Renal Stent Placement for the Treatment of Renal Artery Stenosis in Patients With Resistant Hypertension: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Renal Stent Placement for the Treatment of Renal Artery Stenosis in Patients With Resistant Hypertension (NCT01673373), a na na study. The primary outcome is Primary Patency.

2. Clinical Question

In general, a single-group device study can describe procedural outcomes and follow-up findings in the enrolled group. Without a control group, however, it cannot separate changes associated with the intervention from changes that might occur over time or for other reasons. Blood-pressure control appears among the listed secondary outcomes, but its result is not reported in the registry record. The clinical question can therefore be described from the stated aims and endpoint definition, but the effect on patency or blood pressure cannot be quantified from this record.

3. Trial Design

ARTISAN, officially titled “iCAST™ RX De Novo Stent Placement for the Treatment of Atherosclerotic Renal Artery Stenosis in Patients With Resistant Hypertension,” is recorded as a completed, single-group device study. The registry lists Atrium Medical Corporation as the sponsor and reports enrollment of 68. The start date is 2012-10-23, and the primary completion date is 2018-06-27. Phase is listed as NA.

The intervention was the iCAST™ RX Stent System. The arm description states that all enrolled subjects would receive it. Allocation is listed as NA, and masking is listed as none. The record does not describe a randomized allocation process or a control arm. The study therefore provides no within-trial randomized comparison of stent placement with another treatment or with no stent placement.

The primary outcome was primary patency at 9 months, measured in subject-lesions. The endpoint population was a subset of enrolled subjects with available duplex ultrasound or angiography assessment within the 9-month visit window. The registry also lists secondary outcomes concerning procedure-related major adverse events, technical and acute procedural success, target lesion revascularization, incidental target lesion revascularization, systolic blood pressure control, and secondary patency. The registry lists 13 outcome measures and 2 analyses, but their full analysis methods are not reported in the registry record.

The record does not report the protocol’s statistical plan, sample-size justification, interim analyses, or detailed follow-up procedures. In general, a single-group study can describe outcomes in the treated group, but it cannot use randomization to balance measured and unmeasured factors against a concurrent control. Thus, any observed changes over time would need to be interpreted as observations in this study group, not as a controlled estimate of what the stent caused.

4. Participant Flow and Accounting

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

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Subset of enrolled subjects with available duplex ultrasound or angiography assessment within the 9-month visit window.

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 Primary Patency, measured over 9 months.

Primary patency is a measure of whether a treated lesion remains open without specified failures during follow-up. The registry defines primary patency at 9 months as continuous patency without total occlusion of the original lesion, re-intervention to treat partial or total occlusion of the stented segment, or bypass of the stented segment because of clinically driven restenosis or occlusion. The unit is subject-lesions.

This type of endpoint is used to describe durability of vessel openness after a stent procedure. In general, combining imaging evidence with clinically driven procedures can capture more than complete occlusion alone: a lesion may fail the endpoint after a qualifying re-intervention or bypass even if it has not become completely occluded. The definition therefore depends on both the stated clinical criteria and the availability of follow-up assessment.

The registry specifies that the primary endpoint population includes enrolled subjects with available duplex ultrasound or angiography assessment within the 9-month visit window. This means the endpoint is not described as a result for every enrolled subject regardless of follow-up availability. The number of assessable subject-lesions, the number meeting the patency definition, and an uncertainty interval for the result are not reported in the registry record. The observed primary patency result therefore cannot be characterized from the information recorded.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods are useful only when interpreted in light of the design, endpoint definition, and analysis population. The registry record identifies a single-group study with an endpoint based on lesion patency at 9 months. It does not report a full statistical analysis plan, an inferential method for the primary outcome, a confidence interval, or a p-value. The methods below explain general statistical concepts relevant to this kind of record; they should not be read as a claim that a particular method was used in ARTISAN.

What does a single-group design estimate?

In general, a single-group design describes outcomes observed among participants who receive the intervention. A summary such as a patency proportion, if reported, would describe the observed experience in the analyzed group and depend on the endpoint definition and analysis population. It would not directly estimate a treatment contrast against an untreated or alternatively treated group. Without a concurrent comparator, changes or events may also reflect the condition’s course, other care, or characteristics of the enrolled participants.

Randomization is one way to make groups comparable, on average, for measured and unmeasured characteristics. ARTISAN is recorded as single-group, with allocation listed as NA, so a randomized between-group estimate is not available in the record. Statistical adjustment cannot fully recreate a randomized comparison when there is no comparator group and when relevant information may not have been measured. This limits causal interpretation even if a within-group outcome is precisely estimated.

Why does the endpoint definition matter?

Primary patency is not simply a reading from an image. The registry definition combines continuous patency with the absence of specified events: total occlusion of the original lesion, re-intervention to treat partial or total occlusion of the stented segment, or bypass due to clinically driven restenosis or occlusion. In general, a composite definition can capture several clinically relevant ways an intended outcome may fail. It also means that the result depends on consistent classification of each component and on how follow-up is conducted.

The stated endpoint unit is subject-lesions, while the endpoint population is described as a subset of enrolled subjects with available duplex ultrasound or angiography within the 9-month visit window. The record does not explain how multiple lesions in a subject, if any, were handled statistically. It also does not report the number of subject-lesions assessed or the primary endpoint result. These details matter because a lesion-level summary and a participant-level summary are not necessarily interchangeable.

How should precision be assessed?

In general, a confidence interval describes a range of values compatible with the observed data under a specified statistical model and method. It communicates precision as well as the point estimate: a narrower interval indicates greater precision under those assumptions, while a wider interval indicates more uncertainty. A confidence interval does not correct for bias from missing data, lack of a comparator, or an unsuitable endpoint definition. No confidence interval for primary patency is reported in the registry record, so its precision cannot be assessed.

A p-value, when used, describes how unusual data at least as extreme as those observed would be under a specified null model. It is not the probability that a treatment works, nor does it measure the size or clinical importance of an effect. The registry record does not report a primary-endpoint p-value or identify a null hypothesis or testing procedure. It would therefore be inappropriate to infer statistical significance from the design or from the listed safety counts.

What do the planning illustrations represent?

The planning illustration is described as based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It considers detecting stated fractions of that observed effect. These are planning assumptions, not a description of ARTISAN’s single-group design: the registry does not describe two allocated arms in the study. The illustration is not observed power, and its planning sample sizes should not be read as enrollment targets or results from the trial. For non-time-to-event outcomes, the stated convention is participants per arm for 80% power or other listed planning levels; time-to-event planning uses a total number of events. The numerical planning outputs and the effect values used are not reported in the registry record.

In general, planning calculations depend on assumptions about the effect to detect, variability or event frequency, significance threshold, allocation, and statistical model. A change in those assumptions can change the calculated sample size. A planning illustration cannot establish that the completed study had adequate precision, especially when the illustration uses a comparison design different from the recorded single-group design. The registry does not report the original sample-size justification, so the planning illustration should be kept distinct from the trial’s own design rationale.

Why does follow-up availability matter?

The endpoint population requires available imaging assessment in the 9-month visit window. In general, complete-case summaries use participants or lesions with the necessary observed outcome data. Such summaries are straightforward to interpret when missingness is limited and unrelated to the outcome, but those conditions cannot be assumed without information. If participants with poor outcomes are less likely to have follow-up imaging, for example, the assessed group could give a more favorable picture than the full enrolled group. That is a general possibility, not a finding reported for ARTISAN.

The registry does not report reasons for missing endpoint assessments, a comparison of assessed and unassessed subjects, imputation methods, or sensitivity analyses. It also does not report whether the primary analysis followed a prespecified intention-to-treat or other analysis population. The endpoint definition names the available-assessment subset, but further analysis-population details are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 13 outcome measures and 2 analyses. The primary outcome is primary patency at 9 months; the listed secondary outcomes include procedure-related major adverse events, technical success, acute procedural success, target lesion revascularization, incidental target lesion revascularization, systolic blood pressure control, and secondary patency. The record does not state how the primary and secondary outcomes were ordered for statistical testing, whether particular outcomes were exploratory, or whether any multiplicity adjustment was planned or applied. These procedures are not reported in the registry record.

In general, testing many outcomes can increase the chance that at least one result appears statistically unusual even when there is no underlying effect. Multiplicity procedures can control or describe this issue, but they require a defined testing strategy. Without the analysis plan and outcome-level results, the impact of multiple analyses cannot be assessed for this study. The number of listed outcomes alone does not show that every outcome was tested, or that any particular adjustment was used.

For the primary endpoint, the registry specifies a subset of enrolled subjects with available duplex ultrasound or angiography within the 9-month visit window. It does not report the size of that subset, reasons for unavailable assessments, missing-data handling, or sensitivity analyses. The primary analysis population beyond that description, including any rules for exclusions or protocol deviations, is not reported in the registry record. As a general matter, results among those with available assessments may not represent the full enrolled group if availability is related to outcome status. The record does not provide information to determine whether that concern applies in ARTISAN.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: arterial restenosis (11.8%), angina pectoris (10.3%), cardiac failure congestive (8.8%), pneumonia (8.8%), arrhythmia (7.4%).

The registry records 68 subjects at risk for serious adverse events and 40 affected. It also records 68 at risk for other adverse events and 12 affected, and lists 4 deaths. These are descriptive safety figures. The registry record does not provide a randomized control group or a comparative estimate that would show whether these events occurred more or less often because of the device.

The serious adverse event terms listed with percentages are arterial restenosis, 11.8%; angina pectoris, 10.3%; cardiac failure congestive, 8.8%; pneumonia, 8.8%; arrhythmia, 7.4%; and cerebrovascular accident, 5.9%. These percentages should be read as recorded event-term figures, not as proof of causation. The registry does not report the event-level timing, severity details, attribution judgments, or a comparison group for these terms.

In general, one subject can experience more than one adverse event, so event categories should not be added to infer a total number of affected subjects. The listed serious-event terms are not a complete account of all safety details, and the registry does not report the clinical course for each event. The figures describe what the record lists; they do not by themselves establish the cause of an event or the comparative safety of the device.

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

The record describes a completed single-group study in which all enrolled subjects were to receive the iCAST™ RX Stent System. Its primary endpoint was defined as primary patency at 9 months, with failure criteria that included specified occlusion, re-intervention, or bypass events. The record also lists secondary outcomes related to procedural success, blood-pressure control, revascularization, and patency, along with safety counts.

The primary endpoint result is not reported in the registry record. Therefore, the observed patency result, the number of subject-lesions meeting the definition, and the precision of any estimate cannot be stated. Results for the listed secondary outcomes are also not reported in the registry record. The safety counts and event-term percentages are descriptive records and do not establish that the device caused the listed events.

Even if a within-group result were available, the single-group design would limit what it could establish. In general, a before-and-after or post-treatment description does not show what would have happened to similar patients under a different treatment. Without a concurrent comparator, differences cannot be attributed to the stent alone. The design can describe outcomes in the treated group, but it cannot provide a randomized comparative treatment effect.

The endpoint population also depends on available imaging within the 9-month visit window. The registry does not report how many subject-lesions were assessable, why any assessments were unavailable, or how missing observations were handled. General statistical interpretation therefore requires caution about whether the assessed subset represents the full enrolled group.

The findings that can be stated from this record concern study structure, the stated endpoint definition, and recorded adverse-event counts. The record does not support a quantitative conclusion about primary patency or blood-pressure control, nor a claim that treatment did or did not work. Those conclusions would require reported outcome results, their uncertainty, and—especially for comparative claims—a suitable comparison design.

13. Why This Trial Matters Statistically

This study is statistically informative as an example of why design and endpoint reporting must be considered together. ARTISAN addressed an important clinical context—atherosclerotic renal artery stenosis in patients with resistant hypertension—and specified a 9-month primary patency endpoint. Its definition included imaging-related patency and clinically driven events such as qualifying re-intervention or bypass. Clear endpoint definitions help readers understand what an outcome is intended to capture.

The single-group design is equally important. It can document what was observed among subjects who received the device, but it cannot make a randomized comparison with another management strategy. This distinction matters because a result may be clinically interesting without identifying a causal treatment effect. Descriptive evidence and comparative evidence answer different questions.

The endpoint’s stated analysis population highlights another central issue: outcome availability. The record defines the primary population by the presence of duplex ultrasound or angiography within the 9-month visit window. Without the size of that subset, reasons for unavailable assessments, and missing-data analyses, readers cannot determine how follow-up affected the endpoint summary. Reporting these details would help assess both completeness and potential selection concerns.

Finally, registry transparency is essential for interpretation. The record lists multiple outcomes and analyses, but does not report the statistical analysis plan, multiplicity handling, primary endpoint result, or uncertainty estimate. A detailed result accompanied by its analysis population and precision would allow a more complete assessment. In the absence of those details, the appropriate statistical account is limited to the study’s design, endpoint definition, and recorded safety information.

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 main limitation for interpreting the primary question is that the endpoint result is not reported in the registry record. No primary patency estimate, count of endpoint successes or failures, or uncertainty interval is available in the record. The results for blood-pressure control and other listed secondary outcomes are also not reported.

The single-group design has no randomized or concurrent comparator. Consequently, the registry record cannot support a within-trial comparison of device placement against another strategy. Masking is listed as none, and the record does not describe procedures to reduce the influence of knowledge of treatment on assessment. How endpoint assessments were reviewed or adjudicated is not reported in the registry record.

The endpoint population is limited to enrolled subjects with duplex ultrasound or angiography available within the 9-month visit window. The number assessed, missing-assessment reasons, and any missing-data procedures are not reported. The handling of multiple lesions within a subject, if applicable, and the precise primary analysis population are also not reported in the registry record.

The registry lists 13 outcome measures and 2 analyses, but does not report the statistical analysis plan, sample-size justification, interim analyses, or multiplicity strategy. The planning assumptions described for sample-size illustrations use a two-arm comparison, whereas the study design is listed as single-group; those illustrations should not be mistaken for the trial’s own design rationale or observed power. Detailed safety information, including event timing and attribution, is not reported. These gaps constrain both the evaluation of statistical precision and interpretation of clinical meaning.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Renal Stent Placement for the Treatment of Renal Artery Stenosis in Patients With Resistant Hypertension — NCT01673373.
• Registry record last updated 2020-11-20; status last verified 2020-11.
• Results first posted 2019-08-13.
• 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 record describes ARTISAN as a completed, single-group device study sponsored by Atrium Medical Corporation. It lists enrollment of 68 and the iCAST™ RX Stent System as the intervention received by all enrolled subjects. The study start date is 2012-10-23, and the primary completion date is 2018-06-27. Phase is listed as NA, allocation as NA, and masking as none.

The primary outcome was primary patency at 9 months, measured in subject-lesions among a subset with available duplex ultrasound or angiography assessment within the visit window. The primary endpoint result is not reported in the registry record. Secondary outcomes include procedural events and success, revascularization, systolic blood-pressure control, and secondary patency. The record lists 13 outcome measures and 2 analyses.

Safety information lists 40 subjects affected by serious adverse events and 12 affected by other adverse events, with 68 at risk for each category, and 4 deaths. The record does not establish causation or provide a comparative safety estimate. Statistical analysis details, endpoint precision, and missing-data handling are not reported in the registry record.