By Stephen Beech
Fat people are less likely to die when they go under the knife than people of a "healthy" weight, according to new research.
The finding that overweight older adults face a lower risk of dying after major surgery challenges current weight guidelines for "normal" body mass index (BMI) for people awaiting an op, say American scientists.
The study suggests that people over 65 who are overweight may face a lower risk of death in the first 30 days following major elective surgery compared with those of normal BMI.
Researchers examined the results of surgery on older patients and found that being "overweight" - a BMI of 25 to 29.9 - was associated with the lowest short-term mortality rates.
However, "normal" and "underweight" patients had a significantly higher risk of dying, according to the findings published in JAMA Network Open.
Lead author Dr. Cecilia Canales, of the David Geffen School of Medicine at UCLA, said: "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.
"Older adults have different physiological considerations, and moderate excess weight may actually be protective in the short term after surgery."
The research team analyzed data from 414 adults aged 65 and older undergoing major elective surgery in Southern California between February 2019 and January 2022.
Patients were categorized 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 including age, frailty, and whether a patient had cancer.
On the other hand, underweight patients had a 15% 30-day mortality rate.
Co-author Professor Catherine Sarkisian, of the Geffen School, said: "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."
She added: "It's important to tailor pre-operative evaluation to the physiology of older patients."
The research team says future studies should explore the biological and clinical mechanisms behind the association to inform surgical guidelines.