A research project capturing experiences of patients with critical limb threatening ischemia, with the ultimate goal of setting new standards for diagnosing, describing detailed patient-centered outcomes, and evaluating the variability in therapeutic approaches and their association with outcomes.

An estimated 8 million individuals in America are affected by peripheral arterial disease (PAD). One of its extreme expressions is Critical Limb Ischemia (CLI). It is one of the most severe vascular conditions associated with devastating outcomes, including poorly healing wounds, extreme pain, and a high amputation risk. It is also one of the deadliest conditions, with 6-month and 5-year mortality rates estimated to be 20 and >50%, respectively. To date, however, there is a paucity of prospective clinical evidence about the variability in patients' presentations, their management or their outcomes. Accordingly, little progress has been made in adequately staging the disease and to risk-stratify treatment approaches to patients' individual characteristics. What is desperately needed to advance the care and management of patients with CLI is a focused research effort to set new standards for diagnosing, describing detailed patient-centered outcomes, and evaluating the variability in therapeutic approaches and their association with outcomes. The specific aims of SCOPE-CLI are to generate new evidence on the clinical characteristics, treatment patterns and outcomes of patients with critical limb ischemia (CLI); to describe treatment patterns and variability across practices to identify gaps in delivering quality care; and to perform a series of analyses to examine the associations of patient and treatment characteristics with outcomes. The central objective of SCOPE-CLI is to systematically quantify patients' CLI-specific health status and clinical outcomes and to perform subgroup analyses as a function of different PAD treatments and patient characteristics.

Inclusion Criteria:

1. All race/ethnicity categories, English speaking, men and women

2. Patient presents with current (within 30 days) Rutherford Class 4, 5, or 6

3. Age ≥18 years

4. Supported by any of the following diagnostic evidence:

   • Rutherford Classification 4 or ischemic rest pain and/or resting ankle pressure <50mmHg, flat or barely pulsatile ankle or metatarsal PVR or toe pressure <40mmHg
   • Rutherford Classification 5 or minor tissue loss; non-healing ulcer, focal gangrene with diffuse pedal ischemia resting ankle pressure <50mmHg ankle or metatarsal PVR flat or barely pulsatile or toe pressure <40mmHg
   • Rutherford Classification 6 or major tissue loss: extending above transmetatarsal level, functional foot no longer salvageable, resting ankle pressure <50mmHg ankle or metatarsal PVR flat or barely pulsatile or toe pressure <40mmHg
   • CLI related ICD 10 code (reason for admission or indication for procedure)
   • SPP < 50 mmHg
   • TCPO2 < 50 mmHg
   • Angiographic evidence no straight line to foot or greater than 70% stenosis in all 3 lower extremity arteries (AT, PT, peroneal)
   • ABI* ≤ 0.90
   • non-compressible ABI ≥ 1.40 AND TBI ≤ 0.70
   • TBI* ≤ 0.70

Exclusion Criteria:

1. Acute limb ischemia
2. Unable to provide written informed consent
3. Currently a prisoner (identified at time of enrollment)

Patients will be enrolled from a range of clinical practices combining forces from vascular surgery, vascular medicine (interventional) cardiology, wound care specialists and podiatry clinics that treat CLI patients. All patients will be medically stable, i.e., not actively experiencing a life-threatening critical condition for which emergent care processes are ongoing, before they are approached for inclusion in the study.