Next Steps to Collecting More Data for Peripheral Vascular Patients: A Continued Discussion Regarding Rigorous Scientific Data

This letter intends to expand the discussion started by Dr. Lawrence Garcia in his blog post, “Collecting More Data for Vascular Patients.”

There is definitely a need for rigorous scientific peripheral arterial disease (PAD) data collection for real-world patients. Most clinical trials have lengthy inclusion/exclusion criteria and are designed for device approval, meaning to study devices in a specific setting leading to evaluation of very select groups of patients. Thus the outcomes from these trials are difficult to translate into real-world, everyday practice. 

Historically, there has been a lack of head-to-head device studies, as well as randomized controlled trials. This is likely due to the cost of conducting a trial and company fear of potential undesirable outcomes of profitable devices.

LIBERTY 360º (Cardiovascular Systems, Inc.) is the first study designed in a partnership between industry and leading peripheral interventionalists, to be an all-comers/all-treatment study of PAD. This means that all efforts will be made to ensure that consecutive patients will be enrolled in the study regardless of the type of PAD endovascular treatment that they may receive. Moreover, the inclusion and exclusion criteria are minimal (exclusion of patients <18 years old, pregnant women, or anyone who is not willing or able to sign informed consent form). 

LIBERTY 360º is a prospective, observational, multicenter clinical study focused on evaluating the procedural and long-term clinical, functional, and economic outcomes of endovascular device interventions in patients with distal outflow PAD, defined as atherosclerotic obstructive disease of any length occurring in the anatomy defined from 10 cm above the medial epicondyle to the digital arteries. Approximately 1,200 patients will be enrolled at up to 100 US sites: 500 patients in the claudicant arm (Rutherford category II to III), 500 patients in the critical limb ischemia (CLI) Rutherford category IV to V arm, and 200 patients in the CLI Rutherford category VI arm. 

This is the first study of its kind that will include all advanced Rutherford categories, diabetics, and patients with renal dysfunction. LIBERTY 360º will utilize numerous core laboratory analyses and adjudications: angiographic, duplex ultrasound, 6-minute walk test, and a health economics core laboratory. Acute outcomes will include procedure, lesion and device information, health status questionnaires (VascuQoL and EQ-5D), wound healing, procedural complications (graded dissection, perforation, embolization, unresolved slow flow), and need for bailout stenting. Patient outcomes will include Rutherford classification, Ankle Brachial Index and Toe Brachial Index, mortality, clinically driven target lesion and target vessel revascularization, amputation, wound healing (length and width measurements), duplex ultrasound (claudicant arm only), 6-minute walk test (Rutherford category II to V), health status questionnaires (VascuQoL and EQ-5D), and cost analysis data. 

All patients will be followed for up to 5 years post-treatment. Utilizing such a unique data collection and analysis, the LIBERTY 360º study will evaluate not only clinical but also economic outcomes of varied PAD procedures, details that are certainly becoming more important to our health care systems.

The objectives of the LIBERTY 360º study are as follows: (1) Evaluate procedural and long-term clinical and economic outcomes for patients undergoing peripheral vascular intervention in distal outflow and runoff PAD; (2) Create a universal classification schema to describe the distribution and plaque burden, including calcium, for disease in distal outflow and runoff PAD; (3) Establish objective performance criteria benchmarks for peripheral vascular intervention in distal outflow and runoff PAD; and (4) Align the design and architecture of the clinical study to become the foundation for a national peripheral vascular intervention registry.

Thus, we agree with Dr. Garcia’s common goal — “Push the industry to start comparing apples to apples and devices to each other”…“we just need to get something done.” Dr. Garcia’s ultimate goal to “place all our patients into the world’s greatest registry and have a group make up an independent analysis group for the angiograms and sonograms to avoid the excessive costs of core labs” is gallant but still associated with significant costs and may not be feasible at this time. Therefore, the expense of core lab adjudicated data is needed, but it brings an important, additional level of scientific rigor to help with user bias towards a specific technology or device.

As endovascular options for PAD patients continue to expand, choice of revascularization must be considered in the context of the patient’s clinical status, specific anatomic and lesion characteristics, and the optimal device features to ensure success. Future well-designed and executed randomized control trials that track clinically relevant outcomes, including the cost of the endovascular treatments and long-term outcomes, will enable physicians to determine the optimal therapies for patients with PAD. This will ultimately advance both treatments and outcomes for PAD patients.

Editor’s Note: Disclosure:  The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr. Adams reports consultancy, honoraria, and reimbursement from CSI. Dr. Ansel reports consultancy and reimbursement from CSI. Dr. Gray reports consultancy, grants, and reimbursement from CSI. Dr. Mustapha reports consultancy from CSI and Bard Peripheral Vascular, grants and honoraria from CSI, Bard Peripheral Vascular, Spectranetics, and Covidien, and payment for educational materials and travel for CSI, Bard Peripheral Vascular, and Covidien.

Manuscript received September 4, 2013, provisional acceptance October 23, 2013, accepted November 11, 2013. 

Address for correspondence: George L. Adams, MD, MHS, Rex Healthcare, 300 Health Park Drive, Suite 110, Garner, NC 27529, United States. Email: adamsgla@hotmail.com