We reported that ankle-brachial index (ABI) was lowest at <40 years, and increased with age until 60 years and decreased thereafter in a screened cohort of Japanese general population. We hypothesized that this increase in ABI with age occurs owing to increasing arterial stiffness and wave reflection, and therefore, a high normal ABI is associated with target organ damage.Design and Method:
We measured ABI and brachial-ankle pulse wave velocity (baPWV) by an automatic oscillometric method. A cross-sectional study of ABI and target organ damage was conducted in participants aged 21–89 years from health checkups. Proteinuria was defined as ≥ 1+ by dipstick (n = 13,193). Left ventricle hypertrophy (LVH) was defined by the Minnesota code 3.1 and 3.3 (n = 13,203). Cerebral microbleeds (CMB) were determined with T2*-weighted images (n = 990).Results:
In participants with ABI ≥ 1.0, ABI was positively correlated with SBP, pulse pressure and baPWV, whereas, in participants with ABI < 1.0, all indices were inversely correlated with ABI. The prevalence of proteinuria, LVH, and CMB were 7%, 15%, and 4%, respectively. In participants aged ≥ 60 years, proteinuria was associated with only low ABI (≤ 0.9) compared with normal ABI (1.0 ≤ ABI < 1.2) after multivariate adjustment. In participants aged < 60 years, however, adjusted OR for proteinuria was significantly associated with high normal ABI (1.2 ≤ ABI < 1.4). The prevalence of LVH was only significantly associated with high normal ABI after multivariate adjustment. The cutoff values of ABI and baPWV for the presence of CMB were 1.12 and 16.07 m/s, respectively. Multivariate analysis showed that ABI ≥1.12 and baPWV ≥ 16.07 m/s were independently associated with CMB. Moreover, combination of high ABI and baPWV was strongly associated with CMB.Conclusions:
Our findings provide a new interpretation of ABI as a biomarker for arterial stiffness and target organ damage in younger adults (< 60 years) or low-risk people.