Argatroban for Preventing Occlusion and Restenosis After Intracranial and Extracranial Artery Stenting: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Argatroban for Preventing Occlusion and Restenosis After Intracranial and Extracranial Artery Stenting (NCT01163604), a randomized phase 4 study. The primary outcome is Number of Participants With Occlusion and Restenosis at One Year.

2. Clinical Question

The clinical question concerns whether the registry’s reported frequency of occlusion and restenosis at one year differed between patients assigned to argatroban and patients assigned to no argatroban after intracranial or extracranial artery stenting. The argatroban group received continuous argatroban infusions for 2 days before and 3 days after stenting, alongside aspirin and clopidogrel. The non-argatroban group received aspirin and clopidogrel only.

Population. Patients who underwent intracranial and extracranial artery stenting. The registry lists CVD as the condition. Further eligibility criteria and characteristics of enrolled patients are not reported in the registry record.

Intervention. Argatroban given as a continuous infusion for the stated peri-stenting period, accompanied by aspirin and clopidogrel.

Comparator. Aspirin and clopidogrel treatment without argatroban.

Primary question. How many participants in each group were recorded as having occlusion and restenosis at one year? The posted result lists 58 participants in the Argatroban Group and 56 in the Non-argatroban Treated Group for this endpoint. The comparison reports an event proportion of 1.0 in each group, a risk difference of 0.0, and a risk ratio of 1.0. These registry values describe the posted result; they do not by themselves establish how events were verified, whether all randomized participants were assessed, or whether the comparison was adjusted for any other variables. Those details are not reported in the registry record.

3. Trial Design

The registry describes a Phase 4, randomized, parallel-group study with no masking. It lists enrollment of 114 and identifies Jinling Hospital, China, as the sponsor. The study is marked completed. Its stated purpose was to assess the safety and efficacy of argatroban for preventing occlusion and restenosis after intracranial and extracranial artery stenting.

Participants who underwent stenting were randomly chosen to receive argatroban with aspirin and clopidogrel, or aspirin and clopidogrel without argatroban. In the argatroban arm, the infusion was continuous for 2 days before stenting and 3 days after stenting. The registry does not report details about how the random sequence was generated, how assignments were concealed, or whether allocation was stratified. These design details are not reported in the registry record.

No masking was used according to the record. The registry does not explain whether endpoint assessors or people analyzing the results were masked, so their masking status is not reported in the registry record. This matters because knowledge of treatment assignment can influence some decisions about assessment, recording, or analysis, even when an outcome has an imaging-based definition.

The primary endpoint was the number of participants with occlusion and restenosis at one year. The registry also lists NIHSS and mRS, various adverse effects, and clinical endpoints as secondary outcomes. It records four outcome measures, but posts three secondary outcomes and no analyses. The registry does not describe a prespecified statistical analysis plan, the analysis population, handling of protocol deviations, or how missing outcome information was addressed. These points should not be inferred from the randomized parallel design alone.

The registry lists study start as 2010-08 and primary completion as 2013-12. It does not report the rationale for the planned enrollment, whether recruitment stopped as intended, or whether any interim review was conducted. Such details are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: The present study was a single-center, open-label, prospective, randomized, controlled pilot one. Enrollment of participants began in August 2010, and completed in August 2011. The local ethics committee approved the study, and written informed consent was obtained in all recruited patients.

Overall Study

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 Occlusion and Restenosis at One Year, measured over at one year.

The primary endpoint is titled “Number of Participants With Occlusion and Restenosis at One Year.” It concerns whether a participant was recorded as having occlusion and restenosis at the one-year assessment, rather than the degree of narrowing as a continuous measurement. The registry describes stenosis assessment using DSA, CTA, or MRA and says that stenosis was measured according to the NASCET method. It gives a formula based on the narrowest luminal diameter and the diameter beyond any poststenotic dilatation.

General: A binary endpoint reduces each participant’s status to whether the specified event is recorded or not. That can make a group comparison easier to interpret, but it does not retain all information about severity, location, timing, or progression. Combining occlusion and restenosis in one endpoint also means the posted result does not distinguish between those components. The registry does not provide separate counts for occlusion and restenosis, nor does it explain how an event was adjudicated when imaging modalities differed.

At one year is the stated timeframe for the endpoint. The registry does not report the timing window around that assessment, the number of participants who underwent imaging, or whether the endpoint required confirmation. Nor does it clarify whether the reported count includes any qualifying event during follow-up or only status at the one-year assessment. These measurement details are not reported in the registry record. The distinction is important for interpreting what a count represents, but it cannot be resolved from the endpoint description alone.

7. Results Posted in the Registry

• Non-argatroban Treated Group: 100.0% (56/56) versus 100.0% (58/58) on control; risk difference 0.0 percentage points (95% CI 0.0 to 0.0), risk ratio 1.00 (1.00–1.00); unadjusted two-proportion z-test p = n/a.

8. Statistical Interpretation

9. Statistical Methods Explained

General: A randomized comparison assigns participants to study groups by chance, with the aim of limiting systematic differences in measured and unmeasured characteristics at assignment. Randomization does not guarantee that groups will be identical, especially in a study of this size, and it cannot address biases arising after assignment, such as differential follow-up or incomplete outcome measurement. The registry says allocation was randomized, but it does not describe sequence generation, concealment, or the handling of departures from assigned treatment.

What does a binary endpoint measure?

General: A binary endpoint records whether a defined event occurred for each participant. For a group, the count of participants with the event can be related to the number assessed to describe an event proportion. Here the primary outcome is a participant count for occlusion and restenosis at one year. The registry posts counts and group sizes, and the comparison reports proportions. The record does not explain whether the denominator is all randomized participants, all treated participants, or only participants with available endpoint data. Those populations can differ, so the meaning of a proportion depends on the denominator definition.

Using a binary outcome can simplify communication, but the event definition must be clear and consistently applied. This endpoint joins occlusion and restenosis, conditions that may not be equivalent in mechanism or severity. The posted result does not separate them. The registry describes stenosis measurement through DSA, CTA, or MRA using the NASCET method, but it does not state how occlusion was defined, whether all modalities were accepted for every participant, or how discordant assessments were resolved. Those operational details are not reported in the registry record.

How should the group comparison be read?

General: A risk difference expresses the difference between event proportions in two groups. A value of 0 indicates equal proportions as represented by the calculation. A risk ratio compares the proportions as a ratio, with 1 indicating equal proportions. The registry’s comparison reports a risk difference of 0.0 and a risk ratio of 1.0. These estimates summarize the posted proportions; neither measure describes the quality of data collection or proves that the true underlying risks are equal.

A confidence interval communicates statistical uncertainty around an estimate under the assumptions of the method used. The registry reports an interval from 0.0 to 0.0 for the risk difference and values of 1.0 for the risk-ratio interval’s lower limit, estimate, and upper limit. Those zero-width reported intervals should not be mistaken for confirmation that there is no uncertainty. The record does not state the interval method or explain why the displayed limits have no width. With no analysis details, readers cannot determine whether the reported interval reflects the intended calculation, the nature of the posted data, or a reporting limitation.

A significance test, when reported, addresses compatibility between data and a specified null hypothesis under a statistical model. The registry record does not post a p-value for this primary comparison. The values 1.0 reported for the two group proportions and the risk ratio are not significance-test results. No test procedure is identified, and the registry records no analyses. It would be inappropriate to infer a test result from the point estimates or interval limits alone.

What can be inferred about the statistical plan?

The registry identifies a randomized parallel design and an endpoint, but it does not report a statistical analysis plan. In particular, it does not state the intended primary estimand, the chosen comparison method, any covariate adjustment, or how repeated measurements or deviations from treatment assignment would be handled. The presence of a risk difference and risk ratio in the posted comparison does not establish that both were prespecified or that either came from a full trial analysis.

General: Over-dispersion is relevant when observed variability exceeds what a statistical model assumes. It can make standard errors and confidence intervals too optimistic if a model does not account for that extra variability. For a simple binary endpoint, the appropriate uncertainty calculation depends on the data structure and chosen method; for clustered or otherwise dependent observations, independence assumptions may not hold. The registry does not describe clustering, repeated observations, or a model that would permit assessing over-dispersion. There is no basis in the record to claim that such a method was used or was needed for this comparison.

The study’s stated allocation is randomized and parallel, but no information is reported about adherence, crossover, or treatment receipt beyond the arm descriptions. It is not possible to determine whether the posted comparison follows assignment, treatment received, or another population definition. General: An intention-to-treat analysis usually compares participants according to randomized assignment, while a per-protocol analysis restricts or classifies participants according to adherence criteria. The registry does not say which approach was used. Neither label should be applied to the posted result without a stated analysis population.

The record also includes a planning-illustration description based on the observed effect, equal allocation, a two-sided significance level of 0.05, and a normal approximation. This is a description of planning assumptions, not an account of the trial’s original design calculations. Numeric planning results are not reported in the registry record. Such sample-size illustrations are not observed power and do not supply evidence about the probability that the trial detected an effect.

10. Confidence Intervals and Precision

Precision concerns how much uncertainty surrounds an estimated effect. General: A confidence interval gives a range of values compatible with the observed data under the assumptions of its calculation. A narrower interval generally indicates greater precision, while a wider interval indicates greater uncertainty. The interval does not guarantee that the true effect lies within its limits, and its interpretation depends on the statistical method and data quality.

The registry reports a risk difference of 0.0 with lower and upper limits both at 0.0. It reports a risk ratio of 1.0, with the lower and upper limits also at 1.0. These are the displayed estimates and limits and should be quoted as reported. However, an interval with identical limits communicates no visible range of uncertainty. The registry does not report the interval method, standard error, or explanation for this presentation. It is not possible to assess from the record whether the displayed intervals represent an intended uncertainty calculation or a limitation in the registry entry.

Equal posted proportions do not by themselves imply high precision. Precision depends on the amount of information available, event and non-event counts, outcome completeness, and assumptions used in the calculation. The arm sizes are recorded as 58 and 56, and the arm endpoint counts are recorded as 58 and 56. Since the record does not describe follow-up completeness or the method used for the interval, the displayed limits should not be treated as a complete account of uncertainty.

The registry does not provide a p-value for the primary comparison. Nor does it post a model-based or adjusted estimate with uncertainty. The reported interval is the only posted uncertainty information for the comparison, and its zero width limits what can be learned about precision. No independent recalculation is presented as a substitute for the sponsor’s analysis; the record does not report an analysis to compare against. Further detail about endpoint availability, analysis population, and interval construction is not reported in the registry record.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists the primary endpoint as the number of participants with occlusion and restenosis at one year. It also identifies NIHSS and mRS, various adverse effects, and clinical endpoints as secondary outcomes. Multiple outcomes can create multiplicity concerns because repeated statistical testing can increase the chance of observing an apparently notable result by chance. General: Common approaches include identifying a primary outcome in advance, adjusting inference across a family of tests, or treating secondary analyses as exploratory. The registry record does not report a multiplicity strategy, outcome hierarchy beyond the primary designation, or the analysis of secondary outcomes.

The record lists three secondary outcomes but does not provide their results in the registry record for this analysis. It records four outcome measures and zero analyses. No secondary effect estimates, confidence intervals, or significance tests are reported in the registry record. It is therefore not possible to assess whether outcomes were tested, whether adjustment was applied, or whether any unreported comparisons were planned.

Missing data are a separate concern from multiplicity. The registry does not report how many participants had one-year endpoint information, whether anyone withdrew or was lost to follow-up, or how missing endpoint status was handled. It also does not state whether missingness was assumed to be unrelated to outcome, addressed through imputation, or handled by another method. These details are not reported in the registry record.

Analysis populations are likewise not specified. The registry does not state whether the primary comparison included all randomized participants, only participants who received assigned treatment, or only those with an observed endpoint. It does not report exclusions or protocol deviations. Without those details, the relationship between randomized assignment, the posted arm sizes, and the endpoint denominators remains uncertain. The counts matching the listed arm sizes do not by themselves establish complete follow-up or an intention-to-treat analysis.

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

The posted result says that the registry recorded the same endpoint proportion in the Argatroban Group and the Non-argatroban Treated Group: 1.0 in each. The reported risk difference is 0.0, and the reported risk ratio is 1.0. These values describe the data as entered in the registry. They do not, by themselves, establish whether the treatments have equivalent effects, whether a clinically meaningful difference is absent, or whether the endpoint was completely ascertained.

The arm counts for the primary endpoint match the listed group sizes. This makes it especially important to know how the endpoint was assessed and how participants without available one-year information were handled. The registry does not report the number actually assessed, missing follow-up, imaging completion, or data validation. No conclusion about completeness can be drawn from the matching counts alone.

The endpoint combines occlusion and restenosis, so the aggregate result does not identify the contribution of either component. It also does not describe event timing, severity, or whether an event was detected by DSA, CTA, or MRA. The registry provides a measurement description for stenosis but does not report component-specific outcome results or details of endpoint adjudication.

The record does not post a significance-test result, an adjusted analysis, or a statistical analysis plan. The values 1.0 for the group proportions and risk ratio are not p-values. The reported confidence limits have no displayed width, and the record does not describe their calculation. These limitations prevent a detailed assessment of statistical uncertainty from the registry entry.

Safety should be interpreted with similar care. The record shows zero serious and zero other adverse events in each group, but it does not describe event collection, coding, follow-up, or completeness. Death counts are not reported. The entries do not establish that no safety events occurred; they indicate what the registry records.

General: A clinical trial result is most informative when the endpoint, population, analysis, uncertainty, and completeness of follow-up can be evaluated together. In this case, the posted comparison is a narrow description of registry values. It is not a basis for medical advice or a definitive claim that argatroban works, does not work, or has no effect.

13. Why This Trial Matters Statistically

This trial is statistically notable as a randomized comparison with a clearly named one-year endpoint and an explicitly described treatment contrast. The result is easy to state at the level of the posted proportions: both groups have an event proportion of 1.0, with a reported risk difference of 0.0 and risk ratio of 1.0. The central statistical issue is not the arithmetic of that comparison, but what the registry entry allows readers to know about the endpoint counts and their uncertainty.

The endpoint counts match the recorded arm sizes. That correspondence makes transparent reporting of ascertainment and analysis populations especially important. Without information on participants assessed at one year, missing outcomes, and the denominator used in analysis, readers cannot establish whether the registry’s counts represent complete outcome follow-up. Randomization supports a comparative design, but it does not resolve these reporting questions.

The record also illustrates the difference between a point estimate and an informative account of precision. The posted interval has identical lower and upper limits for each reported measure. Because its method is not described, that display does not offer a usable explanation of uncertainty. A result can be numerically simple yet difficult to interpret when details about measurement and analysis are absent.

Finally, the registry identifies secondary outcomes and safety categories but reports no analyses. This distinction matters: listing outcomes is not the same as reporting their results or explaining how multiple comparisons were handled. The trial therefore underscores the value of a complete statistical record, including endpoint definitions in practice, analysis populations, missing-data handling, uncertainty methods, and safety ascertainment. Those elements are not reported in the registry record.

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.

Several limitations specific to this registry record constrain interpretation. The primary outcome combines occlusion and restenosis, but the record does not post separate counts for either component. It describes imaging methods and the NASCET approach for stenosis, yet does not clarify how occlusion was defined, how imaging assessments were reconciled, or whether outcome assessors used a common process. These details are not reported in the registry record.

The endpoint is stated at one year, but the record does not report how many participants completed assessment, whether there was a visit window, or how losses to follow-up and missing imaging were handled. Arm endpoint counts match the listed arm sizes, but that alone cannot verify that every participant had complete follow-up or that each count was validated.

Although allocation is described as randomized, the method of sequence generation and allocation concealment is not reported. The study is unmasked, and the registry does not state whether outcome assessors or analysts were masked. It also does not provide baseline characteristics, adherence information, protocol deviations, or a definition of the primary analysis population. No adjustment strategy or statistical analysis plan is reported.

The comparison lists a risk difference and risk ratio, but no significance test is reported. The displayed confidence limits have no width, and the interval method is not described. The registry records no analyses, so there is no reported model or adjustment to evaluate. Secondary outcomes are named but their results are not reported in the record. Serious and other adverse-event entries are zero in each group, while death counts are not reported; event ascertainment and safety follow-up are also not described.

These limitations arise from reporting gaps in the registry record. They should not be filled by assuming that a particular protocol, analysis method, or follow-up procedure was used.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Argatroban for Preventing Occlusion and Restenosis After Intracranial and Extracranial Artery Stenting — NCT01163604.
• Registry record last updated 2015-11-23; status last verified 2015-10.
• Results first posted 2014-11-07.
• 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

The registry identifies NCT01163604 as a completed Phase 4 randomized, parallel-group study with no masking. It evaluates argatroban alongside aspirin and clopidogrel against aspirin and clopidogrel without argatroban in patients undergoing intracranial and extracranial artery stenting. The primary endpoint is the number of participants with occlusion and restenosis at one year.

The posted arm counts are 58 and 56, matching their respective listed group sizes. The comparison reports proportions of 1.0 in both groups, a risk difference of 0.0, and a risk ratio of 1.0. The reported intervals have identical lower and upper limits. No significance-test result or analysis is posted. The record lists NIHSS and mRS, various adverse effects, and clinical endpoints as secondary outcomes, but does not report their results in the available record. Adverse-event entries are zero in both groups; death counts are not reported.

Details of endpoint completeness, missing-data handling, analysis populations, statistical methods, and safety ascertainment are not reported in the registry record. The result is therefore best understood as a description of the posted registry entries, with substantial limits on assessing precision and completeness.