Cutting Balloon Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Cutting Balloon Study (NCT01205568), a na na study. The primary outcome is Acute Change in Minimum Lumen Diameter Immediately Post-intervention.

2. Clinical Question

3. Trial Design

The registry identifies NCT01205568 as the Cutting Balloon Study, with the official title “Safety and Efficacy of the Cutting Balloon to Treat Resistant Pulmonary Artery Stenosis.” Boston Children's Hospital is listed as the sponsor. The condition is pulmonary artery stenosis, and the study is marked completed. The recorded study start is 2003-08-01 and the primary completion date is 2009-03-17. Enrollment is listed as 73.

The intervention list includes transcatheter Cutting Balloon therapy and High Pressure Balloon Angioplasty. The arm description says that vessels with resistant pulmonary artery stenosis were identified during catheterization and eligible vessels were randomized to Cutting Balloon or High Pressure Balloon Dilation. It also notes that patients had a variable number of eligible vessels and that each eligible vessel was randomized at the time of the procedure.

Other registry design entries do not align cleanly with that account: allocation is recorded as not applicable and the model is listed as single group. The registry also cautions that this is not a randomized comparison and that the arms are not a like-for-like control comparison. These inconsistencies make it difficult to reconstruct the intended treatment-group structure from the record alone. In particular, the enrollment figure is a patient count, while the primary outcome is defined for vessels; the number of analyzed vessels and their distribution by procedure are not reported in the registry record.

The primary endpoint is an acute angiographic measure. The listed secondary outcome is percent change in minimum lumen diameter at 3 months after intervention. Numerical outcome results and analysis records are not reported. The record therefore supports a description of the study's stated objectives and design entries, but not an assessment of comparative efficacy.

4. Participant Flow and Accounting

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

Before assignment: Among 73 patients, 331 stenotic vessels were identified. 86 vessels were not eligible and 245 vessels were potentially eligible. 72 vessels were considered successfully treated after low-pressure dilation. 173 met eligibility. 66 vessels were randomized to High Pressure Balloon (HPB) and 107 vessels were randomized to Cutting Balloon (CB).

Overall Study

Analysis population for the primary outcome, as defined in the registry: Vessels with resistant Pulmonary Artery Stenosis were identified during catheterization and eligible vessels were randomized to Cutting Balloon or High Pressure Balloon Dilation. Patients had variable number of eligible vessels. Each eligible vessel was randomized at the time of procedure.

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 data prior to vessel randomization

6. Primary Endpoint

The registry lists the primary outcome as Acute Change in Minimum Lumen Diameter Immediately Post-intervention, measured over Pre-intervention to immediate post-intervention (approximately 10 minutes).

The primary endpoint is the percent change in minimum lumen diameter from before the intervention to immediately afterward. The registry describes measurement by angiography and gives the timeframe as pre-intervention to immediate post-intervention, approximately 10 minutes. The endpoint is a continuous measure, summarized in the registry as a mean with standard deviation.

Minimum lumen diameter represents the narrowest measured opening in the treated vessel. A change in this measure is used to describe the immediate anatomical response to an intervention. Expressing the change as a percentage relates the post-intervention measurement to the pre-intervention measurement, rather than reporting only a raw difference. This is a general description of the statistical meaning of a percentage-change endpoint; the registry does not give the actual measurements or the formula used for individual vessel values.

The acute timeframe focuses on a change occurring during the procedure, not on whether that change persists. The listed secondary outcome addresses percent change in minimum lumen diameter at 3 months, but its numerical result is not reported in the registry record. Neither endpoint alone describes symptoms, longer-term clinical outcomes, or the full balance of potential benefits and harms. The primary endpoint is also defined at the vessel level, while enrollment is reported at the patient level. With variable numbers of eligible vessels per patient, the number of outcome observations and the handling of within-patient dependence would be important for interpreting an analysis; those details are not reported.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry characterizes the primary outcome as a continuous measure, with a mean and standard deviation. These summaries answer different questions. A mean describes the central value of a set of measurements, while a standard deviation describes how spread out individual measurements are around that mean. The standard deviation is not the same as the uncertainty in the estimated mean. In general, uncertainty about an estimated mean is conveyed using a confidence interval or another inferential measure. The registry does not report the primary endpoint's mean, standard deviation, or confidence interval.

What does a percentage-change endpoint represent?

The endpoint is defined as percent change in minimum lumen diameter between pre-intervention and immediate post-intervention angiography. In general, percentage change expresses a change relative to a starting measurement. That can help describe the relative size of an anatomical change across vessels that may have different starting measurements. The registry does not report individual baseline and follow-up values, the exact calculation applied, or numerical results. No result should therefore be inferred from the endpoint definition.

The acute measurement is described as occurring approximately 10 minutes after intervention. This timing makes the endpoint a measure of immediate change, not a direct measure of persistence or later clinical outcomes. The secondary endpoint is measured at 3 months, but no numerical results for it are reported. A finding at one time point would not automatically establish what happens at another time point; that would require the corresponding observed data and analysis.

How should the mean and variability be read?

In general, a mean can conceal variation among observations. Two sets of vessel measurements can have similar means while differing in how tightly or widely individual values are distributed. The standard deviation helps describe that variation, but by itself does not indicate how precisely a treatment effect has been estimated. That precision depends on the amount and structure of the data and on the analysis. Since neither the endpoint summaries nor an inferential comparison are posted, the record does not allow these aspects to be evaluated.

In general, a confidence interval places an estimated effect in the context of its uncertainty under the model used. A narrow interval indicates greater precision than a wide interval, while an interval spanning values with different substantive interpretations may leave important uncertainty. These are general statistical concepts, not descriptions of an interval for this study: no confidence interval for the primary outcome is reported in the registry record.

Why does the vessel-level outcome matter?

Enrollment is reported as 73 patients, while the outcome population is described in terms of eligible vessels. The record says patients had a variable number of eligible vessels and that eligibility was determined during catheterization. Patient count and vessel count are not interchangeable. The number of vessels included in the primary analysis, and the number assigned to each procedure, are not reported.

In general, measurements from multiple vessels belonging to one patient may be more alike than measurements from different patients. This is called clustering or within-patient correlation. If an analysis treats correlated vessel measurements as independent, its estimate of uncertainty may be inaccurate. Methods that account for clustering can be appropriate, depending on the design and analysis objective. The registry does not report whether multiple vessel observations were analyzed, what statistical method was used, or whether any dependence was accounted for.

What can be said about planning calculations?

The registry describes sample-size planning illustrations based on a stated fraction of the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It also states that the illustrations are not the study's own design calculations. The numerical effect and planning counts are not reported in the registry record, so their implications cannot be evaluated from the record. Such planning illustrations are hypothetical calculations, not observed power and not evidence about the trial's actual precision.

In general, a sample-size calculation depends on assumptions about the effect to detect, outcome variability, significance level, allocation, and analysis. A planning result answers a conditional question: how much information might be needed under those assumptions. It does not show what the study actually observed or establish that the design was adequate for every endpoint. The registry does not report a sample-size justification for the trial, its statistical analysis plan, or whether interim analyses were planned.

Which analyses are documented?

The registry lists 0 analysis records. It does not report a hypothesis test, a model specification, covariate adjustment, a method for handling missing outcomes, or a method for comparing the two procedures. It is therefore not possible to identify whether the investigators used a paired analysis of pre- and post-intervention measures, a between-procedure comparison, or another approach. These methods can address different questions and rely on different assumptions. Their appropriateness cannot be assessed without the analysis details and outcome data.

In general, a statistical method should reflect the unit of allocation and the unit of measurement. Here, the record describes vessel-level eligibility and variable numbers of eligible vessels per patient, while its design entries are inconsistent about allocation and study model. That combination makes clear reporting of the analysis population, assignment structure, and clustering methods especially relevant. Those details are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures: acute percent change in minimum lumen diameter as the primary outcome and percent change in minimum lumen diameter at 3 months as a secondary outcome. It lists 0 analysis records and does not provide numerical results for either outcome. The statistical analysis plan and any multiplicity adjustment are not reported in the registry record.

In general, multiplicity arises when several outcomes, comparisons, time points, or analyses are examined. The more questions tested, the greater the chance that at least one apparently notable finding could arise by chance if no adjustment or prespecified hierarchy is used. A primary outcome can help identify the main planned question, but its designation alone does not reveal how multiple analyses were handled. There is not enough information in the registry record to determine whether multiplicity was addressed.

Missing-data handling is also not reported. The record does not state how many enrolled patients or eligible vessels had outcome measurements, whether any measurements were unavailable, or how missing values were handled. It does not identify an analysis population such as all enrolled participants, all treated participants, or vessels with paired measurements. These omissions limit interpretation of any estimate, even if a numerical estimate were available, because the included observations and assumptions about missingness can affect both the estimate and its uncertainty.

The population description refers to vessels, but patients could have a variable number of eligible vessels. The registry does not report the number of vessels analyzed or whether the analysis accounted for multiple vessels from the same patient. This is a distinct analysis-population and dependence issue, not merely a question of missing values. Without these details, readers cannot determine which observations underpin the outcome or how their correlation was handled.

11. 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 non-serious adverse event terms

The safety record lists 73 participants at risk for serious adverse events and 0 participants affected. It separately lists 73 at risk for other adverse events and 16 affected. These are the counts recorded in the registry and should be read as separate categories; the 16 other adverse events should not be reclassified as serious events.

The record does not list serious adverse event terms. That absence does not describe the nature of the other adverse events, because their types and severity are not specified in the information available. Deaths are recorded as null, which means the death count is not reported in the registry record; it should not be interpreted as a count of zero.

These figures do not establish comparative safety between procedures. The registry's treatment allocation information is inconsistent, and the adverse-event figures are presented for the patient group rather than as clearly separated treatment-arm results. The record does not report event timing, duration, relationship to intervention, or a detailed safety analysis. In general, adverse-event counts describe events recorded under defined categories, while judgments about relative risk require clear group definitions and comparable follow-up. Those details are not reported in the registry record.

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

The registry record establishes that the study was intended to evaluate transcatheter Cutting Balloon therapy for resistant pulmonary artery stenosis. It identifies immediate percent change in minimum lumen diameter as the primary efficacy measure and describes angiography before and immediately after intervention. It also identifies a 3-month measure and records adverse-event counts. These entries describe the study's questions and some of its recorded safety information.

The record does not report the numerical primary endpoint result, its variability, or a statistical comparison. It also does not report a numerical result for the secondary endpoint. Therefore, the size and precision of any observed change cannot be judged from the registry record. No conclusion about comparative efficacy follows from the presence of an endpoint definition or the listing of procedures.

The record's design descriptions do not establish a clear randomized comparison. The arm description says eligible vessels were randomized, while allocation is marked not applicable, the model is listed as single group, and the record cautions against treating the arms as a like-for-like control comparison. Until this discrepancy is resolved with fuller design and analysis information, a causal comparison between Cutting Balloon and High Pressure Balloon Dilation cannot be interpreted confidently from the registry entries.

The safety counts should also be interpreted within their limits. The registry reports no participants affected in the serious adverse event category and reports 16 affected in the other adverse event category, among 73 at risk in each listing. It does not report deaths, event descriptions, or procedure-specific safety counts. These entries do not establish the overall safety profile or a comparative difference.

In general, a registry entry can document planned questions and selected results, but it is not a substitute for complete outcome reporting. The absence of numerical efficacy results is not evidence that there was no change; it means the magnitude and uncertainty are not reported in this record. The available information supports describing the endpoints, design ambiguity, and recorded adverse-event counts, while leaving the study's efficacy findings unresolved.

13. Why This Trial Matters Statistically

This study raises a statistical issue that is especially important in catheter-based research: the unit of enrollment may differ from the unit of outcome measurement. Enrollment is reported as 73 patients, while eligible vessels were identified and the primary endpoint is defined for vessels. The record also notes that patients could have a variable number of eligible vessels. Clear reporting must distinguish patient counts from vessel counts so readers can understand the amount and structure of the analyzed data.

When one patient contributes multiple measurements, those measurements may be correlated. In general, accounting for that correlation can affect standard errors and confidence intervals. Treating every vessel as an independent observation when vessels are clustered within patients can overstate the amount of independent information. The registry record does not report how many vessels were analyzed or whether the analysis accounted for clustering, so this important statistical feature cannot be evaluated.

The registry also illustrates why design labels and narrative descriptions need to agree. A vessel-level randomization description sits alongside a single-group model and allocation marked not applicable, together with a warning that the arms are not a like-for-like comparison. Without a consistent account of assignment and analysis, readers cannot reliably identify the intended estimand or interpret a between-procedure contrast.

Finally, an endpoint and a completed status do not amount to a result. Numerical estimates and uncertainty are needed to assess the observed response. In this record, the primary and secondary outcome results are not reported. This makes transparent outcome reporting, clear analysis populations, and explicit handling of clustered observations central to statistical interpretation.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The principal limitation of the registry record is that it does not report numerical results for the primary endpoint. The mean percent change, standard deviation, confidence interval, and test result are absent. The secondary outcome at 3 months also lacks a numerical result. Accordingly, the record cannot establish the observed magnitude or precision of either endpoint.

Design information is internally inconsistent. The study model is listed as single group and allocation as not applicable, but the arm description says eligible vessels were randomized between procedures. A registry caution also states that this is not a randomized comparison and the arms are not a like-for-like control comparison. The record does not resolve these descriptions or explain the assignment process. It is therefore not possible to determine the intended comparative structure from the registry entries alone.

The unit-of-analysis information is incomplete. Enrollment is reported at the patient level, while treatment eligibility and the primary endpoint are described at the vessel level. Patients may have had a variable number of eligible vessels, but the total number of vessels, the number analyzed, and their distribution by intervention are not reported. The statistical handling of multiple vessels within a patient is also not reported.

The record does not describe missing outcome data, analysis populations, a statistical analysis plan, or the method used to estimate treatment effects. It lists 0 analysis records. The safety entries lack event descriptions and procedure-specific counts; the death count is not reported. The registry includes planning-illustration assumptions but does not report a trial-specific sample-size justification or numerical planning outputs. These limitations restrict evaluation of both the efficacy question and the reliability of any comparative interpretation.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Cutting Balloon Study — NCT01205568.
• Registry record last updated 2026-08-27; status last verified 2026-08.
• Results first posted 2018-05-25.
• 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.

18. Record Summary

NCT01205568 is recorded as a completed study sponsored by Boston Children's Hospital, with enrollment of 73. It concerns resistant pulmonary artery stenosis and describes transcatheter Cutting Balloon therapy alongside High Pressure Balloon Angioplasty. The primary endpoint is acute percent change in minimum lumen diameter measured by angiography; the secondary endpoint is percent change at 3 months.

The registry record does not report numerical results for either endpoint or list analysis records. Its allocation and model entries conflict with the arm description's account of vessel randomization, and the record cautions against treating the procedures as a like-for-like randomized comparison. Safety listings record 0 participants affected by serious adverse events and 16 affected by other adverse events, each among 73 at risk; deaths are not reported. The available record describes study aims and selected safety counts, but does not permit assessment of the magnitude or precision of efficacy results.