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Procedure and weight loss

Gastric bypass associated with greater weight loss in adults

There was a 19lb difference in weight loss between gastric bypass and sleeve gastrectomy at five years for the average person in this study

Adults with severe obesity had greater initial and sustained weight loss with gastric bypass surgery compared with sleeve gastrectomy or adjustable gastric banding, according to a study published by researchers from the PCORnet Bariatric Study Collaborative. The authors state that this is the largest long-term study of bariatric surgery to date. It included more than 46,000 patients at 41 participating health systems in 11 Clinical Data Research Networks nationwide, using a large new resource called PCORnet, the National Patient-Centered Clinical Research Network.

The paper, ‘Comparative Effectiveness and Safety of Bariatric Procedures for Weight Loss: A PCORnet Cohort Study’, published in the Annals of Internal Medicine, report on a head-to-head comparison of one-, three- and five-year results from the three most commonly performed weight-loss operations: gastric bypass, sleeve gastrectomy and adjustable gastric banding.

"These findings give strong evidence that bypass and sleeve are effective for lasting weight loss for adults with severe obesity," said Kathleen M McTigue, co-study lead and an associate professor of medicine and epidemiology at the University of Pittsburgh. "We hope this helps people to make more informed decisions about their care, as they talk with their health care providers about the respective benefits and risks of the most common weight-loss procedures."

The investigators found that:

  • People who had gastric bypass surgery had lost 31 percent of their weight at the first year and maintained 26 percent of their loss at five years (Figure 1).
  • People who had sleeve gastrectomy had lost 25 percent of their pre-surgery body weight at one year and maintained 19 percent weight loss at five years.
  • That translates into a 19lb difference in weight loss between gastric bypass and sleeve gastrectomy at five years for the average person in this study, who weighed 277 pounds before surgery.
  • By contrast, adjustable gastric banding was much less effective for losing weight and keeping it off, with 14 percent and 12 percent of weight lost at one and five years, respectively.

The researchers found that men, African-Americans, Hispanics, people age 65 and older and people with diabetes or lower BMIs (<50) tended to lose less weight than did other people in the study. But these differences between patient groups were less than 3 percent differences in weight lost at one, three and five years across groups - which was much less than the differences between the procedures. For instance, the difference between weight lost with gastric bypass and sleeve gastrectomy was 6 percent at one year and 7 percent at five years.

Estimated percentage of TWL through 5 y after bariatric surgery, by procedure type: This plot shows the estimated percentage of TWL for a patient with the average baseline covariate profile using results from our sensitivity analysis, which included all follow-up weight measurements from 56 156 patients with any postsurgery weight observations. Additional details are provided in the Methods section of the text and the Statistical Appendix section of the Supplement. Shaded areas indicate pointwise 95% CIs. AGB = adjustable gastric banding; RYGB = Roux-en-Y gastric bypass; SG = sleeve gastrectomy; TWL = total weight loss

The 30-day risk of major adverse events, such as a prolonged hospitalization or another operation, were generally low across all three procedures. Sleeve gastrectomy had the lowest rate of major adverse events (2.6 percent), followed by gastric banding (2.9 percent), and then gastric bypass (5.0 percent).

The new results are among the first to be produced using the resources of PCORnet, an innovative initiative funded by the Patient-Centered Outcomes Research Institute (or PCORI). PCORnet is designed to produce clinical insights faster and less expensively than traditional clinical studies. It involves multiple individual networks that together represent more than 100 million patients.

"Bariatric surgery is widely considered the most effective way to treat severe obesity and induce long-term weight loss," said first author, Dr David Arterburn, an internist and senior investigator at Kaiser Permanente Washington Health Research Institute. "We wondered about sleeve gastrectomy, which has quickly become the most commonly performed bariatric procedure in the US. Because it's the newest, introduced less than a decade ago, less evidence has been available to compare it against the longstanding gastric bypass and adjustable gastric band."

The members of the same PCORnet Bariatric Study Collaborative team had found similar results in teenagers.

To access this paper, please click here

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