Around one-quarter of obese individuals who undergo Roux-en-Y gastric bypass had sustained, long-term remission of obesity, but far fewer achieved body mass index of under 25 kg/m2 or maintained it over 5 years, new research suggests.
Researchers reported on the outcomes of a retrospective cohort study of 219 patients who underwent Roux-en-Y gastric bypass surgery at a single center between 2008 and 2010 and were followed for up to 7 years after the procedure.
Only 16.9% of female patients achieved a BMI of under 25 kg/m2 – during the study period, and only 2.7% reached this BMI by year 2 and sustained it at least to year 5 of follow-up.
Two males in the study achieved BMI of under 25 during follow-up. One was recorded as having maintained this weight at year 1 and the other at year 4, but no further measurements were available for either.
“Given the low number of patients achieving BMI of less than 25 kg/m2, we also wanted to focus on another important clinical goal of obesity remission (BMI less than 30),” wrote, of the University of Michigan, Brehm Center for Diabetes, Ann Arbor, and his coauthors. “Taking into account that the mean BMI prior to surgery in our cohort was 47.1 kg/m2, this target is associated with significant estimated health benefits and likely brings a mortality benefit for patients undergoing gastric bypass.”
The authors said that a conservative estimate of the probability of achieving and sustaining BMI 25 or less after Roux-en-Y gastric bypass was just 2.3%. However, they offered a more liberal estimate – based on the number of patients who were at BMI 25 or under at the last available data point – of 6.8%.
Achieving weight loss to a BMI less than 30 was significantly influenced by age. The group who achieved this weight were on average 3 years younger at baseline than those who did not.
Similarly, initial BMI played a role in outcomes. The women who achieved a BMI below 30 had an initial mean BMI of 43.5, compared with 50.4 in the women who did not achieve this weight (P less than .0001). In males, the mean baseline BMI in those who got their weight below 30 was 44.6, compared with 48.1 in those who did not (P = .18).
Roux-en-Y gastric bypass was also associated with significant and sustained decreases in both systolic and diastolic blood pressure that was similar for both sexes. The maximum mean decrease of 14 ± 7 mm Hg was achieved at 1 year after surgery, and, at 5 years, the mean decrease was 11 ± 3 mm Hg.
The authors commented that, despite “excellent” weight loss being achieved by a majority of patients, the findings show the challenge of weight loss and maintenance in patients with a very high BMI. However, they also pointed to the encouragingly low rates of significant weight regain and the fact that fewer than 1% of patients returned to a weight greater than their preoperative weight. Higher preoperative BMI was correlated with greater weight loss but also negatively correlated with achieving BMI under 30.
The authors concluded with two takeaway messages. First, realistic goals should be set for patients undergoing gastric bypass surgery, with an emphasis on remission of obesity and with a reduced expectation of achievement of BMI under 25 over the long run. In addition, because the higher the initial BMI, the less likely that weight loss will not be maintained, “we should also carefully examine the option of pursuing surgery at lower BMI cutoffs, at which point patients have a greater likelihood of obesity remission.”
The study was supported by the University of Michigan Health System, the National Institutes of Health, and the Nutrition Obesity Research Centers. One author declared grant support and advisory positions with pharmaceutical companies and intellectual property unrelated to the study. Another author is an investigator on a sponsored clinical study. No other conflicts of interest were declared.