Low and Borderline Ankle–Brachial Index Is Associated With Intracranial Aneurysms: A Retrospective Cohort Study

Abstract

BACKGROUND AND OBJECTIVES: A low ankle–brachial index (ABI) has been linked to systemic inflammation and an elevated risk of cardiovascular events, most notably myocardial infarction and stroke. Intracranial aneurysms (IAs) share similar risk factors with other cardiovascular diseases. However, the association between low ABI and IAs has not been sufficiently investigated. Our objective was to investigate the potential connection between ABI values and the prevalence of unruptured IAs. METHODS: This retrospective cohort study reviewed 2751 patients who had ABI measurements at a public tertiary hospital from January 2011 to December 2013. Patients with available cerebrovascular imaging or a diagnosis of ruptured IA were included in the study (n = 776) to examine the association between ABI and saccular IAs. The patients were classified into 4 groups: low ABI (≤0.9, n = 464), borderline ABI (0.91-0.99; n = 47), high ABI (>1.4, n = 57), and normal ABI (1.00-1.40; n = 208). RESULTS: The prevalence of IAs was 20.3% (18.1% unruptured IAs) in the low ABI group, 14.9% (12.8% unruptured IAs) in the borderline ABI group, 7.0% (5.3% unruptured IAs) in the high ABI group, and 2.4% (1.9% unruptured IAs) in the normal ABI group (P < .001). There were no significant differences in the prevalence of ruptured IAs between the ABI groups (P = .277). Sex- and age-adjusted multinomial regression, including clinically relevant variables, revealed that low ABI (odds ratio [OR], 13.02; 95% CI, 4.01-42.24), borderline ABI (OR, 8.68; 95% CI, 2.05-36.69), and smoking history (OR, 2.01; 95% CI, 1.07-3.77) were associated with unruptured IAs. CONCLUSION: The prevalence of unruptured IAs was 9-fold higher in the low ABI group and nearly 7-fold higher in the borderline ABI group when compared with the normal ABI group. ABI measurements could be clinically relevant for identifying individuals at higher risk of IAs and may help guide screening and preventive strategies.