. Its description states that a single procedure with HET was used to treat Grade I and Grade II hemorrhoids. No separate control or comparator arm is described.

The registry records enrollment of 20 participants. The primary endpoint description says that 18 participants were included in the analysis and 2 were lost to follow up. The study status is completed. Its recorded start is 2013-04 and its primary completion is 2014-11. The listed phase is not applicable.

The primary endpoint was the number of participants with resolution of symptoms, including resolution of bleeding and prolapse if present before treatment. The stated timeframe is post-treatment at Month1, Month 3, and Month 6. Secondary outcomes include recurrence of pre-procedure symptoms, recurrence of symptoms that had resolved with treatment, pain recorded as yes or no on a visual analog scale, and mean pain score based on that scale. The registry indicates five outcome measures but does not provide the additional outcome results in the information available for this account.

The study's prospective, single-group design can describe outcomes observed after treatment in the enrolled group. It does not include a concurrent control group to separate outcomes associated with the procedure from the course participants might otherwise have experienced, or from other influences on symptom reporting. The record does not report the recruitment process, detailed eligibility criteria, the methods used to assess symptoms, or whether outcome assessors were independent of treatment. Those design details 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: 18 participants included. 2 participants were lost to follow up.

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 Number of Participants With Resolution of Symptoms, measured over Post treatment at Month1, Month 3, Month 6.

The primary endpoint is the number of participants with resolution of symptoms after treatment. The description identifies bleeding and prolapse as symptoms considered when they were present before treatment. The stated assessment times are post-treatment at Month1, Month 3, and Month 6. The registry gives the endpoint unit as participants, indicating that the intended summary is a participant count rather than a measurement of symptom intensity.

Symptom resolution is a clinically interpretable outcome because it concerns whether symptoms that prompted treatment are reported as resolved. In general, a binary endpoint reduces a complex experience to categories such as resolved or not resolved. That can make a result easier to communicate, but it does not show the degree of improvement, the timing of improvement between scheduled assessments, or whether different symptoms followed different courses. Those distinctions depend on the outcome definition and data collection procedures.

The registry does not specify how resolution was determined when a participant had more than one symptom, whether resolution had to be sustained across visits, or how missing assessments were handled. It also does not give the number of participants meeting the endpoint at any of the listed follow-up times. The fact that an endpoint and assessment schedule are described does not establish the outcome. Without the observed counts and a clear account of the analysis population at each time, the degree and precision of symptom resolution cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation begins with the design. This study is recorded as a single-group, prospective study with no masking. In general, a single-group study observes outcomes in participants who receive an intervention without a concurrent comparison group. Such a design can describe what happened in the observed group, but it does not directly estimate a contrast between treatment strategies. A randomized comparison can help balance factors that influence outcomes across groups; no such allocation is described in this record.

What does a participant count measure?

The primary endpoint is expressed as the number of participants with symptom resolution. This is a count of people meeting the endpoint definition, not a measure of how much each person's symptoms changed. A count needs a corresponding denominator and a clearly specified analysis population to be interpreted. The registry gives the primary analysis population as 18 participants and states that 2 were lost to follow up, but does not give the endpoint count at the scheduled visits. A count alone also does not convey uncertainty; an interval estimate would help show the range of values compatible with the data under the chosen statistical model.

Why do follow-up times matter?

The endpoint is scheduled after treatment at Month1, Month 3, and Month 6. Repeated assessments can describe whether outcomes are maintained or change over follow-up, but the interpretation depends on whether the same participants are assessed at each visit and how missing visits are treated. The registry does not report visit-specific denominators, the number of missing observations at each time, or the method used to analyze repeated assessments. It is therefore not possible to infer a trajectory of symptom resolution from the schedule alone.

What does a confidence interval add?

General statistical explanation: a confidence interval expresses uncertainty around an estimate, reflecting both the observed data and assumptions of the method used. A narrow interval suggests greater precision under those assumptions; a wide interval indicates less precision. It is not a guarantee that the true value lies within the interval, nor does it address sources of bias from study design or measurement. The registry information for this account does not report a confidence interval for the primary endpoint, so its statistical precision cannot be described.

What can a p-value establish?

General statistical explanation: a p-value summarizes how compatible observed data are with a specified null model, given the assumptions used in the calculation. It does not measure the size or clinical importance of an effect, and it does not establish that a treatment caused an outcome. A p-value for a single-group outcome would also not create a missing control group or resolve limitations in the design. No p-value or inferential analysis for the primary endpoint is reported in the registry record.

How should planning calculations be read?

The record describes sample-size illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes the effect to detect as a stated fraction of the observed effect, and says that time-to-event illustrations use a total event count while other illustrations use participants per arm. These are planning assumptions, not a report of the study's design or an observed power calculation. The actual study is recorded as single group, so a two-arm planning framework should not be mistaken for a comparator in this trial. No planning output values or observed effect estimate are reported in the registry record. The illustrations cannot substitute for the missing outcome results or provide evidence that the study was adequately powered.

Why does over-dispersion matter?

General statistical explanation: over-dispersion occurs when observed variability is greater than a statistical model assumes. It can make standard errors too small if ignored, which may make uncertainty appear less than it is. Whether over-dispersion is relevant depends on the outcome and model. The primary endpoint is described as a participant count, but the registry does not report an analysis model or enough outcome detail to assess model fit or over-dispersion. No claim about its presence or absence can be made from the recorded design information alone.

In general, statistical conclusions depend on the endpoint definition, analysis population, handling of missing observations, and method used to quantify uncertainty. Those details are not fully reported for this study. The record therefore supports a description of the planned question and design features, but not an independent reconstruction of the primary 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("HET Arm")
n      <- c(18)
events <- c(18)
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  HET Arm  18  18  100.0  81.5  100.0  82.4  100.0  82.4  99.9

11. Multiplicity, Missing Data and Analysis Populations

Several outcomes and follow-up assessments are described. The primary endpoint concerns symptom resolution, with assessments at Month1, Month 3, and Month 6. Secondary outcomes concern recurrence of pre-procedure symptoms, recurrence of symptoms that had resolved, and pain measured as yes or no and as a mean visual analog pain score. When multiple outcomes or time points are examined, the chance of at least one apparently notable finding can increase. General statistical approaches may account for this multiplicity, or a prespecified hierarchy may distinguish primary from secondary questions. The registry record does not report a multiplicity adjustment or a testing hierarchy beyond identifying the primary endpoint.

The registry indicates that no analyses are listed. It does not report inferential methods, adjustment procedures, or whether results were analyzed separately at each visit. Thus, there is no basis to determine how multiplicity was addressed, or whether it was considered in the reported analyses.

For missing data, the primary endpoint description says that 18 participants were included and 2 were lost to follow up. The record does not say why follow-up was lost, whether missingness applied to all visits or particular outcomes, or whether the missingness was related to participants' health or outcomes. It does not report imputation, complete-case methods, sensitivity analyses, or another strategy for missing observations. In general, these choices can affect estimates when outcomes are unavailable; simply noting the analysis population does not show how such effects were handled.

The record does not provide a full analysis-population definition, including whether all enrolled participants were intended to be included in each endpoint analysis. Although the stated population count is available, the visit-specific denominators and outcome counts are not reported in the registry record. These omissions limit assessment of both missing-data risk and the consistency of outcome reporting across follow-up.

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: internal engorged hemorrhoids (5.0%), bleeding (5.0%), pain (5.0%), urgency (5.0%), skin tags (5.0%).

The registry safety summary lists 2 affected among 20 at risk for serious adverse events in the HET Arm. It lists 5 affected among 20 at risk for other adverse events. The record also lists the serious adverse-event terms internal engorged hemorrhoids, bleeding, pain, urgency, and skin tags, with 5.0% shown for each term.

These figures should be read as descriptive safety information for the treated group, not as a comparison with another intervention. There is no control arm in the recorded design, so the figures do not estimate whether events were more or less common than they would have been under another approach. The registry information does not report event timing, duration, the number of events per affected participant, or the assessment used to determine whether an event was related to the device. The list of terms and their displayed percentages also does not establish the clinical course or seriousness of each listed term beyond the registry's classification.

In general, adverse-event counts and percentages describe events recorded under a study's reporting procedures. They do not, on their own, establish causation or provide a complete account of risk. The available safety summary should therefore be interpreted alongside the absence of a comparator and the lack of additional event details.

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

The registry record documents a prospective, multicenter study of the HET Bipolar System for Stage I and Stage II internal hemorrhoids. It describes a single procedure, a symptom-resolution endpoint, and follow-up after treatment at Month1, Month 3, and Month 6. It also records that 18 participants were included in the primary analysis and 2 were lost to follow up. These details establish what was studied and how the primary question was framed.

They do not establish how many participants experienced symptom resolution. The primary endpoint counts at the scheduled follow-up times are not reported in the registry record. The registry also does not report an effect estimate, confidence interval, or inferential result for the primary endpoint. It is therefore not possible to quantify the observed symptom outcome or its precision from the information.

The design also sets limits on what an observed outcome could mean. Because there is one unmasked treatment group and no randomized comparator, outcomes after the procedure cannot be directly contrasted with outcomes under an alternative. A change after treatment does not, by itself, show that the procedure caused that change. The study can describe the treated group, but it cannot isolate the treatment's contribution from other influences on symptoms.

The safety figures are likewise descriptive. The record lists serious and other adverse-event counts in the HET Arm, but does not provide comparative safety estimates or detailed event histories. The listed terms and values do not establish whether events were caused by the device.

In general, a study's title and stated objective express what investigators set out to evaluate; they are not a substitute for reported outcomes. The available record supports a careful account of the design and the endpoint being asked about. It does not support a conclusion about the amount of symptom resolution, the comparative effect of HET, or the balance of risks and benefits.

14. Why This Trial Matters Statistically

This study is statistically informative as an example of the distinction between a research question and the evidence available to answer it. The registry identifies a primary endpoint and scheduled follow-up, but does not report the primary outcome values. Without those values, the central statistical task—estimating the observed symptom-resolution outcome and its uncertainty—cannot be completed from the registry record.

The design also illustrates why a comparator matters. A single-group study can record what happened after an intervention, but it does not reveal what would have happened to similar participants under another approach. This limits causal interpretation even when follow-up is prospective and a specific endpoint is named. The absence of masking is also relevant in general when outcomes involve reported symptoms: expectations or knowledge of treatment could influence reporting or assessment. The registry does not describe safeguards or independent assessment.

Follow-up completeness is another statistical concern. The record reports 18 participants included in the primary analysis and 2 lost to follow up. That information signals that outcome availability requires attention, but does not explain the missingness pattern or its handling. Without visit-specific denominators and missing-data methods, readers cannot judge whether observed outcomes may represent only participants with available follow-up.

Finally, the presence of multiple outcomes and visits raises questions about how analyses were prioritized and how uncertainty was handled. The registry identifies a primary endpoint, but does not report analysis methods, multiplicity procedures, or inferential results. These gaps show why transparent outcome reporting is essential: a clearly stated objective and design allow readers to understand what was planned, while numerical results and methods are needed to evaluate the evidence.

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 primary limitation for interpreting this trial is that the registry record does not report the primary endpoint counts at Month1, Month 3, or Month 6. It also does not report a confidence interval or other estimate of precision. The stated primary analysis population is 18 participants, with 2 lost to follow up, but no visit-specific denominators or missing-data methods are given.

The single-group design has no randomized comparator and no masking. Outcomes after treatment cannot establish how results would differ under another treatment or without the device. The record does not describe eligibility criteria in detail, participant characteristics, symptom assessment procedures, or whether endpoint assessors were independent. These details are not reported in the registry record.

The endpoint definition is not fully operationalized in the record. It identifies resolution of symptoms, including bleeding and prolapse when present before treatment, but does not explain how multiple symptoms were combined, whether resolution had to persist, or how assessments were conducted. Secondary outcomes are named, but their observed results are not reported in the registry information for this account.

Safety interpretation is limited by the absence of a control group and details about event timing, duration, recurrence, and relationship to the device. The record lists adverse-event summaries, but does not provide a fuller account of individual event histories. It also does not report the statistical analysis methods, multiplicity approach, or a complete analysis-population definition. These omissions constrain assessment of outcome reliability, uncertainty, and generalizability.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety and Efficacy Study of HET Bipolar System for Treatment of Stage I and Stage II Hemorrhoids — NCT01841970.
• Registry record last updated 2017-01-16; status last verified 2016-11.
• Results first posted 2017-01-16.
• 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

NCT01841970 is a completed, prospective, multicenter, single-group study of the HET Bipolar System for Stage I and Stage II internal hemorrhoids. The registry lists no masking and no allocation. The arm description states that one HET procedure was used to treat Grade I and Grade II hemorrhoids. Enrollment is recorded as 20; 18 participants were included in the primary endpoint analysis, and 2 were lost to follow up.

The primary endpoint is the number of participants with resolution of symptoms, including bleeding and prolapse when present before treatment, assessed after treatment at Month1, Month 3, and Month 6. The primary outcome counts and statistical analyses are not reported in the registry record. Safety summaries list 2 affected among 20 at risk for serious adverse events and 5 affected among 20 at risk for other adverse events in the HET Arm. The single-group design does not provide a comparative estimate of efficacy or safety.