People with a genetic risk for being overweight or obese are more likely to have an incisional hernia — or hernia that’s a complication of a surgery — and, if obese, a post-surgical infection as well, a study suggests.
Obesity is thought to be a risk factor for complications after surgery, but most previous studies have been limited in the scope of surgeries assessed, and little attention has been paid to the role of genetics.
Researchers at Vanderbilt University Medical Center (VUMC) addressed these gaps by analyzing two large datasets. The first, from VUMC’s patient health records, covered 736,726 individuals, 68,266 of whom who had undergone an abdominal surgery.
The second dataset, from 12 institutions within the eMERGE Network, covered 65,174 people, with 15,355 having undergone abdominal surgery and a known genetic profile. This enabled the team to determine a genetic risk score associated with body mass index (BMI), a ratio of weight to height, and its correlation with surgical complications.
Both groups were predominantly female and white, and about two-thirds of people in each were classified as overweight (BMI of 25 to 29 kg/m2) or obese (BMI of 30 kg/m2 or greater). Median age was 49 in the first group and 67 in the second.
Incisional hernias develop due to a weakening of muscles caused by an incision made in a surgery, and are most commonly a complication of abdominal surgery.
Results from the first group showed that being obese or overweight was associated with a significantly higher likelihood of developing hernia or infection after surgery. This association was strongest in people with the highest BMI (40 kg/m2 or more), who had an over five times greater risk of a hernia and were twice as likely to have a post-surgery infection than people with a normal BMI.
In the second group, a genetic score predicting a higher likelihood for obesity was also significantly associated with a greater risk for both of these complications. A subsequent analysis revealed that this increased risk in people genetically predicted to be obese was driven mostly by the change in BMI itself.
In both groups, the link between obesity and post-operative complications was maintained when limiting the analysis to people who had undergone general, urologic, or gynecologic abdominal surgery.
Findings also revealed that overweight or obese individuals in the first group had a lower risk of intestinal obstruction but greater risk of mortality within 90 days after surgery, in comparison with patients with a normal BMI.
“This study found that obesity as measured by both BMI and genetic risk is associated with postoperative infections and incisional hernias,” the researchers wrote.