ConsultaTM CRT-D Clinical Evaluation Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for ConsultaTM CRT-D Clinical Evaluation Study (NCT00526162), a na na study. The primary outcome is Freedom From Unanticipated Serious Adverse Device Effects at 1-month Post Implant..

2. Clinical Question

3. Trial Design

The ConsultaTM CRT-D Clinical Evaluation Study was a completed, single-group device study sponsored by Medtronic Cardiac Rhythm and Heart Failure. The registry lists enrollment of 83 and the intervention as implantation of a bi-ventricular implantable cardioverter defibrillator. The study start is recorded as 2007-10 and primary completion as 2008-01. The listed phase is NA.

The record identifies the allocation as NA and masking as NONE. Together with the single-group model, these details indicate that the registry does not describe a randomized comparison or masking. The arm description says participants had an implant attempt with a bi-ventricular implantable cardioverter defibrillator. It does not describe a separate control group. The registry explicitly cautions that the arms are not a like-for-like control comparison because the study was not randomized.

The primary endpoint was assessed at 1-month post implant and was defined around freedom from unanticipated serious adverse device effects. The analysis population was restricted to participants implanted with a Consulta device who either had follow-up for at least 28 days post implant or experienced an unanticipated device effect within 28 days. The record does not give the number of participants included under this definition.

Secondary outcomes listed in the record include adverse events and system performance assessed through Holter records, Save to Disk files, and technical observations. The record lists five outcome measures and one analysis, but it does not give a full account of the analysis procedures. Details such as the recruitment process, eligibility criteria, device programming, follow-up schedule beyond the primary endpoint description, and handling of withdrawals are not reported in the registry record. No protocol-specific sample-size justification is reported.

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 subjects implanted with a Consulta device that were followed at least 28 days post-implant or have had a unanticipated device effect within 28 days after implant were included in the analysis.

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 Freedom From Unanticipated Serious Adverse Device Effects at 1-month Post Implant., measured over 1 month.

The primary endpoint is the percentage of subjects without an unanticipated serious adverse device effect at 1-month post implant. It is a binary outcome: each eligible participant is classified according to whether such an effect occurred within the endpoint window. The registry describes the measure as a percentage of patients and specifies a 97.5% confidence interval, but the endpoint estimate and interval limits are not reported in the registry record.

The endpoint is used to summarize a safety question over a defined period after implantation. A percentage can describe how frequently participants met the endpoint definition in the analysis population, while a confidence interval conveys uncertainty around that estimate. The interval is important because an observed proportion alone does not show how precisely the underlying rate has been estimated.

The endpoint’s analysis population is not simply everyone enrolled. Only participants implanted with a Consulta device and followed for at least 28 days, or participants with an unanticipated device effect within 28 days, were included by the stated definition. This rule affects who contributes to the endpoint denominator. The registry does not report the resulting denominator, event count, estimate, or confidence interval bounds, so the primary safety result cannot be reconstructed from the record.

Freedom from an unanticipated serious adverse device effect should not be treated as interchangeable with freedom from every serious adverse event. An event can be serious without being identified as an unanticipated device effect. The record’s separately listed adverse-event counts therefore do not, by themselves, provide the missing primary endpoint result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a binary percentage endpoint and specifies a 97.5% confidence interval. It does not report the endpoint estimate, interval limits, or the method used for the primary analysis. The explanations below distinguish general statistical principles from the details documented for this study.

What does a binary endpoint summarize?

General: A binary endpoint places each participant into one of two categories according to a prespecified event definition, such as whether an event occurred during a defined follow-up period. The proportion meeting one category is calculated using the participants eligible for that analysis. Its interpretation depends on a clear event definition, a defined time window, and a well-described analysis population.

For this study, the endpoint is the percentage without an unanticipated serious adverse device effect at 1-month post implant. The registry’s population definition includes only participants implanted with a Consulta device who were followed at least 28 days post implant or had an unanticipated device effect within 28 days after implant. The number who qualified, and the count meeting the endpoint, are not reported in the registry record. Without those values, the percentage cannot be checked or independently reconstructed.

What does a confidence interval add?

General: A confidence interval expresses statistical uncertainty around an estimate. It is not a guarantee that the true value lies within the reported interval, nor does it indicate whether an outcome is clinically important. Its width depends on factors including the amount of information in the data and the analysis method. Intervals are most useful when interpreted alongside the point estimate, endpoint definition, and analysis population.

The registry specifies a 97.5% confidence interval for the primary endpoint but gives no numerical limits. It also does not identify the interval calculation method. Therefore, readers cannot assess its width or determine how much uncertainty surrounds the primary percentage from the registry entry alone. No particular interval method should be inferred from the stated confidence level.

How should the safety counts be read?

General: An event count and a count of affected participants are not necessarily the same quantity. A participant may experience more than one event, and event summaries can use different counting rules. A risk-set denominator identifies the group to which a count relates, but interpretation still requires the endpoint definition and the registry’s rules for attribution, timing, and repeated events.

The registry lists 80 at risk and 18 affected for serious adverse events, and 80 at risk and 33 affected for other adverse events. It does not provide enough detail in this record to determine all counting conventions or to map these categories to the primary endpoint. The primary endpoint specifically concerns unanticipated serious adverse device effects, which is a distinct description. The separate adverse-event counts should not be treated as the primary endpoint’s numerator or denominator without documentation establishing that relationship.

What does the planning illustration represent?

General: A sample-size calculation is a design exercise that estimates how many participants may be needed under specified assumptions. It is not an observed study result. An illustration based on a fraction of an observed effect explores how a proposed study might be planned if that assumed effect were relevant; it does not establish that the effect is real or that the completed study had a particular probability of detecting it.

The stated planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The illustration is explicitly not the trial’s own design. The registry describes the actual study as single-group, so an equal-allocation, two-arm planning scenario should not be mistaken for the study structure. Such planning values are not observed power and do not repair the absence of the primary endpoint estimate or its confidence interval in the registry record.

Which analysis details remain unknown?

The record does not report the statistical test or estimation procedure for the primary endpoint, any covariate adjustment, the handling of missing endpoint observations, or the prespecified analysis plan. It also does not describe interim analyses or a protocol-specific sample-size justification. Those details cannot be inferred from the endpoint type, confidence level, or sample-size planning assumptions. General statistical principles can explain what these methods would do, but they do not establish which method was used in this study.

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("Consulta Implant")
n      <- c(80)
events <- c(80)
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  Consulta Implant  80  80  100.0  95.5  100.0  95.4  100.0  95.5  100.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists five outcome measures and one analysis. It names the primary endpoint as freedom from unanticipated serious adverse device effects at 1-month post implant and lists secondary outcomes concerning adverse events and system performance assessments. The record does not explain how the single listed analysis relates to all outcome measures, or whether each outcome was analyzed separately.

Multiplicity arises when several outcomes or hypotheses are assessed. General: examining multiple results can increase the chance that at least one appears noteworthy by chance, depending on the analyses and decision rules. Statistical plans may address this through outcome hierarchy, adjusted thresholds, or other methods. The registry record does not report a multiplicity strategy, a prespecified hierarchy beyond identifying the primary endpoint, or whether any adjustment was used. No adjustment should be assumed.

The endpoint population has an explicit follow-up condition: participants implanted with a Consulta device had to be followed for at least 28 days post implant, unless they had an unanticipated device effect within 28 days. However, the record does not report how many participants met this rule or how missing follow-up, incomplete records, withdrawals, or other unavailable observations were handled. It does not describe imputation, censoring, or sensitivity analyses.

General: Missing outcome data can affect both the denominator and the interpretation of an estimated proportion. The direction and magnitude of any impact depend on why data are missing and how the analysis treats them. Since those details and the primary estimate are not reported in the registry record, the effect of missingness on the primary result cannot be assessed.

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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: lead dislodgement (5.0%), ventricular tachycardia (3.8%), cardiac failure (2.5%), abdominal pain (1.2%), atrial fibrillation (1.2%).

The registry lists a “Consulta Implant” group with 80 at risk for serious adverse events and 18 affected. For other adverse events, it lists 80 at risk and 33 affected. Deaths are listed as 0. These are descriptive safety counts; they do not establish a comparative safety effect because the study is single-group and has no like-for-like control comparison.

These categories should be kept distinct from the primary endpoint. The primary endpoint concerns freedom from unanticipated serious adverse device effects at 1-month post implant. Serious adverse events are not necessarily unanticipated, device-related, or included in that endpoint definition. The registry does not report the primary endpoint’s numerator, denominator, percentage, or confidence interval limits, so the listed safety counts cannot fill that gap.

The record also lists lead dislodgement at 5.0%, ventricular tachycardia at 3.8%, cardiac failure at 2.5%, abdominal pain at 1.2%, atrial fibrillation at 1.2%, and atypical angina at 1.2% among the top serious terms. These entries describe reported terms, but the registry summary does not provide enough detail to interpret attribution, repeated events, timing, or overlap among participants. They should be read as event-term summaries, not as proof that the events were caused by the device.

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

This study is a registry-recorded evaluation of the safety and clinical performance of the Consulta CRT-D. Its primary question is whether implanted participants remained free from unanticipated serious adverse device effects through 1-month post implant. The record describes the endpoint and an analysis-population rule, but does not report the endpoint result or its confidence interval limits. A conclusion about the observed primary endpoint percentage or its precision is therefore not possible from this record.

The posted safety information includes serious and other adverse-event counts, a zero death count, and several serious event terms with percentages. These are useful descriptions of what the registry lists for the study group. They are not a randomized comparison and do not demonstrate whether the device caused any particular event. Nor can the listed serious adverse events be assumed to be the same as the primary endpoint’s unanticipated serious adverse device effects.

The single-group design is central to interpretation. Without a like-for-like control group, observed events cannot be contrasted with concurrent outcomes under another device or treatment. The registry specifically warns that the arms are not a like-for-like control comparison. The findings therefore describe the study experience rather than a comparative estimate.

General: An absence of a reported estimate is not evidence that the endpoint had no events, and it is not evidence that the endpoint was met. Likewise, a reported event count alone does not show whether a device is safe or unsafe. Such judgments require the endpoint definitions, analysis population, complete results, uncertainty, and appropriate context. The available record supports a description of study design and certain safety summaries, but leaves the primary endpoint result and several analysis details unreported.

14. Why This Trial Matters Statistically

This trial matters statistically because it illustrates how study design determines what a result can support. A single-group device evaluation can document events observed after implantation and assess a prespecified safety endpoint, but without a randomized comparator it cannot provide a like-for-like estimate of relative outcomes. The registry explicitly identifies the absence of a randomized comparison as a limitation on comparing arms.

The primary endpoint also demonstrates why an endpoint definition and an analysis population must be read together. The endpoint is framed as freedom from unanticipated serious adverse device effects at 1-month post implant, while eligibility for the analysis requires implantation and a specified follow-up condition or an event within the early follow-up window. The registry does not report how many participants qualified, so even the denominator underlying the primary percentage is unknown.

Another statistical lesson is the distinction between related-sounding safety outcomes. Serious adverse events, other adverse events, and unanticipated serious adverse device effects are not interchangeable labels. The record gives counts for the first two categories but not the primary endpoint result. Keeping these measures separate prevents descriptive safety summaries from being misread as a complete answer to the primary question.

Finally, specifying a confidence interval is not enough to communicate precision when the estimate and interval limits are absent. A clear report needs the endpoint result, the population analyzed, and the uncertainty measure. The planning assumptions also illustrate the difference between a hypothetical design calculation and the completed study’s actual design. Here, the planning illustration describes equal allocation between two arms, whereas the registered study is single-group; those planning assumptions do not characterize the observed trial.

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 registry record does not report the primary endpoint percentage, event count, denominator, or 97.5% confidence interval bounds. This is the main limitation for interpreting the study’s stated primary question. The analysis population definition is given, but the number of participants meeting it is not reported.

The study is single-group, and the record does not describe a randomized control group. The registry cautions against treating the arms as a like-for-like control comparison. Accordingly, observed adverse-event counts are descriptive and do not establish comparative outcomes or device causation.

The record lists serious and other adverse-event counts, deaths, and several serious event terms, but does not explain all counting conventions, attribution rules, timing, or possible overlap. It also does not establish that these event categories correspond to the primary endpoint’s unanticipated serious adverse device effects. Their relationship should not be assumed.

Important analysis details are not reported in the registry record, including the primary endpoint estimation method, handling of missing data, and whether sensitivity analyses were conducted. The protocol-specific sample-size justification and multiplicity plan are also not reported. Although the record names secondary outcome areas, it does not give enough detail to assess their analysis or how multiple outcomes were addressed.

The listed planning assumptions describe a hypothetical two-arm calculation and are not the actual single-group design. They cannot be interpreted as evidence of observed power or as a justification for the enrolled sample. These limitations reflect what the registry record documents; they do not establish that additional information was absent from study materials outside the record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: ConsultaTM CRT-D Clinical Evaluation Study — NCT00526162.
• Registry record last updated 2025-07-02; status last verified 2019-03.
• Results first posted 2009-06-10.
• 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

The ConsultaTM CRT-D Clinical Evaluation Study is recorded as completed, with enrollment of 83 and a single-group design. The intervention was an implant attempt with a bi-ventricular implantable cardioverter defibrillator. The study start is listed as 2007-10 and primary completion as 2008-01.

The primary endpoint was freedom from unanticipated serious adverse device effects at 1-month post implant, with a stated 97.5% confidence interval. The registry defines a restricted analysis population but does not report the primary endpoint result, its denominator, or confidence interval limits. Safety summaries list serious adverse events, other adverse events, deaths, and serious event terms for the Consulta Implant group. These data are descriptive and do not constitute a randomized comparison.