SPIRIT Small Vessel Registry: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for SPIRIT Small Vessel Registry (NCT00783796), a na na study. The primary outcome is Composite Rate of Cardiac Death, Target Vessel Myocardial Infarction (MI) (Per Protocol Definition) & Clinically Indicated Target Lesion Revascularization (CI-TLR)..

2. Clinical Question

The clinical question concerns the safety and effectiveness of a specific small-diameter coronary stent in a defined setting: small native-vessel lesions in people with ischemic heart disease. The registry description permits a maximum of two lesions, and specifies that they must be in different epicardial vessels. It does not establish a comparison with another device or treatment. Accordingly, the question is descriptive: what outcomes were recorded among participants who received the stent?

The endpoint combines events involving death, myocardial infarction, and repeat treatment of the target lesion. These events represent distinct clinical outcomes, but each participant meeting any component can contribute to the composite. The primary assessment was at one year. The record also lists secondary measurements relating to procedural success, device success, and vessel narrowing after treatment. Those measures broaden the scope of the registry, but do not change its single-group design or supply a concurrent control for interpreting outcomes.

3. Trial Design

SPIRIT Small Vessel Registry (SPIRIT SV) was a single-group device registry sponsored by Abbott Medical Devices. The registry lists an enrollment of 150 and describes one intervention: the 2.25 mm XIENCE V Everolimus Eluting Coronary Stent System. The intervention arm is described as patients receiving the 2.25 mm XIENCE V stent. The study model is single group; allocation is listed as not applicable, and masking is listed as none. Phase is listed as not applicable.

The recorded start was 2008-10 and primary completion was 2010-10. The current registry status is terminated. A reason for termination is not reported in the registry record. The registry description identifies people with ischemic heart disease and small-vessel de novo native coronary lesions as the intended population. Eligible cases could involve up to two lesions, each in a different epicardial vessel.

The design supports description of outcomes among participants receiving the study device. It does not support a randomized estimate of how outcomes would differ under an alternative treatment, because there is no control arm and no allocation between arms. The absence of masking is also part of the recorded design; the registry does not provide further details about how outcome assessment was conducted.

The primary endpoint was a one-year composite rate of cardiac death, target-vessel myocardial infarction under the protocol definition, and clinically indicated target-lesion revascularization. The registry lists secondary outcomes covering device success per lesion, procedural success per subject, and several late-loss and diameter-stenosis measures. It lists 99 outcome measures in total, while the number of analysis records is 0. That count does not provide the missing outcome results or explain how all listed measures were handled.

The registered enrollment should not be confused with the number analyzed for a particular endpoint. For the primary endpoint, the registry describes a full-analysis-set population based on receiving the study device, with exclusions for people truly lost to follow-up through the relevant timepoint without any DMR. The number in that endpoint population is not reported in the registry record. The adverse-event denominator is separately recorded as 139 at risk.

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.

Before assignment: Subjects were screened for study eligibility by a member of the study team. Subjects meeting eligibility criteria were asked to sign an informed consent form. Pre-procedure angiography was used for final assessment of eligibility.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The number of participants analyzed is based on FAS population, defined as subjects who have received the investigational study device (2.25 mm XIENCE V stent) and excludes subjects who are truly lost-to-follow-up, defined as subjects who are lost to follow-up through given timepoint without any DMR event (all death, all MI, all revascularization).

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, Target Vessel Myocardial Infarction (MI) (Per Protocol Definition) & Clinically Indicated Target Lesion Revascularization (CI-TLR)., measured over 1 year.

The primary endpoint is the percentage of participants with at least one event in a composite of cardiac death, target-vessel myocardial infarction under the protocol definition, or clinically indicated target-lesion revascularization. Its timeframe is one year. The registry describes the measure as a number of participants and identifies the unit as a percentage of participants.

A composite endpoint combines multiple outcomes into one measure. In general, this can capture a broader range of clinically important events than any single component and can provide a concise summary of whether participants experienced one or more specified outcomes. The components remain distinct, however. A composite result alone does not show how much each component contributed, whether one component occurred more often than the others, or whether the components had similar clinical importance. Component-level counts and definitions are needed for those interpretations.

Here, the registry record supplies the endpoint definition and analysis-population description but does not report the primary event count or percentage. It therefore does not allow a reader to assess the observed frequency of the composite, the frequency of its individual components, or the precision of an estimated percentage. No confidence interval for the primary result is reported in the registry record.

The FAS description says the analysis was based on subjects who received the investigational device and excludes subjects considered truly lost to follow-up through the timepoint without any DMR. The record does not explain the DMR abbreviation or provide a separate count of people excluded under that rule. That definition is relevant to interpreting the endpoint because the analyzed population and its follow-up status determine which participants contribute to the reported percentage.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry’s statistical interpretation begins with its design. It is a single-group study, with one listed intervention and no like-for-like control arm. Allocation is not applicable, and masking is listed as none. Those features determine the kinds of questions the data can address. A single-group registry can describe observed outcomes among recipients, but a treatment contrast requires a comparison group and a defined comparison. The registry record does not report such a comparison.

What does a percentage endpoint represent?

The primary endpoint is expressed as a percentage of participants. For a binary outcome such as whether a participant experienced at least one event in a specified period, the percentage describes the proportion classified as having the outcome under the stated definition. The composite includes cardiac death, target-vessel myocardial infarction under the protocol definition, and clinically indicated target-lesion revascularization, with assessment at one year. The registry record does not include the number of participants with the composite or the resulting percentage, so the outcome’s observed frequency cannot be interpreted.

When a result is available, its estimate should be read alongside its denominator and uncertainty. A confidence interval is a statistical range that conveys how imprecise an estimate may be under the analysis assumptions. A narrow interval generally indicates greater precision than a wide interval, while neither interval alone resolves concerns about bias, missing follow-up, or the suitability of the design. No primary confidence interval is reported in the registry record.

What does the composite add?

In general, combining outcomes can make a summary endpoint capture more than one kind of event. The trade-off is that the composite does not, by itself, show which component occurred, how often each occurred, or whether one component dominates the overall result. A component-level breakdown is important for interpreting what a composite represents. The registry record defines the components but does not report their individual primary-endpoint results.

Composite components can also differ in severity and in how they are ascertained. Those differences matter when interpreting a combined measure. The registry specifies that target-vessel myocardial infarction follows a protocol definition and that revascularization must be clinically indicated, but it does not give further adjudication or ascertainment details in the information recorded. Such details are not reported in the registry record.

How does the analysis population affect interpretation?

The primary endpoint population is described as the full analysis set, defined as subjects who received the investigational study device, excluding subjects truly lost to follow-up through the given timepoint without any DMR. This definition indicates that receipt of the device and follow-up status are relevant to inclusion. The record does not provide the number in this population, the number excluded, or the meaning of DMR. Those omissions prevent a reader from reconstructing the denominator or assessing the extent of loss to follow-up.

In general, missing outcome information can affect an estimate if participants whose outcomes are unknown differ from those with recorded outcomes. Methods for addressing missing outcomes may include specified assumptions or sensitivity analyses, but no such approach is reported in the registry record. The FAS definition gives some information about exclusions, but it does not describe how missing data among included participants were handled.

What can adverse-event counts tell us?

The registry lists 139 participants at risk for serious adverse events and 139 at risk for other adverse events. It lists 79 affected for serious events and 83 affected for other events. These are descriptive counts, not randomized comparisons. The record gives no treatment-control contrast and does not identify a causal effect. The serious-event terms are accompanied by percentages, but the record does not explain whether terms can overlap within a participant, or how each percentage was calculated. In general, one participant may experience multiple event types, so term percentages should not be assumed to represent mutually exclusive groups unless the reporting method says so.

Over-dispersion is a general statistical issue that arises when variation in count data exceeds what a simple model assumes. It can make standard errors and confidence intervals too small if the model fails to account for the extra variation. The registry information does not identify a count model or report an analysis of over-dispersion; this concept therefore does not establish anything about the analyses used for this study.

How should planning illustrations be read?

Sample-size calculations are planning tools, not measurements of what a trial observed. The planning assumptions described for this registry’s page use a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects defined as fractions of the observed effect. For time-to-event outcomes, the stated planning approach uses a total event count; for other outcomes, it uses participants per arm. These assumptions describe hypothetical planning comparisons and do not change the fact that the registry itself is single-group.

Such calculations should not be interpreted as observed power. Observed power is not a substitute for reporting an estimated effect and its confidence interval. Planning numbers can illustrate how sample size depends on assumptions about the effect and design, but cannot establish that the registry was designed around those assumptions. The registry record does not report its own sample-size justification, and no trial-specific design rationale should be inferred from a planning illustration.

The registry lists 99 outcome measures and 0 analysis records. The number of outcomes alone does not identify which were treated as confirmatory, how results were selected for reporting, or what models were used. The analysis methods, including any adjustment for multiple testing, are not 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("2.25mm XIENCE V®")
n      <- c(136)
events <- c(11)
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  2.25mm XIENCE V®  136  11  8.1  4.1  14.0  4.6  13.9  4.6  13.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 99 outcome measures, including the primary composite and secondary device, procedural, late-loss, and diameter-stenosis measures. It lists 0 analysis records. The number of listed outcomes does not show which analyses were planned as primary, secondary, exploratory, or confirmatory, nor does it establish how many statistical tests were performed. A multiplicity adjustment or other strategy for handling multiple comparisons is not reported in the registry record.

Multiplicity matters in general because examining many outcomes or comparisons can increase the chance of finding an apparently unusual result by chance. Methods for addressing that issue depend on the analysis plan and the goals of the study. Since the registry record does not report a statistical analysis plan or multiplicity procedure, readers should not assume that any particular adjustment was used.

The primary endpoint population is described as the FAS: subjects who received the investigational study device, excluding those truly lost to follow-up through the relevant timepoint without any DMR. The record does not report the number included in that population, how many were excluded as truly lost, or what DMR means. It also does not describe methods for handling other missing outcome data, censoring, or incomplete assessments. The extent and potential effect of missing data therefore cannot be evaluated from the registry record.

In general, missing data can affect a result when the probability that an outcome is unobserved is related to the participant’s outcome or characteristics. Statistical approaches rely on assumptions about that process, and sensitivity analyses can examine how conclusions change under alternative assumptions. Neither a missing-data strategy nor sensitivity analyses are reported in the registry record. The information available supports identifying the stated FAS rule, but not determining how fully follow-up was achieved or how missing observations influenced reported results.

12. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: angina pectoris (19.4%), angina unstable (5.8%), atrial fibrillation (4.3%), coronary artery disease (4.3%), coronary artery stenosis (4.3%).

The adverse-event summary lists 139 participants at risk for serious adverse events and 79 affected. For other adverse events, it lists 139 at risk and 83 affected. These counts describe the registry’s recorded safety summaries; they are not comparisons with a control group. The record does not report a causal attribution analysis, so the counts should not be read as proof that the stent caused the events or that it did not cause them.

The listed serious-event terms and percentages are angina pectoris, 19.4%; angina unstable, 5.8%; atrial fibrillation, 4.3%; coronary artery disease, 4.3%; coronary artery stenosis, 4.3%; and non-cardiac chest pain, 4.3%. The registry record does not state whether a participant could contribute to more than one term or give the calculation details for these percentages. The terms therefore should not be added together or interpreted as separate, non-overlapping groups.

Deaths are not reported in the adverse-event summary. This does not establish that no deaths occurred; it means the registry record does not give a death count in this summary. The safety denominator is not necessarily the same as the primary endpoint analysis population, whose count is not reported. Safety counts and the primary composite should consequently be interpreted as distinct reported measures.

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

The registry record establishes that SPIRIT SV evaluated the 2.25 mm XIENCE V Everolimus Eluting Coronary Stent System in a single group of participants with ischemic heart disease and small-vessel native coronary lesions. It identifies a one-year primary composite of cardiac death, target-vessel myocardial infarction under the protocol definition, and clinically indicated target-lesion revascularization. It also describes a population definition for the primary analysis and reports some adverse-event counts and serious-event terms.

The record does not report the primary composite’s event count, percentage, or confidence interval. It therefore does not permit a reader to quantify the primary outcome or assess its precision. It also does not provide a concurrent control group, so the design cannot establish how outcomes compare with another device or treatment. This is a limitation of the study design, not a conclusion about whether the device is beneficial or harmful.

The serious and other adverse-event counts are descriptive. Without a comparison group, event attribution and comparative safety cannot be estimated from these figures alone. The listed serious-event terms identify events recorded in the registry, but the reporting information does not establish whether categories overlap or whether events were considered related to the device.

The enrollment is listed as 150, while the adverse-event denominator is 139. The record does not explain the difference, and the primary endpoint denominator is not stated. Those counts should not be treated as interchangeable. The registry status is terminated, but its reason is not reported; the status by itself does not reveal the effect on study conduct or results.

In short, the available information defines the study question and provides limited descriptive safety information, but it does not include the primary outcome result or a comparative treatment estimate. It cannot establish a treatment effect, rule out clinically important outcomes, or show how precise the primary endpoint estimate would have been.

14. Why This Trial Matters Statistically

This registry is statistically informative as an example of the distinction between describing outcomes and estimating comparative effects. A single-group design can record outcomes among people receiving a device, but it does not supply the randomized counterfactual comparison needed to attribute differences in outcomes to a treatment. That distinction matters when readers encounter a named primary endpoint and a substantial set of secondary measures: the existence of outcome definitions does not itself establish an interpretable treatment contrast.

The primary outcome is a composite, which makes clarity about components and analysis populations especially important. The registry defines the component events and the one-year timepoint, and gives a rule for the FAS population. However, it does not report the event count or percentage, a confidence interval, the analysis denominator, or component-specific results. Without those elements, the endpoint cannot be evaluated for frequency, precision, or contribution of its separate components.

The record also illustrates why safety denominators and outcome populations should be kept distinct. It lists an enrollment of 150, adverse-event denominators of 139, and a primary FAS definition without an analysis count. Those values represent different recorded elements, and the record does not reconcile them. Clear denominators are essential for interpreting percentages and understanding who contributed data.

Finally, a long list of outcomes does not reveal the statistical analysis plan. The registry lists 99 outcome measures but 0 analysis records. Without reported multiplicity handling, missing-data methods, or analysis details, the presence of many registered measures cannot be used to infer how results were selected or tested. These limitations make the registry a useful case for separating what is explicitly recorded from what remains unknown.

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 chief limitation is the single-group design. There is no concurrent control arm, and allocation is listed as not applicable. Thus, the registry can describe recorded outcomes among recipients but does not provide a randomized estimate of differences between treatments. Masking is listed as none, and the record does not give further information about outcome assessment or adjudication.

The primary outcome result is not reported in the registry record. The event count, percentage, confidence interval, and primary analysis denominator are absent. Although the FAS definition describes who was intended to contribute, the number analyzed and the number excluded are not reported. The definition also uses DMR without explanation in the registry record. Missing-data handling and follow-up completeness are not reported.

The record lists enrollment of 150 and an adverse-event denominator of 139, but does not explain the difference. It reports 79 affected by serious adverse events and 83 affected by other adverse events, but does not provide a control group or causal attribution information. Deaths are not reported in the adverse-event summary. The serious-event term percentages are listed without calculation details or an explanation of overlap between terms.

The registry lists 99 outcome measures and 0 analysis records. A statistical analysis plan, multiplicity method, sample-size justification, interim-analysis plan, and detailed model specifications are not reported in the registry record. The status is terminated, but the reason is not reported. These gaps limit interpretation of both the primary outcome and the wider set of recorded measures.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: SPIRIT Small Vessel Registry — NCT00783796.
• Registry record last updated 2019-05-08; status last verified 2019-04.
• Results first posted 2012-01-05.
• 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

SPIRIT Small Vessel Registry (SPIRIT SV), sponsored by Abbott Medical Devices, evaluated the 2.25 mm XIENCE V Everolimus Eluting Coronary Stent System in a single group. The registry lists enrollment of 150, phase as not applicable, allocation as not applicable, and masking as none. The recorded start was 2008-10, primary completion was 2010-10, and status is terminated. The reason for termination is not reported in the registry record.

The primary endpoint was the percentage of participants with cardiac death, target-vessel myocardial infarction under the protocol definition, or clinically indicated target-lesion revascularization at one year. The primary event count and percentage are not reported in the registry record. The adverse-event summary lists 139 at risk, with 79 affected by serious events and 83 affected by other events. It also lists serious-event terms with percentages. The registry includes 99 outcome measures and 0 analysis records; statistical analysis details are not reported in the registry record.