Prior studies evaluating metabolic syndrome (MetS) and incident peripheral 
artery disease (PAD) have been limited by use of modified MetS criteria and 
restriction to clinical PAD end points. We investigated MetS and risk of 
developing a low ankle-brachial index (ABI) and clinical PAD in the 
Cardiovascular Health Study, a population-based cohort of adults aged ≥65 years. 
Participants with MetS met at least 3 of 5 Adult Treatment Panel III criteria. 
Baseline C-reactive protein-MetS or fibrinogen-MetS were defined as presence of 
3 of 6 components, with elevated C-reactive protein (>3 mg/L) or fibrinogen 
(>341 mg/dL) as a sixth component. Incident low ABI, defined as ABI <0.9 and 
decline of ≥0.15, was assessed among a subset of 1899 individuals with 2 ABI 
measurements 6 years apart. Over a median follow-up of 13.7 years, 4632 
individuals were followed up for clinical PAD, defined as revascularization or 
diagnosed claudication. Adult Treatment Panel III MetS was associated with both 
incident low ABI (risk ratio, 1.26; 95% confidence interval [CI], 1.00-1.58) and 
clinical PAD (hazard ratio, 1.47; 95% CI, 1.11-1.94). Incorporating C-reactive 
protein or fibrinogen into Adult Treatment Panel III criteria identified an 
additional 16% to 20% of individuals as having MetS, and both C-reactive 
protein-MetS and fibrinogen-MetS were associated with incident low ABI (risk 
ratio, 1.36; 95% CI, 1.07-1.72 and risk ratio, 1.43; 95% CI, 1.13-1.81, 
respectively) and clinical PAD (hazard ratio, 1.56; 95% CI, 1.17-2.08 and hazard 
ratio, 1.55; 95% CI, 1.17-2.07, respectively). Among Adult Treatment Panel III 
MetS criteria, risk of PAD was most strongly associated with hypertension.