Overweight older adults face lower risk of death after major surgery

Older adults who are overweight may face a lower risk of death in the first 30 days following major elective surgery compared with those who have a normal body mass index (BMI), researchers from the University of California, Los Angeles, have reported.

The study examined the outcomes in older surgical patients and found that being overweight (BMI 25–29.9) was associated with the lowest short-term mortality rates. In contrast, normal and underweight patients had a significantly higher risk of death.

"Traditional surgical guidelines often emphasise having a normal BMI before surgery, but our findings suggest that these recommendations may need to be reconsidered for older adults," said lead author, Dr Cecilia Canales, assistant professor in the Department of Anesthesiology & Perioperative Medicine at the David Geffen School of Medicine at UCLA. "Older adults have different physiological considerations, and moderate excess weight may actually be protective in the short term after surgery."

The researchers analysed data from 414 adults aged 65 and older undergoing major elective surgery at a large academic centre in Southern California between February 2019 and January 2022. Patients were categorised by BMI and compared for 30-day and one-year mortality, postoperative delirium, discharge disposition, and complications.

Patients in the overweight category had a 0.8% 30-day all-cause mortality rate, compared to 18.8% for those with a normal BMI, a difference that remained significant after adjusting for factors such as age, frailty, and comorbidities - including whether a patient had cancer. Underweight patients had a 15.0% 30-day mortality rate.

"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 these findings may have implications for preoperative counselling and BMI-based surgical risk calculators, which are often derived from younger or mixed-age populations.

They recommend further research to explore the biological and clinical mechanisms behind this association and to inform surgical guidelines for older adults.

The findings were reported in the paper, ‘Body Mass Index and Postsurgical Outcomes in Older Adults’, published in JAMA Network Open. To access this paper, please click here