# Anterior to posterior preoperative risk assessment of abdominal thickness compared to BMI in ventral hernias

## TL;DR

This study compares abdominal thickness measurements to BMI for predicting hernia recurrence, finding that abdominal thickness is a better predictor.

## Contribution

The study introduces anterior-to-posterior abdominal wall depth (APD) as a more effective predictor of hernia recurrence than BMI.

## Key findings

- An APD threshold of 29.7 cm was associated with higher hernia recurrence.
- APD measurements showed better predictive value than BMI for recurrence.
- Five-year recurrence-free survival was 70% for patients with APD ≤ 29.7 cm.

## Abstract

Obesity is a known risk factor for recurrence following ventral hernia repair. BMI is often used to define obesity, and we have previously shown a BMI > 33.67 associated with higher recurrence. In 2023, AMA policy highlighted BMI as an imperfect measurement of obesity and recommended limitations to its use. This study’s objective was to evaluate the association between anterior-to-posterior abdominal wall depth (APD) in CT measurements with hernia recurrence as an alternative to BMI.

Data was retrospectively collected for patients from a county healthcare system, undergoing elective ventral hernia repair from 2014 to 2020 with fascial defects > 4 cm and preoperative CT scans. CART analysis was performed to determine the APD threshold for recurrence. Receiver operating characteristic (ROC) curve analysis was performed to compare APD and BMI as predictors of recurrence. Kaplan–Meier analysis was used to depict the recurrence-free survival period.

267 patients met our inclusion criteria. Mean APD at L4 was 27.67 cm. APD of 29.7 cm was determined as the threshold for recurrence. Area under the curve for APD > 29.7 cm and BMI > 33.67 were 0.617 (p = 0.046) and 0.577 (p=0.189) respectively. Five-year recurrence free survival was 70% for APD ≤ 29.7 cm and 37% for APD > 29.7 cm.

In our study, the use of APD CT measurements provided an objective, reproducible, and rapid method to augment preoperative evaluation for visceral obesity and the risk for hernia recurrence that was not reliant on traditional BMI, and, in fact, improved upon a simple BMI threshold.