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Bypass patients maintain 20% weight loss vs 5% non-surgical

Surgical vs non-surgical outcomes - Weight loss was maintained better after gastric bypass than after sleeve gastrectomy and non-surgical patents.

People with severe obesity who underwent bariatric surgery maintained significantly more weight loss at five years than those who did not have surgery, according to a Kaiser Permanente study. Although some weight regain was common after surgery, regain to within 5% of baseline was rare, especially in patients who had gastric bypass instead of sleeve gastrectomy.

David Arterburn
David Arterburn

"Earlier research has shown that bariatric surgery is the most effective weight-loss treatment for patients with severe obesity," said first author, Dr David Arterburn, a senior investigator at Kaiser Permanente Washington Health Research Institute and internal medicine physician at Kaiser Permanente in Washington. "Our new results could help ease concerns about long-term weight regain, which have contributed to a low rate of bariatric surgery - only about one in 100 eligible patients choose to have these procedures each year.”

In the study, ‘Weight Outcomes of Sleeve Gastrectomy and Gastric Bypass Compared to Nonsurgical Treatment’, published in the Annals of Surgery, the investigators sought to assess weight trajectories among patients with severe obesity undergoing sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB) and non-surgical treatment.

In this retrospective, matched cohort study, adult patients who underwent RYGB (n=17,258) or SG (n=13,900) procedures were matched to 87,965 non-surgical patients. Their percent total weight loss (%TWL) and regain at five years among RYGB, SG, and non-surgical patients, and at ten years for RYGB and nonsurgical patients was examined. Longer-term results were not available for sleeve gastrectomy because it is a newer procedure.

The study found that at five years after gastric bypass:

  • People had lost, on average, 22% of their initial body weigh

  • 25% had lost 30% or more of their total body weight

  • Only 4% had regained weight to within 5% of their pre-surgical weight

At five years after sleeve gastrectomy:

  • People had lost 16% of their initial body weight

  • 8% had lost 30% or more of their total body weight

  • About 10% had regained weight to within 5% of their pre-surgical weight

At ten years after gastric bypass:

  • People who had gastric bypass maintained 20% weight loss compared to 5% weight loss among those with usual medical care

Importantly, the study also reported that people who stopped losing weight early - within the first year, not the second - tended to have a greater risk of weight regain by five years.

This weight-maintenance information is important because sleeve gastrectomy, which is simpler to perform than gastric bypass, now accounts for more than two in three bariatric surgery procedures. However, earlier research from the same team showed fewer reoperations and interventions to address problems or complications after sleeve gastrectomy than after gastric bypass, over a five-year follow-up period.

"It's important to monitor patients closely for early signs of weight regain and to intervene early with a detailed nutritional and medical evaluation to look for behavioural and surgical explanations for weight regain," added Arterburn.

Previously, the same research team showed that bariatric surgery was associated with half the risk of microvascular complications (nephropathy, neuropathy, and retinopathy) and of heart attacks and strokes, compared to patients with type 2 diabetes and severe obesity undergoing usual medical care.

"Providers should engage all patients with severe obesity, especially those who also have type 2 diabetes, in a shared-decision-making conversation to discuss the benefits and risks of different bariatric procedures," concluded Arterburn. "And more ten-year follow-up studies of bariatric surgery, particularly sleeve gastrectomy, are needed."


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