Adams: Real-World Data From Liberty 360

August 12, 2021 — The Liberty 360 study was a prospective, observational, multicenter study to evaluate the procedural and long-term clinical and economic outcomes of endovascular device interventions in patients across all Rutherford classifications starting from 3 to 6.

During AMP 2021, George L. Adams, MD, MHS, MBA, from UNC REX Healthcare in Raleigh, North Carolina, reviewed the Liberty 360 3-year outcomes and shared with attendees a 2-year cost analysis of the trial.

Liberty 360 included any FDA approved or cleared technology to treat claudication and used 4 core laboratories for independent analysis.

In total, 1204 subjects were enrolled at 51 sites and were followed for up to 5 years.

Of the 1204 subject enrolled, 500 were Rutherford 2-3, 589 were Rutherford 4-5, and 100 were Rutherford 6 (excluding those who withdrew or were lost to follow-up), making this the largest trial to date looking at endovascular interventions in Rutherford 6 patients. Corresponding mortality across these 3 groupings were 12.2%, 15.9%, and 29.0% at 3 years.

“We have talked about mortality in this population of Rutherford 4-6 being anywhere from 15% to 70%,” noted Adams.

Overall, patients with claudication at baseline were at lower risk for major adverse events compared with RC 4-5 and RC 6 patients during the 3-year follow-up.

At 3 years, the Kaplan-Meier survival rates were 86.0% in RC 2-3, 79.8% in RC 4-5, and 62.0% in RC 6. Corresponding estimates of freedom from major amputation at 3 years were 98.5%, 94.0%, and 79.9%, respectively.

The findings indicate “durable results from year one through three years, through all Rutherford classes. The Rutherford 6 subjects that survive past the first year saw similar benefits in amputation-free survival compared to Rutherford 2-3 and Rutherford 4-5,” noted Adams (Figures 1-2, below).

Quality of life, including vascular QoL, improved from baseline and persisted up to 3 years in all patients.

“We looked at quality of life metrics, and again what you see is very interesting. You get an increase in quality of life across the board, even in the highest-risk patients, so saying that the people who had the highest risk derived the greatest benefit, there's no question [of this] based on the outcome data I’ve shown and now the [quality of life data.]”

The 3-year outcomes of Liberty 360 published online in the Journal of Endovascular Therapy in late 2020.

Two-Year Cost Analysis

The Liberty 360 investigators have also conducted a cost analysis, published online in May 2021 in the Journal of Medical Economics.

Overall, mean cost associated with the index procedure (including the facility stay) increased with Rutherford classification, noted Adams, with higher follow-up costs driven by both repeat endovascular procedures (mainly for Rutherford 4-5) and outpatient care (mainly for Rutherford 6).

Mean total index procedure hospitalization costs were $10,304, $11,418, and $19,403 for Rutherford 2–3, 4–5, and 6, respectively (p< 0.01 in all pairwise comparisons).

Mean total 2-year follow-up costs were $11,416, $24,846, and $25,720 for Rutherford 2–3, 4–5, and 6, respectively (p < 0.001 comparing Rutherford 2–3 to the other 2 groups; p = 0.09 comparing Rutherford 4–5 and Rutherford 6). (Figure 3, below)

Of note, orbital atherectomy (R2-6; N=503) turned out to be slightly cost saving, with mean index procedure cost of $11,729 and by 2-year the mean costs of $29,474, numerically lower than the overall LIBERTY (all-devices) mean 2-year cost of $30,491 (Figure 4, below).

Dr. Adams noted that with increasing emphasis on alternative payment models this data supporting the assertion that higher risk patients are costlier to treat, may have important implications for health care resource allocation and reimbursement.

He concluded: “The results of this novel all-comers PAD study continue to suggest that percutaneous vascular intervention is a reasonable treatment option for RC 2-3 and RC 4-5.”

“Primary amputation may not be necessary in Rutherford 6 and peripheral vascular intervention can be successful in this patient population, as evidenced at 3 year by high freedom from major amputation (79.9%) and improvement in QOL,” he added.