Obesity and abdominal hernia in ambulatory patients, 2018-2023.

Purpose: To determine the relationship between abdominal hernia and obesity. Although obesity is frequently cited as a risk factor for abdominal hernia, few studies have confirmed this association (Menzo et al. Surg Obes Relat Dis 14:1221-1232. 10.1016/j.soard.2018.07.005, 2018).

Methods: A cross-sectional study of primary care ambulatory patients aged older than 16 years treated at UCLA Health from 01/01/2018 to 06/06/2023. Abdominal hernia was identified by clinic encounter ICD-10 codes (K40-K46).

Results: There were 41,703 hernias identified among 1,362,440 patients (306.1 per10,000) with a mean age of 62.5 ± 16.1 years, and 57.6% were men. Nearly half (44.7%) of all abdominal hernias were diaphragmatic. There was an approximately equal distribution of the ventral (28.7%) and inguinal (24.3%) hernia. Each hernia type had a different relationship with obesity: The odds of having a ventral hernia increased with BMI in both sexes: BMI 25-29.9 kg/m odds ratio (OR) = 1.65, (CI 1.56-1.74); BMI 30-39.9 kg/m OR = 2.42 (CI 2.29-2.56), BMI 40-49.9 kg/m OR = 2.28 (CI 2.05-2.54) and BMI >  = 50 kg/m OR = 2.54 (CI 2.03-3.17) all relative to normal BMI. In contrast, the odds of having an inguinal hernia decreased with obesity relative to normal weight [obesity (BMI 30-39.9 kg/m): OR = 0.60 (CI 0.56-0.65)], morbid obesity (BMI 40-49.9 kg/m): OR = 0.29 (CI 0.23-0.37). The OR for diaphragmatic hernia peaks with obesity in women and overweight status in men but was found to decrease with morbid obesity [OR = 1.18 (CI 1.07-1.30)]. There was no significant difference between men and women in the prevalence of femoral hernia (men: 0.7/per10,000, women: 0.9/per10,000, p = 0.19).

Conclusions: The relationship between hernia and obesity is complex with some hernias decreasing in prevalence as obesity increases. Further research is needed to better understand this paradoxical relationship.