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 Observational Study to Evaluate PAD Treatment Clinical and Economic Outcomes (NCT01855412), a registered phase not stated study. The primary outcome is Procedural Success of Endovascular PAD Treatment(s).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01855412 |
| Phase | Phase not stated |
| Condition | Peripheral Arterial Occlusive Disease |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 1204 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Abbott Medical Devices |
| Results posted | Yes |
2. Clinical Question
The clinical question concerns outcomes after endovascular procedures for peripheral arterial disease (PAD). The registry describes a prospective, observational, multi-center study and identifies procedural success as its primary outcome. It also states that the study’s purpose was to evaluate acute and long-term clinical and economic outcomes. The registry record does not report the primary endpoint result or detailed economic findings.
Population
Patients diagnosed with PAD, grouped by Rutherford classification: Claudication (Rutherford 2-3), CLI Rutherford 4-5, and CLI Rutherford 6. The record’s official title refers to patients with distal outflow PAD.
Intervention
Endovascular PAD treatment. The group descriptions state that patients may be treated with any FDA-cleared endovascular PAD treatment; the registry does not specify a single device or procedure for all participants.
Comparator
No randomized comparator is described. The Rutherford groups are clinical categories, not like-for-like control groups, and allocation is not stated. Differences between them would not establish an effect of treatment.
Primary question
What proportion of procedures met the registry’s definition of procedural success: less than 50% residual stenosis in all treated lesions and no angiographic complications, as determined by the Angiographic Core Laboratory?
The question is descriptive rather than a randomized treatment comparison. The registry gives an enrollment of 1204 and identifies an analysis population of 1,106 subjects with sufficient information to assess procedural success. However, the endpoint estimate and its confidence interval are not reported in the registry record. The clinical question can therefore be described, but the posted information does not establish the observed frequency of procedural success or how precisely it was estimated.
3. Trial Design
LIBERTY 360 is described as a prospective, observational, multi-center clinical study evaluating acute and long-term clinical and economic outcomes after endovascular device intervention for PAD. The registry lists Abbott Medical Devices as sponsor. The study began in 2013-05, had primary completion on 2019-04-11, and is marked completed. Its listed enrollment is 1204.
The registry describes three clinical groups: Claudication (Rutherford 2-3), CLI Rutherford 4-5, and CLI Rutherford 6. Each description allows any FDA-cleared endovascular PAD treatment. The record does not describe a single standardized device intervention or a randomized allocation process. Allocation is not stated, and the groups are not a like-for-like control comparison. Their clinical categories should therefore not be interpreted as treatment arms assigned to estimate comparative efficacy.
The primary outcome is procedural success, assessed from the baseline procedure through hospital discharge, with an expected average duration of less than 24 hours. The registry also lists adverse-event observation periods extending through 30 days, from 31 days to 365 days, and from 366 days post-procedure or greater. These are distinct reporting windows; the registry entries do not describe a uniform follow-up schedule for all other clinical or economic outcomes.
The record lists three outcome measures, but the other measures are not described in the available information. It identifies 1,106 enrolled subjects with sufficient information for the primary assessment. Fifteen subjects were excluded due to site closure and lack of investigator signature. The record also states that 83 subjects were excluded for lack of sufficient stenosis and/or angiographic complications, but further detail on that exclusion is not reported in the registry record. No statistical analysis results are listed.
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 subject was considered enrolled when a signed informed consent was in place and all inclusion/no exclusion criteria were met.
Overall Study
| Stage | Claudication (Rutherford 2-3) | CLI Rutherford 4-5 | CLI Rutherford 6 |
|---|---|---|---|
| STARTED | 501 | 603 | 100 |
| COMPLETED | 289 | 260 | 24 |
| NOT COMPLETED | 212 | 343 | 76 |
Reasons for not completing this period:
| Reason | Claudication (Rutherford 2-3) | CLI Rutherford 4-5 | CLI Rutherford 6 |
|---|---|---|---|
| Death | 77 | 123 | 30 |
| Lost to Follow-up | 28 | 46 | 15 |
| Withdrawal by Subject | 77 | 123 | 24 |
| Physician Decision | 25 | 31 | 3 |
| Site Closure | 4 | 18 | 1 |
| Reason not Specified | 1 | 2 | 3 |
Analysis population for the primary outcome, as defined in the registry: Analysis population consists of data from 1,106 enrolled subjects with sufficient information to assess procedural success. Fifteen subjects were excluded due to site closure and lack of investigator signature, 83 subjects were excluded due to lack of sufficient stenosis and/or angiographic complication data to determine success or failure.
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.
Population: Baseline analysis population consists of data from 1,189 enrolled subjects with Investigator signed baseline and procedure patient records. Due to site closure and lack of Investigator signature, 15 subjects were excluded from the cohort.
| Characteristic | Unit | Claudication (Rutherford 2-3) | CLI Rutherford 4-5 | CLI Rutherford 6 | Total |
|---|---|---|---|---|---|
| Participants analysed | 500 | 589 | 100 | 1189 | |
| Age, Continuous | years | 69.7 (SD 10.0) | 70.3 (SD 10.9) | 68.0 (SD 13.0) | 69.8 (SD 10.7) |
| Sex: Female, Male: Female | Participants | 167 | 225 | 27 | 419 |
| Sex: Female, Male: Male | Participants | 333 | 364 | 73 | 770 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 77 | 63 | 29 | 169 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 423 | 526 | 71 | 1020 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 | 0 |
| Race/Ethnicity, Customized: Caucasian | Participants | 411 | 483 | 78 | 972 |
| Race/Ethnicity, Customized: Black or African American | Participants | 68 | 89 | 21 | 178 |
| Race/Ethnicity, Customized: Asian | Participants | 5 | 1 | 1 | 7 |
| Race/Ethnicity, Customized: Native Hawaiian or Other Pacific Islander | Participants | 1 | 1 | 0 | 2 |
| Race/Ethnicity, Customized: Native American | Participants | 1 | 4 | 0 | 5 |
| Race/Ethnicity, Customized: Other | Participants | 14 | 11 | 0 | 25 |
| Region of Enrollment: United States | participants | 500 | 589 | 100 | 1189 |
| Baseline Rutherford Classification (RC): RC 2 | Participants | 97 | 0 | 0 | 97 |
| Baseline Rutherford Classification (RC): RC 3 | Participants | 403 | 0 | 0 | 403 |
| Baseline Rutherford Classification (RC): RC 4 | Participants | 0 | 285 | 0 | 285 |
| Baseline Rutherford Classification (RC): RC 5 | Participants | 0 | 304 | 0 | 304 |
| Baseline Rutherford Classification (RC): RC 6 | Participants | 0 | 0 | 100 | 100 |
6. Primary Endpoint
The registry lists the primary outcome as Procedural Success of Endovascular PAD Treatment(s), measured over Participants were followed from baseline procedure through hospital discharge, an expected average of less than 24 hours.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | percent of procedures |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is procedural success of endovascular PAD treatment, expressed as a percent of procedures. Success is defined by the final post-procedural result: less than 50% residual stenosis for all treated lesions for a participant during the index procedure, with no angiographic complications. The Angiographic Core Laboratory determined whether the angiographic criteria were met.
This endpoint combines a measure of residual narrowing with the absence of angiographic complications. It is assessed around the procedure itself, from baseline procedure through hospital discharge, for which the registry gives an expected average of less than 24 hours. It therefore addresses an immediate technical outcome, not long-term durability, symptoms, quality of life, or economic outcomes. The study’s broader stated purpose includes acute and long-term clinical and economic outcomes, but those aims should not be confused with the specifically defined primary endpoint.
The registry lists a 95% confidence interval as the endpoint’s dispersion measure. However, the endpoint estimate and its interval are not reported in the registry record. Without those values, the frequency of success and the precision of its estimate cannot be assessed from the posted results. The endpoint definition is reported; the result is not.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record identifies a clinically defined primary endpoint and an analysis population of 1,106 enrolled subjects with sufficient information to assess it. It does not report the observed procedural-success percentage or the numerical 95% confidence interval. As a result, no conclusion about the observed level of procedural success or its precision can be drawn from the primary endpoint information in the registry record.
The study is observational, and the record does not describe randomized allocation. Its Rutherford categories describe disease severity and symptoms, rather than treatment groups created to make a causal comparison. Any differences in outcomes across those categories could reflect differences in the patients’ clinical status, treatment choices, or other factors. The record does not provide an adjusted comparison that would account for such differences. Thus, the group descriptions and outcome counts should be read descriptively, not as evidence that one treatment or group caused better or worse outcomes.
The registry lists adverse-event counts for three groups across three post-procedure time windows. These figures are counts of affected participants, other adverse events, and deaths as listed in each group. They do not by themselves establish why an event occurred or whether it was attributable to a particular device or procedure. The registry’s leading serious-event terms include peripheral artery restenosis, peripheral artery stenosis, new/worsening wound, new/worsening infection, peripheral artery dissection, and death-unknown cause, with percentages listed for those terms. The record does not supply denominators or further context for those term percentages in the registry entries, so they should not be treated as comparative risks.
The registry lists three outcome measures but no statistical analyses. No inferential comparison, adjusted estimate, hypothesis test, or analysis result is reported in the registry record. Although the primary outcome’s dispersion is identified as a 95% confidence interval, its numerical bounds are absent. A confidence interval, in general, describes the uncertainty around an estimate under the method used to calculate it; it does not address bias from study design or missing observations.
Overall, the posted information supports a description of the study design, endpoint definition, analysis population, and adverse-event reporting structure. It does not provide enough primary-outcome or comparative-analysis information to quantify procedural success, estimate treatment effects, or evaluate the precision of clinical comparisons. The study’s stated economic aims also cannot be evaluated from the outcome details reported in the available information.
9. Statistical Methods Explained
What does the primary endpoint measure?
The primary outcome is a binary procedural criterion summarized as a percent of procedures: the final result must show less than 50% residual stenosis in all treated lesions for a participant during the index procedure, and there must be no angiographic complications. The Angiographic Core Laboratory is identified as the source of the angiographic determination. This makes the endpoint a technical measure of the immediate procedural result, rather than a direct measure of longer-term clinical status.
The registry identifies a 95% confidence interval as the dispersion measure. In general, a confidence interval gives a range of values compatible with the observed estimate under the assumptions of the calculation. It communicates sampling uncertainty, not all sources of uncertainty: it cannot by itself resolve bias from participant selection, treatment choice, missing information, or differences between clinical groups. The numerical endpoint estimate and its confidence interval are not reported in the registry record.
What can an observational design establish?
In general, an observational study records exposures and outcomes without randomized assignment. This design can describe what occurred in the enrolled population and can identify patterns in outcomes. It does not, by itself, ensure that outcome differences are caused by the procedure or by a specific device. In this study, the three groups are defined by Rutherford classification, and any FDA-cleared endovascular PAD treatment may be used. They are not stated to be randomized treatment arms, and allocation is not stated.
For a causal comparison, differences in prognosis, treatment selection, and other measured or unmeasured factors need to be addressed by an appropriate design and analysis. The registry record does not report a comparative statistical analysis or adjustment strategy. This means the event counts should be read as descriptive registry results, not as evidence of comparative treatment effects.
How should the adverse-event windows be read?
The adverse-event listings separate the procedure-through-30-days period, the period from 31 days to 365 days post-procedure, and the period beginning at 366 days post-procedure or greater. These time windows organize reporting; they do not mean every participant had identical observation time in each window. The available record does not describe the follow-up rules, censoring approach, or handling of participants who were not observed throughout a window.
Counts and percentages have different interpretations. A count gives the number of affected participants recorded for a group and time window. A percentage can describe a proportion only when its denominator and definition are clear. The listed serious-event term percentages are not accompanied in the registry entries by term-specific denominators or additional calculation details. They should therefore be treated as registry-reported descriptive percentages, not as a basis for comparing groups.
What does the planning illustration represent?
The registry’s planning assumptions describe an illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. Such calculations are planning illustrations, not observed power and not a record of the study’s original design justification. The registry does not report the specific planning values in the information. Its equal-allocation assumption is a hypothetical planning condition and does not change the observational nature of LIBERTY 360.
In general, a sample-size calculation asks what enrollment might be needed to detect a specified effect under chosen assumptions. Its result depends on the effect size, variability, allocation, and statistical method. If the assumptions differ from the study setting, the illustration may not describe what the study could detect in practice. It also cannot substitute for an observed estimate and its uncertainty.
What statistical analysis is reported?
The registry lists three outcome measures and zero analyses. The registry entries do not include a statistical analysis plan, model specification, hypothesis tests, adjusted estimates, or numerical confidence intervals. It is therefore not possible to assess whether any unreported analysis accounted for differences among participants, multiple outcomes, or incomplete follow-up. The stated endpoint dispersion measure does not fill that gap because the actual interval is not reported in the registry record.
In general, statistical methods should follow the question being asked and the structure of the data. A comparison of groups in an observational study requires care because the groups may differ before treatment. Repeated event reporting over time may also require explicit rules for follow-up and event counting. These are general methodological considerations; the registry record does not report how such issues were handled for analyses beyond the endpoint description.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists three outcome measures but the available information describes the primary endpoint in detail only. The other outcome measures and their results are not reported in the registry record. It lists zero analyses, so no analysis results, model details, or multiplicity adjustments are available to assess.
Multiplicity arises when several outcomes or comparisons are tested. In general, repeated testing can increase the chance of a nominally notable finding occurring by chance, so a statistical plan may specify which outcomes are primary and how secondary analyses will be interpreted. The record identifies a primary outcome, but does not report a multiplicity strategy or a statistical analysis plan. No claim can be made about whether adjustment was planned or used.
For the primary endpoint, the record states that 1,106 enrolled subjects had sufficient information for assessment. It also reports that 15 subjects were excluded due to site closure and lack of investigator signature, and that 83 subjects were excluded for lack of sufficient stenosis and/or angiographic complications. The full detail of the latter exclusion is not reported in the registry record. The available information does not explain how missing measurements were handled, whether excluded subjects differed from those assessed, or whether a sensitivity analysis was performed.
In general, excluding participants with incomplete outcome information can affect an estimate if the availability of measurements is related to outcome or clinical status. A description of the analysis population helps readers understand who contributed to the endpoint assessment, but it does not by itself establish that missingness had no effect. No imputation method, missing-data assumption, or sensitivity analysis is 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 |
|---|---|---|---|
| Claudication Rutherford 2-3 Procedure Through 30 Days | 72 | 501 | 14.4% |
| CLI Rutherford 4-5 Procedure Through 30 Days | 112 | 603 | 18.6% |
| CLI Rutherford 6 Procedure Through 30 Days | 24 | 100 | 24.0% |
| Rutherford 2-3 31 Days - 365 Days Post-Procedure | 145 | 501 | 28.9% |
| CLI Rutherford 4-5 31 Days - 365 Days Post-Procedure | 249 | 603 | 41.3% |
| CLI Rutherford 6 31 Days - 365 Days Post-Procedure | 40 | 100 | 40.0% |
| Claudication Rutherford 2-3 366 Days Post-Procedure or Greater | 167 | 501 | 33.3% |
| CLI Rutherford 4-5 366 Days Post-Procedure or Greater | 227 | 603 | 37.6% |
| CLI Rutherford 6 366 Days Post-Procedure or Greater | 24 | 100 | 24.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Claudication Rutherford 2-3 Procedure Through 30 Days | 2 of 501 |
| CLI Rutherford 4-5 Procedure Through 30 Days | 2 of 603 |
| CLI Rutherford 6 Procedure Through 30 Days | 4 of 100 |
| Rutherford 2-3 31 Days - 365 Days Post-Procedure | 18 of 501 |
| CLI Rutherford 4-5 31 Days - 365 Days Post-Procedure | 40 of 603 |
| CLI Rutherford 6 31 Days - 365 Days Post-Procedure | 17 of 100 |
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 |
|---|---|
| Claudication Rutherford 2-3 Procedure Through 30 Days | 28 of 501 |
| CLI Rutherford 4-5 Procedure Through 30 Days | 31 of 603 |
| CLI Rutherford 6 Procedure Through 30 Days | 2 of 100 |
| Rutherford 2-3 31 Days - 365 Days Post-Procedure | 0 of 501 |
| CLI Rutherford 4-5 31 Days - 365 Days Post-Procedure | 0 of 603 |
| CLI Rutherford 6 31 Days - 365 Days Post-Procedure | 0 of 100 |
Most frequent serious adverse event terms
| Event term | Organ system | Claudication Rutherford 2-3 Procedure Through 30 Days | CLI Rutherford 4-5 Procedure Through 30 Days | CLI Rutherford 6 Procedure Through 30 Days | Rutherford 2-3 31 Days - 365 Days Post-Procedure | CLI Rutherford 4-5 31 Days - 365 Days Post-Procedure | CLI Rutherford 6 31 Days - 365 Days Post-Procedure |
|---|---|---|---|---|---|---|---|
| Peripheral artery restenosis | Vascular disorders | 1 of 501 | 15 of 603 | 2 of 100 | 80 of 501 | 131 of 603 | 18 of 100 |
| Peripheral artery stenosis | Vascular disorders | 6 of 501 | 18 of 603 | 2 of 100 | 71 of 501 | 129 of 603 | 11 of 100 |
| Peripheral artery dissection | Injury, poisoning and procedural complications | 43 of 501 | 28 of 603 | 2 of 100 | 0 of 501 | 0 of 603 | 0 of 100 |
| New/worsening wound | Vascular disorders | 0 of 501 | 11 of 603 | 10 of 100 | 5 of 501 | 21 of 603 | 11 of 100 |
| New/worsening infection | Vascular disorders | 0 of 501 | 8 of 603 | 6 of 100 | 1 of 501 | 27 of 603 | 9 of 100 |
| Death-unknown cause | General disorders | 1 of 501 | 0 of 603 | 0 of 100 | 4 of 501 | 10 of 603 | 7 of 100 |
| Peripheral artery thrombus/thrombosis | Injury, poisoning and procedural complications | 6 of 501 | 11 of 603 | 1 of 100 | 0 of 501 | 0 of 603 | 0 of 100 |
| Peripheral artery perforation | Injury, poisoning and procedural complications | 7 of 501 | 7 of 603 | 0 of 100 | 0 of 501 | 0 of 603 | 0 of 100 |
| Myocardial infarction | Cardiac disorders | 0 of 501 | 6 of 603 | 1 of 100 | 3 of 501 | 2 of 603 | 1 of 100 |
| Cardiac/cardiopulmonary arrest | Cardiac disorders | 0 of 501 | 0 of 603 | 3 of 100 | 2 of 501 | 4 of 603 | 1 of 100 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Claudication Rutherford 2-3 Procedure Through 30 Days | CLI Rutherford 4-5 Procedure Through 30 Days | CLI Rutherford 6 Procedure Through 30 Days | Rutherford 2-3 31 Days - 365 Days Post-Procedure | CLI Rutherford 4-5 31 Days - 365 Days Post-Procedure | CLI Rutherford 6 31 Days - 365 Days Post-Procedure |
|---|---|---|---|---|---|---|---|
| Peripheral artery dissection | Injury, poisoning and procedural complications | 28 of 501 | 31 of 603 | 2 of 100 | 0 of 501 | 0 of 603 | 0 of 100 |
Serious events with the highest arm-level rate: peripheral artery restenosis (21.7%), peripheral artery stenosis (21.4%), new/worsening wound (11.0%), new/worsening infection (9.0%), peripheral artery dissection (8.6%).
The adverse-event listings divide reporting into three Rutherford groups and three time windows: procedure through 30 days, 31 days to 365 days post-procedure, and 366 days post-procedure or greater. Within each group and period, the registry gives the number at risk, the number affected by serious adverse events, the number affected by other adverse events, and deaths. These are descriptive counts; they are not adjusted comparisons and do not establish that the procedure caused an event.
For example, the Claudication Rutherford 2-3 group lists 72 serious-adverse-event participants among 501 at risk in the procedure-through-30-days period, and 2 deaths. The CLI Rutherford 4-5 group lists 112 serious-adverse-event participants among 603 at risk in that period, and 2 deaths. The CLI Rutherford 6 group lists 24 serious-adverse-event participants among 100 at risk in that period, and 4 deaths. These counts should be read in the context of different clinical groups and the stated observation window, not as a randomized comparison.
The registry also lists serious-event terms with percentages, including peripheral artery restenosis at 21.7%, peripheral artery stenosis at 21.4%, and new/worsening wound at 11.0%. The registry entries do not specify their denominators or further calculation details. The counts and term percentages should not be added together or assumed to represent mutually exclusive events or participants.
12. What the Result Does, and Does Not, Mean
The study record describes an observational assessment of endovascular PAD treatment, with a defined primary endpoint and adverse-event reporting across Rutherford groups and follow-up periods. The primary endpoint definition is specific: a participant meets the procedural criterion when all treated lesions have less than 50% residual stenosis and no angiographic complications are determined by the Angiographic Core Laboratory. This clarifies what the registry intended to measure.
However, the primary endpoint result and its 95% confidence interval are not reported in the registry record. The available information therefore does not show the observed percentage of successful procedures or how precisely it was estimated. The adverse-event listings provide counts, but those counts do not establish treatment causation or comparative safety. The registry does not report a statistical analysis comparing the clinical groups.
The study’s observational structure also limits causal interpretation. The Rutherford groups represent different clinical categories, and the record states that any FDA-cleared endovascular PAD treatment may be used. No randomized treatment allocation or like-for-like control comparison is described. Differences between groups could not be attributed to treatment from these registry entries alone.
The broader study purpose includes acute and long-term clinical and economic outcomes. The endpoint and adverse-event details do not provide enough information to evaluate the economic outcomes or the full range of long-term clinical outcomes. The registry record also does not report detailed follow-up methods, a statistical analysis plan, or missing-data sensitivity analyses.
Accordingly, the record supports understanding the study’s intended question, population categories, endpoint definition, and reported safety structure. It does not provide the primary outcome estimate, numerical uncertainty, or analyses needed for a quantitative judgment about procedural success or comparative effects. The absence of those results in the registry record should not be mistaken for evidence that an outcome did or did not occur.
13. Why This Trial Matters Statistically
This study is statistically notable for the distinction between an endpoint that is clearly defined and a result that is not available in the registry information. Procedural success is specified using residual stenosis across all treated lesions and the absence of angiographic complications, with assessment by an Angiographic Core Laboratory. Yet the numerical percentage and its stated 95% confidence interval are not reported. Readers can understand the measurement rule, but cannot evaluate its observed frequency or precision.
The design also illustrates why clinical categories are not automatically valid comparison groups. The registry organizes participants by Rutherford classification and permits any FDA-cleared endovascular PAD treatment. Since the study is observational and allocation is not stated, group differences may reflect clinical characteristics and treatment selection as well as outcomes. A descriptive count does not isolate a treatment effect.
In addition, adverse events are reported across several time windows, and the registry includes both serious-event counts and percentages for leading serious-event terms. Interpreting these reports requires attention to who is included, the period observed, and how each event measure is defined. The available information does not report all such analysis details or a statistical analysis plan.
Finally, the record states a broad aim that includes clinical and economic outcomes, while the available outcome details are limited. This gap matters for readers distinguishing a study’s intended scope from the results that can be evaluated. The registry provides useful design and endpoint context, but the missing endpoint estimate and absence of listed analyses sharply limit statistical interpretation.
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 most important limitation for interpreting the primary outcome is that the registry record does not report its numerical result or the numerical 95% confidence interval, despite defining the endpoint and analysis population. The record lists 1,106 subjects with sufficient information for the assessment, but does not explain how missing or insufficient information was handled beyond the stated exclusions. Further detail about the exclusion of 83 subjects is not reported in the registry record.
The study is observational, and allocation is not stated. Participants are grouped by Rutherford classification, and any FDA-cleared endovascular PAD treatment may be used. The record does not describe a randomized control group or a statistical adjustment strategy for differences among groups. Accordingly, the group-specific adverse-event counts cannot support a causal treatment comparison.
Follow-up is described differently for the procedural endpoint and adverse-event listings. The primary endpoint is assessed through hospital discharge, with an expected average of less than 24 hours, while adverse events are listed for periods through 30 days, 31 days to 365 days, and 366 days or greater. The registry entries do not specify follow-up completeness, event adjudication details beyond the primary angiographic assessment, or how participants with different observation durations were handled.
The record lists three outcome measures but supplies detailed information only for the primary endpoint and adverse-event categories. Economic outcome definitions and results are not reported in the registry record. Nor are a statistical analysis plan, numerical analysis results, multiplicity handling, or missing-data sensitivity analyses listed. These gaps restrict both the range of questions that can be answered and the precision with which the posted findings can be interpreted.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Observational Study to Evaluate PAD Treatment Clinical and Economic Outcomes — NCT01855412.
- Registry record last updated 2023-07-18; status last verified 2023-07.
- Results first posted 2021-05-18.
- 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
LIBERTY 360 (NCT01855412) is a completed, prospective, observational, multi-center study sponsored by Abbott Medical Devices. Its stated purpose was to evaluate acute and long-term clinical and economic outcomes of endovascular procedures for PAD. The registry lists enrollment of 1204 and describes three Rutherford-based clinical groups.
The primary endpoint is procedural success, defined by less than 50% residual stenosis in all treated lesions and no angiographic complications, as determined by the Angiographic Core Laboratory. The endpoint is assessed through hospital discharge, with an expected average of less than 24 hours. The registry identifies 1,106 subjects with sufficient information for endpoint assessment, but does not report the endpoint estimate or numerical confidence interval.
Adverse-event counts are listed across three clinical groups and post-procedure periods. The registry lists three outcome measures and zero analyses. Comparative statistical results, detailed economic outcomes, and a statistical analysis plan are not reported in the registry record.