Pooled data analysis of primary ventral (PVH) and incisional hernia (IH) repair is no more acceptable: results of a systematic review and metanalysis of current literature

Purpose: Primary (PVHs) and incisional (IHs) ventral hernias represent a common indication for surgery. Nevertheless, most of the papers presented in literature analyze both types of defect together, thus potentially introducing a bias in the results of interpretation. The purpose of this systematic review and meta-analysis is to highlight the differences between these two entities. Methods: Methods MEDLINE, Scopus, and Web of Science databases were reviewed to identify studies evaluating the outcomes of both open and laparoscopic repair with mesh of PVHs vs IHs. Search was restricted to English language literature. Risk of bias was assessed with MINORS score. Primary outcome was recurrence, and secondary outcomes were baseline characteristics and intraoperative and postoperative data. Fixed effects model was used unless significant heterogeneity, assessed with the Higgins I square (I2), was encountered. Results: The search resulted in 783 hits, after screening; 11 retrospective trials were selected including 38,727 patients. Mean MINORS of included trials was 15.2 (range 5–21). The estimated pooled proportion difference for recurrence was − 0.09 (− 0.11; − 0.07) between the two groups in favor of the PVH group. On metanalysis, PVHs were smaller in area and diameters, affected younger and less comorbid patients, and were more frequently singular; the operative time and length of stay was quicker. Other complications did not differ significantly. Conclusion: Our paper supports the hypothesis that PVH and IH are different conditions with the latter being more challenging to treat. Accordingly, EHS classifications should be adopted systematically as well as pooling data analysis should be no longer performed in clinical trials.