Impact of chronic kidney disease on the association of high ankle-brachial index with cardiovascular mortality and all-cause mortality

This study aims to investigate the impact of chronic kidney disease (CKD) on the association of ankle-brachial index (ABI) with long-term cardiovascular and all-cause mortality. This cohort study utilised the data from the National Health and Nutrition Examination Survey (NHANES), with mortality follow-up tracked through the National Death Index until December 31, 2019. CKD was defined by an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73m2 and/or a urinary albumin-to-creatinine ratio (UACR) ≥30 mg/g. ABI categories were defined as ≤0.9 (low), 0.9-1.4 (normal), and >1.4 (high). Cox proportional hazards models were employed to evaluate the association of ABI with long-term cardiovascular and all-cause mortality in individuals with or without CKD. A total of 6,318 individuals were included, with 1,311 (20.8%) having CKD. The median follow-up duration was 203 (IQR: 183-223) months. After adjustments, compared to those with normal ABI, high ABI was associated with increased cardiovascular and all-cause mortality in individuals with CKD (hazard ratio [HR] 3.64, 95% CI 1.30-10.23 for cardiovascular mortality; HR 2.10, 95% CI 1.14-3.89 for all-cause mortality) but not in those without CKD. Low ABI was associated with an increased risk of cardiovascular and all-cause mortality in both CKD (HR 1.95, 95% CI 1.31-2.92 and HR 1.49, 95% CI 1.13-1.97, respectively) and non-CKD individuals (HR 1.90, 95% CI 1.27-2.82 and HR 1.60, 95% CI 1.32-1.94, respectively). High ABI was associated with increased cardiovascular and all-cause mortality in patients with CKD, but not in those without CKD.