Assessmet of Patients With PAH Right Ventricular Volume: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Assessmet of Patients With PAH Right Ventricular Volume (NCT01557582), a na na study. The primary outcome is Observed Mean (Std Err) for % Difference Between VMS and MRI..

2. Clinical Question

This is a measurement-comparison question, not a comparison of two treatments. Each method is described as being used on day 1, but the registry record does not report whether every participant received both procedures or the exact pairing and analysis details. Nor does it report the observed mean percent differences, their standard errors, or whether the stated positive-trial criteria were met. The primary question is therefore clear in concept, while the posted record does not give the estimates needed to judge the degree of agreement.

3. Trial Design

The registry identifies this as a completed, single-group device study in patients with pulmonary arterial hypertension. The intervention is the Ventripoint Medical System, and the arm description characterizes the study as a comparison of VMS right ventricular volume measurements with cMRI measurements. The registry lists enrollment as 103. It gives a start date of 2012-04 and a primary completion date of 2013-11.

Allocation and phase are listed as NA, and masking is listed as NONE. The record does not describe a randomized allocation, a separate control arm, or blinding. This is therefore not a randomized treatment comparison: the central design question concerns two measurement methods, rather than differences in outcomes between assigned groups. The study is registered under Pulmonary Arterial Hypertension and lists VentriPoint Diagnostics Ltd. as sponsor.

The registry describes both procedures as occurring on day 1. VMS measurement is described as requiring 15 minutes, while MRI measurement is described as requiring 1 hour. The record does not report the sequence of procedures, whether the same operators performed the measurements, or whether the VMS and MRI readings were interpreted without knowledge of the other measurement.

Two secondary outcomes are named: inter-observer variability and intra-observer variability. Their presence indicates that measurement reproducibility was also of interest, but the registry record does not report the corresponding estimates or explain the specific procedures used to assess variability. It lists three outcome measures and three analyses, but does not provide enough detail to reconstruct the complete analysis plan. The completed status describes the study’s registry status; it does not, by itself, establish whether the stated primary criteria were satisfied.

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: Only evaluable participants were analyzed

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: Demographic information was not available for 2 patients. One subject failed to disclose metal in his abdomen and the other was due to user error.

6. Primary Endpoint

The registry lists the primary outcome as Observed Mean (Std Err) for % Difference Between VMS and MRI., measured over VMS occured on day 1 and required 15 minutes and MRI occurred on day 1 and required 1 hour..

The primary outcome is described as the observed mean percent difference between VMS and MRI measurements. The registry’s outcome title specifies a mean and standard error. Its description says that percent difference was measured for right ventricular end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF). The brief summary’s stated positive-trial rule focuses on RVEDV and RVESV: the mean VMS-cMRI percent difference must fall between -10% and 10% for each, under the specified one-sided significance criterion, and there must be no safety concerns.

Comparing a new measurement method with a reference measurement can show whether the methods yield similar values on average. A mean percent difference describes the direction and average size of the discrepancy on the percentage scale. It does not, by itself, show how widely individual participants’ paired measurements differ. The registry’s criterion uses bounds around zero to define the range considered acceptable for the mean difference. The clinical or technical rationale for selecting the 10% bounds is not reported in the registry record.

The observed means, standard errors, confidence intervals, and significance tests for the endpoint are not reported in the registry record. Consequently, the posted record does not establish how close the observed estimates were to the bounds or whether the positive-trial rule was met. The EF outcome appears in the outcome description, but the stated positive-trial criterion does not specify EF.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean percent difference describe?

The primary outcome is a continuous measurement: a percent difference between VMS and cMRI readings. A mean summarizes the average difference across the analyzed participants. Its sign indicates the direction of the average difference according to the VMS-cMRI convention, while its size indicates how far the average is from zero on the percentage scale. The registry record does not give the formula used to calculate the percent difference, so the precise denominator and implementation cannot be verified from the record.

A mean is useful for describing average agreement, but it does not fully describe agreement for individual participants. A mean near zero could coexist with substantial participant-level differences in opposite directions. Assessing individual agreement would generally require additional information about the distribution of paired differences or limits of agreement. Such information is not reported in the registry record.

How should the standard error be understood?

The outcome title reports a mean with a standard error. In general, the standard error describes the sampling precision of an estimated mean: it indicates how much the estimate would tend to vary across repeated samples under the analysis assumptions. It is not the same as the standard deviation, which describes variation among individual observations. A standard error alone does not reveal the full distribution of participant-level differences.

Confidence intervals are commonly used to express uncertainty around an estimate. In general, a confidence interval gives a range of values compatible with the data and the method’s assumptions at a stated confidence level. For an equivalence-style question, the interval’s position relative to the prespecified bounds is important. The registry record does not report confidence intervals, their confidence level, or the method used to construct them, so no interval-based conclusion can be drawn.

What is the role of the stated bounds?

The stated positive-trial rule sets lower and upper limits of -10% and 10% for the mean VMS-cMRI percent difference, separately for RVEDV and RVESV. In general, an equivalence assessment asks whether the data support a difference small enough to lie within predefined bounds. Failing to find a statistically significant difference from zero in a conventional difference test would not, by itself, establish equivalence; the uncertainty must be sufficiently contained within the acceptable range. The registry specifies a one-sided 0.025 significance level for its rule, but does not report the test statistic, exact testing procedure, or observed results.

The brief summary also requires no safety concerns for the trial to be considered positive. Thus, even evidence satisfying the measurement bounds would not alone establish that the full stated criterion was met. The registry does not report a formal safety decision tied to that rule.

What can be inferred from the design?

The study is described as single-group, with VMS measurements compared against cMRI measurements. This setup addresses measurement agreement rather than a treatment effect between randomized groups. In general, comparisons of measurement methods are strongest when both methods are applied to the same participants and the paired nature of the data is handled in the analysis. Although the registry describes the two procedures on day 1, it does not fully specify whether all measurements were paired, how readings were matched, or how missing pairs were handled.

Masking is listed as NONE. That is a design characteristic, but the record does not clarify which study personnel were unmasked or whether the readers of each measurement knew the other result. Knowledge of one reading while making another can potentially influence measurement or interpretation; whether this occurred cannot be established from the registry entries.

How should planning illustrations be read?

The registry describes sample-size planning illustrations as based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It also says the effect to detect is a stated fraction of the observed effect. Those are planning assumptions, not the design of this single-group measurement study. The illustrations should not be read as observed power, nor as evidence that the trial was adequately powered. The record does not report a sample-size justification for the actual study design.

In general, a planning calculation depends on the target effect, variability, significance level, power target, and design assumptions. If the assumed effect is a fraction of an observed effect, the resulting calculation is conditional on that effect estimate and its uncertainty. The registry record does not report the observed endpoint estimates or the specific fractions used in the planning illustrations, so their numerical basis cannot be evaluated from the record.

10. Multiplicity, Missing Data and Analysis Populations

The registry describes measurements of EDV, ESV, and EF, while its stated positive-trial criterion identifies RVEDV and RVESV. It also lists inter-observer and intra-observer variability as secondary outcomes. These are multiple outcome questions, but the registry record does not report how multiplicity was handled, whether the two primary volume measures were treated as co-primary outcomes, or whether any adjustment to significance levels was planned for multiple tests. The stated one-sided 0.025 criterion is not enough to determine the full multiplicity strategy.

The record says that only evaluable participants were analyzed for the primary outcome. It does not define evaluability, report the number included in the analysis, describe missing measurements, or explain how incomplete or unusable VMS or MRI readings were handled. It also does not report whether any participants were excluded after enrollment or why. These details matter because the primary estimate may depend on which participants had usable measurements and whether missingness was related to the measurement difference.

The registry record does not describe an intention-to-measure analysis set, a per-protocol analysis set, a sensitivity analysis, or an imputation method. Those approaches should not be assumed. Nor does the record provide a statistical analysis plan that would clarify prespecified decisions about outliers, repeated readings, or protocol deviations. The analysis population and missing-data approach therefore remain insufficiently described for a full assessment of robustness.

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.

The safety fields list 103 participants at risk for serious adverse events and 103 at risk for other adverse events. The corresponding affected counts are both zero. These entries mean that the registry records no affected participants in those fields; they should not be interpreted as proof that no adverse experiences occurred or that the procedure is free of risk. The record does not describe how adverse events were collected, the observation period, or the severity criteria used.

The deaths field is null, which means deaths are not reported in the registry record; it is not a reported zero. No top serious adverse-event terms are listed. The record also does not state whether the investigators judged that there were no safety concerns for purposes of the trial’s positive-trial rule. That judgment is a separate part of the stated criterion, and it cannot be confirmed from the listed counts alone.

Because this was a single-group study, the safety entries do not provide a randomized comparison against a control group. They describe the recorded event counts in the study group, not a comparative estimate of risk.

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

This study asks whether VMS measurements of right ventricular volume are sufficiently close, on average, to cMRI measurements in patients with PAH. Its stated rule sets bounds for the mean percent difference in RVEDV and RVESV and includes a safety condition. That is a focused question about measurement comparison, distinct from whether a treatment changes health outcomes.

The registry record does not report the observed primary means, standard errors, confidence intervals, or p-values. It therefore cannot establish whether the average measurements were inside the specified bounds, how precisely any difference was estimated, or whether the stated positive-trial criterion was met. The absence of those values in the registry record is not evidence that the criterion failed, just as the completed status is not evidence that it succeeded.

Even if an average difference were within the bounds, that result would not automatically show that every individual measurement was close to cMRI. Average agreement and individual-level agreement are different properties. The record does not report the distribution of paired differences or other results that would permit an assessment of individual-level agreement.

The registry also does not establish whether the measurement method’s performance generalizes beyond the participants and procedures in this study. The number of evaluable participants, detailed measurement procedures, handling of missing readings, and reproducibility results are not reported in the registry record. The named observer-variability outcomes indicate that repeatability was of interest, but their results are not reported.

Accordingly, the record can be used to understand the intended comparison, the stated decision boundaries, and the broad study design. It cannot support a conclusion about the observed degree of agreement, the precision of the estimates, individual measurement performance, or whether the protocol’s overall positive-trial rule was satisfied.

13. Why This Trial Matters Statistically

Measurement studies require a different statistical reading from randomized treatment trials. Here, the key question is whether estimates from VMS are close enough to cMRI measurements under a prespecified criterion. A conventional test for a difference is not interchangeable with an equivalence-style assessment: the latter depends on defined acceptable bounds and uncertainty around the estimate. The registry’s stated bounds make that distinction important.

The endpoint is a mean percent difference, which captures average discrepancy but may conceal variation among participants. A complete statistical interpretation would ideally consider both the uncertainty around the mean and the distribution of individual paired differences. The registry identifies standard errors as part of the outcome but does not report the actual estimates or additional agreement results.

The study also highlights the importance of specifying the analysis population. The record says only evaluable participants were analyzed, but does not report the evaluable count or criteria. Without that information, readers cannot judge how much the analysis depends on the availability of usable measurements. The secondary outcomes of inter-observer and intra-observer variability are relevant to reproducibility, yet their estimates are not reported.

Finally, planning calculations need to be separated from observed evidence. The registry describes sample-size illustrations based on an observed effect and assumptions that include two-arm allocation, even though the trial itself is described as single-group. Such illustrations can aid future planning, but they do not show the power actually achieved or resolve the missing primary results. The statistical importance of this record lies in its defined measurement question and decision rule, alongside the need for complete endpoint and analysis reporting to evaluate them.

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 most consequential limitation for interpreting the registry record is that the observed primary endpoint results are not reported. Without means, standard errors, confidence intervals, or test results, the degree and precision of agreement cannot be assessed. The criterion for a positive trial is stated, but whether it was met is not reported in the registry record.

The analysis population is described only as evaluable participants. The record does not explain how evaluability was defined, how many participants were included in the primary analysis, or how missing or unusable measurements were handled. This leaves uncertainty about the relationship between enrollment and the analyzed data.

Although the registry describes both procedures on day 1, it does not report their sequence, the pairing and reading procedures, or whether readers were blinded to the other method’s result. Masking is listed as NONE, but the record does not specify which personnel or measurement stages that designation covers. These details can matter in a study comparing measurement methods.

The outcome description includes EDV, ESV, and EF, whereas the stated positive-trial rule names RVEDV and RVESV. The registry does not clarify how EF relates to the primary decision rule or how multiplicity across outcomes was addressed. It also does not report results for the listed observer-variability outcomes.

Finally, the safety record has zero affected counts in the serious and other adverse-event fields, but the deaths field is null and the event-collection details are not reported. The registry does not document the investigators’ overall safety judgment. These limitations prevent a complete evaluation of the measurement and safety criteria from the registry record alone.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Assessmet of Patients With PAH Right Ventricular Volume — NCT01557582.
• Registry record last updated 2015-03-27; status last verified 2012-10.
• Results first posted 2015-03-27.
• 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

The record describes a completed, single-group study of the Ventripoint Medical System in patients with pulmonary arterial hypertension, with enrollment listed as 103. VMS right ventricular volume measurements were compared with cMRI measurements. Both procedures are described as occurring on day 1; VMS required 15 minutes and MRI required 1 hour.

The primary outcome is the mean percent difference between VMS and MRI measurements. The stated positive-trial rule applies bounds of -10% and 10% to RVEDV and RVESV at a one-sided 0.025 significance level, and also requires no safety concerns. Inter-observer and intra-observer variability are listed as secondary outcomes.

Observed endpoint estimates, analysis details, and results for the secondary outcomes are not reported in the registry record. Safety fields record zero affected participants for serious and other adverse events, while deaths are not reported. The record defines the intended measurement question and decision rule but does not establish whether the criteria were met.