Limitations
There are certain limitations in this study that should be acknowledged.
First, all studies were non-randomized and retrospective in nature and
thus impart the risk of selection bias. Additionally, since this study
is a meta-analysis, we didn’t have access to individual patient data.
Moreover, not all reports contained all variables of interest and there
were differences in the definitions of the reported items between the
included studies, thus relative rates were estimated based on the
availability of data. Finally, the procedures in the included studies
were performed in various centers by different surgeons and this could
have confounded our results.