Changes in ankle brachial index in symptomatic and asymptomatic subjects in the general population

Objective: To determine changes over time in the ankle brachial index (ABI) among subjects with and without intermittent claudication in the general population. Design of study: Population cohort study. Setting: General population in Edinburgh, Scotland. Subjects. A total of 1592 men and women aged 55 to 74 years selected at random from age-sex registers of 11 general practices and followed up over 12 years. Main outcome measures. Changes in ABI for each leg recorded at baseline in 1988 and at subsequent 5-year and 12-year clinical examinations. Results. Overall, 695 subjects (348 men and 347 women) had valid ABI measurements on both legs at all three examinations. At baseline, the ABI was on average .03 higher in the right leg than the left (P less than or equal to .001). Men had a mean ABI that was .07 higher than women (P less than or equal to .001). Mean ABI in the worse leg showed little change over 12 years in both men and women. However, in the whole population, the ABI in the better leg showed a significant drop, 1.15 to 1.08 (P less than or equal to .001). A total of 179 cases of intermittent claudication were identified during the 12-year follow-up. At baseline, ABI in the worse leg of the claudicants was significantly lower than in healthy subjects (.99 vs 1.08; P less than or equal to .01). In claudicants, mean ABI in the worse leg fell by .04 over 5 years (P less than or equal to .05) and in the better leg showed a highly significant drop of .09 (P less than or equal to .001) to levels similar to those of the worse leg. Conclusions: The mean ABI in the worse leg of study subjects showed little progression over 12 years. Individuals with intermittent claudication experienced a greater decline in both legs compared with those without claudication. Deterioration occurred more rapidly in the limb with a higher ABI at baseline, which possibly indicates a systemic tendency to atherosclerosis.