Risk factors of hemorrhagic transformation in acute ischaemic stroke: A systematic review and meta-analysis

Background: Hemorrhagic transformation (HT) following reperfusion therapies for acute ischaemic stroke often predicts a poor prognosis. This systematic review and meta-analysis aims to identify risk factors for HT, and how these vary with hyperacute treatment [intravenous thrombolysis (IVT) and endovascular thrombectomy (EVT)].Methods: Electronic databases PubMed and EMBASE were used to search relevant studies. Pooled odds ratio (OR) with 95% confidence interval (CI) were estimated.Results: A total of 120 studies were included. Atrial fibrillation and NIHSS score were common predictors for any intracerebral hemorrhage (ICH) after reperfusion therapies (both IVT and EVT), while a hyperdense artery sign (OR = 2.605, 95% CI 1.212-5.599, I-2 = 0.0%) and number of thrombectomy passes (OR = 1.151, 95% CI 1.041-1.272, I-2 = 54.3%) were predictors of any ICH after IVT and EVT, respectively. Common predictors for symptomatic ICH (sICH) after reperfusion therapies were age and serum glucose level. Atrial fibrillation (OR = 3.867, 95% CI 1.970-7.591, I-2 = 29.1%), NIHSS score (OR = 1.082, 95% CI 1.060-1.105, I-2 = 54.5%) and onset-to-treatment time (OR = 1.003, 95% CI 1.001-1.005, I-2 = 0.0%) were predictors of sICH after IVT. Alberta Stroke Program Early CT score (ASPECTS) (OR = 0.686, 95% CI 0.565-0.833, I-2 =77.6%) and number of thrombectomy passes (OR = 1.374, 95% CI 1.012-1.866, I-2 = 86.4%) were predictors of sICH after EVT.Conclusion: Several predictors of ICH were identified, which varied by treatment type. Studies based on larger and multi-center data sets should be prioritized to confirm the results.