Association of Chronic Kidney Disease With the Spectrum of Ankle Brachial Index

Background: Chronic kidney disease (CKD) is an important risk factor for cardiovascular disease (CVD) events. A high ankle brachial index (ABI) - a marker of lower extremity arterial stiffness – is associated with CVD events and mortality. The association between CKD and high ABI is unknown. Methods: The Cardiovascular Health Study enrolled community-living persons > 65 years, and measured kidney function and ABI. Glomerular filtration rate (GFR) was estimated using equations that incorporated either cystatin C or creatinine, and CKD was defined by estimated GFR < 60 ml/min/1.73m 2 . The ABI was categorized as low (< 0.90), low-normal (0.90 – 1.09), normal (1.10 – 1.40), and high (> 1.40 or incompressible). Multinomial logistic regression was used to evaluate the associations of CKD with the ABI categories. Results: Among 4,513 participants, 23% had CKD, 13% had low ABI, and 3% had high ABI. In models adjusted for age, sex, race, hypertension, diabetes, smoking, BMI, LDL cholesterol, HDL cholesterol, and CRP, cystatin C based CKD was associated with both low ABI (relative risk [RR] 2.0; 95% confidence interval [CI] 1.6 – 2.5; P value < 0.001) and high ABI (RR 1.6; 95% CI 1.0 – 2.3; P = 0.03). Results were similar when CKD was defined by creatinine. Conclusions: CKD is associated with both the high and low extremes of ABI in community-living older persons. Future studies should evaluate whether arterial stiffness is an important mechanism leading to CVD in persons with CKD.