Association of Ankle-Brachial and Toe-Brachial Indexes With Mortality in Patients With CKD.

RATIONALE &

objectiveA low ankle-brachial index (ABI) is used to diagnose peripheral artery disease (PAD) but may be normal or elevated in patients with medial arterial calcification and stiff vessels, as is common in chronic kidney disease (CKD). The toe-brachial index (TBI) has been recommended because it is not influenced by medial arterial calcification, but alone the TBI does not capture risk associated with medial arterial calcification. We hypothesized that the difference between ABI and TBI (ABI - TBI) would capture both PAD and medial arterial calcification and thus better identify mortality risk from PAD, particularly in those with CKD. STUDY

designProspective cohort study. SETTING &

participants471 patients with clinical suspicion for PAD referred for vascular testing. EXPOSURES: ABI, TBI, and ABI - TBI. OUTCOME: All-cause mortality. ANALYTICAL APPROACH: Cox proportional hazards models evaluating the association of ABI - TBI with mortality over 7 years.

resultsMean age was 68 years, 89% were men, 35% had diabetes, 64% had CKD, and mean estimated glomerular filtration rate was 55 mL/min/1.73 m LIMITATIONS: Mainly male cohort derived from a vascular laboratory; lack of limb outcomes and data for albuminuria.

conclusionsA high ABI - TBI value may be associated with higher risk for mortality in persons with CKD and a normal ABI. Age affects this association, and further studies evaluating ABI - TBI in larger populations are required.