XIENCE PRIME Japan Post-Marketing Surveillance (PMS): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for XIENCE PRIME Japan Post-Marketing Surveillance (PMS) (NCT01721096), a registered phase not stated study. The primary outcome is Number of Participants With Acute Stent Thrombosis (ST).

2. Clinical Question

3. Trial Design

This was a completed post-marketing surveillance study of the XIENCE PRIME everolimus-eluting coronary stent in Japan. The registry lists Abbott Medical Devices as the sponsor, an enrollment of 536, a start date of 2012-10, and a primary completion date of 2014-06. The study objective was to observe the frequency, type, and degree of device deficiency and to collect information for evaluation of device efficacy and safety for reevaluation.

The registry describes two groups based on stent size. The Long Length group included 323 participants treated with at least one long-size stent, identified as 28, 33, and 38 mm lengths. The Core Size group included 213 participants treated with stents of 8, 12, 15, 18, and 23 mm lengths. The record does not state how participants were allocated. It explicitly does not describe a randomized comparison, and the groups are not a like-for-like control comparison. Their differing stent-size definitions matter when interpreting any apparent difference in outcomes.

The primary outcome is the number of participants with acute stent thrombosis, with an acute time window of 0-24 hours after implantation. The record also lists success outcomes and Target Lesion Failure among secondary outcomes. It reports 88 outcome measures, but the posted record does not provide a count of statistical analyses; the analyses count is 0. The study status is COMPLETED. A detailed protocol, planned sample-size justification, interim-analysis plan, and statistical analysis plan are not reported in the registry record.

The group descriptions include a statement that the groups did not significantly differ on several baseline characteristics, but the excerpt is truncated and does not provide the supporting estimates or the method used to assess those characteristics. That statement should not be treated as proof that the groups were equivalent or exchangeable. Without stated allocation and a documented analysis plan, the design is best read as surveillance reporting rather than a randomized efficacy comparison.

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: To date, out of 536 patients, 524 (320 in LL arm and 204 in CS arm) have terminated the surveillance before completing their follow-ups

Overall Study

Analysis population for the primary outcome, as defined in the registry: The number of participants analyzed excludes subjects who were lost-to-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 Number of Participants With Acute Stent Thrombosis (ST), measured over Time Frame: Acute (0-24 hours).

The primary endpoint counts participants with acute stent thrombosis during the period from implantation through 0-24 hours. It is a binary participant-level outcome in the sense that each participant either meets the endpoint definition or does not. The registry identifies the unit as participants and describes the measure as a count of participants.

Stent thrombosis is classified using Academic Research Consortium criteria. Definite thrombosis requires angiographic confirmation together with specified evidence of ischemia or pathological confirmation. Probable thrombosis includes specified unexplained deaths and myocardial infarction related to documented acute ischemia in the stented territory without angiographic confirmation and without another obvious cause. Possible thrombosis includes unexplained death after the initial post-stenting period through the end of follow-up. The endpoint description also distinguishes acute, subacute, late, and possible timing categories; the primary outcome specifically concerns the acute interval.

Using an explicit case definition helps make an uncommon but clinically important event more consistently identifiable across surveillance records. Counting participants gives a direct event frequency rather than a measure of event severity or time to event. The definition's timing and classification criteria are part of what the count means: it is not a count of every suspected event, nor does it summarize all stent-related outcomes. The registry record does not report the primary count, the number analyzed after exclusions, or an uncertainty interval. Consequently, the posted information does not establish how often the endpoint occurred in this surveillance cohort or how precisely its frequency was estimated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Outcome scale and estimand. The primary measure is a count of participants with an event, not a continuous measurement. A participant-level count is commonly analyzed as a binary outcome: each participant is classified as having or not having the defined event during the specified observation window. The registry describes the measure as a count and gives the acute timeframe as 0-24 hours. The number of participants meeting the endpoint is not reported in the registry record, so neither an event proportion nor an uncertainty interval can be interpreted from the posted information.

In general, a confidence interval describes a range of values compatible with the data under the statistical method used. Its width reflects precision, and it should be read together with the estimate and the analysis assumptions. No confidence interval for the primary outcome is reported in the registry record. A p-value, even if reported, would address compatibility with a particular null hypothesis under a model; it would not by itself describe the size or precision of an effect. No primary-outcome p-value is reported.

Event definition and timing. The endpoint applies ARC criteria to classify stent thrombosis as definite, probable, or possible. The description relies on angiographic, clinical, and pathological evidence, including specified ischemic symptoms, ECG changes, biomarkers, myocardial infarction, or unexplained death, according to the category. It also defines timing categories, while the primary endpoint focuses on acute thrombosis in the first 0-24 hours after implantation. Clear definitions matter because a count depends on both the events observed and the rules used to classify them. A count using a broader definition would not necessarily represent the same outcome.

The registry says participants lost to follow-up are excluded from the primary analysis population. This describes an exclusion, but the number lost to follow-up and the number included in the primary analysis are not reported in the registry record. In general, excluding participants with missing outcome information can affect an estimate if the likelihood of being lost is related to the outcome. The direction and size of any such effect cannot be determined without information about missingness and the excluded participants. The record does not describe an imputation method or sensitivity analysis.

Group comparisons. The Long Length and Core Size groups have different stent-length definitions and different enrollment counts. Allocation is not stated, and the record does not describe a randomized comparison. In general, an unadjusted comparison of group event proportions describes the observed groups, but does not necessarily estimate a causal effect. Differences in patient features, lesions, or clinical decisions may contribute to the observed contrast. Adjustment can address measured differences under appropriate assumptions, but an adjusted comparison and its specification are not reported in the registry record.

The group descriptions state that there were no significant differences in several background and disease characteristics. General statistical interpretation cautions that failure to find a statistically significant difference is not evidence that the groups are identical. Baseline tests are also not a substitute for random allocation. The registry excerpt does not give the exact variables, estimates, tests, or uncertainty associated with that statement, so its statistical meaning cannot be assessed further.

Multiplicity and outcome reporting. The record lists 88 outcome measures and several secondary outcome titles, including success rates and Target Lesion Failure. When many outcomes are considered, the chance of at least one apparently unusual result can increase if each is tested separately without accounting for multiplicity. In general, a prespecified primary outcome and a stated multiplicity strategy help distinguish confirmatory from exploratory analyses. Neither a multiplicity plan nor a statistical analysis plan is reported in the registry record. The record reports zero analyses, which does not establish that no analyses were conducted; it means that analyses are not listed in the registry information represented.

Sample-size illustrations. Planning illustrations based on an observed effect are not observed power. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation, with the target effect expressed as a fraction of the observed effect. For time-to-event outcomes, the illustration uses a total number of events; for other outcomes, it gives participants per arm. Such calculations are hypothetical planning aids, not evidence that the original surveillance study was designed around those assumptions. The registry record does not report its own sample-size justification, and no numerical planning results are available in the record details.

Over-dispersion and model choice. General statistical context: over-dispersion occurs when observed variability exceeds what a chosen model assumes. It can make standard errors too small if the model does not allow for the extra variability. This concept is most relevant to certain count models, whereas the primary endpoint is described as a participant count for a binary event. No model, dispersion estimate, or variance adjustment is reported in the registry record, so there is no basis to claim that over-dispersion was assessed or present.

Overall, the registry gives the primary endpoint definition and a lost-to-follow-up exclusion rule, but not the statistical methods needed to reproduce or fully evaluate the primary analysis. The model, treatment of missing outcomes, adjustment strategy, multiplicity handling, and uncertainty estimates are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 88 outcome measures, including success rates for device, lesion, and patient-level outcomes and repeated listings of Target Lesion Failure. Considering many outcomes can create a multiplicity problem: when numerous hypotheses are tested, some results may appear statistically notable by chance even if no underlying effect exists. General approaches include identifying a primary outcome in advance, using a hierarchical testing strategy, or adjusting inference for multiple comparisons. The registry record does not report a multiplicity plan, the complete analysis hierarchy, or which secondary outcomes were formally tested.

The primary endpoint is identified as the number of participants with acute stent thrombosis, but its result and inferential statistics are not reported in the registry record. The record also reports zero analyses. This does not establish that investigators performed no analyses; the registry information does not list analyses. A statistical analysis plan, including model choice, covariate adjustment, and handling of multiple outcomes, is not reported in the registry record.

For the primary outcome, participants lost to follow-up are excluded from the analyzed population. The record does not report how many participants were lost, how many were included in the endpoint analysis, or whether missing outcome status was handled in any other way. In general, complete-case analysis can be biased when missingness is associated with the outcome or with participant characteristics related to the outcome. Imputation or sensitivity analyses can explore assumptions about missing outcomes, but the registry record does not report whether either was used. The available information therefore identifies an exclusion rule but does not quantify its impact.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: angina pectoris (9.0%), coronary artery stenosis (8.8%), death (8.8%), coronary artery restenosis (5.8%), heart failure (4.3%).

The safety record lists 536 participants at risk for serious adverse events and 221 affected. It also lists 536 participants at risk for other adverse events and 254 affected, with 47 deaths. These are overall figures for the combined Long Length and Core Size group, not separate group-specific estimates. The registry record does not provide the event observation period, definitions for these categories, or a breakdown that would clarify whether participants could appear in more than one category.

The listed serious-event terms include angina pectoris at 9.0%, coronary artery stenosis at 8.8%, death at 8.8%, coronary artery restenosis at 5.8%, heart failure at 4.3%, and angiopathy at 2.2%. These percentages are registry-listed term frequencies; the record details do not specify their denominator or explain whether terms refer to events or affected participants. The listed death term and the total deaths should not be assumed to use identical accounting without further detail.

These safety figures describe reported adverse events in the surveillance cohort. They do not, on their own, establish that the device caused an event or allow a comparison with an untreated or randomized control group. Causal attribution, event timing, severity definitions, and comparative analyses are not reported in the registry record.

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

The posted information describes a completed post-marketing surveillance study with 536 enrolled participants and two groups defined by stent size. It identifies acute stent thrombosis as the primary endpoint and specifies the endpoint's classification framework and acute observation window. It also describes the study objective as collecting information on device deficiency and evaluating safety and efficacy for reevaluation. These details establish what the surveillance was intended to observe.

The record does not report the primary endpoint count, an endpoint proportion, an uncertainty interval, or a statistical comparison. Accordingly, it does not permit a conclusion about the observed frequency of acute stent thrombosis in the analyzed population. It also does not permit a conclusion that the Long Length and Core Size groups differed, or did not differ, on that outcome. The groups were not described as randomized or as a like-for-like control comparison, and allocation was not stated.

The safety figures report affected participants and deaths, alongside a list of serious adverse-event terms and percentages. They are descriptive surveillance data. Without definitions, timing, attribution, and an appropriate comparison, they cannot establish that the device caused those events or quantify a relative safety effect.

More generally, a registry record is not a substitute for a complete protocol and statistical report. The analysis population, missing outcome counts, model specifications, multiplicity approach, and detailed outcome results are not reported in the registry record. These omissions limit reproducibility and restrict interpretation to the study's stated purpose, group descriptions, endpoint definition, and listed safety figures. No recommendation about clinical use follows from these posted data alone.

13. Why This Trial Matters Statistically

Post-marketing surveillance addresses questions that arise after a device enters routine use: what device deficiencies and safety outcomes are observed, and what information is available for ongoing evaluation. This record is statistically relevant because it distinguishes a surveillance objective from a randomized efficacy comparison. The stated enrollment and group definitions describe the data collection setting, while the primary endpoint definition identifies a specific event and time window to be counted.

The record also illustrates why endpoint definitions and analysis populations matter. Acute stent thrombosis is classified using explicit criteria, and participants lost to follow-up are excluded from the primary analysis population. Those choices define what an eventual count would represent. Yet the count, analysis denominator, and uncertainty are not reported, so the endpoint cannot be quantitatively evaluated from the posted record.

The Long Length and Core Size groups differ by stent-size category, and allocation is not stated. A contrast between them would therefore not automatically have the interpretation of a randomized treatment effect. The statement that certain background characteristics did not differ significantly does not establish equivalence, particularly when supporting estimates and analysis methods are unavailable.

Finally, the record lists many outcomes but does not report a multiplicity strategy or a statistical analysis plan. This makes it difficult to distinguish prespecified confirmatory findings from exploratory reporting. The study remains useful as a record of surveillance purpose, enrollment, outcome definitions, and listed safety observations, while the unreported analysis details set clear limits on what can be inferred statistically.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The primary endpoint result is not reported in the registry record. There is no count of participants with acute stent thrombosis, no analysis denominator, and no confidence interval or other precision estimate. Therefore, the primary outcome cannot be quantitatively interpreted from the posted record.

The registry does not state how participants were allocated. It describes the groups by stent length and explicitly does not describe a randomized, like-for-like control comparison. The group descriptions state that several background and disease characteristics did not differ significantly, but the excerpt does not provide supporting values or methods. This does not establish group equivalence or remove the possibility of confounding.

The record says participants lost to follow-up are excluded from the primary analysis, but the number lost and the number analyzed are not reported. It does not report whether missing data were addressed through imputation or sensitivity analysis. The result's susceptibility to missing outcome information therefore cannot be assessed.

Although the registry lists 88 outcome measures, it does not report the statistical analysis plan or multiplicity approach. The count of analyses is 0, but that registry field does not establish that no analyses were conducted. The record also does not report the original sample-size justification, interim analyses, model specifications, or adjustment strategy.

The safety information is limited to listed affected counts, deaths, and selected adverse-event terms and percentages. Definitions, observation period, attribution, and potential overlap among categories are not reported. These limitations restrict causal interpretation and make comparisons with other populations or studies unsupported by the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: XIENCE PRIME Japan Post-Marketing Surveillance (PMS) — NCT01721096.
• Registry record last updated 2019-12-20; status last verified 2019-05.
• Results first posted 2016-07-19.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT01721096 is a completed Japanese post-marketing surveillance study of the XIENCE PRIME everolimus-eluting coronary stent, sponsored by Abbott Medical Devices. The registry lists 536 participants, a study start of 2012-10, and primary completion in 2014-06. The stated objective was to observe device deficiency and collect information for evaluation of safety and efficacy.

The record describes a Long Length group of 323 participants and a Core Size group of 213 participants. Allocation is not stated, and the groups are not a randomized, like-for-like control comparison. The primary outcome is the number of participants with acute stent thrombosis during 0-24 hours after implantation, classified using ARC criteria. The primary outcome result and its precision are not reported in the registry record.

The record lists 88 outcome measures and overall safety counts, including 221 participants affected by serious adverse events, 254 affected by other adverse events, and 47 deaths. Detailed analysis methods, the multiplicity plan, the original sample-size justification, and the number lost to follow-up are not reported in the registry record.