Medicare beneficiaries who underwent Roux-en-Y gastric bypass (RYGB) saw a 73% higher risk for nonvertebral fractures compared with those who underwent adjustable gastric banding (ABG) (adjusted HR 1.73, 95% CI 1.45-2.08), Elaine Yu, MD, of Massachusetts General Hospital in Boston, and colleagues wrote in JAMA Surgery.
Roux-en-Y patients saw a fracture incidence rate of 6.6 (95% CI 6.0-7.2) per 1,000 person-years during the average 3.3-year follow-up, while gastric banding patients saw a 4.6 (95% CI 3.9-5.3) incidence rate in the 4 years following surgery.
This elevated fracture risk after Roux-en-Y versus gastric banding was mainly driven by an elevated risk for hip and wrist fractures:
- Hip fracture: HR 2.81 (95% CI 1.82-4.49)
- Wrist fracture: HR 1.70 (95% CI 1.33-2.14)
- Pelvis fracture: HR 1.48 (95% CI 1.08-2.07)
“Thus, although bariatric surgery is associated with myriad health benefits, increased fracture risk is an important factor to discuss with patients seeking RYGB, and aggressive management of bone health (e.g., bone density scans, calcium and vitamin D supplementation and physical activity) is warranted,” Yu’s group wrote.
They also highlighted clinical practice guidelines for nonsurgical support of bariatric surgery patients, which recommend lifelong 1,200-1,500 mg daily of calcium citrate and at least 3,000 units a day of vitamin D supplements after all types of bariatric surgery, including gastric bypass and banding.
The retrospective analysis included over 42,000 Medicare beneficiaries with severe obesity (BMI ≥40). Nearly 30,000 underwent Roux-en-Y and almost 13,000 underwent gastric banding. Patient data was collected using Part A, Part B, and Part D Medicare claims. The cohort included beneficiaries age 65 and older, individuals younger than 65, but with certain types of disabilities — including obesity-related musculoskeletal, respiratory, or cardiovascular disabilities — as well as individuals with end-stage renal disease requiring dialysis or a transplant.
There were 658 total fracture events during the follow up period, the authors said. RYBG patients tended to be slightly younger, with an average age of 51 compared with an average age of 55 for gastric banding patients. Women accounted for over 75% of both surgical groups.
When calculating hazard ratios, the researchers adjusted for several demographic and clinical factors, some of which included osteoporosis status, prior fractures, heart disease, stroke history, and use of several medications such as oral glucocorticoids and insulin.
In a subanalysis restricted only to patients age 65 and older, results were comparable to the entire cohort, with an increased risk for nonvertebral fracture (HR 1.75, 95% CI 1.22-2.52) in RYBG patients versus gastric banding. Similarly, this risk was mainly driven by hip fracture (HR 2.51, 95% CI 1.25-5.93).
In an accompanying commentary, Margaret Smith, MD, and Amir Ghaferi, MD, both of the University of Michigan in Ann Arbor, praised the authors for quantifying one of the “unintended consequences” of bariatric surgery and shifting focus to long-term outcomes and management of these patients. However, they noted that one significant limitation to the analysis was the exclusion of sleeve gastrectomy — now the most popular form of bariatric surgery. In the same vein, comparing Roux-en-Y to adjustable gastric banding, which they describe as a “a rapidly declining operation” therefore “adds minimal relevant information to conversations with patients on the risk of [RYGB].” Instead, they recommended a future study comparing fracture risk after Roux-en-Y to sleeve gastrectomy.
Smith and Ghaferi also noted that, despite the researchers identifying this increased fracture risk with Roux-en-Y, “the clinical effect of minimal absolute differences in fractures is likely insignificant.”
“For example, despite a hazard ratio of 2.81, only 103 patients undergoing RYGB (0.4%) experienced a hip fracture compared with 25 (0.2%) of the ABG cohort,” the commentators said.
The study was supported by grants from the National Institutes of Health, and the Clinical Scientist Development Award from the Doris Duke Charitable Foundation.
Yu reported grants to Massachusetts General Hospital from Seres Therapeutics for unrelated studies. Kim reported receiving research grants to Brigham and Women’s Hospital from Pfizer, Bristol-Myers Squibb, and Roche for unrelated studies. No other conflicts were reported.
Commentary author Smith reported grant support from the National Institute of Health’s Obesity Surgery Scientist Training Grant. Ghaferi reported grant support from the Agency for Healthcare Research and Quality and a Patient-Centered Outcomes Research Institute Award, and receives salary support from Blue Cross Blue Shield of Michigan as the director of the Michigan Bariatric Surgery Collaborative.