Requiring prospective bariatric surgery patients to lose weight before they can undergo the procedure may not be necessary or safe, University of Pennsylvania researchers found in a new study published recently in the journal Obesity Surgery.

The practice of having patients follow a medically supervised weight-loss program before the surgery is rooted in 28-year-old guidelines from the National Institutes of Health, which concluded that clinicians should first determine that patients could not succeed with nonsurgical attempts to drop weight. It was later interpreted to require patients to try dieting before the surgery, researchers found.

"There was little data to support the need for the weight loss requirement,” said lead author Colleen Tewksbury, senior research investigator and bariatric program manager with Penn Medicine.

“We wanted to actually measure it,” she said.

The researchers looked at data from about 349,000 patients during 2015 to 2017 who had undergone either a sleeve gastrectomy, in which a large part of the stomach is removed, or a Roux-en-Y gastric bypass, which involves creating a small pouch from the stomach and attaching it directly to the small intestine.

There was little evidence to support the conclusion that weight loss before surgery reduced 30-day complications including readmission, corrective surgeries, death or infections, said Tewksbury.

What they found was that patients may actually do more harm by trying to diet first, she said.

Weight loss before surgery was associated with readmission for abdominal pain and increases in urinary tract and surgical site infections, researchers found.

The tradition may also be tied to insurance carriers who require weight loss and counseling before surgical treatment.

“If we don’t adhere to the third-party payer requirement for prior authorization, patients will not get the surgery regardless of whether it is clinically indicated,” Tewksbury said.

But the time spent waiting for patients to achieve a modest weight loss needs to be looked at in the context of putting off the health benefits of having the surgery, Tewksbury said. In addition, faced with the requirement, some patients change their minds about the surgery, she said.

“Obesity as a whole is considered the second leading cause of death,” Tewksbury said. The risk of surgery is less than not seeking treatment, she said.

The American Society for Metabolic and Bariatric Surgery has recently come out against the requirement. It stated mandating preoperative weight loss "contributes to patient attrition, causes unnecessary delay of lifesaving treatment, leads to the progression of life-threatening co-morbid conditions, is unethical, and should be abandoned.”

There is almost a systemic bias when it comes to weight, Tewksbury said. Providers do not require the same level of scrutiny or counseling for patients that need a hip or knee replacement, which is an elective procedure to help improve quality of life, she said.

“Overall this is a study that is one step to showing that weight loss before surgery may not be as necessary as we once thought," she said.