People who have gastric bypass surgery for weight loss face an increased risk of fracture, according to a large study in Sweden.
The researchers found that the risk of fractures increases by about 30% after a gastric bypass operation. Falls also increase after the procedure.
However, the researchers stressed that the benefits of the surgery still outweigh the risks.
“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,” said Mattias Lorentzon, professor of geriatrics at Sahlgrenska Academy, University of Gothenburg, and chief physician at the University Hospital.
With a gastric bypass, most of the stomach and part of the small intestine is removed. Food goes directly into the small intestine instead of passing through the entire stomach, which means it takes less food to make you feel full and you absorb fewer calories from the food you eat.
The study is based on the records of 38,971 patients who underwent gastric bypass operations, of whom 7,758 had diabetes and 31,213 did not. Those who had the operation were compared with an equal number of matched individuals who had not been operated on.
Regardless of diabetes status, those who had surgery had about a 30% increased risk of fractures. Individuals without diabetes had an increased risk of 32% and those with diabetes had an increased risk of 26%.
The most common hypothesis of the mechanism behind increased fracture after obesity surgery has been weight loss and the skeleton becoming weaker with the reduced load, the University of Gothenburg noted.
While the study did not show a relationship between the fracture rate and the degree of weight loss, it found an increased risk of falls after surgery, which in itself could contribute to increased risk of fractures.
However, it’s not yet clear why individuals who have had operations fall more often, with or without fractures as a consequence.
“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,” commented Kristian Axelsson, doctoral student at Sahlgrenska Academy, University of Gothenburg, and resident physician in orthopaedics at Skaraborg Hospital Skövde.
The findings of the study have been published in the Journal of Bone and Mineral Research.