Prevalence and risk factors of unruptured intracranial aneurysms in ischemic stroke patients – A global meta-analysis

Background: Unruptured intracranial aneurysms (UIAs) have an estimated global prevalence of 2.8% in the adult population; however, UIA was identified among more than 10% of ischemic stroke patients. Many epidemiological studies and reviews have pointed to the presence of UIA among patients with ischemic stroke; yet, the extent of this association is not fully known. We performed a systematic review and meta-analysis to determine the prevalence of UIA in patients admitted to hospitals with ischemic stroke and transient ischemic attack (TIA) at both global and continental levels and evaluate factors associated with UIA in this population. Methods: We identified, in five databases, all studies describing UIA in ischemic stroke and TIA patients between January 1, 2000, and December 20, 2021. Included studies were of observational and experimental design. Results: Our search yielded 3581 articles of which 23 were included, with a total of 25,420 patients. The pooled prevalence of UIA was 5% (95% confidence interval [CI] = 4-6%) with stratified results showing 6% (95% CI = 4-9%), 6% (95% CI = 5-7%), and 4% (95% CI = 2-5%) in North America, Asia, and Europe, respectively. Significant risk factors were large vessel occlusion (odds ratios [OR] = 1.22, 95% CI = 1.01-1.47) and hypertension (OR = 1.45, 95% CI = 1.24-1.69), while protective factors were male sex (OR = 0.60, 95% CI = 0.53-0.68) and diabetes (OR = 0.82, 95% CI = 0.72-0.95). Conclusion: The prevalence of UIA is notably higher in ischemic stroke patients than the general population. Physicians should be aware of common risk factors in stroke and aneurysm formation for appropriate prevention.