Risk Factors for Intracranial Aneurysm Rupture: A Systematic Review

BACKGROUND: Intracranial aneurysm rupture prediction is poor, with only a few risk factors for rupture identified and used in clinical practice. OBJECTIVE: To provide an overview of all the risk factors (including genetic, molecular, morphological, and hemodynamic factors) that have potential for use in clinical practice. METHODS: We systematically searched PubMed and EMBASE and focused on factors that can be easily assessed in clinical practice, might be used for rupture prediction in clinical practice, and/or are potential targets for further research. Studies were categorized according to methodological quality, and a meta-analysis was performed, if possible. RESULTS: We included 102 studies describing 144 risk factors that fulfilled predefined criteria. There was strong evidence for the morphological factors irregular shape (studied in 4 prospective cohort studies of high-quality, pooled odds ratio [OR] of 4.8 [95% confidence interval 2.7-8.7]), aspect ratio (pooled OR 10.2 [4.3-24.6]), size ratio, bottleneck factor, and height-to-width ratio to increase rupture risk. Moderate level of evidence was found for presence of contact with the perianeurysmal environment (pooled OR 3.5 [1.4-8.4]), unbalanced nature of this contact (pooled OR 17.8 [8.3-38.5]), volume-to-ostium ratio, and direction of the aneurysm dome (pooled OR 1.5 [1.2-1.9]). CONCLUSION: Irregular aneurysm shape was identified as a risk factor with potential for use in clinical practice. The risk factors aspect ratio, size ratio, bottleneck factor, height-to-width ratio, contact with the perianeurysmal environment, volume-to-ostium ratio, and dome-direction should first be confirmed in multivariate analysis and incorporated in prediction models.