Resolute Integrity US Extended Length Sub-Study(RI US XL): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Resolute Integrity US Extended Length Sub-Study(RI US XL) (NCT01913600), a na na study. The primary outcome is Composite Rate of Cardiac Death and Target Vessel Myocardial Infarction (MI).

2. Clinical Question

The study was designed to assess safety and efficacy in patients receiving extended length stents for the specified coronary lesions. Its single-group design can describe outcomes among enrolled participants, but it does not provide a randomized comparison with another treatment or a control group. Consequently, any observed outcomes would need to be interpreted as descriptive of this study population and follow-up, rather than as an estimate of a comparative treatment effect.

The registry record does not report a numerical primary endpoint result, such as the number of participants with the endpoint, or an estimate of its precision. It also does not report a separate analysis clarifying whether the primary measure followed the title’s cardiac death and target vessel MI wording or the broader description including all-cause mortality and any revascularization. The clinical question is therefore identifiable from the endpoint title, but its reported answer and exact operational definition are not reported in the registry record.

3. Trial Design

The Resolute Integrity US Extended Length Sub-Study (RI US XL), registered as NCT01913600, was a prospective, multicenter, non-randomized, single-arm, open-label postapproval study. Its stated purpose was to assess safety and efficacy of the Resolute Integrity Stent in patients with de novo lesions in native coronary arteries and a reference vessel diameter of 2.25 mm to 4.2 mm who received extended length stents. The brief description identifies the extended lengths as 34 mm or 38 mm.

The registry record lists an enrollment of 56 and a single Resolute Integrity group. There was no randomized allocation and no masking. With one group and no like-for-like control, outcomes can be described for participants in the study, but the design does not isolate differences attributable to the stent from other influences or provide a randomized estimate of comparative effects.

The study started in 2013-07, reached primary completion in 2016-10, and is listed as completed. Its phase is listed as NA. The primary endpoint timeframe is 12 months. The registry record does not report the detailed visit schedule, the criteria used to select participants beyond the lesion and vessel descriptions, or the precise procedures for endpoint adjudication.

The endpoint title names a composite rate of cardiac death and target vessel myocardial infarction. Its description instead calls the outcome a combined clinical outcome of all-cause mortality, MI, or any revascularization. That difference matters because the components determine what counts as an event. A more detailed endpoint definition or explanation reconciling the two descriptions is not reported in the registry record. The record lists several secondary clinical and composite outcomes, but does not report outcome analyses for them.

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

Analysis population for the primary outcome, as defined in the registry: 2 subjects did not complete the 12 month follow up

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 Composite Rate of Cardiac Death and Target Vessel Myocardial Infarction (MI), measured over 12 months.

The primary endpoint is titled the composite rate of cardiac death and target vessel myocardial infarction (MI), with participants as the unit of measure and a 12 months timeframe. A composite endpoint combines multiple clinical events into one outcome. It can capture more than one kind of event in a single measure, but its meaning depends on which events are included and how each event is defined.

There is an important wording difference in the registry record: the endpoint description says the combined clinical outcome is all-cause mortality, MI, or any revascularization. That description is broader than the endpoint title, which specifies cardiac death and target vessel MI. The record does not clarify whether the description is shorthand, whether the components changed, or which definition was used for the reported analysis. That clarification is not reported in the registry record.

The primary outcome’s timeframe is 12 months, and the population note says 2 subjects did not complete the 12 month follow up. The registry record does not report the number of participants who experienced the primary endpoint, an estimate of the composite rate, or a confidence interval. Without those results, the endpoint’s observed frequency and precision cannot be described. In general, confidence intervals communicate the uncertainty around an estimated quantity; they do not resolve uncertainty about which events were included in the endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group study estimate?

In a single-group study, participants receive the same study intervention, and outcomes are described within that group. The design can document what was recorded among enrolled participants during follow-up. It does not create a concurrent control group, so it cannot directly estimate how outcomes would differ under another intervention. Randomization, when used, helps create comparable groups for a treatment comparison; there was no randomized allocation in this study.

The registry record lists an enrollment of 56 and one intervention group. It does not report an adjusted comparative analysis, and it lists zero analyses in the posted analysis information. A result expressed as a count or proportion within this group would remain a descriptive study result, not a randomized treatment effect. No numerical primary endpoint result is reported in the registry record.

What does a composite endpoint represent?

A composite endpoint treats the occurrence of any one of several specified events as an endpoint event. This approach can combine distinct outcomes, but readers need the exact list of components and their definitions to interpret the result. A composite can be driven by one component more than another, so an overall result does not by itself show the frequency of each component.

Here, the primary endpoint title names cardiac death and target vessel MI. The description instead names all-cause mortality, MI, or any revascularization. The registry record does not reconcile those definitions or report component-specific primary results. The endpoint wording therefore limits interpretation even apart from the absence of a numerical result.

How should counts and uncertainty be read?

A count reports how many participants met an event definition; it is not, by itself, a measure of precision. An estimate of a rate or proportion describes the observed frequency relative to a defined denominator. A confidence interval gives a range of values compatible with the data under the method’s assumptions and communicates statistical uncertainty. In general, less information about the event and denominator makes a result harder to interpret precisely. The posted primary outcome does not include a count, rate, or confidence interval, so no such interpretation can be made for that endpoint.

For binary outcomes, an analysis needs a defined event, a defined follow-up period, and a clearly stated population. This study’s primary timeframe is 12 months, and the population note records 2 subjects who did not complete that follow up. The handling of those participants’ data is not reported in the registry record. Without the analysis denominator and missing-data approach, readers cannot tell how incomplete follow-up was reflected in a primary endpoint estimate.

What does open-label, non-randomized design imply?

Open-label means the study was not masked. Non-randomized means the registry record does not describe assignment by chance to different study groups. These features are relevant because outcome measurement and clinical decisions can be influenced by knowledge of treatment, while the absence of randomization leaves no randomized comparison to balance participant characteristics across groups. The registry record does not report further procedures intended to address these issues.

These design features do not invalidate descriptive observations. They do, however, limit what can be inferred from a result. A single-group outcome cannot show what would have happened to the same participants under a different intervention. Statistical adjustment cannot be assumed: an adjustment method or adjusted estimate is not reported in the registry record.

What is the role of planning calculations?

Planning illustrations are hypothetical calculations that explore how many participants might be needed under stated assumptions. The stated illustration uses a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a fraction of the observed effect. It is described as a planning illustration, not as the study’s original design calculation. The registry record does not report the protocol’s sample-size justification or a randomized two-arm design for this study.

Such an illustration is not observed power. Observed power is not a replacement for reporting an outcome estimate and its uncertainty. Planning figures depend on assumptions about the effect to detect and the statistical model; they do not establish that an outcome was observed at a particular frequency or that a treatment effect exists. The record does not report the study’s own sample-size justification or a statistical plan explaining how the primary endpoint was to be analyzed.

Why can excess variability matter?

In general, over-dispersion means that observed variability exceeds what a chosen statistical model expects. If a model assumes less variability than the data contain, its uncertainty estimates can be too small, making results appear more precise than they are. Model choice should match the outcome and design. The registry record does not report a model-based primary analysis, a dispersion estimate, or a finding of over-dispersion, so no such issue can be attributed to this study’s results.

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("Resolute Integrity US Extended Length Sub-Study (R")
n      <- c(54)
events <- c(4)
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  Resolute Integrity US Extended Length Sub-Study (R  54  4  7.4  2.1  17.9  2.9  17.6  3.0  17.6

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists multiple secondary outcomes alongside the primary endpoint. When many outcomes or repeated statistical tests are examined, the chance of at least one apparently unusual result can increase. General methods for addressing this include specifying a testing hierarchy or adjusting for multiple comparisons. The statistical plan, any multiplicity adjustment, and any planned hierarchy are not reported in the registry record. No secondary-outcome analyses are reported in the posted results.

Missing follow-up is relevant to the primary endpoint because the timeframe is 12 months and the population note states that 2 subjects did not complete the 12 month follow up. The record does not say whether these participants were excluded, counted as having no event, handled with another method, or included through a particular missing-data procedure. Those details are not reported in the registry record. It also does not report whether there were other missing endpoint data.

The analysis population is not reported in the registry record. The record therefore does not establish whether the primary endpoint was analyzed in all enrolled participants, only those with available follow-up, or another defined group. The analysis approach, protocol deviations, and sensitivity analyses for missing data are also not reported. These omissions matter because different analysis populations or assumptions about missing outcomes can lead to different estimates. Since there is no numerical primary endpoint result or stated uncertainty measure, the effect of missing follow-up on the posted 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: angina unstable (7.1%), acute mi (5.4%), coronary artery dissection (5.4%), cardiac failure congestive (3.6%), coronary artery disease (3.6%).

The registry safety summary lists 56 participants at risk and 45 affected in the serious adverse-event category. It also lists 56 at risk and 45 affected in the other adverse-event category, along with 1 death. The record does not explain whether the same participants appear in both categories or how the categories relate, so the two counts should not be added together or treated as separate sets of people.

The listed serious adverse-event terms include Angina Unstable at 7.1%, Acute MI at 5.4%, Coronary Artery Dissection at 5.4%, Cardiac Failure Congestive at 3.6%, Coronary Artery Disease at 3.6%, and Hypertension at 3.6%. These are registry-listed terms and percentages. The record does not report the event definitions, timing, recurrence, or whether an event was considered related to the study device. The listed percentages should therefore be read as descriptive safety information, not as evidence of causation.

The safety summary does not provide a concurrent control group for comparison. It also does not report the methods used to collect or adjudicate adverse events. These limitations constrain comparisons and interpretation; the figures describe what the registry lists for this study group.

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

The registry record establishes that the study evaluated the Resolute Integrity Stent in a prospective, multicenter, single-group, open-label postapproval study. It describes the intended population, the extended stent lengths, the primary endpoint timeframe, and selected safety summaries. It also lists several secondary outcome names. These registry entries help define the study’s scope and the information recorded.

The record does not report a numerical primary endpoint result. Therefore, the posted information does not show how many participants experienced the primary endpoint, what the endpoint rate was, or how precisely it was estimated. It cannot answer the primary clinical question quantitatively. The difference between the endpoint title and its description adds further uncertainty about which events the primary measure was intended to include.

The single-group, non-randomized design does not provide a control comparison. Even if a within-group event count were available, it would describe participants in this study rather than establish what would happen under another treatment. The record does not report an adjusted comparison or a statistical analysis that could support a comparative claim.

The safety listing reports adverse-event counts and selected terms, but it does not establish that the device caused those events. The record does not provide a randomized comparator, detailed event attribution, or a complete explanation of how serious and other adverse-event categories overlap. The listed summaries should be interpreted within those limits.

More broadly, an absent or unreported result is not evidence that an endpoint did or did not occur. It means the registry record does not provide the information needed to quantify it. The study’s completed status and its listed enrollment do not fill that gap. The posted information supports a careful description of design and selected safety data, but not a conclusion about the primary endpoint’s frequency, comparative effect, or clinical meaning.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of how design determines the scope of conclusions. A prospective single-group study can collect outcomes in a defined population and provide descriptive safety information. Without randomization or a comparator group, however, it cannot estimate a randomized difference between treatments. The distinction between describing an outcome and attributing a difference to an intervention is central to interpreting clinical research.

The endpoint wording is another important statistical issue. The title identifies cardiac death and target vessel MI, while the description includes all-cause mortality, MI, or any revascularization. A composite result is interpretable only when its components are clear. If endpoint language differs across registry fields, the analysis definition needs clarification before a numerical estimate can be meaningfully understood. That clarification is not reported in the registry record.

The record also illustrates why outcome counts need context. A count requires a defined denominator, follow-up period, event definition, and analysis population. The primary timeframe is stated as 12 months, and 2 subjects did not complete that follow up, but the handling of their information is not reported. The primary outcome itself has no numerical result in the posted record.

Finally, planning calculations and observed results answer different questions. A planning illustration explores sample-size requirements under assumptions; it is not a substitute for an observed endpoint estimate and is not observed power. The registry record does not report its own sample-size justification or the planned primary analysis. Clear reporting of endpoint definitions, analysis populations, missing-data handling, and uncertainty would be necessary to interpret the clinical outcome more fully.

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 most direct limitation of the posted record is that it does not report a numerical primary endpoint result. There is no reported participant count with the endpoint, rate, or confidence interval. The primary clinical outcome therefore cannot be assessed quantitatively from this record.

The endpoint is not described consistently: the title names cardiac death and target vessel MI, while the description refers to all-cause mortality, MI, or any revascularization. The record does not clarify which definition was used or provide component-specific results. The method for endpoint adjudication is also not reported in the registry record.

The study was non-randomized, single-group, and open-label. It has no concurrent comparator, limiting interpretation to descriptions of the enrolled group rather than randomized comparative effects. The registry record does not report an adjusted analysis or a statistical plan that would explain how potential differences in participant characteristics were addressed.

Although the primary endpoint population note identifies 2 subjects who did not complete the 12 month follow up, the missing-data approach and analysis population are not reported. The record also does not report the sample-size justification, planned interim analyses, multiplicity procedures, or sensitivity analyses. Those details should not be inferred from the study’s enrollment or completion status.

The safety summary supplies selected counts and terms, but does not explain overlap between serious and other adverse-event categories, event attribution, recurrence, or collection and adjudication methods. These limitations are specific to the information reported for this study and constrain interpretation of both its primary outcome and safety summaries.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Resolute Integrity US Extended Length Sub-Study(RI US XL) — NCT01913600.
• Registry record last updated 2019-05-08; status last verified 2019-04.
• Results first posted 2017-11-17.
• 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

NCT01913600, the Resolute Integrity US Extended Length Sub-Study (RI US XL), is listed as a completed, prospective, multicenter, non-randomized, single-arm, open-label postapproval study sponsored by Medtronic Vascular. It enrolled 56 participants and evaluated the Resolute Integrity Stent for de novo lesions in native coronary arteries with a reference vessel diameter of 2.25 mm to 4.2 mm among patients receiving extended length stents. The record identifies stent lengths of 34 mm or 38 mm.

The study started in 2013-07 and reached primary completion in 2016-10. The primary endpoint timeframe was 12 months. Its title and description do not use fully consistent endpoint definitions, and a numerical primary result is not reported in the registry record. The record notes that 2 subjects did not complete the 12 month follow up. Safety summaries list 45 participants affected in each of the serious and other adverse-event categories among 56 at risk, and 1 death; the relationship between those categories is not explained.