Relationship between body mass index and the incidence of inguinal hernia repairs: a population-based study in Olmsted County, MN.

PURPOSE: The relationship between body mass index (BMI) and the risk of inguinal hernia development is unclear. To explore the relationship, we determined whether the incidence of inguinal hernia repairs (IHR) varied across patients with different BMI categories.

STUDY DESIGN: A population-based incidence study was undertaken. We reviewed all IHR performed on adult residents of Olmsted County, MN from 2004 to 2008. Cases were ascertained through the Rochester Epidemiology Project, a records-linkage system with more than 97% population coverage.

RESULTS: During the study period, a total of 1,168 IHR were performed on 879 men and 107 women. The median BMI of the cohort was 26.7 kg/m2 (range 14.9-58.1, interquartile range 23.9-28.9). Incidence rates varied significantly as a function of BMI (p<0.001). Rates were highest among men who were either normal weight or overweight (419.8 and 421.1 per 100,000 person-years for BMI<25 and BMI 25-29.9, respectively), and lowest for obese and morbidly obese men (273.5 and 99.4 per 100,000 person-years for BMI 30-34.9 and BMI C 35, respectively). Findings were similar across all age categories and in patients who had an IHR that was initial or recurrent, direct or indirect, and unilateral or bilateral.

CONCLUSIONS: The incidence of IHR decreased as BMI increased. Obese and morbidly obese patients had a lower incidence of IHR than those who were normal weight or overweight. The causal mechanisms leading to such a relationship are unclear and warrant further study.