The SPACER Trial - Repair of Tricuspid Valve Regurgitation Using the Edwards TricuSPid TrAnsCatheter REpaiR System: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The SPACER Trial - Repair of Tricuspid Valve Regurgitation Using the Edwards TricuSPid TrAnsCatheter REpaiR System (NCT02787408), a na na study. The primary outcome is All-cause Mortality.

2. Clinical Question

3. Trial Design

The SPACER Trial (NCT02787408) is listed as a completed, single-group device study. Its purpose was to assess the safety and device performance of the Edwards Tricuspid Transcatheter Repair System in patients described as having clinically significant, symptomatic tricuspid regurgitation and high surgical risk for standard repair or replacement. The record lists enrollment of 25. It gives a start date of 2016-09-14 and a primary completion date of 2018-01-30.

The study has no concurrent comparison arm. Allocation is listed as NA and masking as NONE. The record therefore does not describe a randomized, masked comparison of the device with another treatment. There is no like-for-like control group from which to make a treatment-group contrast. The proposed primary comparison was instead with a literature-derived performance goal based on high-risk surgical outcomes. The numerical goal, its source, and its derivation are not reported in the registry record.

The primary endpoint was all-cause mortality at 30 days in the as-treated cohort, defined as enrolled subjects who undergo the study procedure, with a chest incision given as the procedural criterion. The primary endpoint description states that early termination meant the desired statistical power was not attained; consequently, the planned performance-goal analysis was not performed. The record lists mortality as a number of deaths and percentage of patients only. It does not report a 30-day endpoint estimate or a comparison result.

Other listed outcomes include technical, device, and procedural success; heart-failure rehospitalization; tricuspid-regurgitation re-intervention; changes in peripheral edema, New York Heart Association class, and six-minute walk distance. The registry record does not give their results in the registry record for this analysis. The reason for early termination and the exact termination date 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: As Treated (AT) Cohort: All subjects who are enrolled and undergo the study procedure (chest incision)

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 All-cause Mortality, measured over At 30 days..

All-cause mortality counts deaths from any cause within the specified follow-up period, rather than deaths attributed only to the device or procedure. The registry identifies the primary endpoint timeframe as 30 days and states that mortality was to be assessed in the as-treated cohort. That cohort is defined by undergoing the study procedure after enrollment.

Mortality is a clinically direct safety outcome: it records whether a participant died within the stated period, without requiring a judgment that a particular cause is related to the intervention. In a single-group study, a mortality count can describe what occurred among the participants assessed. It cannot, by itself, establish how the result would compare with an untreated group or another procedure.

The registry describes an intended comparison with a literature-derived performance goal based on high-risk surgical outcomes for tricuspid repair or replacement. Such a goal can serve as an external benchmark when there is no concurrent control, but its interpretation depends on how closely the external population and outcome definitions match the study population and follow-up. The numerical goal and its supporting details are not reported in the registry record. The planned comparison was not performed because the study terminated early and desired statistical power was not attained. The 30-day primary endpoint result is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group design allow?

In a single-group study, participants receive the intervention under study and outcomes are described for that group. The design can document observed events and device performance outcomes, but it does not create a concurrent untreated or alternative-treatment group. As a general statistical matter, a between-group effect requires a meaningful comparison: outcomes in the intervention group must be contrasted with outcomes in a suitable comparator group or benchmark. Without that contrast, a count is descriptive rather than a direct estimate of a comparative treatment effect.

The SPACER Trial has allocation listed as NA, masking listed as NONE, and is identified as a single-group study. Its primary endpoint description proposed an external performance-goal comparison rather than a randomized control comparison. The performance-goal value, literature source, and methods for matching or adjusting populations are not reported in the registry record. The planned comparison was not performed.

What is the role of a performance goal?

As a general concept, a performance goal is a benchmark against which an observed outcome may be assessed. An external benchmark is not equivalent to a concurrent control: differences in participant eligibility, clinical practice, follow-up, endpoint definitions, and event ascertainment can affect comparability. A valid interpretation therefore depends on details about both the benchmark and the study population. Those details, including the numerical goal, are not reported in the registry record. The record states that the comparison was not performed, so no conclusion about meeting or failing the goal can be drawn from the posted primary-endpoint information.

What do counts and percentages communicate?

A count reports how many participants or events were recorded, depending on the definition used. A percentage places a count in relation to a denominator, but its meaning depends on which participants are included and how events are counted. The adverse-event entry lists 20 affected among 25 at risk for serious events, 23 affected among 25 at risk for other events, and 16 deaths. The registry record does not explain in the registry record how the death count relates in timing or classification to the primary 30-day mortality endpoint. These figures should therefore be interpreted as separate registry entries unless the record explicitly connects them.

For the listed serious-event terms, percentages are reported for Cardiac failure, Cardiac arrest, Cardiogenic shock, Sepsis, Procedural haemorrhage, and Renal failure. The denominator for those percentages and whether one participant could appear under multiple terms are not reported in the registry record. In general, adverse-event categories need not be mutually exclusive: a participant may experience more than one event, and a participant may potentially be represented in several event categories. No assumption about overlap or causality is justified by the listed percentages alone.

How should uncertainty be understood?

As a general statistical concept, an estimate is more informative when accompanied by a measure of uncertainty, such as a confidence interval. A confidence interval describes a range of values compatible with the observed data under the assumptions of the analysis. It is not a guarantee that the true value falls within that range, and its interpretation depends on the analysis model and sampling process. A p-value, when reported, describes how unusual data at least as inconsistent with a specified null hypothesis would be under that hypothesis and model; it does not measure the probability that a treatment works.

The registry record lists no analyses. A confidence interval, p-value, or completed primary comparison is not reported in the registry record. The statement that desired statistical power was not attained explains why the planned comparison was not conducted, but it does not furnish a result or quantify uncertainty. The record does not report the target power, the assumed benchmark rate, the planned sample-size justification, or an interim-analysis plan.

What does power mean in this setting?

In general, statistical power is the probability that a specified analysis will detect an effect of a defined size when that effect is present, subject to assumptions about the design and data. Power is tied to the planned hypothesis test, the chosen threshold, the assumed event frequency, and the number of observations. It is not a measure of the probability that a result is true. Nor can power be inferred simply by observing whether a result is statistically significant.

The registry specifically says the study ended early and desired statistical power was not attained. That statement is not evidence that the intervention failed, nor is it evidence that it succeeded. No observed-power calculation is reported in the registry record. Any sample-size illustration based on an observed effect would be a planning exercise rather than a measure of the evidence generated by this trial. The registry record does not report the trial's own sample-size justification or the details of any such planning calculation.

What can be inferred from the listed analysis status?

The record lists zero analyses. This indicates that inferential analysis results are not listed in the registry record; it does not mean that no outcomes occurred or that the adverse-event counts should be disregarded. Descriptive counts can still characterize what was entered, while questions requiring a formal comparison, uncertainty interval, or adjustment remain unanswered. No adjusted or unadjusted primary comparison, model specification, missing-data procedure, or analysis population beyond the endpoint's as-treated definition is reported in the registry record.

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("EW Tricuspid Transcatheter Repair System")
n      <- c(25)
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  EW Tricuspid Transcatheter Repair System  25  2  8.0  1.0  26.0  2.2  25.0  2.4  25.1

11. Multiplicity, Missing Data and Analysis Populations

The registry lists several secondary outcomes in addition to the primary mortality endpoint: technical success, device success, procedural success, heart-failure rehospitalization, tricuspid-regurgitation re-intervention, changes in peripheral edema, change in New York Heart Association class, and change in six-minute walk distance. Considering multiple outcomes can raise a general statistical issue called multiplicity. When many hypotheses are tested, the chance of obtaining at least one apparently unusual result may increase unless the analysis plan accounts for the number and structure of tests. The registry record does not report a multiplicity strategy, a hierarchy for interpreting secondary outcomes, or inferential analyses for these outcomes.

Missing-data handling is also relevant because incomplete follow-up can affect outcome estimates. The registry entries do not report how missing endpoint observations were handled, whether follow-up was complete, or how participants with unavailable measurements were included in analyses. For the primary endpoint, the as-treated population is defined as enrolled subjects who undergo the procedure, but the number in that population and its relation to the listed enrollment are not reported in the registry record.

The record does not report an analysis plan, an interim-analysis plan, or a rationale for sample size. It states that early termination meant desired statistical power was not attained and the planned primary comparison was not performed. The reason for early termination is not reported in the registry record. These gaps limit assessment of whether outcome selection, missingness, and analysis decisions were prespecified or how they may affect interpretation. They do not justify assumptions that data were missing, that the analysis was biased, or that a particular correction was or was not used.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cardiac failure (36.0%), cardiac arrest (16.0%), cardiogenic shock (12.0%), sepsis (12.0%), procedural haemorrhage (12.0%).

The device-group safety entry lists 20 affected among 25 at risk for serious events and 23 affected among 25 at risk for other events. It also reports 16 deaths. These are registry counts; they should be read as descriptions of the recorded safety data, not as evidence that the device caused each event. The registry entries available do not specify the timeframe for the adverse-event counts or deaths, so these figures cannot be assumed to correspond to the primary endpoint's 30-day window.

The listed serious-event terms and percentages are Cardiac failure, 36.0%; Cardiac arrest, 16.0%; Cardiogenic shock, 12.0%; Sepsis, 12.0%; Procedural haemorrhage, 12.0%; and Renal failure, 12.0%. The denominator for those percentages is not reported in the registry record. Nor is it reported whether participants could be counted under more than one term. The term percentages should therefore not be added, treated as non-overlapping groups, or interpreted as percentages of all participants without a stated denominator.

The registry record does not provide enough detail to assess event timing, individual participant histories, or attribution to the device or procedure. The separate adverse-event death count should not be substituted for the unreported 30-day primary mortality result.

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

The registry record establishes that SPACER was a completed, single-group device study with enrollment listed as 25. It documents a study purpose focused on safety and device performance in patients described as having symptomatic, clinically significant tricuspid regurgitation and high surgical risk for standard repair or replacement. It also lists adverse-event counts for the device group and gives several serious-event terms with percentages. Those details describe the scope of the study and the safety information entered in the registry.

The record does not provide the primary 30-day mortality result in the registry record for this analysis. Although the endpoint description says mortality is presented as a death count and percentage, the actual primary-endpoint values are not reported in the registry record. The 16 deaths listed in the adverse-event entry have no stated timeframe and cannot be assumed to be the 30-day endpoint count. The record also states that early termination prevented attainment of desired statistical power and that the planned comparison with a literature-derived performance goal was not performed.

Accordingly, the registry information does not establish whether mortality was above, below, or similar to the external goal. It does not support a comparative conclusion about the device versus another treatment because there was no concurrent control group. It also does not show that the device caused or prevented any particular adverse event. The serious-event counts and listed terms are safety descriptions, not causal estimates.

For secondary outcomes, the registry lists endpoint names but no corresponding results in the registry record. Technical success, device success, procedural success, rehospitalization, re-intervention, edema, NYHA class, and walking-distance outcomes therefore cannot be characterized from this record information. Missing analysis details, including uncertainty estimates and missing-data handling, further constrain interpretation. The appropriate statistical reading is descriptive and limited to the details actually entered in the registry.

14. Why This Trial Matters Statistically

This trial matters statistically because it illustrates the difference between collecting outcome data and completing a comparative analysis. The registry identifies a 30-day mortality endpoint and an external performance-goal comparison, but also states that early termination meant desired statistical power was not attained and the comparison was not performed. A study can have a specified endpoint without producing the inferential result needed to assess it against a benchmark.

The single-group design is also important. With no concurrent control group, the design does not directly estimate a difference between the device strategy and another treatment. An external performance goal may offer context in some study designs, but it depends on how the benchmark was selected and how comparable its population and outcome definitions are. The goal and its derivation are not reported in the registry record, and no comparison result is available.

The record further emphasizes why safety counts need careful context. The entry includes affected-participant counts, deaths, and term-specific percentages, but the registry entries do not specify the event timeframe, denominator for term percentages, or overlap among terms. Without these details, readers should resist treating categories as independent or attributing events to the device solely because they appear in the device group's safety record.

Finally, the listed secondary outcomes raise general questions about multiplicity, missing data, and analysis populations. Those issues are not resolved by outcome names alone. The registry record does not report the statistical plan or inferential analyses. The case therefore shows why endpoint definitions, comparator choice, analysis execution, and transparent reporting are all needed to move from recorded events to a precise statistical conclusion.

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 is that the intended 30-day mortality comparison was not performed. The registry attributes this to early termination and failure to attain desired statistical power. The numerical mortality result for the primary endpoint is not reported in the registry record, and the external performance-goal value and its derivation are also not reported. The reason and exact date of early termination are not reported in the registry record.

The design was single-group, with allocation listed as NA and masking as NONE. It therefore lacks a concurrent control group. The primary endpoint description refers to an external literature-derived performance goal, but the available information does not permit evaluation of its comparability with the study cohort. No inferential analyses are listed in the registry record, and confidence intervals, p-values, or adjusted estimates are not reported.

The primary endpoint population is defined as enrolled subjects who undergo the study procedure, but its size is not reported in the registry record. The enrollment listing of 25 should not be assumed to equal the as-treated population. The adverse-event entry reports serious and other affected counts and deaths, but the event timeframe and the relationship of the death count to 30-day mortality are not specified in the registry record. Denominators and potential overlap for serious-event term percentages are not reported in the registry record.

The record lists secondary outcomes but their results are not reported in the registry record for this analysis. The statistical analysis plan, sample-size justification, missing-data handling, and multiplicity approach are not reported in the registry record. These limitations restrict the precision and scope of conclusions; they do not establish that an unreported outcome was favorable or unfavorable.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The SPACER Trial - Repair of Tricuspid Valve Regurgitation Using the Edwards TricuSPid TrAnsCatheter REpaiR System — NCT02787408.
• Registry record last updated 2022-10-25; status last verified 2022-04.
• Results first posted 2022-10-25.
• 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.

19. Record Summary

NCT02787408, the SPACER Trial, is listed as completed and as a single-group study of the EW Tricuspid Transcatheter Repair System. The record lists enrollment of 25, a start date of 2016-09-14, and a primary completion date of 2018-01-30. The study purpose was to assess safety and device performance in patients with clinically significant, symptomatic tricuspid regurgitation who were at high surgical risk for standard repair or replacement.

The primary endpoint was all-cause mortality at 30 days in the as-treated cohort. The registry states that early termination meant desired statistical power was not attained, and the planned comparison with a literature-derived performance goal was not performed. The primary mortality result, the goal's value, and inferential analyses are not reported in the registry record. The safety entry lists 20 affected among 25 at risk for serious events, 23 affected among 25 at risk for other events, and 16 deaths; the timeframe for these entries is not specified in the registry record.