This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for A Multi-center Clinical Trial of the Misago™ Self-Expanding Stent System for Superficial Femoral Artery (NCT01118117), a na na study. The primary outcome is Primary Safety Endpoint.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01118117 |
| Phase | NA |
| Condition | Peripheral Vascular Disease |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 276 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Terumo Medical Corporation |
| Results posted | Yes |
2. Clinical Question
Population
People with atherosclerotic stenosis or occlusions of the superficial femoral artery (SFA) who met the study’s inclusion and exclusion criteria. The registry describes enrollment after informed consent and eligibility were established.
Intervention
The Misago™ Self-Expanding Stent System, used in an SFA stent procedure. The study was prospective and evaluated efficacy and safety after the procedure and during follow-up.
Comparator
There was no concurrent randomized control group. The study objective was to compare outcomes with historical PTA and stent outcomes and published objective performance goals; these benchmarks are not a like-for-like control arm.
Primary question
The registry’s primary safety endpoint asks what proportion of subjects were free from major adverse events (MAE) at 30 days after the procedure, and whether the lower bound of the 95% confidence interval exceeded the 88% performance goal. The study summary also identifies stent patency at 12 months as the primary endpoint, so the record presents more than one description of primary focus.
This is a performance-goal question, not a randomized treatment comparison. The main safety outcome combines target lesion revascularization (TLR), amputation of the treated limb, and death into the MAE definition. The study also lists effectiveness outcomes, including an effectiveness endpoint in the modified intent-to-treat (mITT) cohort, a version using a peak systolic velocity ratio of ≤ 2.4, target lesion revascularization, technical success, procedural success, clinical success, and major adverse events through 12 months.
3. Trial Design
OSPREY is described in the registry as a multi-center, prospective, single-arm, non-randomized clinical trial of the Misago™ Self-Expanding Stent System for SFA disease. The registry lists the allocation as not applicable and masking as none. Participants underwent an SFA stent procedure after meeting the study’s eligibility criteria. The record lists an enrollment of 276 and the study status as completed.
The intervention was assessed immediately after the procedure and at 30 days, 6, 12, 24, and 36 months. The registry summary identifies stent patency at 12 months as a primary endpoint. The outcomes listing also identifies the primary safety endpoint as freedom from MAE at 30 days, with MAE defined as TLR, amputation of the treated limb, or death. The record therefore gives different descriptions of the primary focus; it does not explain the relationship between them.
The study objective was to evaluate safety and efficacy against historical PTA and stent outcomes and published performance goals. That design does not create a concurrent control group: any comparison with historical results depends on whether the historical benchmark and the study population, outcome definitions, follow-up, and measurement methods are sufficiently comparable. The record does not report enough detail to assess all of those aspects.
The adverse-event listing separates a group labeled “Non-Randomized” from a “Long Length Stent Sub-study Cohort.” These are registry group labels, not randomized treatment arms. The listing does not establish that the groups are mutually exclusive or provide a basis for treating them as independent comparative groups. The registry record does not report the statistical analysis plan, a sample-size justification, or interim analyses.
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: A total of 261 subjects were enrolled in the pivotal study cohort. An additional 15 subjects were implanted with a single, 150mm stent as part of a long length stent (LL) sub-study. The LL sub-study included safety data through 30 days post-procedure and was analyzed separately from the pivotal study cohort.
Overall Study
| Stage | Misago™ Self-Expanding Stent System | Long Length Stent Sub-Study Cohort |
|---|---|---|
| STARTED | 261 | 15 |
| COMPLETED | 240 | 15 |
| NOT COMPLETED | 21 | 0 |
Reasons for not completing this period:
| Reason | Misago™ Self-Expanding Stent System | Long Length Stent Sub-Study Cohort |
|---|---|---|
| Death | 8 | 0 |
| Lost to Follow-up | 6 | 0 |
| Missed 12 Month Visit | 7 | 0 |
Analysis population for the primary outcome, as defined in the registry: Analysis comprised of 261 subjects enrolled in pivotal trial and missing data imputed as loss of patency under the intention-to-treat (ITT) analysis. Study success was based on the proportion of patients with stent patency when tested against a performance goal of 66% using the lower bound of the 95% confidence interval.
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.
| Characteristic | Unit | Misago™ Self-Expanding Stent System | Long Length (150mm) Misago™ Self-Expanding Stent System | Total |
|---|---|---|---|---|
| Participants analysed | 261 | 15 | 276 | |
| Age, Continuous | years | 69.3 (SD 10) | 70.7 (SD 10.9) | NA (SD NA) |
| Sex: Female, Male: Female | Participants | 92 | 8 | 100 |
| Sex: Female, Male: Male | Participants | 169 | 7 | 176 |
| Region of Enrollment: United States | participants | 201 | 15 | 216 |
| Region of Enrollment: Japan | participants | 50 | 0 | 50 |
| Region of Enrollment: Taiwan | participants | 9 | 0 | 9 |
| Region of Enrollment: Korea, Republic of | participants | 1 | 0 | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Primary Safety Endpoint, measured over 30 days post-procedure.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | percentage of subjects without a MAE |
| Endpoint classification | not reduced to a single comparison |
The stated primary safety endpoint is the percentage of subjects without a major adverse event at 30 days after the procedure. MAE includes TLR, amputation of the treated limb, or death. The endpoint therefore records whether any event meeting that composite definition occurred during the specified period; it is not a measure of each component separately.
The registry says study success was based on comparing the lower bound of a 95% confidence interval for the freedom-from-MAE proportion with an 88% performance goal. It reports that the lower confidence interval exceeded the prespecified goal in both cohorts, but the posted record excerpt does not give the underlying proportion or confidence interval limits. It also does not identify the cohorts in that sentence clearly enough to map them to the adverse-event group labels.
In general, a confidence interval expresses uncertainty around an estimate. Using its lower bound as the criterion is a conservative performance-goal rule: the observed data must support a value above the target even at the lower end of the interval. This endpoint is used to assess whether the observed safety proportion meets the stated benchmark, not to estimate a causal advantage over a concurrent control. The registry’s study summary separately calls 12-month stent patency the primary endpoint; its relationship to the listed 30-day primary safety endpoint is not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry reports that the lower bound of the 95% confidence interval for freedom from MAE exceeded the prespecified 88% performance goal in both cohorts. This is the clearest posted statement about the primary safety result. The exact freedom-from-MAE estimates, confidence interval limits, and cohort definitions are not reported in the record excerpt, so the size and precision of the result cannot be independently assessed from those values.
The performance-goal finding should be read as a comparison with a benchmark, not as evidence from a randomized comparison. Participants were not assigned to Misago or to a concurrent control treatment. Historical PTA and stent outcomes were the stated reference, and the registry says the goal was based on published objective performance goals. Differences between historical and study populations or outcome ascertainment could affect such a comparison; the record does not provide enough information to judge their impact.
The registry presents an additional ambiguity: its study summary identifies 12-month stent patency as the primary endpoint, whereas the outcomes listing calls freedom from MAE at 30 days the primary safety endpoint. The posted record does not clarify whether these are co-primary endpoints, whether one is the principal endpoint and the other a key safety measure, or how the study’s conclusions were organized around them. The listed secondary outcomes include effectiveness measures, success measures, target lesion revascularization, and MAEs through 12 months, but no analysis results for those outcomes are included in the registry record for this account.
The adverse-event figures are descriptive. The registry lists serious adverse events for the “Non-Randomized” group with 261 at risk and 135 affected, and for the “Long Length Stent Sub-study Cohort” with 15 at risk and 1 affected. It also lists other adverse-event figures for those groups. These group labels and counts do not establish a comparative treatment effect, and the record does not say that the groups can be combined. The serious-event terms and percentages provide additional descriptive information, but their context and analysis details are limited.
Overall, the posted statement supports the narrow conclusion that the reported lower confidence bound cleared the registry’s stated safety performance goal. It does not, by itself, establish superiority to another treatment, resolve the primary-endpoint ambiguity, or describe longer-term patency and effectiveness results. The registry record does not report the full outcome estimates needed to assess the magnitude of effects or their precision in detail.
9. Statistical Methods Explained
What does the performance-goal test ask?
The registry describes a single-group assessment of the proportion free from MAE at 30 days. Its stated criterion compares the lower bound of a 95% confidence interval with an 88% performance goal. In general, a performance goal is a fixed benchmark used to judge whether an observed outcome meets a prespecified standard. It is different from a control group observed alongside the intervention in the same trial.
In general, a confidence interval represents statistical uncertainty around an estimated quantity. A wider interval indicates less precision, while a narrower interval indicates greater precision, subject to the assumptions of the method used. Requiring the lower bound to exceed the target means that the criterion is based not only on the point estimate but also on its uncertainty. The registry says this condition was met in both cohorts. The numerical estimates and intervals are not reported in the registry record excerpt, so their width and the distance from the performance goal cannot be described.
Why does the design matter?
The trial is described as single-arm and non-randomized. In general, randomization helps make treatment groups comparable on average, including on characteristics that may not be measured. A single-arm study does not have this protection against differences between the trial population and a historical benchmark. The stated historical PTA and stent outcomes and the published objective performance goal therefore provide context, but they are not a concurrent randomized comparison.
For a historical comparison to be informative, the population, endpoint definitions, follow-up period, and outcome measurement should be sufficiently aligned. This is a general consideration, not a claim that any particular mismatch occurred in OSPREY. The registry record does not report enough detail to evaluate all such alignment or the basis for selecting the historical benchmark.
What do the endpoint labels mean?
The listed safety endpoint is a composite: freedom from MAE at 30 days, with MAE defined as TLR, amputation of the treated limb, or death. In general, a composite endpoint combines multiple outcomes into a single measure. This can capture more than one clinically important event, but the overall result does not show how much each component contributed. Component-specific primary safety estimates are not reported in the registry record excerpt.
The record also identifies 12-month stent patency as a primary endpoint in the study summary, while the outcomes listing calls the 30-day safety measure the primary safety endpoint. These descriptions may refer to different aspects of the study, but their formal relationship is not reported. The registry lists 11 outcome measures and no analyses. Detailed endpoint definitions and analysis results beyond the stated safety criterion are not reported in the registry record.
How should the planning illustrations be read?
The sample-size section describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect. For time-to-event illustrations, the reported quantity is the total number of events; for other illustrations, it is participants per arm.
These are planning illustrations, not observed power and not the trial’s own design justification. The trial itself is single-arm, whereas the illustration assumptions describe equal allocation between two arms. In general, a sample-size calculation estimates the amount of information a future design might need under specified assumptions. It does not show that a completed study had a particular probability of detecting an effect, and it does not replace the trial’s observed estimates or confidence intervals. The registry record does not report the original sample-size justification or the assumptions used to design this trial.
What is not available about the analysis?
The registry record lists no analyses. The statistical analysis plan, handling of missing outcomes, analysis populations, and approach to multiplicity are not reported in the registry record. These details matter because they describe how outcomes were selected, how incomplete follow-up was treated, and how uncertainty was quantified. Without them, the posted performance-goal statement can be relayed, but the analysis cannot be fully reproduced or checked from the record excerpt.
In general, over-dispersion matters when a count outcome varies more than a model assumes; ignoring it can make uncertainty appear too small. That concept applies only when a suitable count model is being used. The record does not report such a model for these adverse-event figures, so no conclusion about over-dispersion or its handling can be drawn for this trial.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 11 outcome measures, including the 30-day safety endpoint, effectiveness outcomes, success measures, target lesion revascularization, and MAEs through 12 months. It also lists no analyses. The record does not report a statistical analysis plan, a testing hierarchy, or a multiplicity adjustment. It is therefore not possible to determine from the registry record whether the outcomes were treated as confirmatory, exploratory, or according to another prespecified structure. In general, testing many outcomes can increase the chance of a chance-positive finding unless the analysis plan accounts for multiple testing; that general concern cannot be quantified for this study from the posted information.
The registry does not report missing-data counts, reasons for missingness, methods for handling missing follow-up, or sensitivity analyses. These details are important because incomplete outcome ascertainment can affect the estimated proportion with freedom from MAE and the precision of that estimate. The registry record also does not specify the analysis populations for the primary safety result. Although the outcomes list names an mITT cohort for effectiveness measures, the record excerpt does not establish which population was used for the primary safety analysis.
The endpoint descriptions themselves are not fully aligned: the study summary calls 12-month stent patency the primary endpoint, while the outcomes listing identifies 30-day freedom from MAE as the primary safety endpoint. The record does not explain how these outcomes relate in the formal testing plan. As a result, the registry’s statement that the lower confidence bound exceeded the 88% goal can be reported, but the handling of missing data and the broader inferential context are not reported in the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Non-Randomized | 135 | 261 | 51.7% |
| Long Length Stent Sub-study Cohort | 1 | 15 | 6.7% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Non-Randomized | 167 of 261 |
| Long Length Stent Sub-study Cohort | 7 of 15 |
Most frequent serious adverse event terms
| Event term | Organ system | Non-Randomized | Long Length Stent Sub-study Cohort |
|---|---|---|---|
| Peripheral Artery Restenosis | Injury, poisoning and procedural complications | 30 of 261 | 0 of 15 |
| Intermittent Claudication | Vascular disorders | 15 of 261 | 0 of 15 |
| Peripheral Artery Stenosis | Vascular disorders | 11 of 261 | 0 of 15 |
| Coronary Artery Disease | Cardiac disorders | 7 of 261 | 0 of 15 |
| Renal Failure Acute | Renal and urinary disorders | 7 of 261 | 0 of 15 |
| Acute Myocardial Infarction | Cardiac disorders | 6 of 261 | 0 of 15 |
| Pneumonia | Infections and infestations | 6 of 261 | 0 of 15 |
| Anaemia | Blood and lymphatic system disorders | 5 of 261 | 0 of 15 |
| Cardiac Failure Congestive | Cardiac disorders | 5 of 261 | 0 of 15 |
| Peripheral Vascular Disorder | Vascular disorders | 5 of 261 | 0 of 15 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Non-Randomized | Long Length Stent Sub-study Cohort |
|---|---|---|---|
| Peripheral Artery Restenosis | Injury, poisoning and procedural complications | 41 of 261 | 0 of 15 |
| Intermittent Claudication | Vascular disorders | 27 of 261 | 0 of 15 |
| Hypertension | Vascular disorders | 22 of 261 | 0 of 15 |
| Back Pain | Musculoskeletal and connective tissue disorders | 21 of 261 | 0 of 15 |
| Peripheral Artery Stenosis | Vascular disorders | 16 of 261 | 0 of 15 |
| Pain in Exteremity | Musculoskeletal and connective tissue disorders | 14 of 261 | 0 of 15 |
| Anaemia | Blood and lymphatic system disorders | 13 of 261 | 0 of 15 |
| Haematoma | Vascular disorders | 13 of 261 | 0 of 15 |
| Post Dilatation Dissection | Vascular disorders | 0 of 261 | 1 of 15 |
| Non-Cardiac Chest Pain | General disorders | 0 of 261 | 1 of 15 |
Serious events with the highest arm-level rate: peripheral artery restenosis (11.5%), right lower extremity pain (6.7%), intermittent claudication (5.7%), peripheral artery stenosis (4.2%), coronary artery disease (2.7%).
The registry lists serious adverse events separately for the “Non-Randomized” group and the “Long Length Stent Sub-study Cohort.” The serious-event listing reports 261 at risk and 135 affected for the former, and 15 at risk and 1 affected for the latter. The record also lists other adverse-event figures for these groups. These are descriptive registry entries, not randomized comparisons, and the group labels do not establish that the groups are mutually exclusive.
The listed serious-event terms include Peripheral Artery Restenosis at 11.5%, Right Lower Extremity Pain at 6.7%, Intermittent Claudication at 5.7%, Peripheral Artery Stenosis at 4.2%, Coronary Artery Disease at 2.7%, and Renal Failure Acute at 2.7%. These entries should not be read as the primary safety endpoint: the endpoint is freedom from the defined MAE composite at 30 days, while these terms are adverse-event listings. The record excerpt does not give the context needed to determine the denominator or follow-up associated with each term percentage.
Deaths are not reported in the adverse-event listing. Their absence from the displayed figures should not be interpreted as zero deaths. The registry record does not provide further detail about event timing, severity criteria beyond the serious-event classification, or the relation of each listed term to the primary endpoint.
12. What the Result Does, and Does Not, Mean
The posted result supports a limited statistical statement: the registry says that the lower bound of the 95% confidence interval for freedom from MAE exceeded the 88% performance goal in both cohorts. This indicates that the result met the registry’s stated lower-bound criterion. The exact point estimates and confidence interval limits are not reported in the registry record excerpt, so the magnitude and precision of the estimated safety proportion cannot be evaluated from the available figures.
This finding is not a randomized comparison with another stent, PTA, or a no-treatment group. The trial was single-arm and non-randomized, and historical outcomes served as a reference. It therefore does not establish that Misago is superior to another option or that observed outcomes were caused by the device rather than other factors. The registry’s statement about meeting a performance goal should not be extended beyond that specific benchmark assessment.
The study summary identifies 12-month stent patency as a primary endpoint, while the outcomes listing identifies 30-day freedom from MAE as the primary safety endpoint. The posted record does not reconcile these descriptions, and the result information does not provide a numerical 12-month patency estimate. Nor does it provide detailed results for the listed secondary outcomes.
The serious adverse-event figures and terms are useful descriptive context, but they do not replace the defined primary safety analysis. The record does not report deaths in the adverse-event listing, which is not evidence that none occurred. Missing-data methods, analysis populations, and the formal statistical plan are also not reported in the registry record. Accordingly, the result can be described as meeting the stated safety performance-goal criterion, while broader claims about comparative effectiveness, long-term outcomes, or the full safety profile are not established by the posted information.
13. Why This Trial Matters Statistically
This trial is statistically notable for its use of a performance goal in a prospective, single-arm design. That structure focuses interpretation on whether an estimated outcome clears a benchmark, rather than on a treatment contrast between randomized groups. Recognizing the distinction helps prevent a benchmark result from being mistaken for evidence of superiority or equivalence to a concurrent comparator.
The stated lower-bound rule makes uncertainty part of the success criterion. In general, this is more informative than relying only on a point estimate, because it asks whether the data remain above the target after accounting for sampling uncertainty. The registry reports that the lower confidence bound exceeded the 88% goal, but the numerical estimate and interval are not reported in the registry record excerpt. Those missing values limit assessment of how close the result was to the goal and how precisely it was estimated.
The record also illustrates why consistent endpoint labeling matters. It identifies 12-month stent patency as a primary endpoint in the study summary and 30-day freedom from MAE as a primary safety endpoint in the outcomes listing. Without a reported analysis plan explaining their relationship, readers cannot determine from the record how the endpoints were prioritized or how conclusions were tied to them.
Finally, the adverse-event listings demonstrate the need to distinguish descriptive event reporting from a prespecified endpoint analysis. The listed cohorts are not randomized arms, and the registry does not state that their figures should be compared or combined. Clear definitions of populations, follow-up, missing-data handling, and analysis methods would strengthen interpretation of both the benchmark result and the safety listings.
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 registry’s descriptions of the primary endpoint are not fully consistent. The study summary calls 12-month stent patency the primary endpoint, while the outcome listing identifies 30-day freedom from MAE as the primary safety endpoint. The record does not explain whether these were co-primary outcomes or how they were prioritized. The posted result statement concerns the safety performance goal, but no numerical patency result is included in the registry record.
The exact freedom-from-MAE estimate and its 95% confidence interval are not reported in the registry record excerpt. Although the registry says the lower bound exceeded the 88% goal in both cohorts, it does not identify those cohorts clearly in that statement. This limits assessment of the result’s precision and its relation to the separately labeled adverse-event groups.
The study was single-arm and non-randomized, so its historical benchmark does not provide a concurrent control. The registry record does not report enough detail to assess the comparability of the historical outcomes and study population, or the methods used to select and apply the performance goal. It also does not report the statistical analysis plan, sample-size justification, interim analyses, missing-data methods, multiplicity approach, or complete analysis populations.
The serious adverse-event listing gives group counts and selected terms but does not provide enough context in the record excerpt to interpret every term’s denominator, timing, or relation to the primary endpoint. Deaths are not reported in that listing, which must not be treated as a zero count. The adverse-event groups are not randomized arms, and the record does not establish that they are mutually exclusive. These limitations restrict both comparative interpretation and assessment of the overall safety profile.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Multi-center Clinical Trial of the Misago™ Self-Expanding Stent System for Superficial Femoral Artery — NCT01118117.
- Registry record last updated 2017-11-20; status last verified 2017-10.
- Results first posted 2015-07-14.
- 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.
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18. Record Summary
The registry describes OSPREY, a completed, multi-center, prospective, single-arm, non-randomized study of the Misago™ Self-Expanding Stent System for atherosclerotic stenosis and occlusions of the SFA. It lists enrollment of 276 and follow-up immediately after the procedure and at 30 days, 6, 12, 24, and 36 months.
The primary safety endpoint is freedom from MAE at 30 days, with MAE defined as TLR, amputation of the treated limb, or death. The registry reports that the lower bound of the 95% confidence interval exceeded the 88% performance goal in both cohorts, but the exact estimate and interval are not reported in the registry record excerpt. The study summary also identifies 12-month stent patency as a primary endpoint.
Historical PTA and stent outcomes were the stated reference, not a concurrent randomized control. The record lists adverse-event groups and terms, but does not report the analysis plan, missing-data methods, or a sample-size justification.