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
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.