High ankle-brachial index and risk of cardiovascular or all-cause mortality: A meta-analysis

Background and aims: Studies on high ankle-brachial index (ABI) to predict mortality risk have yielded conflicting results. This meta-analysis aimed to evaluate the association between abnormally high ABI and risk of cardiovascular or all-cause mortality. Methods: Pubmed and Embase databases were systematically searched for relevant articles published up to August 15, 2018. Longitudinal observational studies that evaluated the association between abnormally high ABI at baseline and risk of cardiovascular or all-cause mortality were included. Pooled results were expressed as risk ratio (RR) with 95% confidence intervals (CI) for the abnormal high versus the reference normal ABI category. Results: Eighteen studies enrolling 60,467 participants were included. Abnormally high ABI was associated with an increased risk of all-cause mortality (RR 1.50; 95% CI 1.27-1.77) and cardiovascular mortality (RR 1.84; 95% CI 1.54-2.20). The pooled RR of all-cause mortality was 1.45 (95% CI 1.16-1.82) for the general population, 1.67 (95% CI 1.03-2.71) for chronic kidney disease (CKD)/hemodialysis patients, and 1.55 (95% CI 1.10-2.20) for suspected or established cardiovascular disease (CVD) patients, respectively. The pooled RR of cardiovascular mortality was 1.84 (95% CI 1.43-2.38) for the general population, 4.28 (95% CI 2.18-8.40) for CKD/hemodialysis patients, and 1.58 (95% CI 1.22-2.05) for suspected or established CVD patients, respectively. Conclusions: Abnormally high ABI is independently associated with an increased risk of all-cause mortality. However, interpretation of the association between abnormally high ABI and cardiovascular mortality should be done with caution because of the likelihood of publication bias.