Researchers have found that patients with myasthenia gravis (MG) who are overweight or obese have a greater risk of postoperative complications after a thymectomy — the removal of the thymus.
The study, “Influence of body mass index on postoperative complications after thymectomy in myasthenia gravis patients,” was published in the journal Oncotarget.
MG, an autoimmune disorder, can become life-threatening if respiratory problems take place. Therefore, a thymectomy is often performed to try and treat the disease.
The procedure consists of the removal of the thymus, and has been shown to be beneficial for patients with MG with thymoma (tumor) or thymic hyperplasia (enlarged thymus). It has also been shown to help patients with non-thymomatous MG.
Obesity has been reported to be associated with higher rates of postoperative complications, but this remains controversial. Excess fat can cause hypoxia (low levels of oxygen), and myasthenia gravis is known to be vulnerable to oxygen.
Therefore, researchers in China set out to determine whether a patient’s body mass index (BMI), a frequently used measure of obesity, is linked to postoperative complications in patients with MG. In particular, researchers wanted to determine if obesity is related to severe complications such as postoperative respiratory failure.
Researchers retrospectively analyzed 59 patients who underwent a thymectomy and who had both low or high BMI, as categorized for patients with Asian-Pacific heritage. Then, researchers statistically analyzed the results to determine an association between BMI and post-surgery complications and time spent in the hospital.
Results showed that MG patients with high BMI had significantly higher rates of major adverse complications. In fact, the high BMI group had a significantly higher rate of postoperative respiratory failure compared to patients in the low BMI group.
The optimal cutoff value of BMI to predict patients with postoperative respiratory failure was a BMI of 23.3 kg/m2, which had a sensitivity of 75% and a specificity of 64.7%.
Sensitivity is the ability of a test to correctly identify those with a disease or condition, while specificity is the ability of the test to correctly identify those without the disease or condition.
Myasthenia gravis patients with high BMI rates also had longer postoperative hospitalizations compared to those with low BMI rates, which could be due to the higher number of postoperative complications.
Interestingly, the groups were not significantly different when it came to operative time, days of drainage, and total drainage volume.
“The data supports that being overweight or obese is a risk factor for postoperative adverse situations in MG patients,” the researchers wrote. “Thus, close monitoring must be performed when surgery is necessary.”