Peripheral arterial disease (PAD) increases with age and ankle-brachial index (ABI) ≤ 0.9 is a noninvasive marker of PAD. The purpose of this study was to identify risk factors related to a low ABI in the elderly using two different methods of ABI calculation (traditional and modified definition using lower instead of higher ankle pressure). A cross-sectional study was carried out with 65 hypertensive patients aged 65 years or older. PAD was present in 18% of individuals by current ABI definition and in 32% by modified method. Diabetes, cardiovascular diseases, metabolic syndrome, higher levels of systolic blood pressure and pulse pressure, elevated risk by Framingham Risk Score (FRS), and a higher number of total and antihypertensive drugs in use were associated with low ABI by both definitions. Smoking and LDL-cholesterol were associated with low ABI only by the modified definition. Low ABI by the modified definition detected 9 new cases of PAD but cardiovascular risk had not been considered high in 3 patients when calculated by FRS. In conclusion, given that a simple modification of ABI calculation would be able to identify more patients at high risk, it should be considered for cardiovascular risk prediction in all elderly hypertensive outpatients
