Nonvertebral fracture risk higher following RYGB compared with gastric banding
The risk of nonvertebral fractures is dependent on type of bariatric surgery, with a higher risk in patients with severe obesity who undergo Roux-en-Y gastric bypass (RYGB) compared with adjustable gastric banding (AGB), according to a recent retrospective study.
“[W]e found a 73 percent increased risk of nonvertebral fractures after RYGB vs AGB, especially at the hip and wrist. This increased risk was maintained in patients 65 years and older and included a 151 percent increased risk of hip fracture,” said Dr Elaine Yu from Massachusetts General Hospital, Boston, Massachusetts, US, and co-authors.
The researchers used Medicare claims data to identify 42,345 adults (78.5 percent female) with severe obesity (BMI ≥40 kg/m2), of whom 29,624 and 12,721 underwent RYGB and AGB, respectively (mean age, 51 and 55 years, respectively).
A total of 658 nonvertebral (ie, hip, wrist, humerus, or pelvis) fractures occurred over a mean 3.5-year follow-up period, with a 73 percent higher risk among patients who underwent RYGB compared with AGB (incidence rate [IR], 6.6 vs 4.6 per 1,000 person-years, adjusted hazard ratio [adjHR], 1.73, 95 percent confidence interval [CI], 1.45–2.08). [JAMA Surg 2019;doi:10.1001/jamasurg.2019.1157]
When assessed by site, the risk of fracture was higher following RYGB vs AGB for fracture of the hip (HR, 2.81, 95 percent CI, 1.82–4.49), wrist (HR, 1.70, 95 percent CI, 1.33–2.14), and pelvis (HR, 1.48, 95 percent CI, 1.08–2.07).
The increased risk of nonvertebral fractures following RYGB over AGB was also noted in a subgroup analysis of patients aged ≥65 years (IR, 9.9 vs 5.3 per 1,000 person-years, HR, 1.75, 95 percent CI, 1.22–2.52), specifically fractures of the hip (HR, 2.51, 95 percent CI, 1.25–5.93) and wrist (HR, 1.65, 95 percent CI, 1.25–2.77). The risk of fracture in older adults appeared similar to that of the overall study population.
Aside from the elevated incidence of nonvertebral fractures following either surgery in older, female, or Caucasian patients, the association between RYGB and risk of fracture was not modified by age, sex, race, or diabetes status.
While AGB has not been associated with an elevated fracture risk, [BMJ 2016;354:i3794] the same cannot be said for RYGB, with some studies showing an elevated fracture risk following this procedure and others demonstrating inconclusive findings. [J Bone Miner Res 2017;32:1229-1236; BMJ 2012;345:e5085]
The lack of certainty regarding RYGB-related fracture risk could be attributed to the small patient populations in previous studies, said Yu and colleagues. Furthermore, previous studies have focused on bariatric surgery in a younger population; as such, the fracture risk in an older population has not been established, they added.
“[W]e discovered that older age did not further magnify RYGB-associated fracture risk. Nevertheless, … the greater baseline rate of fractures among patients 65 years and older led to quantitatively more fractures among older patients who received RYGB,” they added, highlighting the elevated risk of hip fractures which could have serious consequences in the older population.
Managing long-term consequences
As to the mechanisms behind the fracture risk, weight loss-induced “skeletal unloading” and “surgically-induced calcium malabsorption” may be among contributing factors, said the authors.
“[A]lthough 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 … is warranted,” they said, calling for further research to identify ways to reduce this elevated fracture risk, particularly among patients with a high risk of fractures.
In an accompanying editorial, Dr Margaret Smith and Associate Professor Amir Ghaferi from the University of Michigan, Ann Arbor, Michigan, US, recommended that future research compare fracture outcomes following RYGB vs sleeve gastrectomy, the most common bariatric surgery. [JAMA Surg 2019;doi:10.1001/jamasurg.2019.1158]
“[The authors] highlight a necessary shift in perspective from short-term outcomes of bariatric surgery to the long-term management and mitigation of potential unintended effects. As bariatric surgery is often referred to as a “lifelong” treatment for obesity, physicians should focus on long-term outcomes and managing the longitudinal effects of this life-saving treatment,” they added.