July 01, 2019
2 min read

Weight loss before bariatric surgery may increase infection risk

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Weight loss before bariatric surgery was not associated with overall 30-day rates of readmission, reoperation, mortality or intervention, but may have increased the risk for superficial surgical site infections, according to findings published in Obesity Surgery.

Colleen Tewksbury

“A commonly practiced recommendation prior to bariatric surgery is requiring patients to lose weight,” Colleen Tewksbury, PhD, MPH, RD, CSOWM, LDN, a senior research investigator and bariatric program manager at the University of Pennsylvania, told Endocrine Today. “It always seemed to an extent like we were having patients prove they could lose weight in order to receive obesity treatment, which seems counterintuitive. We were interested in seeing, does this [requirement] even really matter? Does weight loss before bariatric surgery have any impact, particularly on the first 30 days postoperatively?”

In a retrospective study, Tewksbury and colleagues analyzed data from 394,016 adults who underwent Roux-en-Y gastric bypass or sleeve gastrectomy (n = 282,463) between 2015 and 2017, utilizing data from the national Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program Participant Use File (mean age, 45 years; 80.1% women; 73.8% white). The mean preoperative weight and BMI for the cohort were 124.1 kg and 44.5 kg/m², respectively. Researchers used logistic regression analysis to assess the relationship between preoperative weight loss and 30-day readmission, reoperation, mortality, intervention and morbidity.

Researchers found that preoperative weight loss, BMI reduction and percent weight loss were not associated with 30-day postoperative overall readmission, reoperation, mortality or intervention (P > .01 for all). Preoperative percent weight loss was associated with increased incidence of superficial surgical site infections, with each additional percent body weight loss associated with a 2.3% increase in superficial surgical site infections (OR = 1.023; 95% CI, 1.009-1.036) and a 4.4% increased risk for urinary tract infections (OR = 1.044; 95% CI, 1.03-1.059).

Weight loss before bariatric surgery had no effect on overall 30-day rates of readmission, reoperation, mortality or intervention, but may have increased the risk for superficial surgical site infections.
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“The results were very surprising from a surgical standpoint,” Tewksbury said. “As a clinician, these are things that aren’t that surprising to me anecdotally treating patients. Preoperative weight loss by all measures — sheer weight loss by kilograms, BMI weight loss and also percent weight loss — were not associated with any of the major 30-day complications.”

The researchers noted that 30-day readmission trended toward preoperative weight loss being associated with lower risk, but did not rise to significance (P = .02).

“Overall, we know that bariatric surgery is very safe and low risk,” Tewksbury said. “That is why we are looking at some of these more minor complications and how we can improve those. From a weight loss standpoint, if surgeons do request that patients lose weight preoperatively to improve technical aspects of the surgery, a dietitian should guide that patient. Unhelpful weight loss may be what is underlying here.” – by Regina Schaffer

For more information:

Colleen Tewksbury, PhD, MPH, RD, CSOWM, LDN, can be reached at the Perelman School of Medicine, University of Pennsylvania, 3400 Spruce St., 4th Floor, Silverstein Building, Philadelphia, PA 19104; email: colleen.tweksbury@uphs.upenn.edu.

Disclosure: One of the study authors reports she has received grants from Novo Nordisk and personal fees from Weight Watchers International.