Bariatric-surgery candidates with a lower baseline body mass index (BMI) are more likely to achieve success with the surgery, both in terms of weight loss and remission of comorbidities, new research shows.
The results argue against delaying surgery until patients reach higher BMIs, the researchers say.
The findings were published online July 26 in JAMA Surgery by Oliver A Varban, MD, and colleagues from the Michigan Bariatric Surgery Collaborative, a statewide quality-improvement collaborative of 38 bariatric-surgery programs and 70 surgeons, with prospective data collection.
Among more than 20,000 bariatric surgery patients, those with a preoperative BMI of 40 kg/m2 were significantly more likely to achieve a BMI of less than 30 kg/m2 — the obesity threshold — and to have remission of comorbidities including diabetes, hypertension, and sleep apnea at 1 year postsurgery.
“Bariatric surgery is optimal in patients with a BMI of less than 40,” Dr Varban and colleagues write. “Policies and practice patterns that delay bariatric surgery until the BMI is 50 or greater can result in significantly inferior outcomes.”
In a brief editorial, Bruce M Wolfe, MD, and Elizaveta Walker, MPH, of Oregon Health & Science University, Portland, write, “The authors’ conclusion that bariatric surgery should be more liberally applied to patients with less severe obesity is consistent with multiple reports of improved control of type 2 diabetes, if not remission, among lower-BMI patient populations following [metabolic bariatric surgery]. However, these reports generally do not refute the importance of weight loss in achieving important clinical benefit among patients with obesity-related comorbid disease.”
Asked to comment, American Society of Metabolic and Bariatric Surgery president Stacy Brethauer, MD, of Cleveland Clinic Lemer College of Medicine, Ohio, told Medscape Medical News, “It makes sense that if most of our procedures will result in a 10- to 15-point BMI drop that the lower BMI you start out with, the more likely you are to get out of the obese range.”
The main point, he said, “is really to emphasize that we’re treating a chronic disease, and the earlier you intervene in any chronic disease, the better your outcomes are going to be.”
But Dr Brethauer also agreed with the editorialists’ point that the weight loss per se makes a difference, even if patients don’t achieve a BMI below 30. “Even for those who don’t get to below 30, they still do well, their quality of life is better, and comorbidities are better. Most patients don’t achieve a BMI below 30, so don’t take the study to mean that 30 should be everyone’s goal.”
Moreover, he said, these findings also “shouldn’t be used as a way to discourage someone with a BMI of 50 to undergo bariatric surgery, because they’ll still derive benefit.”
Baseline BMI, Surgery Type Predict BMI < 30
The study included a total of 27,320 adults undergoing primary bariatric surgery between June 2006 and May 2015 at both teaching and nonteaching hospitals in the Michigan collaborative. The mean preoperative BMI was 48 kg/m2 and mean postoperative BMI 33 kg/m2.
Bariatric procedures included laparoscopic or open Roux-en-Y gastric bypass (RYGB) in 44%, laparoscopic sleeve gastrectomy (LSG) in 38%, laparoscopic adjustable gastric banding (LAGB) in 16%, and biliopancreatic diversion with duodenal switch (BPD/DS) in 1%.
A total of 9713 patients (36%) achieved a BMI of less than 30 kg/m2 at 1 year after surgery. In this group, the mean preoperative BMI was 42.7 kg/m2. More had received RYGB than had the cohort as a whole (57%).
Significant predictors of achieving BMI < 30 kg/m2 at 1 year postsurgery included preoperative BMI < 40 kg/m2 (odds ratio [OR], 12.88; P < .001) and private insurance (OR, 1.09; P = .002).
Only 8.5% of patients with a BMI of 50 kg/m2 or greater achieved a BMI of less than 30 kg/m2 after bariatric surgery.
Patients who underwent the metabolic procedures LSG, RYGB, and BPD/DS were more likely to achieve BMI < 30 compared with those who had LAGB, a purely restrictive procedure, with odds ratios of 8.37, 21.43, and 82.93, respectively (P < .001).
The third of patients who achieved a BMI of less than 30 were significantly more likely to discontinue medications for hyperlipidemia (60.7% vs 43.2%, P < .001), diabetes (insulin: 67.7% vs 50.0%, P < .001; oral medications: 78.5% vs 64.3%, P < .001), and hypertension (54.7% vs 34.6%, P < .001), and to experience sleep apnea remission (72.5% vs 49.3%, P < .001).
Those patients were also more likely than the ones not achieving BMI below 30 to report feeling highly satisfied with their surgery (92.8% vs 78.0%, P < .001).
Overall and serious risk-adjusted 30-day complication rates were similar between the patients who did and did not achieve BMI <30 at 1 year after surgery (8.29% vs 7.08%, P = .87, and 2.28% vs 1.97%, P = .73, respectively).
When Will Current Practice Change?
Currently, just 1% to 2% of people who meet eligibility criteria for bariatric surgery end up receiving it, and that proportion hasn’t changed in the past decade, Dr Brethauer noted.
In May 2016, six international diabetes organizations issued a statement advising consideration of “metabolic surgery” (ie, bariatric surgery) with the intent to treat type 2 diabetes as a treatment option even in those with mild obesity (BMI 30–34.9) if their glucose levels are inadequately controlled with medication. And they recommended surgery for those with diabetes who are more obese.
Although the obesity community saw that document as a “breakthrough,” most payers still haven’t come around to reimbursing for use of the surgery in patients with mild obesity, despite evidence of cost-effectiveness in terms of reduced medication and healthcare utilization.
Dr Brethauer believes findings such as those in the current study — along with other measures — will help turn the tide eventually. “For now, it’s really continuing messaging around obesity as a chronic disease, overcoming denial about obesity as a disease rather than a lack of willpower…and generating high-level data.”
This study was funded by Blue Cross Blue Shield of Michigan/Blue Care Network. Dr Varban obtain salary support from Blue Cross Blue Shield for participating in quality improvement initiatives and the Executive Committee of the Michigan Bariatric Surgery Collaborative. Disclosures for the coauthors are listed in the paper. Dr Brethauer has no relevant financial relationships, nor do the editorialists.
JAMA Surgery. Published online July 26, 2017. Abstract, Editorial
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