Not that surgeons really didn’t know this before but there is now a very good study that directly links the percentage of body fat with the risk of a surgical site infection. Most of the earlier studies used Body Mass Index (BMI) as the measure of weight in looking at surgical site infections which are infections that occur at the spot where the surgery was performed such as your arm, abdomen, etc. The trouble with using BMI as a standard is that some people have increased BMI’s and are not really obese-they are just big people. The newer study by Waisbren et al in the Journal of the American College of Surgeons uses the percentage of body fat as the measure instead of BMI. The more fat you have in relation to your muscles and other tissues, the higher your percentage of body fat will be. This probably is a better indicator about the risk of excess body fat and obesity in relation to the risk of developing an infection after surgery.
The results are very clear; obese patients based on the percentage of their body fat had a 5-fold increase infection risk. That is greater than the effect of smoking, diabetes, and anemia. This gives surgeons even more reasons to push patients who are overweight and obese to try and lose weight before their elective surgeries.
It really does make sense; you want to be in the best shape you can be before having surgery and that means trying to lose weight, stop smoking, and get any underlying medical conditions under control before facing the knife.
Herluf Lund MD