Ankle-Arm Index as a Predictor of Cardiovascular Disease and Mortality in the Cardiovascular Health Study

Peripheral arterial disease (PAD) in the legs, measured noninvasively by the ankle-arm index (AAI) is associated with clinically manifest cardiovascular disease (CVD) and its risk factors. To determine risk of total mortality, coronary heart disease, or stroke mortality and incident versus recurrent CVD associated with a low AAI, we examined the relationship of the AAI to subsequent CVD events in 5888 older adults with and without CVD. The AAI was measured in 5888 participants >/=65 years old at the baseline examination of the Cardiovascular Health Study. All participants had a detailed assessment of prevalent CVD and were contacted every 6 months for total mortality and CVD events (including CVD mortality, fatal and nonfatal myocardial infarction, congestive heart failure, angina, stroke, and hospitalized PAD). The crude mortality rate at 6 years was highest (32.3%) in those participants with prevalent CVD and a low AAI (P<0.9), and it was lowest in those with neither of these findings (8.7%, P<0.01). Similar patterns emerged from analysis of recurrent CVD and incident CVD. The risk for incident congestive heart failure (relative risk RR=1.61) and for total mortality (RR=1.62) in those without CVD at baseline but with a low AAI remained significantly elevated after adjustment for cardiovascular risk factors. Hospitalized PAD events occurred months to years after the AAI was measured, with an adjusted RR of 5.55 (95% CI, 3.08 to 9.98) in those at risk for incident events. A statistically significant decline in survival was seen at each 0.1 decrement in the AAI. An AAI of <0.9 is an independent risk factor for incident CVD, recurrent CVD, and mortality in this group of older adults in the Cardiovascular Health Study.