Abstract 13580: Impact of Chronic Kidney Disease on the Association of Ankle Brachial Index With Cardiovascular and All-Cause Mortality

Introduction: The association of low Ankle brachial index (ABI) with increased risk of cardiovascular (CV) as well as all-cause mortality is well established. Similarly, there is an independent association of chronic kidney disease (CKD) with CV and all-cause mortality. Little is known about the association of low ABI with CV and all-cause mortality by CKD status.

Methods: We used data on 4,614 subjects from the National Health and Nutritional Examination Survey (NHANES) from January 1, 1999, to December 31, 2002. Those with available data on ABI and CKD status were included. Subjects were categorized as: 1) normal ABI (

0.9), no CKD (eGFR 60 ml/min/m ² , reference), 2) normal ABI and CKD, 3) Abnormal ABI, no CKD, 4) Abnormal ABI and CKD. NHANES-linked National death index records were used to determine CV and all-cause mortality. We used Cox proportional-hazards models and controlled for age, race, gender, income, educational status, smoking history, diabetes, systolic blood pressure, HDL and total cholesterol levels and history of CV disease.

Results: Mean age was 55.7 years with 51% females and 4% blacks. Low ABI was present in 7%, while 6.4% had CKD and 1.3% had both low ABI and CKD. Median follow-up was 10.3 years. ABI<0.9 was associated with risk of all-cause [Hazard ratio: 1.59 (95% confidence interval: 1.21-2.01)] and CV mortality [2.80 (1.72-4.56)] compared to normal ABI. Similarly, CKD was associated with risk of all-cause [1.34 (1.04-1.71)] and CV mortality [1.69 (1.0-2.96)] compared to no CKD. Among categories, the risk was [1.29 (0.9-1.8)], [1.57 (1.1-2.2)] and [1.92 (1.3-2.6)] for all cause mortality, and [1.2 (0.5-2.9)], [2.3 (1.3-4.0)] and [4.72, (2.6-8.4)] for CV mortality in groups normal ABI with CKD, abnormal ABI without CKD and abnormal ABI and CKD both, respectively compared to the reference group.

Conclusion: Low ABI confers a much higher risk of CV and all-cause mortality in those with CKD than those without CKD. More aggressive risk factor modification might be warranted in those with CKD and low ABI to lower risk.