Publication bias and meta-regression
The visual inspection of Funnel plots revealed asymmetries among studies
reporting major postoperative outcomes (Supplemental Figure 1). Based on
the Egger’s test, there were significant for all major outcomes,
including postoperative stroke (p <0.0001), SCI (p = 0.004),
acute kidney injury (p <0.0001), bleeding (p
<0.0001), and in-hospital mortality (p <0.0001). The
univariate meta-regression showed significant relationships between the
HCA time and the development of postoperative stroke (p = 0.04) and SCI
(p = 0.05). Also, the bubble plots revealed that with increasing HCA
time, the effect sizes for postoperative stroke and SCI enhance. The
regression line provides a good fit for the data because most studies
are relatively close (Figure 4).