Fracture rates are increased after gastric bypass surgery compared with non-surgical weight-loss strategies, gastric banding or vertical banded gastroplasty, researchers say. "The mechanism(s) behind this finding is not clear," Dr. Sofie Ahlin of the University of Gothenburg told Reuters Health by email. "Weakening of the bone may play a role in the increased fracture risk in these patients, but in a previous study we showed that patients treated with gastric bypass have a higher risk of injurious falls." (https://bit.ly/2IHoeMn) "Until we know the mechanism behind the increased fracture risk after gastric bypass surgery, we suggest that bone health be prioritized in the post-operative follow-up, with regular control of bone health to early detect possible weakening of the bone and optimized treatment of nutritional deficiencies." Dr. Ahlin and colleagues analyzed incidence rates and hazard ratios for fractures using data from the ongoing nonrandomized Swedish Obese Subjects study. Hazard ratios were adjusted for osteoporosis risk factors, including age, sex, smoking, excessive alcohol consumption, premature menopause and a history of previous fracture. As reported in the Journal of Internal Medicine, 2,007 bariatric surgery patients who underwent gastric bypass (13.3%), gastric banding (18.7%) and vertical banded gastroplasty (68%), were included as were 2,040 matched controls. Overall, the mean age was about 48 and about 28% were men. The median follow-up was between 15 and 18 years for the different treatment groups. The highest incidence rate per 1,000 person-years for first-time fracture was seen in the gastric bypass group (22.9), followed by vertical banded gastroplasty (10.4), gastric banding (10.7), and controls (9.3). The fracture risk was higher for gastric bypass group compared with controls (adjusted hazard ratio, 2.58), gastric banding (aHR, 1.99), and vertical banded gastroplasty (aHR, 2.15). The authors state, "Our results show that gastric bypass surgery is associated with an increased long-term risk of fracture...This should be considered a serious long-term side effect as fracture leads to disability, lost productivity, increased direct medical costs and individual suffering." Dr. Timothy Shope, director of Bariatric Surgery at MedStar Washington Hospital Center in Washington, D.C., commented in an email to Reuters Health, "This is a well done study from a reliable source." "Bone health, and therefore fracture risk, is largely regulated...by a complex interaction of calcium, vitamin D and parathyroid hormone (calcium homeostasis)," he said. "Vitamin D and calcium are absorbed in substantial amounts in the part of the intestine that is bypassed in a gastric bypass operation, so it stands to reason that these patients are more likely to develop these deficiencies and therefore be at higher risk for problems related to the deficiency—in this case, bony fracture." "Other studies have shown a modest increased risk for parathyroid hormone abnormalities in gastric bypass patients as well, potentially further increasing this risk," he added. However, he pointed out, information about vitamin and mineral supplementation was retrieved from questionnaires, the surgeon was responsible for supplementation recommendations and no adherence information was available. "This is critical for several reasons," he said. "There is no standardization regarding supplementing these micronutrients or even a comment about whether or not there was any monitoring for development of a deficiency." Further, he said, "In the US, these procedures are done overwhelmingly in the context of an accredited program with oversight by the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP, administered through the American College of Surgeons). These programs often include bariatric-specific registered dietitians with advanced training in dietary supplementation specific to bariatric surgery patients." "Monitoring of laboratory studies specific to these (and other) vitamin/mineral deficiencies is done on a regular basis as part of participation in the MBSAQIP program," he noted. "It is therefore unlikely that, given appropriate participation by both patient and the care team, a deficiency will occur, or at least will persist to the point where the consequences of the deficiency are realized." —Marilynn Larkin Source
