THURSDAY, Aug. 28, 2025 (HealthDay News) -- Older adults (aged 65 years and older) with overweight who undergo elective surgery have a lower rate of 30-day all-cause mortality compared with those with a normal body mass index (BMI), according to a study published online Aug. 26 in JAMA Network Open.Cecilia Canales, M.D., M.P.H., from the University of California, Los Angeles, and colleagues examined whether higher BMI in older adults undergoing major elective surgery is associated with rates of all-cause mortality in an observational cohort study. A total of 414 older adults (mean age, 75.9 years) undergoing major elective surgery were included.The researchers found that the prevalence of frailty and prefrailty was 24.2 and 37.0 percent, respectively. Within the cohort, the overall 30-day all-cause mortality rate was 11.0 percent. The lowest 30-day all-cause mortality rate was seen for patients categorized as overweight (BMI, 25.0 to 29.9 kg/m2), with a significant risk reduction compared with patients with a normal BMI (0.8 versus 18.8 percent; odds ratio, 0.03). After adjustment for potential confounders, the association remained significant (odds ratio, 0.14). The highest 30-day all-cause mortality rate was seen for patients categorized as underweight (BMI <18.5 kg/m2; 75.0 percent)."These findings challenge traditional preoperative guidelines emphasizing achievement of normal weight before surgery for older adults," the authors write.One author disclosed ties to the medical device industry; a second author disclosed ties to the publishing industry.Abstract/Full Text.Sign up for our weekly HealthDay newsletter