According to the U.S. Centers for Disease Control and Prevention, a BMI below 18.5 is underweight, between 18.5 and 24.9 is normal, 25 to 29.9 is overweight, and 30 and above is obese.
Patients who underwent exploratory abdominal surgery were at the greatest risk of death (nearly 14 percent), compared to other operations. The lowest risk was for breast lumpectomy, to remove small tumors (0.1 percent).
Other procedures where BMI appeared to be a factor included colostomy, wound cleaning, musculoskeletal system procedures, upper gastrointestinal procedures, colorectal surgery and hernia repair, the study authors noted.
"Unfortunately, our research does not shed any light on why BMI is a risk factor for mortality," Stukenborg said. "This is an interesting question, though, and something we should think more about," he added.
Commenting on the study, Dr. Nestor de la Cruz-Munoz, chief of bariatric surgery at the University of Miami Miller School of Medicine, said that he was not surprised by the finding. "It's kind of something we suspected but no one has ever looked at it in a big series like this," he said.
It makes sense that underweight people have a greater risk of dying, de la Cruz-Munoz noted.
"A lot of these patients are malnourished -- maybe cancer patients, patients undergoing treatment for other medical problems. A lot of time these patients don't have the defenses to do well with a major surgery," he said. "These patients are not your skinny young girl, but more like a frail 80-year-old woman."
For more information on BMI, visit the U.S. National Library of Medicine.
SOURCES: George J. Stukenborg, Ph.D., associate professor, department of public health sciences, University of
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