Ankle-brachial index is associated with vascular calcification in pre-dialysis Chronic kidney disease patients
Description
Background Ankle brachial index (ABI) is a noninvasive measure of subclinical cardiovascular disease (CVD) and atherosclerosis of the lower extremities. Low and high levels of ABI are associated with cardiovascular mortality and vascular calcification in dialysis chronic kidney disease (CKD) patients. However, the association of the spectrum of vascular calcification with low and high ABI is not well studied in pre-dialysis CKD patients. The purpose of this study is to investigate the association of both low and high ABI with the risk of vascular calcification in CKD patients. Methods We recruited 243 patients with pre-dialysis CKD from the great New Orleans area between 2010 and 2012. Our study used a cross-sectional design with ABI and CAC measured at the same visit. Continuous ABI measurements were taken and further classified into four categories : <=0.9 (low ABI) >0.9-<1.0 (borderline), 1.0-<1.4 (normal), >=1.4 (high). Level of vascular calcification were considered as the outcome and calculated by agatston score. Three categories of CAC is defined as: CAC agaston score=0, 0-100, >100. Three cumulative logit models were applied to the data. The first is an unadjusted univariate model, the second adjusts for baseline demographics, and the third adjusts for baseline demographics and covariates that are associated with CAC. Logistic regression methods were used to calculate the odds ratio of having a higher CAC score for CKD patients. Results We found a significant association between ABI and vascular calcification. All three models returned consistently significant result (p=0.0005, 0.0005, 0.0037, respectively) for the association between ABI and CAC. In addition, low ABI (ABI≤0.9) is also associated with an increased risk of CAC and severe CAC (OR=6.183, 95%CI(1.085, 35.228)). High ABI (>1.4) is also associated with an increase in CAC and severe CAC (OR=5.064, 95%CI (1.696, 15.122)). Borderline ABI (0.9