Abstract No. 270 Effectiveness of Chemical Component Separation Using Computed Tomography-Guided OnabotulinumtoxinA Injection in Postoperative Recurrence of Large Complex Ventral Abdominal Hernias: A Propensity Score-Weighted Analysis

To evaluate the effectiveness of chemical component separation (CCS) via computed tomography (CT)-guided intramuscular injection of OnabotulinumtoxinA in postoperative recurrence of large complex ventral abdominal hernias. A total of 100 patients with large ventral abdominal hernias who underwent complex hernia repair between 11/2017–4/2023 after (n=41) or without (n=59) OnabotulinumtoxinA injection were included in the study. Numerical or categorical variables were summarized as mean ± standard deviation or percentage, respectively. Postoperative hernia recurrence was compared between groups with or without pre-surgical CT-guided CCS using the Fisher's exact test. The absolute treatment effect for CCS was calculated using the inverse probability propensity score-weighted treatment effect analysis. All analyses were done with Stata BE version 18.0, and statistical significance level was set at 0.05. Patients' mean age was 60±13 years and 53% were females; 42% had history of hernia repair. Etiology of hernia was incisional in 98%, and mean hernia cavity volume and hernia-to-abdominal cavity ratios were 944±1324 cm3 and 16±26%, respectively. The most common surgical techniques were open repair with retro-rectus mesh (65%) and open repair with component separation and mesh (22%). Surgical component separation was performed in 32% of the subjects most commonly bilateral external oblique release (37%) or unilateral transverse abdominis release (31%). Compared to those with pre-surgical CCS, postoperative hernia recurrence was significantly higher in patients with no CCS (19% vs. 2%, P=0.013). Comparing baseline status, CCS+ group had lower rates of active cigarette smoking (never/former/current: 41/54/5% for CCS+ and 49/36/15% for CCS-, P=0.016), and surgical component separation was performed more frequently in this group (46% vs. 22%, P=0.016). Otherwise, there was no significant difference between the two groups in terms of their demographics, comorbidities and pre- and intra-surgical conditions. Propensity score (PS)-weighted analysis using these two variables for calculation of the PSs showed significant treatment benefit for CT-guided CCS with 15% reduction in the risk of postoperative hernia recurrence (P=0.002). No complications associated with CT-guided CCS were reported. CT-guided chemical component separation with intramuscular injection of OnabotulinumtoxinA is safe and effective with an average 15% reduction in the risk of post-surgical repair recurrence of large complex ventral abdominal hernias.