Abstract 3079: Ethnicity and Risk Factors for Prospective Changes in the Ankle-Brachial Index: The Multi-Ethnic Study of Atherosclerosis
Background: In this study, we aimed to determine the traditional and novel CVD risk factors associated with conversion from a normal to either a low or high ABI.
Methods: Subjects were participants in the Multi-Ethnic Study of Atherosclerosis (MESA) who were free of clinical CVD at baseline and had two separate measurements of the ABI over a 3-year period of time.
Results: At baseline, the mean age was 62 years and 50% were women, 28% African American, 12% Asian, 22% Hispanic and 38% White. The reproducibility of the ABI measurement was 0.95. Of the 5,514 MESA participants with a baseline ABI between 0.9 and 1.4, at follow-up 89 (1.6%) had an ABI <<26> 0.9 (“low ABI group”) and 71 (1.3%) had an ABI >= 1.4 (“high ABI group”). Using stepwise multivariable logistic modeling, the odds for having progressed into the low ABI group were significant for baseline age (OR: 1.67 per decade, p < 0.01), baseline ABI (5.5 per 0.1 ABI unit decrease, p < 0.01), pack-years of cigarette smoking (1.06 per 10 pack-years, p = 0.05) and homocysteine (1.04 per μmol/L, p = 0.02). In this model, diabetes and hypertension were of borderline significance (1.74, p = 0.06 and 1.57, p = 0.09; respectively). The odds for progression into the high ABI group were significant for baseline ABI (3.42 per 0.1 ABI unit increase, p < 0.01) and body mass index (1.05 per BMI unit, p < 0.01). None of the novel or inflammatory biomarkers were significantly associated with progression into the high ABI group. In the same models and compared to Whites, African Americans had an increased odds for progression to the low ABI group that was of borderline significance (1.67, p = 0.07). There was a suggestion of a reduced risk for progression to the high ABI group in African Americans but this was not statistically significant (0.70, p = 0.35). Compared to Whites, neither Asian nor Hispanic ethnicity was significantly associated with progression to the low or high ABI groups.
Conclusions: Beyond baseline ABI, these results suggest that the risk factors for progression to a low and high ABI may be different. Of the novel and inflammatory CVD risk factors, only homocysteine was significant for progression to a low, but not high, ABI. African Americans may have an increased odds for progression to a low ABI and a tendency for reduced odds for a high ABI.
This research has received full or partial funding support from the American Heart Association, AHA National Center.