For an average of six years after undergoing gastric bypass surgery, severely obese patients not only lost a lot of weight, but also showed frequent remission and lower incidence of type 2 diabetes, plus lower rates of high blood pressure, abnormal cholesterol, and other cardiovascular risk factors, compared with a control group of similar patients who did not have the surgery.
These were the findings of a JAMA study published on 19 September, that was led by researchers from the University of Utah School of Medicine, Salt Lake City, in the US.
The authors, and an expert writing in a separate commentary, say the findings are important because they show obesity surgery has enduring health benefits.
Speaking about their work at a JAMA media briefing, lead author Ted D. Adams, of the School and also of Intermountain Healthcare at Salt Lake City, said the rate of extreme obesity is rising faster in the US than the rate of moderate obesity.
But unfortunately, tackling extreme obesity with lifestyle changes doesn’t work very well in the long term for extremely obese patients, and neither does drug therapy.
This leaves surgery as the only effective option to help severely obese people sustain weight loss, says Adams. But, as he and his colleagues note in the background section of their paper:
“For this high-risk population, however, the number of studies reporting long-term weight loss following bariatric surgery are limited and generally have incomplete follow-up.”
For their study, Adams and colleagues examined links between Roux-en-Y gastric bypass (RYGB) surgery and weight loss, type 2 diabetes, and other health risks, 6 years after surgery.
The participants were 1,156 severely obese people aged between 18 and 72. Severe obesity is defined as having a Body Mass Index (BMI) of 35 and over. A person’s BMI is their weight in kilos divided by the square of their height in meters. 82% of the participants were female, and the average BMI was 46.
The participants were in three groups (one intervention group and two control groups): 418 who sought and received RYGB surgery, 417 who sought it but did not receive it (Adams said the main reason was on grounds of insufficient insurance coverage), and 321 who were randomly selected from a population-based sample.
The results showed that the average unadjusted weight loss in the surgical group was 27.7% between the beginning of the study and year 6, while over the same period, control group 1 (the ones who sought but did not have surgery) gained an average of 0.2% in weight, and control group 2 (the random population sample) did not gain or lose weight.
The authors write:
“At 2 years, 99 percent of surgical patients had maintained more than 10 percent weight loss from baseline and 94 percent had maintained more than 20 percent weight loss,” plus:
“At 6 years, 96 percent of surgical patients had maintained more than 10 percent weight loss from baseline and 76 percent had maintained more than 20 percent weight loss.”
As well as sustaining weight loss, the surgery group showed favorable improvements in other indicators.
Remission rates for type 2 diabetes over the 6 years were significantly higher in the surgery group than in either of the two control groups: 62% compared with 8% in control group 1 and 6% in control group 2.
Incidence of type 2 diabetes was also significantly lower in the surgery group: 2% versus 17% and 15% in control groups 1 and 2 respectively.
This favorable pattern was also reflected in other health measures, for example, remission rates for high blood pressure, low HDL-C (the “good” cholesterol), high LDL-C (the “bad” cholesterol), and high triglycerides were higher in the surgery group than in the two control groups, with improvements in high blood pressure and low HDL-C being especially significant.
The authors remark that improvements in metabolic and cardiovascular risk profiles were sustained in the surgery group over 6 years, while:
“In contrast, cardiovascular and metabolic status of severely obese control participants generally worsened during the 6-year period.”
“These findings are important considering the rapid increase in total numbers of bariatric surgical operations performed in the United States and worldwide, and may have significant ramifications for the projected 31 million US individuals meeting criteria for bariatric surgery,” conclude the authors.
In an accompanying editorial, Anita P. Courcoulas, a bariatric and general surgeon with University of Pittsburgh Medical Center, comments that an important feature of the study is that although the weight loss waned in years 2 to 6 in the surgery group, the control of the health risks remained “very good”.
“These findings are important because they show in a RYGB cohort and control group with nearly complete follow-up at 6 years that weight loss and associated health benefits following RYGB are durable,” writes Courcoulas.
“The mortality rates in this study were too small to assess statistically, but serve as a reminder of an uncommon but important outcome needing objective monitoring,” she adds.
Grants from the National Institutes of Health/The National Institute of Diabetes and Digestive and Kidney Diseases and the National Center for Research Resources helped fund the study.
Written by Catharine Paddock PhD