Association of the ankle-brachial index with history of myocardial infarction and stroke.

BACKGROUND

Ankle-brachial index (ABI) testing is a simple, noninvasive method to diagnose peripheral artery disease (PAD) and is associated with all-cause mortality. The association of ABI levels and myocardial infarction (MI) and stroke is less certain. We sought to further characterize the association between ABI levels and history of MI and stroke.

METHODS

Using data from the Life Line Screening program, 3.6 million self-referred participants from 2003 to 2008 completed a medical questionnaire and had bilateral ABIs performed. Logistic regression was used to estimate the association between ABI cutoff points (ABI <0.90 and ABI >1.40) and ABI levels with history of MI, stroke, and MI or stroke (MI/stroke). Models were adjusted for age, sex, race/ethnicity, smoking, diabetes, hypertension, hypercholesterolemia, physical activity, and family history of cardiovascular disease. Separate sex-specific models were performed.

RESULTS

Overall, 155,552 (4.5%) had an ABI <0.90, and 42,890 (1.2%) had an ABI >1.40. An ABI <0.90 was associated with higher odds of MI (adjusted odds ratio [OR] 1.67, 95% CI 1.63-1.71), stroke (OR 1.77, 95% CI 1.72-1.82), and MI/stroke (OR 1.71, 95% CI 1.67-1.74), all P < .001. An ABI >1.40 was also associated with higher odds of MI (OR 1.19, 95% CI 1.14-1.24), stroke (OR 1.30, 95% CI 1.22-1.38), and MI/stroke (OR 1.22, 95% CI 1.17-1.27), all P < .001. The ORs for MI/stroke for different ABI levels formed a reverse J-shaped curve in both women and men.

CONCLUSIONS

In a large national screening database, there is a strong, consistent relationship between ABI levels and a history of prevalent MI, stroke, and MI/stroke.