Pooled estimates of outcomes
The means of hospital and intensive care unit length of stay were 16.9 (95% CI 13 to 20.8; reported by eighteen studies including 2806 patients) and 5.1 (95% CI 4 to 6.2; reported by twenty-two studies including 2975 patients) days, respectively. The pooled estimation of reoperation for postoperative bleeding was 7% (95% CI 5 to 8; I2 = 84.73%; reported by thirty-nine studies including 4796 patients; Figure 2). The number of patients with postoperative bleeding was reported by five studies including 469 patients, and pooled estimation was 17% (95% CI 7 to 28; I2 = 87.6%; Figure 3). The mean volume of transfused packed blood cells and fresh frozen plasma was 1677 ml (95% CI 1066.4 to 2287.6; reporting by fifteen studies including 2375 patients) and 1016.5 ml (95% CI 450.7 to 1582.3; reporting by ten studies including 2097 patients). The rate of in-hospital mortality was 8% (95% CI 6 to 10; I2 = 79.34%) based on the pooled proportion from thirty studies including 4272 patients (Supplementary Figure 1).