Risk of mortality and cardiovascular disease associated with the ankle-brachial index: Systematic review.

OBJECTIVE To determine the strength and consistency with which a low ankle brachial pressure index (ABI), measured in the general population, is associated with an increased risk of subsequent death and/or cardiovascular events. DESIGN Systematic review. DATA SOURCES Medline, Embase, reference lists and grey literature were searched; studies known to experts were also retrieved. MAIN OUTCOME MEASURES All cause mortality, fatal and non-fatal coronary heart disease and stroke. REVIEW METHODS Longitudinal studies in which participants were representative of the general population (all ages, either sex) and which used any standard method for measurement and calculation of the ABI. Studies in which participants were selected according to presence of pre-existing disease or were post intervention (e.g. angioplasty or peripheral arterial grafting) were excluded. RESULTS 11 studies comprising 44,590 subjects from six different countries were included. Despite clinical heterogeneity between studies, the findings were remarkably consistent in demonstrating an increased risk of clinical cardiovascular disease associated with a low ABI. A low ABI (<0.9) was associated with an increased risk of subsequent all cause mortality (pooled RR 1.60, 95% CI 1.32-1.95), cardiovascular mortality (pooled RR 1.96, 95% CI 1.46-2.64), coronary heart disease (pooled RR 1.45, 95% CI 1.08-1.93) and stroke (pooled RR 1.35, 95% CI 1.10-1.65) after adjustment for age, sex, conventional cardiovascular risk factors and prevalent cardiovascular disease. CONCLUSIONS The ABI may help to identify asymptomatic individuals in the general population who are at increased risk of subsequent cardiovascular events. Evaluation is now required of the potential of incorporating ABI measurement into cardiovascular prevention programmes.