Cryo Balloon for Residual Barrett's Esophagus: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Cryo Balloon for Residual Barrett's Esophagus (NCT02230410), a na na study. The primary outcome is Eradication of Barrett's Esophagus.

2. Clinical Question

The study’s stated purpose is to assess whether focal cryotherapy can eliminate residual Barrett’s esophagus after a previous ablation or endoscopic mucosal resection. The population description is therefore centered on residual disease following earlier endoscopic treatment, rather than on an untreated comparison population. The record’s arm description specifies residual Barrett’s esophagus less than 3 cm and one CryoBalloon Focal Ablation treatment. It does not provide further details about how residual disease was identified, how participants were selected, or whether additional treatments were allowed.

Because the study has one group and no reported comparator, its primary question is descriptive: the number of participants with the stated endpoint at the specified follow-up. A one-group observation can describe what was recorded after treatment, but by itself does not provide a direct estimate of how that outcome would differ under another treatment or no treatment. The result needed to answer even the descriptive question is not reported in the registry record.

3. Trial Design

The registry identifies NCT02230410 as a completed pilot study titled “Cryo Balloon for Residual Barrett’s Esophagus.” Mayo Clinic is listed as the sponsor. The study is classified as single group, with allocation recorded as NA and masking as NONE. Its phase is also listed as NA. Enrollment is reported as 18. The record gives a start date of 2014-08 and a primary completion date of 2017-05-26.

The intervention is CryoBalloon Focal Ablation, categorized as a device. The arm description states that subjects with residual Barrett’s esophagus less than 3 cm after ablation will undergo one CryoBalloon Focal Ablation treatment. The brief summary refers to residual disease following radiofrequency ablation or endoscopic mucosal resection. No separate control arm or concurrent comparator is described. Accordingly, the study does not provide a randomized, like-for-like treatment comparison.

The single primary outcome measure is titled “Eradication of Barrett’s Esophagus.” It is expressed as a count of participants and has a timeframe of 3 months post Cryoballoon Focal Ablation. The record lists one outcome measure and no analyses. It does not report the endpoint count, a percentage, a comparison, an uncertainty interval, or a statistical test. Consequently, completion status and enrollment describe the trial record but do not establish the primary endpoint result. Details such as the precise analysis population, follow-up completeness, and operational definition of eradication 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:

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 Eradication of Barrett's Esophagus, measured over 3 months post Cryoballon Focal Ablation.

The primary endpoint is the number of participants recorded as having eradication of Barrett’s esophagus after CryoBalloon Focal Ablation, assessed at 3 months post treatment. It is a binary participant-level outcome summarized as a count: a participant either meets the endpoint definition or does not. The registry does not state the operational criteria used to determine eradication, the method or assessor used to evaluate it, or how an indeterminate assessment would be handled. Those details are not reported in the registry record.

A count can provide a direct description of how many participants met a prespecified clinical outcome. It is useful for communicating the observed frequency in the group being followed, provided the assessment rules and the number evaluated are clear. A count alone, however, does not describe the uncertainty around the result or make a comparison with another treatment. The record does not report the observed count, the number with endpoint assessments, or an estimate of uncertainty. Therefore, the primary endpoint’s stated purpose and timing are available, but its observed result cannot be interpreted from the registry record.

In general, a clear endpoint definition supports consistent measurement and interpretation. For this endpoint, readers would need the criteria for eradication, the assessment population, and the result at the stated follow-up. These are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a participant count express?

For a binary endpoint, a participant-level count records how many people meet a stated outcome definition. Here, the listed outcome is eradication of Barrett’s esophagus at 3 months after Cryoballoon Focal Ablation. The registry defines the measure as a count of participants, but does not report the count or explain the detailed criteria for classifying an assessment as eradication. Without a reported denominator, a count would not establish what share of the assessed group met the outcome. A denominator also makes clear whether the summary concerns everyone enrolled, everyone treated, or only those with an evaluable follow-up assessment. The relevant analysis population and denominator are not reported in the registry record.

What can a single-group study estimate?

In general, a single-group study can describe outcomes observed among participants in that group. It does not, on its own, estimate a comparative treatment effect because there is no concurrent control outcome in the record against which to contrast the treated group. A before-and-after comparison would also require an explicitly reported baseline measure and a defined analysis; neither is described for this primary endpoint. The study is listed as single group, and no like-for-like comparator is reported. The record therefore supports no randomized comparison or treatment-effect estimate.

In a controlled study, the comparison of outcomes can help distinguish a treatment-associated difference from differences that might have occurred for other reasons. In general, random allocation can support comparability of groups, although its success and implications depend on study conduct and analysis. This trial’s allocation is listed as NA and masking as NONE. No randomized allocation is described, and no blinded assessment method is reported. The record does not provide enough information to evaluate the effect of those design features on outcome measurement.

How should precision be understood?

In general, a confidence interval gives a range of values compatible with an estimate under the assumptions of the method used. A narrower interval indicates greater statistical precision, while a wider interval indicates greater uncertainty. It does not remove possible bias or limitations in the design. The registry reports no confidence interval or other precision measure for the primary endpoint. Since it also reports no endpoint count, there is no estimate from this record whose precision can be evaluated.

A p-value, in general, measures how incompatible the observed data are with a specified null model, under the assumptions of a test. It is not the probability that a treatment is effective, nor does it measure the size or clinical importance of an outcome. No p-value or statistical test is reported. With no comparative analysis described, the registry record does not support a significance claim about a treatment contrast.

What do the planning assumptions mean?

The registry’s sample-size note describes planning 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 states that the effect to detect is a specified fraction of the observed effect. These are assumptions for hypothetical planning calculations, not a description of this single-group study’s allocation or a report of its observed outcome. The note distinguishes participants per arm for ordinary outcomes from a total event count for time-to-event calculations. The record does not give numerical planning illustrations, the effect estimate used, or a study-specific sample-size justification. Those details are not reported in the registry record.

In general, planning calculations ask how much information a future study might need under chosen assumptions. They do not measure the probability that a completed study has demonstrated an effect. Sample-size planning illustrations must not be read as observed power or as a substitute for a reported estimate and its uncertainty. Here, the registry reports enrollment but no primary endpoint analysis, so it is not possible to assess whether the achieved information was adequate for a particular effect or precision target.

Why does outcome definition matter?

General measurement principles require an outcome to be defined in a way that allows consistent classification. For an eradication endpoint, readers need to know the clinical or endoscopic criteria, the timing and procedure for assessment, and how uncertain or missing evaluations were treated. The registry gives the outcome title and three-month timeframe, but not those operational details. It also does not report whether assessors were blinded or whether a protocol specified confirmation. These details cannot be assumed from the endpoint label. Clear reporting of the definition, denominator, and analysis would allow readers to understand what the participant count represents and how much confidence to place in it.

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("Focal Cryo Ablation")
n      <- c(15)
events <- c(2)
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  Focal Cryo Ablation  15  2  13.3  1.7  40.5  3.7  37.9  4.0  38.3

11. Multiplicity, Missing Data and Analysis Populations

The record lists one primary outcome measure, eradication of Barrett’s esophagus, and no analyses. It does not report a statistical analysis plan, a hierarchy of outcomes, or a multiplicity adjustment. Multiple testing can arise when several outcomes, time points, subgroups, or analyses are examined; in general, testing many questions can increase the chance of a chance-positive finding unless the analysis plan accounts for that. The registry record does not describe whether any such analyses were planned or conducted. Therefore, no conclusion about multiplicity control can be drawn.

Missing-data handling is also not reported in the registry record. The endpoint is timed at 3 months, but the record does not give the number with an assessment, the number missing, reasons for missing assessments, or any method for handling missing outcomes. It does not state whether participants without an assessment would be counted as not having eradication, excluded, or handled by another approach. These are distinct analytical choices and should not be assumed.

The analysis population is not reported in the registry record. Enrollment of 18 does not establish which participants contributed to the primary endpoint analysis, whether all enrolled participants received treatment, or whether the analysis used an intention-to-treat or another population. The record’s single-group description identifies the broad design but does not resolve these endpoint-specific questions. With no analysis results, no population definition, missing-data method, or multiplicity approach documented, the robustness of an outcome estimate cannot be evaluated.

12. 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 non-serious adverse event terms

The adverse-event record lists the Focal Cryo Ablation group with 18 at risk for serious adverse events and 0 affected. It separately lists 18 at risk for other adverse events and 1 affected, and reports 1 death. These are registry counts, not estimates of comparative risk: the study has no reported control group. The count of 0 serious adverse events applies to the serious-event field as recorded; it does not by itself establish that no other safety issues occurred or that all possible events were captured.

The record does not give the term for the other adverse event, the timing of the death, whether the death was considered treatment-related, or how the death relates to the other event count. It lists no top serious adverse-event terms. These details are not reported in the registry record. No causal relationship between the intervention and an event can be inferred from the counts alone. General safety interpretation also depends on the event definitions, observation period, completeness of reporting, and attribution procedures, none of which is fully.

Because there is no comparator, these figures describe only the recorded group and cannot show whether an event occurred more or less often than it would under another approach. The counts should be read as registry reporting, not as a complete assessment of safety or of causation.

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

The registry record identifies a completed pilot study of one CryoBalloon Focal Ablation treatment for residual Barrett’s esophagus after prior ablation or endoscopic mucosal resection. It specifies eradication of Barrett’s esophagus at 3 months as the primary endpoint and records enrollment of 18. These details describe the study’s question and design, but the record does not report the endpoint count, its denominator, or an analysis. As a result, the primary outcome cannot be characterized as showing eradication or failing to show eradication.

Even if an outcome count were available, the single-group design would limit what could be concluded about treatment effects. A count after treatment could describe the group’s observed outcome, but without a concurrent comparator it would not establish what would have happened under another intervention or without focal cryotherapy. General causal interpretation requires more than a post-treatment observation. It depends on a credible comparison and assumptions that the design and analysis support.

The registry record also does not provide the operational definition of eradication, assessment details, missing-data handling, or analysis population. These omissions make it difficult to evaluate how the endpoint would have been classified and who contributed to any result. The serious adverse-event and other event counts offer limited descriptive safety information; they do not establish attribution or comparative risk.

Accordingly, the record supports a description of the study’s aim, single-group structure, intervention, follow-up time, and selected safety counts. It does not support a numerical estimate of the primary outcome, an estimate of precision, a statistical significance claim, or a causal claim about the intervention. The absence of an outcome result in the registry should not be interpreted as a null result. It means the result is not reported in the registry record.

14. Why This Trial Matters Statistically

This study illustrates why a trial’s design and outcome reporting must be interpreted together. Its question is understandable as a descriptive one: whether participants with residual Barrett’s esophagus meet an eradication endpoint after focal cryoablation. The registry gives a defined follow-up time and describes a single treatment, but does not report the endpoint result. Without that result, the most important statistical quantity for the primary question is unavailable.

The single-group structure is also consequential. Statistical summaries can describe outcomes within a treated group, but a treatment effect is inherently comparative. Without a concurrent control group, the record cannot separate an outcome observed after treatment from changes that might arise through other processes. This is a general limitation of interpreting uncontrolled clinical observations, not a statement about what the missing result would have been.

Statistical transparency also depends on more than a point estimate. Readers need the outcome definition, the number assessed, the analysis population, treatment of missing observations, and an uncertainty measure to judge what an estimate can support. Those details are not reported in the registry record. The record’s planning note describes general assumptions for hypothetical sample-size illustrations, but those assumptions do not replace the missing primary analysis or establish the study’s precision.

For biostatisticians and clinical researchers, the record is a useful example of the distinction between a registered outcome and a reported result. A named endpoint does not itself provide evidence about that endpoint. Likewise, completed status and enrollment are not substitutes for an estimate, uncertainty interval, or comparator. The statistical reading must remain bounded by what is actually reported.

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 interpretation is that the registry record does not report the outcome count for its only listed primary measure. It also does not report a denominator for the endpoint analysis, an uncertainty interval, or a statistical test. The endpoint’s operational definition and method of assessment are not reported, so the precise classification rule for eradication cannot be evaluated.

The single-group design has no reported concurrent comparator and is not described as randomized. This precludes a direct between-group comparison in the registry record. Masking is listed as NONE, while details about outcome-assessor procedures are not reported. The record does not specify the analysis population, follow-up completeness, reasons for missing endpoint assessments, or how missing data would be handled. These omissions limit assessment of both potential measurement bias and the representativeness of any endpoint count.

The registry lists enrollment of 18, but enrollment alone does not show how many participants received the intervention or contributed an evaluable three-month assessment. The record does not report a study-specific sample-size justification, numerical planning results, or a statistical analysis plan. Although the planning note names assumptions for hypothetical illustrations, it does not provide the values needed to assess their relevance to this study.

Safety interpretation is similarly limited by the absence of event descriptions, attribution, timing, and comparator data. The recorded counts cannot establish causality or comparative risk. Together, these limitations mean that the registry supports an account of the design and intended endpoint, but not a quantitative assessment of efficacy, precision, or comparative safety.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Cryo Balloon for Residual Barrett's Esophagus — NCT02230410.
• Registry record last updated 2022-02-10; status last verified 2022-01.
• Results first posted 2022-02-10.
• 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

NCT02230410 is a completed, single-group pilot study sponsored by Mayo Clinic, with enrollment of 18. It evaluates one CryoBalloon Focal Ablation treatment for residual Barrett’s esophagus after prior ablation or endoscopic mucosal resection. The primary endpoint is the participant count with eradication at 3 months post treatment.

The registry reports no analyses and does not report the primary endpoint result, denominator, or uncertainty. No concurrent comparator is described. Safety entries list 0 serious adverse events among 18 at risk, 1 other adverse event among 18 at risk, and 1 death; event attribution and further details are not reported in the registry record. Thus, the record describes the study question and selected safety counts, but does not provide a primary outcome estimate or comparative treatment effect.