Bariatric Surgery, Including Sleeve Gastrectomy, Linked to Fracture Risk

VANCOUVER, Canada — Patients who undergo either Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy are at an increased risk of fracture, compared with patients with obesity who do not undergo surgery, according to a new analysis of a predominantly male group of US veterans.

Previous studies involving premenopausal women have found a risk of bone mineral density loss and fracture with bariatric surgery, but little was known about the risk among men. Research has also shown an increase in risk after RYGB, but there is less information on risks associated with sleeve gastrectomy, though it is now the most common surgery for weight loss.

Bone density loss after bariatric surgery has been shown to be significant, according to Eileen H. Koh, MD. "It's quite a lot of bone loss, quickly," said Koh, a graduated fellow from the endocrinology program at the University of California, San Francisco, who is moving to the University of Washington, Seattle.

Those observations generally come from studies of younger women. The purpose of the new study "was to see if we see the same risk of fracture in veterans who are older men, so kind of the opposite of the typical bariatric patient," said Koh, who presented the research at the American Society for Bone and Mineral Research (ASBMR) 2023 Annual Meeting.

The researchers analyzed data from 8299 US veterans who underwent sleeve gastrectomy (41%), RYGB (51%), adjustable gastric banding (4%), or an unspecified bariatric procedure (4%) between 2000 and 2020. They were matched with 24,877 individuals with obesity who did not undergo surgery. The investigators excluded individuals who were at high risk of fracture because of another condition, such as organ transplantation or dialysis. Men made up 70% of both surgical and nonsurgical groups. The mean age was 52 years for both, and 89% and 88% were not Hispanic or Latino, respectively. The proportion of White individuals was 72% and 64%, and the proportion of Black individuals was 18% and 24%.

After adjustment for demographic variables and comorbidities, bariatric surgery was associated with a 68% increased risk of fracture (hazard ratio [HR], 1.68; 95% CI, 1.57 – 1.80), including hip fractures (HR, 2.42; 95% CI, 1.98 – 2.97), spine (HR, 1.82; 95% CI, 1.61 – 2.06), radius/ulna (HR, 2.38; 95% CI, 2.05 – 2.77), humerus (HR, 1.56; 95% CI, 1.28-1.89), pelvis (HR, 2.41; 95% CI, 1.68-3.46), and tibia/fibula/ankle (HR, 1.50; 95% CI, 1.33 – 1.69). Increased fracture risk was associated with RYGB (HR, 1.93; 95% CI, 1.75 – 2.12) and sleeve gastrectomy (HR, 1.50; 95% CI, 1.33 – 1.69) but not adjustable gastric banding.

Compared with sleeve gastrectomy, adjustable gastric banding was associated with a decreased risk of fracture (HR, 0.64; 95% CI, 0.49 – 0.84; P = .0012).

The study's predominantly male population is important because men also get osteoporosis and are frequently overlooked, according to Anne Schafer, MD, who was the lead author of the study. "Even after they fracture, men are sometimes less likely to get care to prevent the next fracture. We've shown here that especially men who are on the older side, who go through surgical weight loss, do have a higher risk of fracture compared to those who are similarly obese but have not had the operation," said Schafer, a professor of medicine at the University of California, San Francisco, and chief of endocrinology and metabolism at the San Francisco VA Medical Center.

There are limited data on fracture risk after sleeve gastrectomy. "I think this is one of the first times that I've been able to demonstrate that there was a higher risk of fracture with sleeve gastrectomy in comparison with nonsurgical cohorts. Of course, it's necessary to confirm these findings in further studies, but it's interesting," said Julien Paccou, MD, who attended the poster session and was asked for comment. His group's study of a French population showed an increased fracture risk associated with RYGB but not sleeve gastrectomy. Another study found a reduction of fracture risk associated with sleeve gastrectomy and no difference between RYGB and nonsurgical matched control patients in a Medicare population.

In fact, there is a belief that fracture risk may be lower with sleeve gastrectomy, according to Schafer. "It's part of why it's so popular," she said.

The reasons for increased fracture risk following surgical weight loss remains unknown, according to Paccou, but they could include mechanical unloading, loss of lean mass, and hormone and nutrition changes. "There are many, many factors," said Paccou, a professor of rheumatology at Hospital Roger Salengro in Lille, France.

The study's findings of increased risk of fracture after sleeve gastrectomy may be an argument against malabsorption because the procedure shouldn't affect nutrient absorption. It suggests that other factors are at play. "It's not the only reason," Schafer said.

There are recommendations for postbariatric surgery care to optimize bone health, such as protein intake and calcium and vitamin D targets, along with lifestyle factors. "Despite all those [efforts], we still know that bone loss occurs," Koh said. In fact, the group is conducting a study funded by Amgen of the use of denosumab (Prolia) for the prevention of high-turnover bone loss after RYGB and sleeve gastrectomy.

Schafer has received research support from Bone Health Technologies and Amgen. Koh and Paccou have disclosed no relevant financial relationships.

American Society for Bone and Mineral Research (ASBMR) 2023 Annual Meeting: Abstract FRI-074. Presented October 13, 2023.

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Cite this: Bariatric Surgery, Including Sleeve Gastrectomy, Linked to Fracture Risk - Medscape - Oct 24, 2023.