Abnormal ankle-brachial index and risk of cardiovascular or all-cause mortality in patients with chronic kidney disease: a meta-analysis

Prognostic role of ankle-brachial index (ABI) in patients with chronic kidney disease (CKD) is controversial. We aimed to evaluate whether abnormal ABI was an independent predictor of cardiovascular or all-cause mortality in CKD patients with or without hemodialysis by conducting a meta-analysis. We systematically searched Pubmed and Embase databases for prospective observational studies that investigated baseline abnormal ABI and subsequent cardiovascular or all-cause mortality risk in CKD patients with or without hemodialysis. An ABI value of 0.9 to 1.3 was defined as normal. Pooled hazard risk (HR) with 95% confidence interval (CI) was calculated for the abnormal vs. normal ABI category. Six studies enrolling 5820 patients were identified and analyzed. Overall, abnormal ABI was associated with an increased risk of all-cause mortality (HR 2.26; 95% CI 1.60-3.18) and cardiovascular mortality (HR 3.58; 95% CI 2.53-5.06). Subgroup analysis indicated that patients with abnormally low ABI increased by 2.45-fold all-cause mortality and 5.18-fold cardiovascular mortality. Similarly, an abnormally high ABI increased by 1.94-fold all-cause mortality and 4.04-fold cardiovascular mortality. In addition, the effect of abnormal ABI on all-cause mortality was more pronounced among hemodialysis patients (HR 3.06; 95% CI 2.30-4.07) but not in CKD patients (HR 1.42; 95% CI 0.98-2.05). Abnormally low and high ABI are independently associated with cardiovascular or all-cause mortality risk in maintenance hemodialysis patients. This meta-analysis highlighted an U-shaped relationship between ABI and mortality risk in CKD patients undergoing hemodialysis. However, findings of this meta-analysis were undermined by the small number of included studies.