Fracture risk higher after Roux-en-Y gastric bypass than after banding

Last Updated: 2017-03-30

By Anne Harding

NEW YORK (Reuters Health) - Roux-en-Y gastric bypass (RYGB) is associated with a higher risk of fracture compared with adjustable gastric banding (AGB), new research shows.

Two years after surgery, patients who had RYGB were 43% more likely to have nonvertebral fractures than those who underwent AGB, Dr. Elaine Yu and colleagues from Massachusetts General Hospital and Harvard Medical School in Boston found.

“The many benefits of gastric bypass continue to outweigh the fracture risk for most patients, but physicians should discuss potential skeletal consequences and consider a comprehensive skeletal evaluation for their gastric bypass patients,” Dr. Yu told Reuters Health by email.

Research has shown increased bone loss after RYGB, Dr. Yu and her team note in the Journal of Bone and Mineral Research, online March 20. However, the clinical effect of metabolic bone disease on fracture risk after bariatric surgery “has been controversial,” they add.

Dr. Yu and her colleagues used claims data from a commercial health plan on more than 15,000 patients who received either RYGB or AGB in 2005-2013. The group consisted of 7,516 RYGB-AGB patient pairs who had been matched by propensity score.

During a mean follow-up of 2.3 years, 281 non-vertebral fractures occurred. Overall, RYGB patients had a 43% greater risk of fracture (hazard ratio, 1.43; 95% confidence interval, 1.13 to 1.81).

The individual risks of hip and wrist fractures were also significantly increased with RYGB (HR, 1.54 and 1.45, respectively). The greater risk was seen starting two years after surgery, and was highest five years after surgery (HR, 3.91).

Current guidelines suggest that patients have bone density scans before and one to two years after gastric bypass, Dr. Yu noted. But less than 4% of patients in the study had undergone DXA before surgery, while 11% of RYGB patients received post-operative DXA scans.

“This is an area where we can do better,” she said.

“The current study was unable to address mechanisms of this bone loss, but our previous research suggests that weight loss and calcium/vitamin D malabsorption, both of which occur after RYGB, are unlikely to be the primary drivers of this bone loss,” Dr. Yu added. “Bone loss occurs even with aggressive supplementation of calcium/vitamin D and prevention of secondary hyperparathyroidism.”

RYGB could lead to changes in gastrointestinal hormones, adipokines, or the gut microbiome that affect bone health, the researcher suggested.

“We’re now studying whether there are interventions that can slow or prevent bone loss and ultimately reduce fracture risk in patients undergoing RYGB,” Dr. Yu said.

SOURCE: http://bit.ly/2nOIySB

J Bone Miner Res 2017.