The risk of a patient experiencing a fracture increases by about 30% after a gastric bypass operation, according to a Swedish study.
Gastric bypass surgery was associated with a higher fracture risk that appeared to increase with time and was not associated with the degree of weight loss or calcium and vitamin D supplementation.
“It will be important to follow patients and evaluate the fracture risk”
The study was based on the records of 38,971 patients who underwent gastric bypass operations, of which 7,758 had diabetes and 31,213 did not.
Those who had had the operation were compared with an equally large group of individuals who had not been operated on and who had the equivalent morbidity and background data.
Regardless of diabetes status, patients who had been operated on had about a 30% increased risk of fractures, said the researchers.
More specifically, individuals without diabetes had an increased risk of 32% and those with diabetes had an increased risk of 26%.
The risk increase applies to fractures in general, with the exception of the lower leg, said the study authors. After surgery, fractures of the lower legs occurred less frequently.
“Naturally our findings do not mean that you should stop providing these types of operations”
The researchers said their results corresponded well with earlier research in the field, but highlighted that their study was statistically stronger due to its size.
They noted that the most common hypothesis of the mechanism behind increased fracture after obesity surgery had been weight loss and that the skeleton becomes weaker with the less load.
The new study, published in the Journal of Bone and Mineral Research, did not show a relationship between the fracture rate and the degree of weight loss.
An increased risk of falls after surgery was noted though, which in itself could contribute to increased risk of fractures, said the researchers.
However, they said the question of why individuals who have had operations fall more often, with or without fractures as a consequence, had no clear answer yet.
“During a median follow‐up time of 3.1 years, gastric bypass was associated with increased risk of any fracture, in patients with and without diabetes,” the researchers said in the journal.
They stated: “Using flexible parameter models, the fracture risk appeared to increase with time. The risk of fall injury without fracture was also increased after gastric bypass.
Source: Skaraborg Hospital
“Larger weight loss or poor calcium and vitamin D supplementation after surgery were not associated with increased fracture risk,” they said.
Lead study author Kristian Axelsson, from the University of Gothenburg, said: “The fact that the risk of fractures increases and also seems to increase over time means that it will be important to follow patients, evaluate the fracture risk and, when required, institute measures to prevent fractures.”
Senior author Mattias Lorentzon, professor of geriatrics at the university, added: “Gastric bypass is a well-established method that has proven effective in reducing obesity, diabetes and mortality, so naturally our findings do not mean that you should stop providing these types of operations.”