Open Access Study protocol

The FReedom from Ischemic Events - New Dimensions for Survival (FRIENDS) registry: design of a prospective cohort study of patients with advanced peripheral artery disease

Hong H Keo1, Sue Duval2, Iris Baumgartner3, Niki C Oldenburg2, Michael R Jaff4, JoAnne Goldman5, James M Peacock6, Alexander S Tretinyak5, Timothy D Henry5, Russell V Luepker7 and Alan T Hirsch2*

Author Affiliations

1 Division of Angiology, Kantonsspital Aarau AG, Aarau, Switzerland

2 Vascular Medicine Program, Lillehei Heart Institute and Cardiovascular Division, University of Minnesota Medical School, Minneapolis, MN, USA

3 Swiss Cardiovascular Center, Division of Angiology, University Hospital Bern, Bern, Switzerland

4 Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA

5 Minneapolis Heart Institute Foundation at Abbott Northwestern Hospital, Minneapolis, MN, USA

6 Minnesota Department of Health, Heart Disease and Stroke Prevention Unit, Saint Paul, MN, USA

7 Division of Epidemiology and Community Health, University of Minnesota School of Public Health, Minneapolis, MN, USA

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BMC Cardiovascular Disorders 2013, 13:120  doi:10.1186/1471-2261-13-120

Published: 19 December 2013



Advanced lower extremity peripheral artery disease (PAD), whether presenting as acute limb ischemia (ALI) or chronic critical limb ischemia (CLI), is associated with high rates of cardiovascular ischemic events, amputation, and death. Past research has focused on strategies of revascularization, but few data are available that prospectively evaluate the impact of key process of care factors (spanning pre-admission, acute hospitalization, and post-discharge) that might contribute to improving short and long-term health outcomes.


The FRIENDS registry is designed to prospectively evaluate a range of patient and health system care delivery factors that might serve as future targets for efforts to improve limb and systemic outcomes for patients with ALI or CLI. This hypothesis-driven registry was designed to evaluate the contributions of: (i) pre-hospital limb ischemia symptom duration, (ii) use of leg revascularization strategies, and (iii) use of risk-reduction pharmacotherapies, as pre-specified factors that may affect amputation-free survival. Sequential patients would be included at an index “vascular specialist-defined” ALI or CLI episode, and patients excluded only for non-vascular etiologies of limb threat. Data including baseline demographics, functional status, co-morbidities, pre-hospital time segments, and use of medical therapies; hospital-based use of revascularization strategies, time segments, and pharmacotherapies; and rates of systemic ischemic events (e.g., myocardial infarction, stroke, hospitalization, and death) and limb ischemic events (e.g., hospitalization for revascularization or amputation) will be recorded during a minimum of one year follow-up.


The FRIENDS registry is designed to evaluate the potential impact of key factors that may contribute to adverse outcomes for patients with ALI or CLI. Definition of new “health system-based” therapeutic targets could then become the focus of future interventional clinical trials for individuals with advanced PAD.

Peripheral artery disease; Amputation; Atherosclerosis; Health service research; Outcomes research