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.