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Mandated pre-operative weight loss

Mandated pre-operative weight loss has no bearing on surgical outcomes

Researchers question value of making patients with severe obesity

Despite the requirement for some patients to lose weight over a period of six months or more before insurers approve bariatric surgery, researchers from Stanford University School of Medicine suggests this requirement does nothing to improve weight loss after surgery. In their study, ‘Pre-operative weight loss: Is waiting longer before bariatric surgery more effective?’, presented at ObesityWeek 2017 - the largest international event focused on the basic science, clinical application and prevention and treatment of obesity hosted by the American Society for Metabolic and Bariatric Surgery and The Obesity Society – they found that six months after surgery, patients on average lost more than 25 percent of their body weight no matter how long they waited to have surgery.

John Morton

“The majority of patients seeking bariatric surgery are delayed or deterred from having surgery because of an arbitrary insurance requirement,” said Dr John M Morton, Chief, Bariatric and Minimally Invasive Surgery at Stanford School of Medicine. “Based on the evidence, these policies are not helping patients. In fact, it could be hurting them as medical problems may become worse and patients suffer unnecessarily. Mandated preoperative wait times should be re-evaluated with a greater emphasis given to goal directed, and not time-mandated preoperative weight loss.”

In the study, the investigators examined the effect of wait time between initial clinic visit and surgery on either pre- (and post-) operative weight loss and whether time-to-surgery (TTS) affects pre-op and/or post-op weight loss - TTS was calculated as the duration in days between the first consult visit and the pre-operative visit. Comorbidity was defined based on standing prescriptions for diabetes, hyperlipidemia, and hypertension. Linear regression with two-sided unpaired-t tests was performed to compare TTS with percent of excess weight lost (%EWL) at pre-op and post-op.

The study included the waiting periods of 427 patients undergoing laparoscopic Roux-en-Y gastric bypass (n=263), sleeve gastrectomy (n=152) or adjustable gastric banding (n=12) at Stanford University Medical Center between 2014 and 2015. The average time between the initial surgical consult and the actual surgery was nearly seven months, but was as little as seven days to as much as five years.

Researchers say about two-third of the patients in the study had to wait six months before surgery due to insurance requirements for pre-operative weight loss. However, patients lost little weight during this time. The average body mass index (BMI) went from 47 to 46. Once patients did have surgery, regardless of how long they had to wait for it, the average BMI dropped to about 35 – a 25 percent drop.

Participants had an average BMI47.42+/-0.45 at the consult visit, 46.45+/-0.418 at the pre-operative visit, and 35.14+/-0.44 at the six-month post-operative visit. TTS ranged from seven to 1,813 days with an average wait of 209.23+/-10.92 days. There was a weak, yet statistically significant negative correlation between TTS and %EWL at the pre-operative visit (r=-0.19; p=0.00009 two-tailed). At six-month post-operation, there was a similar effect (r=-0.132, p=0.008 two-tailed) when controlled for pre-op BMI and type of surgery.

Patients with co-morbidities requiring medication achieved significantly higher %EWL before surgery than patients without comorbidities requiring medications (5.973+/-1.202 %EWL vs. 3.104+/-0.5158 %EWL; p=0.0325 two-tailed). Patients not requiring medications demonstrated a significant negative correlation between time-to-surgery and %EWL at the pre-operative visit (r -0.1868; p=0.0003), with a trend towards significance in patients actively taking medications (r=-0.2285; p=0.0716).

“The results from this study demonstrate that longer pre-operative wait times do not result in improved weight loss,” they concluded. “Given these results, mandated preoperative weight times should be re-evaluated. Emphasis should be given to goal directed, not time-mandated preoperative weight loss.”

“We have to go where the evidence takes us, and there is no evidence supporting preoperative weight loss requirements without consideration of the individual patient, his or her severity of disease and the determination of his or her doctor,” said Dr Stacy Brethauer, ASMBS President and associate professor of surgery specialising in advanced laparoscopy and bariatric surgery at the Cleveland Clinic in Ohio, who was not involved with the study.

In a 2016 position statement the ASMBS concluded, “insurance-mandated preoperative weight loss is not sup- ported by medical evidence and has not been shown to be effective for preoperative weight loss before bariatric surgery or to provide any benefit for bariatric outcomes.

The co-authors of this study were Drs Victor Eng, Habib Khoury, John Morton, Dan E Azagury. 

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American Society for Metabolic and Bariatric Surgery

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