Different risk factors between intracranial and extracranial atherosclerotic stenosis in Asian population: a systematic review and meta-analysis

Sex, hypertension, diabetes, dyslipidemia, smoking, age and metabolic syndrome (MetS) are major vascular risk factors for intracranial or extracranial atherosclerotic stenosis (ICAS or ECAS) in Asian population. Here, we performed a meta-analysis to evaluate the different influence of these factors on ICAS compared to ECAS in Asian population, by searching PUBMED, EMBASE and Web of Science databases. Sensitivity analysis was performed by repeating the fixed or random effects model meta-analysis with removing each study individually. All statistical analysis was conducted with Stata 11.0. Finally, 15 studies including 3787 patients were identified, 2661 patients in ICAS group and 1126 patients in ECAS group, respectively. Our results showed that female or the patients with MetS were more likely to suffer from ICAS than ECAS, which pooled ORs of ICAS versus ECAS were 2.16 (95% CI: 1.65-2.83, p < 0.0001) and 1.68 (95% CI: 1.32-2.12, p < 0.0001), respectively. Meanwhile, the smoker or the patients with dyslipidemia were more likely to suffer from ECAS than ICAS, which pooled ORs of ICAS versus ECAS were 0.71 (95% CI: 0.61-0.84, p < 0.0001) and 0.75 (95% CI: 0.63-0.90, p = 0.002), respectively. However, age, hypertension and diabetes had not different influence on the location of atherosclerotic stenosis, and the pooled MD and ORs were -0.69 (95% CI: -1.52-0.15, p = 0.11), 1.08 (95% CI: 0.92-1.27, p = 0.34) and 1.02 (95% CI: 0.88-1.19, p = 0.76), respectively. Our results suggested that female sex and MetS were more associated with ICAS, while smoking and dyslipidemia were more associated with ECAS. There was no significant difference between ICAS and ECAS in terms of age, hypertension and diabetes.