Incidence and Risk Factors of Incisional Hernia Formation Following Abdominal Organ Transplantation

Carter T Smith, MD, Micah G Katz, Janet M Bellingham, MD, Bridget Welch, Glen E Leverson, PhD, Luke Funk, MD, MPH, Jacob A Greenberg, MD, EdM. University of Wisconsin Hospital and Clinics.

INTRODUCTION: The purpose of this study is to estimate the incidence of and risk factors for incisional hernia formation following primary abdominal solid organ transplantation. Hernia formation is common following abdominal operations and transplant patients are at increased risk due to their need for long-term immunosuppression.

METHODS AND PROCEDURES: We performed a single institution retrospective review of a prospectively collected database to evaluate all patients who underwent primary liver, kidney, or pancreas transplant over a ten year period. 3460 transplants were performed in the study period: 2247 kidney only, 718 liver only, and 495 pancreas or simultaneous pancreas and kidney (pancreas group). Patients who developed an incisional hernia at their transplant incision were identified. Univariate and multivariable Cox proportional hazards models were used to evaluate potential risk factors for incisional hernia formation. At our institution renal transplants are typically done through a flank, pancreas through a midline and liver through a bilateral subcostal incision.

RESULTS: The overall incisional hernia rate was 7.46% (n=258). The Kaplan-Meier rates of hernia formation at 1, 5 and 10 years were 2.46%, 4.86% and 7.04% for  kidney; 4.46%, 8.67% and 19.04% for liver; and 2.49%, 12.7% and 21.76% for pancreas groups. Univariate analysis identified that surgical site infection (SSI) was associated with a statistically significant increase in hernia formation in all 3 groups as was BMI>25 in the kidney and liver groups (Table). Delayed graft function (DGF), not starting a calcineurin inhibitor, and not starting mycophenolic acid (MMF) during initial hospital stay were associated with an increase in hernia formation in the kidney group. As were the use of cyclosporine and the lack of MMF during the initial hospital stay in the pancreas group. Age, race, and gender and model end organ liver disease score (MELD) score were not associated with an increased hernia risk. On multivariate analysis, SSI was an independent risk factor for incisional hernia formation in all groups. Not including MMF in the induction regimen was predictive of hernia formation in the kidney group as was the use of cyclosporine in the pancreas group. Median follow up was 4.55, 4.17 and 5.63 years in the kidney, liver, and pancreas groups.

CONCLUSIONS: Incisional hernias are common following abdominal organ transplant. SSI is a known risk factor for hernia formation and was highly associated in all groups. Hernia rates were significantly lower in the renal transplant group, likely due to a retroperitoneal approach. Patients with a BMI>25 showed increased risk in the liver and kidney groups, but not in the pancreas group likely due to a lower mean BMI in this group. Initial immunosuppression appears to be important in rate of hernia formation.

Results of univariate analysis
  Kidney (n=2247) Liver (n=718) Pancreas (n=495)
Age 1.01 0.116 1.01 0.284 1.03 0.136
Male 0.980 0.909 1.50 0.097 1.03 0.902
African American 0.50 0.13 0.506 0.499 0.335 0.278
MELD NA NA 0.995 0.693 NA NA
Diabetes 0.88 0.581 NA NA NA NA
BMI<18.5 1.26 0.756 1.24 0.781 0 0.982
BMI>25 1.77 0.015 1.85 0.0437 1.06 0.808
SSI 28.75 <0.0001 13.241 <0.0001 12.95 0.0006
DGF 1.94 0.0026 NA NA NA NA


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