Sleeve Gastrectomy Beneficial at Lower BMI; Call to Lower Threshold

Marlene Busko

November 19, 2019

LAS VEGAS — In a state-wide registry study of patients who had sleeve gastrectomy, less obese individuals — those with an initial body mass index (BMI) < 35 kg/m2 — had similar and even sometimes better early outcomes compared to patients with a BMI ≥ 35 kg/m2, researchers report.  

At 1 year, more than half of patients in both groups discontinued medications for diabetes, hypertension, or hyperlipidemia, and patients in both arms had similar complication rates, Oliver Varban, MD, said at a session of top papers of the American Society of Metabolic and Bariatric Surgery (ASMBS), during Obesity Week 2019.

Moreover, at 1 year, patients in the lower-BMI group were much more likely to have a normal body weight and they also rated their quality of life extremely high, said Varban, director of adult bariatric surgery, University of Michigan, Ann Arbor.

"We believe with these data we can start the conversation of changing some of the current guidelines for bariatric surgery to consider the focus to be more on metabolic disease rather than BMI alone as the only cutoff," Varban told the audience.

He noted many follow National Institutes of Health (NIH) guidance from 2012 that indicates bariatric surgery should be limited to individuals with BMI > 40 kg/m2 or > 35 kg/m2 with comorbidities. But more recent advice from ASBMR and the American Diabetes Association (ADA), among other organizations, calls for relaxation of this rule to include those with a BMI > 30 kg/m2.

"We hope the study encourages more patients to consider weight-loss surgery earlier in their disease and for more health insurers to recognize the benefits of lowering the current BMI threshold so more people who could benefit from the surgery have access," he added in a statement issued by ASMBR.

"Insurance coverage is the price of admission for most patients and it is currently serving as a barrier," he said.

"It's Not About BMI; It's About Treating Metabolic Disease"

Assigned discussant of the study Mona Misra, MD, said: "Although from one state [Michigan], this was quite a robust database, with 43 centers and more than 45,000 patients with more than 1000 patients" having a BMI < 35 kg/m2.

"It's challenging enough to even convince physicians to refer morbidly obese patients for these clearly much needed and lifesaving procedures," noted Misra, from Cedars Sinai Medical Center, Los Angeles, California.

"But with even lower BMIs, do you have any thoughts on how we can educate and mobilize this population?" she asked Varban.

He replied that "the idea is to reframe the conversation with the patient about what success looks like. It's not about BMI; it's about treating metabolic disease."

"Do you think it is now justified to expand indications for [lower-BMI] surgery — not just for diabetes, but for other comorbidities as well, or even no comorbidities?" Misra then asked.

Varban said yes, adding that bariatric surgery may be needed for reasons other than possible remission of type 2 diabetes.

"We have [obese] patients now that need a kidney transplant and can't get it," because their BMI disqualifies them, for example, he noted, adding that hip repair and hernia repair operations would be "instant failures" in such patients without weight-loss surgery.

This study "highlights that there are weight-independent effects of these [sleeve gastrectomy] operations that improve blood sugar, control your blood pressure, cholesterol, and things like that," he reiterated to Medscape Medical News.

Invited to comment, Ali Aminian, MD, a bariatric surgeon and associate professor of surgery at the Cleveland Clinic, Ohio, who was not involved with the study, told Medscape Medical News the study showed a BMI cut-point of 35 kg/m2 is arbitrary.

It would be "sad" to have a patient with a BMI of 33 kg/m2, with uncontrolled type 2 diabetes, hypertension, hypercholesterolemia, fatty liver disease, with a "very high risk of cardiometabolic future, who wouldn't be eligible for surgery based on the insurance criteria," whereas a patient with a BMI of 37 kg/mwithout any of these risk factors would be eligible, he stressed.

This illustrates why "we should go away from the BMI-threshold-based criteria to cardiometabolic risk criteria," Aminian said, echoing Varban.

Study Indicates BMI of 35 kg/m2 Is an Arbitrary Cutoff

"The current NIH guidelines for sleeve gastrectomy use a cutoff of a BMI of 35 kg/m2," Varban noted.

This latest study was designed to answer the question: Did patients who underwent sleeve gastrectomy below the 35 kg/m2 cutoff have similar benefits as patients above the cutoff?

Researchers analyzed data from the Michigan Bariatric Surgery Collaborative (MBSC) (2006-2018) — including perioperative data, 30-day complications, and 1-year patient-reported outcomes — for patients who had laparoscopic sleeve gastrostomies.

They identified 1073 patients who had a BMI < 35 kg/m2 at the time of sleeve gastrectomy. On average, their BMI was 33.7 kg/m2 and they weighed 208 kg (approximately 460 pounds).

Another 44,511 patients had a BMI ≥ 35 kg/m2 at the time of surgery. And on average they had a mean BMI of 46.7 kg/m2 and weighed 289 pounds.

Varban said that, of the 1073 patients with lower BMIs, about 333 patients had a BMI < 35 kg/m2 at the initial evaluation, and the rest had a BMI of 35 kg/m2 but lost weight on a weight-loss program prior to surgery.  

Those in the lower-BMI group were older (mean age 51 vs 45 years) and included fewer women (78% vs 84%) and less nonwhite patients (17% vs 19%) compared with patients in the higher-BMI group (all P < .001), Varban reported.

Based on the survey replies, at 1 year, patients in the lower- vs higher-BMI group lost less weight (46 vs 78 pounds) but more had a normal BMI of ≤ 25 kg/m2 (36% vs 6%).

"The lower-BMI group [had] a remarkably high rate of discontinuation of medications [for comorbidities] — well over 50%," which was comparable to the typical group of patients with a higher BMI who underwent sleeve gastrectomy, Varban pointed out.

Specifically, patients in the lower- and higher-BMI groups had similar discontinuation rates for antihypertensives (60% vs 54%), hyperlipidemia medications (54% vs 52%), oral diabetes therapies (79% vs 78%), and insulin (64% vs 62%).

However, those in the lower-BMI group were more likely to discontinue continuous positive airway pressure (CPAP) therapy for sleep apnea (66% vs 55%; P = .006). They were also more likely to report being very satisfied with their quality of life (90% vs 84%; P = .0009) and had higher scores for body image and psychological well-being.

The 30-day rates of risk-adjusted complications were comparable in the lower- and higher-BMI groups (5.9% vs 5.3%; P = .41).

Mortality rates were also similar: two patients (0.44%) in the lower-BMI group versus 32 patients (0.15%) in the higher-BMI group died (P = .16).

Call to Update 2019 Guidelines, Broaden Insurance Coverage

A statement issued by the ASMBS in conjunction with the study notes, "Most health insurers still follow guidelines developed by the NIH nearly 30 years ago, when bariatric surgery was performed as an open procedure."

"[Those] state weight-loss surgery can be considered for patients who have a BMI > 40 kg/m2, or 'in certain instances' in patients with BMIs between 35 and 40 kg/m2 who also have a serious obesity-related condition such as diabetes or high blood pressure."

But in a position statement released in 2018, the ASMBS revised its recommendation from 2012 and "urged the consideration of bariatric surgery for individuals with a BMI between 30 and 35 kg/m2."

The 2018 statement notes that "there is no current justification on grounds of evidence of clinical effectiveness, cost-effectiveness, ethics, or equity that this group should be excluded from life-saving treatment."

Meanwhile, in 2016, 45 professional societies including the ADA, issued a joint statement that metabolic surgery should be considered for patients with type 2 diabetes and a BMI of 30.0–34.9 kg/m2 if hyperglycemia is inadequately controlled despite optimal treatment with either oral or injectable medications.

Obesity Week 2019. Abstract A105. Presented November 5, 2019.

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