From the Journals

Better bariatric surgery outcomes with lower preoperative BMI

 

Key clinical point: A BMI below 40 prior to undergoing bariatric surgery gives patients a significantly better chance of achieving a 1-year postoperative BMI under 30.

Major finding: Obese patients with a BMI less than 40 before undergoing bariatric surgery are more than 12 times more likely to achieve a postoperative BMI of under 30.

Data source: A retrospective study using prospectively gathered clinical data of 27, 320 adults who underwent bariatric surgery.

Disclosures: Blue Cross Blue Shield of Michigan/Blue Care Network funded the study. Three authors had received salary support from Blue Cross Blue Shield. No other conflicts of interest were declared.

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Results confirm benefits of BMI below 30 after bariatric surgery

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 MBS [metabolic and 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.

One strength of the present study is that it is a clinical database. However, 50% attrition of the follow-up weight loss data at 1 year is potentially problematic.

Bruce M. Wolfe, MD, FACS, and Elizaveta Walker, MPH, are in the division of bariatric surgery, department of surgery, at Oregon Health & Science University, Portland. These comments are taken from an accompanying editorial (JAMA Surgery 2017 Jul 26. doi: 10.1001/jamasurg.2017.2349). No conflicts of interest were declared.


 

FROM JAMA SURGERY

Delaying bariatric surgery until body mass index is highly elevated may reduce the likelihood of achieving a BMI of less than 30 within a year, according to a paper published online July 26 in JAMA Surgery.

A retrospective study using prospectively gathered clinical data of 27,320 adults who underwent bariatric surgery in Michigan showed around one in three (36%) achieved a BMI below 30 within a year after surgery (JAMA Surgery 2017, July 26. doi: 10.1001/jamasurg.2017.2348). But obese patients with a body mass index of less than 40 kg/m2 before undergoing bariatric surgery are significantly more likely to achieve a postoperative BMI of under 30.

Individuals who had a preoperative BMI of less than 40 had a 12-fold higher chance of getting their BMI below 30, compared to those whose preoperative BMI was 40 or above (95% confidence interval 1.71-14.16, P less than .001). Only 8.5% of individuals with a BMI at or above 50 achieved a postoperative BMI below 30.

Dr. Oliver A. Varban of the University of Michigan Health Systems

Dr. Oliver A. Varban

“It is important to note that EWL [excess weight loss] percentage may appear exaggerated in relation to actual mass lost in patients with lower initial BMI in these studies,” wrote Oliver A. Varban, MD, FACS, of the University of Michigan Health Systems, and his coauthors. “However, it also highlights the advantages of early surgical management of obesity in that smaller amounts of weight loss are required to achieve the desired effect.”

The likelihood of getting below 30 within a year was eightfold higher in patients who had a sleeve gastrectomy, 21 times greater in those who underwent Roux-en-Y bypass, and 82 times higher in those who had a duodenal switch, compared with patients who had adjustable gastric banding (P less than .001).

The researchers also compared other outcomes in individuals whose BMI dropped below 30 and in those who did not achieve this degree of weight loss. The analysis showed that those with a BMI below 30 after 1 year had at least a twofold greater chance of discontinuing cholesterol-lowering medications, insulin, diabetes medications, antihypertensives, and CPAP for sleep apnea, compared with those whose BMI remained at 30 or above. They were also more than three times more likely to report being ‘very satisfied’ with the outcomes of surgery.

The authors noted that the cohort’s mean BMI was 48, which was above the established threshold for bariatric surgery, namely a BMI of 40, or 35 with weight-related comorbidities.

“Our results suggest that patients with morbid obesity should be targeted for surgery when their BMI is still less than 40, as these patients are more likely to achieve a target BMI that results in substantial reduction in weight-related comorbidities,” the authors wrote.

However, they stressed that their findings should not be taken as a reason to exclude patients with a BMI above 40 from surgery, pointing out that even for patients with higher preoperative BMIs, bariatric surgery offered substantial health and quality of life benefits.

They also acknowledged that 1-year weight data was available for around 50% of patients in the registry, which may have led to selection bias.

“Policies and practice patterns that delay or incentivize patients to pursue bariatric surgery only once the BMI is highly elevated can result in inferior outcomes,” the investigators concluded.

Blue Cross Blue Shield of Michigan/Blue Care Network funded the study. Three authors had received salary support from Blue Cross Blue Shield. No other conflicts of interest were declared.

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