Meta-regression
In univariable meta-regression analysis, there was no significant association between the hypothermic circulatory arrest time and the reoperation for bleeding (β-coefficient 0.007 [95% CI -0.004 to 0.0019], z-value = 1.26, p = 0.207). In addition, the bubble plot demonstrated that the effect size of reoperation for postoperative bleeding enhanced with increasing the duration of hypothermic circulatory arrest time; however, the regression line did not show a good fit of the data because most studies were relatively far to it (Figure 8).
Multivariable meta-regression analysis showed that age and male gender significantly impacted on the reoperation for postoperative bleeding (Table 3).