Regular readers of these posts will by now be quite familiar with the seemingly paradoxical survival benefit of carrying extra pounds in patients who have chronic diseases like heart or kidney failure, chronic lung disease or even critical illness that requires admission to an intensive care unit.
A new study by Mullen JT and colleagues from Harvard Medical School, Boston, USA, just out in the Annals of Surgery, suggests that the same may may be true for patient undergoing general surgery, i.e. surgery for reasons other than weight loss.
Their prospective, multi-institutional, risk-adjusted cohort study included 118,707 patients undergoing nonbariatric general surgery who were included in the National Surgical Quality Improvement Program Participant Use database in 2005 and 2006.
The risk of death according to BMI exhibited a reverse J-shaped relationship, with the highest rates in the underweight and morbidly obese extremes and the lowest rates in patients with overweight and moderate oebsity. Overweight and moderately obese patients had a 15% and 25% lower risk of death than normal weight patients, respectively.
However, beyond the moderately obese category, there was a progressive increase in the likelihood of a complication with increasing BMI class, almost entirely due to increasing rates of wound infection.
This finding is thus in line with previous data suggesting that overweight and moderately obese patients with critical illness have paradoxically “lower” risks of mortality compared with patients at a “normal” weight.
While this finding does not mean that normal weight people need to gain extra pounds prior to undergoing general surgery, it certainly does not support the idea that overweight or moderately obese individuals need to lose weight prior to undergoing an operation.
Recommendations to overweight and moderately obese individuals to lose weight prior to surgery may be more a reflection of weight bias than sound clinical judgement.