ARRS 2022 Abstracts

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1590. Sarcopenia as a Predictor of Radiologic Incisional Hernia Following Robotic Nephrectomy
Authors * Denotes Presenting Author
  1. Simin Hajian *; University of Southern California
  2. Alireza Ghoreifi; University of Southern California
  3. Steven Cen; University of Southern California
  4. Darryl Hwang; University of Southern California
  5. Bino Varghese; University of Southern California
  6. Hooman Djaladat; University of Southern California
  7. Vinay Duddalwar; University of Southern California
Objective:
Incisional hernia (IH) is one of the most common complications following minimally invasive surgeries. Various risk factors, including musculoskeletal factors and frailty, may contribute to the development of IH. Radiologic indicators of sarcopenia have been associated with adverse operative outcomes in some surgical populations. However, as a marker of chronic muscle depletion and frailty, the correlation between sarcopenia and IH has not been fully investigated. This study aims to assess the effect of sarcopenia on the radiologic IH following robotic nephrectomy.

Materials and Methods:
Using an IRB-approved database, the records of patients who underwent robotic partial or radical nephrectomy for kidney tumors between 2011 and 2017 were retrospectively reviewed. All pre- and post-operative CT scans, obtained for oncological follow-up, were re-reviewed by an experienced radiologist for detection of radiologic IH. Radiologic IH features, including size, location, and type, were recorded. The Tonouchi classification was used to classify the IH into early-onset, late-onset, and bowel/fat-containing types. Cross-sectional psoas muscle mass at the level of L3 and L4 vertebral bodies was analyzed from preoperative CT images. Specifically, using the Synapse 3D software, a semi-automated calculation was performed from manually segmented regions of interest contouring of the right and left psoas muscles based on the Hounsfield Unit (HU) threshold for muscle (-30 to +150 HU). Psoas muscle index (PMI), defined as total psoas muscle area/the square of the body height, was applied to assess sarcopenia. Cox proportional hazard model was used to examine the risk of sarcopenia for radiologic IH. Proportional hazard assumption was assessed by supremum test and Schoenfeld residual plots.

Results:
A total of 236 patients were included in this study. Median (IQR) age was 64 (54-70) years, including 169 (71.6%) and 67 (28.4%) men and women, respectively. The BMI was similar between patients with and without IH (30±6 vs. 30±8 kg/m2). In a median (IQR) follow-up of 23 (13.8-38) months, 62 (26.3%) patients developed radiologic IH. The location of IH was medial, anterolateral, and posterior in 37 (60%), 21 (34%), and 3 (6%), respectively. IH was graded as early-onset (n=29, 47%), late-onset (n=26, 42%), and bowel/fat-containing (n=7, 11%). The median (IQR) hernia size was 7.8 (4.5-13.5) millimeters. On Cox proportional hazard model, different thresholds for sarcopenia were identified for L3 and L4. At the L4 level, the preoperative PMI below 75% percentile has a statistically significant risk of radiologic IH with HR of 2.25 (p=0.02). At the L3 level, the pre-surgery PMI below median has a borderline statistically significant risk of radiologic IH with HR of 1.63 (p=0.06). All results met the assumption for radiologic IH. Demographic information such as sex and age were tested as potential confounders in the final analysis.

Conclusion:
Sarcopenia is an independent risk factor for the development of radiologic incisional hernia in patients who undergo robotic nephrectomy.