Table I.

Characteristics of Four Cohorts Contributing Peripheral Artery Disease Participants to Analyses

Cohort/years of study	Inclusion Criteria	Primary Aim of Study	Primary Results
WALCS 1998–2002	Age 55 and older and ABI ≤ 0.90	To compare baseline objective measures of lower extremity functioning and annual rates of decline in these objective measures of lower extremity functioning between participants with and without PAD. Objective measures of functioning included the six-minute walk and four-meter walking velocity.	People with PAD had greater functional impairment and faster functional decline than those without PAD, and this phenomenon was observed even in PAD participants without classical symptoms of intermittent claudication.
WALCS II 2002–2006	Included participants from WALCS who consented to WALCS II and newly identified participants age 59 and older and ABI ≤0.90.	To compare baseline measures of computed tomography-measured calf skeletal muscle quantity and percent fat composition between participants with and without PAD. To determine whether smaller calf muscle quantity and higher fat composition were associated with faster functional decline among participants with PAD.	Participants with PAD had smaller calf muscle area and a higher calf muscle fat content than those without PAD. More adverse calf muscle characteristics were associated with higher rates of mobility loss.
WALCS III 2008–2013	ABI < 1.00 and eligible for magnetic resonance imaging.*	To determine whether magnetic resonance imaging (MRI) measured superficial femoral artery plaque quantity and composition were associated with rates of functional decline in participants with PAD.	Greater MRI-measured plaque quantity and smaller lumen area in the superficial femoral artery were associated with greater functional impairment.
BRAVO 2009–2013	Presence of PAD defined as ABI < 0.90, medical record documented lower extremity revascularization, or evidence of PAD from a medical center-based non-invasive vascular laboratory.	To determine whether inflammatory biomarkers and D-dimer levels, measured every two months, increased immediately before acute coronary events in participants with PAD.	Levels of D-dimer obtained within two months of an acute coronary event were higher than values obtained 10–32 months previously. A similar phenomenon was not observed for C-reactive protein or serum amyloid A.

^*Only participants with ABI <0.90 were included in these analyses. WALCS- Walking and leg circulation study. BRAVO- Biomarker risk assessment in vulnerable outpatients. ABI- Ankle brachial index. PAD-Peripheral artery disease.