Fracture risk increased following bariatric surgery

ENDO 2011

BOSTON — New data demonstrate an increased risk for fracture following bariatric surgery.

Researchers found that patients who underwent bariatric surgery appear to have a 2.3-fold increased risk for fracture compared with the general population. The finding from the final analysis is higher than the 1.8-fold increased fracture risk reported 2 years ago in an interim analysis of this study population.

Patients who had bariatric surgery had an increased risk for fracture at nearly all skeletal sites studied, according to Kurt Kennel, MD, who presented the final analysis results at a press conference.

The standardized incidence ratio for any fracture was 2.3 (95% CI, 1.8-2.8). Notable findings reported at other skeletal sites include:

• First fracture at hip, wrist, spine or humerus (SIR=1.9; 95% CI, 1.1-2.9).
• First fracture at all other sites (SIR=2.5; 95% CI, 2.0-3.2).
• Fracture of the foot (SIR=3.2; 95% CI, 2.1-4.6).
• Fracture of the hand (SIR=3.4; 95% CI, 2.0-5.4).

Examining fracture risk

The researchers used the Rochester Epidemiology Project to retrospectively study fracture rates in a subset of 258 Olmsted County, Minnesota, residents. All had undergone a first bariatric surgery procedure between 1985 and 2004. The mean age of the patients was 44 years and the majority (82%) were women. Ninety-four percent of patients underwent gastric bypass surgery. Kennel said the type of bariatric surgery procedures has changed over the years so their study did not include patients with procedures that are more popular today, such as laparoscopic adjustable gastric banding and sleeve gastrectomy.

During the average follow-up of 7 years, a total of 79 patients had 132 fractures. The average age at first fracture was the mid-40s, according to Kennel. On average, patients experienced their first fracture about 5 years after surgery.

“As a clinician who follows these patients, many aren’t being followed by their bariatric surgery program 5 years after surgery. They are [typically] being followed by their primary doctor, maybe not even that close at all at that point,” Kennel, assistant professor of medicine in the endocrinology division at Mayo Clinic, said.

After adjusting for age, the researchers found that patients who were more physically active before surgery had a lower fracture risk compared with those who were less active (HR=0.4; 95% CI, 0.2-0.8).

History of fractures prior to bariatric surgery was not associated with subsequent fracture risk, according to the researchers.

Measures to optimize bone health

Kennel said the link between bone health and bariatric surgery is not a new issue. However, “the problem is that lately we see evidence in the literature that people who are trying to get enough vitamin D and calcium still show signs that their bones are changing in a negative way,” he said at the press conference.

Of note, patients who developed fractures did not necessarily develop osteoporosis, the researchers said.

“We need to start looking at the skeleton as one of the key issues for long-term follow-up [of bariatric surgery],” Kennel said. Clinicians may also need to consider other measures to improve post-surgery bone health, such as proper calcium and vitamin D nutrition and fall prevention, he added. - by Katie Kalvaitis

Disclosure: The researchers report no relevant financial disclosures.

For more information:

• Nakamura K. OR44-5. Presented at: The Endocrine Society 93rd Annual Meeting & Expo; June 4-7, 2011; Boston.

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