Association between serum calcium and hemorrhagic transformation in ischemic stroke: A systematic review and meta-analysis

Background: Hemorrhagic transformation (HT) is a common complication of ischemic stroke. A growing number of studies have found that serum calcium levels are lower in HT groups than in control groups. However, the relationship between serum calcium and HT remains controversial. We performed a meta-analysis to assess the relationship between serum calcium levels and HT. Methods and results: Electronic databases were searched for studies on serum calcium and HT from inception to November 6, 2021. Ten studies included in present meta-analysis with a total of 3212 participants. Due to the high heterogeneity (I2 = 81%), we chose the random effects model. The results showed that the serum calcium level in the HT group was significantly lower than that in the control group (pooled mean difference,-0.05; 95% confidence interval (CI), (-0.09,-0.02); P = 0.001). Whether thrombolytic or not the results were applied (pooled mean difference,-0.07; 95% CI, (-0.13,-0.01); P = 0.02 and pooled mean difference,-0.03; 95% CI, (-0.06,-0.01); P = 0.007). Conclusions: Serum calcium was related to HT and may be one of the risk factors for HT.