Older adults who are overweight may have a lower risk of death in the first 30 days after major elective surgery compared to those with a normal body mass index (BMI), according to new research published in JAMA Network Open.
The study examined outcomes for 414 adults aged 65 and older who underwent major elective surgery at a large academic center in Southern California between February 2019 and January 2022. Patients were grouped by BMI and compared for mortality rates, postoperative delirium, discharge disposition, and complications over both 30-day and one-year periods.
Researchers found that patients classified as overweight (BMI 25–29.9) had the lowest short-term mortality rate at 0.8%. In contrast, those with a normal BMI had an 18.8% mortality rate within the same period, while underweight patients had a rate of 15.0%. These differences remained significant even after adjusting for factors such as age, frailty, comorbidities, and cancer status.
“Traditional surgical guidelines often emphasize having a normal BMI before surgery, but our findings suggest that these recommendations may need to be reconsidered for older adults,” said lead author , assistant professor in the at the . “Older adults have different physiological considerations, and moderate excess weight may actually be protective in the short term after surgery.”
“This study adds to a growing body of evidence on the so-called ‘obesity paradox,’ where a higher BMI appears to be linked with better survival in certain older adult populations,” said co-author Dr. Catherine Sarkisian, professor of medicine in the division of general internal medicine and health services research at the Geffen School. “It’s important to tailor preoperative evaluation to the physiology of older patients.”
The authors note that current preoperative counseling practices and BMI-based surgical risk calculators are often based on data from younger or mixed-age groups. They recommend further research into why moderate excess weight might offer protection after surgery for older adults and how these findings could inform future surgical guidelines.
Study co-authors include Myles Anderson, Dr. David Elashoff, Tristan Grogan, Dr. Marcia Russell, Dr. Victor Duval, Dr. Robert Whittington, Dr. Maxime Cannesson, and Dr. Catherine Sarkisian of UCLA.
Funding for this research was provided by the University of California at Los Angeles (UCLA) RCMAR/CHIME NIA (5P30AG021684) and UCLA Clinical and Translational Research Center NCATS (UL1TR001881).
