The Right Ventricular Pulmonary Circulation Continuum in Mitral Valve Disease Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Right Ventricular Pulmonary Circulation Continuum in Mitral Valve Disease Study (NCT03155373), a registered phase not stated study. The primary outcome is Impaired Post-operative Functional Capacity.

2. Clinical Question

The registry describes a prospective clinical question about measures of function around mitral valve operation, rather than an efficacy question comparing randomized treatments. The listed secondary outcomes are right heart catheterisation, quality of life assessed by the SF36 survey and myocardial histology. The record does not report results for these outcomes, nor does it provide an analysis linking any functional measure to prognosis. The endpoint definition gives a way to classify post-operative function, but the registry does not report how many participants met that definition. The clinical question can therefore be described from the planned measurements and endpoint, but an answer about observed functional capacity cannot be drawn from the posted results.

3. Trial Design

The registry record identifies NCT03155373 as a completed study sponsored by Imperial College London. Enrollment is 50. The recorded start date is 2017-02-15, and the primary completion date is 2019-03-01. These administrative details describe the registered study but do not by themselves provide outcome evidence.

The record groups participants in three clinical categories. Group A comprises asymptomatic or mildly symptomatic participants with normal pre-operative left ventricular function, defined in the record as left ventricular ejection fraction above 60%. Group B comprises symptomatic participants with normal pre-operative function, defined as left ventricular ejection fraction greater than or equal to 60%. Group C comprises participants with impaired pre-operative function, defined as left ventricular ejection fraction below 60%. These definitions overlap at the 60% boundary as written for groups A and B, so their classification cannot be clarified from the registry record.

This is not a randomized comparison, and allocation is not stated. The groups therefore should not be read as treatment arms or as evidence from a controlled contrast. Differences between clinical groups could reflect the characteristics used to define those groups, as well as other features not described in the registry record. The record does not give further details about recruitment, the timing or sequence of assessments, or whether all participants underwent every listed procedure.

Assessments and procedures listed include cardiac catheterisation, cardiopulmonary exercise testing, pulmonary function tests, cardiac MRI, a quality of life survey, mitral valve operation and myocardial biopsies. The primary endpoint is assessed at 1 year and concerns impaired post-operative functional capacity. Three secondary outcomes are named: right heart catheterisation, SF36 quality of life and myocardial histology. Although the record lists 5 outcome measures, detailed definitions and results for the other measures are not reported in the registry record. The statistical analysis plan, sample-size justification, interim analyses and analysis populations are also 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 Impaired Post-operative Functional Capacity, measured over 1 year.

The primary endpoint is a binary classification of impaired post-operative functional capacity at 1 year. A participant meets the endpoint if post-operative left ventricular ejection fraction is below 50% and/or predicted peak VO2 is at or below 84%. The use of “and/or” means that either criterion can qualify a participant, as can both. The registry describes the outcome unit as participants and the measure as a count of participants.

Left ventricular ejection fraction reflects the proportion of blood in the left ventricle pumped out with each contraction. Peak VO2, or peak oxygen uptake, is a measure obtained during exercise testing; expressing it as a percentage of predicted values relates the measured capacity to a predicted reference. In general, combining a cardiac measure and an exercise-capacity measure can capture different aspects of post-operative function. A dichotomous endpoint simplifies reporting into whether the defined threshold was met, but it discards information about how close an individual value is to the threshold and about the range of measurements within each category.

The stated project aim is to identify an objective functional-capacity marker that relates to prognostic surrogates, detects early decline and returns to normal after surgery. The endpoint is relevant to that aim because it uses post-operative cardiac and exercise measurements. However, the registry record does not report the number of participants meeting either criterion, the separate results for each component, or any relationship between the endpoint and prognosis. The definition alone cannot establish whether the marker performed as intended or whether values changed after surgery.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods determine how observed measurements are converted into estimates and how much uncertainty is attached to those estimates. The registry record identifies a participant-count endpoint but does not report the statistical analysis plan, model, test, confidence intervals or analysis population. The explanations below are general descriptions of issues relevant to this type of study, not descriptions of methods confirmed by the registry.

What does a binary endpoint represent?

In general, a binary endpoint assigns each participant to one of two categories, such as meeting or not meeting a prespecified definition. Here, the registry’s definition combines post-operative left ventricular ejection fraction below 50% and/or predicted peak VO2 at or below 84%. A participant meeting either criterion qualifies. A count of participants meeting the endpoint is directly interpretable as a frequency, but its interpretation depends on the denominator: the number assessed for the outcome must be known. Enrollment is 50, but the number with a recorded primary outcome is not reported in the registry record. It would not be appropriate to assume that every enrolled participant had an evaluable endpoint.

Thresholding continuous measurements has a trade-off. It can make a result easier to communicate as a category, while losing distinctions between values just on either side of a cut-off and values much farther from it. General good practice is to report the component measurements or distributions as well as the binary classification when those data are available. The registry record does not report those component results.

How should clinical groups be interpreted?

In general, group comparisons in a non-randomized study are vulnerable to confounding. Confounding occurs when a characteristic related to group membership is also related to the outcome, making a simple difference between groups hard to attribute to any particular exposure or care. In this study, groups are defined by symptoms and pre-operative ventricular function, which are clinical characteristics. The registry explicitly says this is not a randomized comparison, and allocation is not stated. Therefore, a comparison between categories would describe an association unless additional design and analysis information supported a stronger interpretation. The record does not report adjusted estimates or the covariates, if any, used in an analysis.

The group definitions also place the 60% boundary in both the definition for group A and group B: group A is described as above 60%, while group B is described as greater than or equal to 60%. As written, a value at 60% meets the stated function criterion for both groups, with symptoms distinguishing the descriptions but not resolving the overlap for all possible participants. The registry record does not clarify how classification was handled at this boundary. This matters for reproducibility: readers need unambiguous rules to understand how participants were assigned to categories.

What would uncertainty estimates add?

In general, a point estimate gives a central summary, while a confidence interval communicates its statistical uncertainty. The interval’s width depends on factors such as the amount of information and the variability of the data, as well as the method used. A narrow interval indicates greater precision than a wide interval under the same approach, but an interval does not correct bias from study design or measurement. No primary estimate or confidence interval is reported in the registry record, so neither the magnitude nor precision of an outcome association can be assessed.

For a binary outcome, an analysis might describe the number meeting the endpoint and the denominator, then estimate an event frequency or compare frequencies between groups. The exact estimand, statistical model and handling of any incomplete outcomes should be stated in a full analysis report. These details are not reported in the registry record. No p-value is reported for the primary endpoint, and no evidence of a prespecified test can be inferred from the endpoint definition alone.

Why does over-dispersion matter in general?

Over-dispersion describes data that vary more than a statistical model expects. For example, a model for counts may assume a particular relationship between the mean and variability; if observed variation exceeds that assumption, standard errors can be too small and confidence intervals too narrow. Model choice and diagnostics matter when data are clustered, heterogeneous or otherwise more variable than expected. The registry record does not report a count model or data structure requiring this issue to be addressed. This is a general consideration, not a claim about the study’s actual analysis.

What can be inferred from planning calculations?

In general, sample-size calculations are planning tools that depend on assumptions about the effect to detect, variability, allocation and testing approach. They do not show whether an observed effect is real, and they are not a substitute for an estimate with its uncertainty. The stated planning illustration uses a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation, with the effect defined as a stated fraction of the observed effect. The registry record does not report the observed primary outcome effect needed to interpret such an illustration, nor does it report that these assumptions were used to design the study. Any planning count should be understood as an illustration, not observed power. The study’s own sample-size justification is not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 5 outcome measures and names a primary outcome and secondary outcomes. It does not report a multiplicity strategy, such as whether testing across outcomes was adjusted or whether secondary analyses were intended to be descriptive. In general, assessing many outcomes or contrasts can increase the chance of at least one apparently unusual finding when each is tested separately. Methods for controlling or describing that issue depend on the prespecified questions and analysis plan. Since no analysis plan or results are reported in the registry record, the impact of multiplicity cannot be evaluated.

Missing data are also important for interpreting a participant-count endpoint. The endpoint is defined using post-operative measurements, but the registry record does not state how many participants had each measurement, whether any measurements were missing, or how missing values were handled. Missingness can affect both the denominator and the representativeness of the analyzed participants. In general, complete-case results may be biased if the availability of measurements is related to participants’ health or outcomes; other approaches rely on assumptions that should be made explicit. No such approach is reported in the registry record.

The record does not describe the primary analysis population, exclusions after enrollment, or whether participants were analyzed according to an intention-to-treat, per-protocol or other rule. Those labels should not be inferred from enrollment or completion status. The endpoint count, denominator, handling of missing measurements and analysis population would all be needed to assess how closely the reported analysis reflects the enrolled cohort. None of these details are reported in the registry record.

11. 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.

The registry reports 0 serious adverse events among 50 participants at risk and 0 other adverse events among 50 participants at risk. It also records 2 deaths in the overall cohort. These are distinct entries: the event counts do not explain the deaths, and the record does not state whether the deaths were classified as adverse events or whether they were related to study procedures or the underlying condition.

The registry record does not report the timing, causes or circumstances of the deaths, the duration of safety follow-up, or definitions used for event classification. It also lists no leading serious adverse event terms. The absence of a listed term does not supply information about how events were collected or adjudicated. The zero counts should therefore be read as the posted registry figures, not as evidence that no unrecorded events occurred.

In general, safety counts are most informative when accompanied by clear follow-up periods, definitions, denominators and event-level context. They cannot, on their own, establish a difference in safety between treatments, particularly when the study is not a randomized comparison and no control arm is described. The registry’s counts are descriptive; the record does not provide a comparative safety analysis.

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

The record establishes that a completed study enrolled 50 participants and was designed around a question about functional capacity in mitral regurgitation. It specifies a post-operative endpoint at 1 year and lists diagnostic assessments, a mitral valve operation, myocardial biopsies and secondary outcomes. It also gives clinical categories based on symptoms and pre-operative ventricular function. These details help define what the study set out to assess.

The record does not report primary endpoint results. It therefore does not show how many participants met the endpoint, whether the two endpoint components gave similar or different findings, or how precise any estimated outcome frequency might be. It also does not report analyses connecting function to prognosis or demonstrating that a measure detects early decline or returns to normal after surgery. Those are aims in the brief summary, not findings established by the posted results.

The study is not described as a randomized comparison. Its clinical groups are not equivalent to randomized treatment arms, and contrasts between them would need to account for differences in symptoms and pre-operative function. The record gives no adjusted results or analysis details that could support such an interpretation. The data do not establish a causal effect of operation, a treatment benefit, or a treatment failure.

The safety figures provide counts, including 0 serious adverse events, 0 other adverse events and 2 deaths, but the record lacks context about timing, cause and relatedness. They cannot be used to explain the deaths or to compare safety across treatments.

In general, a registry record can document study intent, design features and results when they are posted, but completion status alone does not establish that a result is available or conclusive. The appropriate conclusion from this record is limited: it defines an interesting functional-capacity question and reports some study and safety details, while leaving the clinical outcome findings and their uncertainty unreported. No conclusion about whether surgery should be performed for an individual follows from these registry entries.

13. Why This Trial Matters Statistically

This study is statistically notable for asking whether functional capacity can be assessed with objective measurements in mitral regurgitation, rather than relying only on symptom status. Its stated rationale points to variation in referral patterns and the difficulty of judging symptoms. That makes endpoint definition important: a measure intended to inform clinical decisions needs a clear, reproducible definition and evidence about how well it relates to outcomes of interest.

The registry combines two post-operative criteria into a binary endpoint: left ventricular ejection fraction below 50% and/or predicted peak VO2 at or below 84%. This creates a practical classification rule, but it can conceal whether participants meet one criterion or both, and whether values are close to the thresholds. Reporting the component measurements and endpoint denominator would help readers judge how much information the binary classification retains.

The clinical grouping also illustrates a central design issue. Symptoms and pre-operative function define the groups, while the record says the study is not randomized. Those characteristics may be related to post-operative measurements, so group contrasts cannot automatically be interpreted as effects of a treatment or of a single baseline feature. Clear definitions, analysis plans and appropriately cautious interpretation are especially important in this setting.

Finally, the gap between a completed registry entry and posted outcome analyses is itself relevant to evidence appraisal. Enrollment, endpoint definitions and safety counts describe the study, but they do not answer its primary statistical question. Without outcome counts, denominators, estimates and uncertainty, readers cannot evaluate the strength or precision of evidence for the proposed functional marker. The record’s aims are clinically motivated, yet the statistical conclusions remain unreported.

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.

A major limitation of the available record is that it does not report the primary outcome count, component outcomes or estimates. The study’s completion status and enrollment total do not establish that outcome data were analyzed or posted. The record lists zero analyses, and no confidence intervals, p-values or other inferential results are given. As a result, the central functional-capacity question cannot be answered from the registry record.

The study is not a randomized comparison, and the allocation description is not stated. Its three groups are clinical categories based on symptoms and pre-operative function rather than stated treatment assignments. This limits the interpretation of any group contrast and makes potential confounding an important concern. The registry record does not describe adjustment methods or a prespecified comparison between groups.

The written group definitions include an overlap at the 60% left ventricular ejection fraction boundary for groups A and B. The record does not clarify how participants at that boundary were classified. It also does not report detailed eligibility criteria, recruitment methods, the analysis population or whether all participants completed each assessment. These omissions limit reproducibility and make the enrolled cohort difficult to characterize fully.

Endpoint reporting is incomplete for interpretation: the definition is available, but the number assessed, missing measurements and handling of missing data are not. The registry lists 5 outcome measures, but detailed results and a multiplicity strategy are not reported. Safety reporting is also limited by the absence of event timing, death causes and relatedness. These limitations concern the available registry information; they do not establish that the underlying study lacked further methods or analyses.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: The Right Ventricular Pulmonary Circulation Continuum in Mitral Valve Disease Study — NCT03155373.
• Registry record last updated 2023-02-28; status last verified 2023-02.
• Results first posted 2023-02-28.
• 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

NCT03155373 is a completed study sponsored by Imperial College London, with enrollment of 50. The recorded start date is 2017-02-15, and the primary completion date is 2019-03-01. The study concerns mitral regurgitation and pulmonary hypertension and aims to assess objective markers of functional capacity around mitral valve operation.

The primary endpoint is impaired post-operative functional capacity at 1 year, defined by post-operative left ventricular ejection fraction below 50% and/or predicted peak VO2 at or below 84%. The registry describes three clinical groups based on symptoms and pre-operative ventricular function, and lists cardiac testing, exercise testing, quality of life assessment, operation and biopsy procedures. The study is not a randomized comparison.

Primary and secondary outcome results are not reported in the registry record. The record lists 0 serious adverse events, 0 other adverse events and 2 deaths in the overall cohort, without reporting further context for the deaths. The statistical analysis plan, missing-data handling, analysis populations and sample-size justification are not reported in the registry record.