Risk of fracture in patients with bariatric surgeryandmatched controls: A population-based cohort study in the United Kingdom

Introduction: Bariatric surgery can be considered among patients with morbid obesity. The surgery has been associated with reduced bone mineral density, probably as a result from malabsorption, and from secondary hyperparathyroidism. However, risk of fracture has not been determined. Objective of this study was to estimate fracture risk in bariatric surgery patients versus matched controls. Methods: A retrospective cohort study was conducted within the UKGPRD (1987-2010). Patients had a record of bariatric surgery (n=2,346), and were matched to up to six controls without bariatric surgery by age, sex, practice, and body mass index. They were followed from the date of bariatric surgery for the occurrence of any fracture. Disease and medication adjusted (adj.) hazard ratios (HRs)were calculated using time dependent Cox regression. Results: No increased risk of fracture was seen in patients who underwent bariatric surgery, compared to matched controls (adj. HR 0.92; 95 % CI 0.73-1.15). Fracture risk remained steady over time since bariatric surgery. We found a significantly increased risk among patients aged(greater-than or equal to)60 years (adj. HR 1.52; 95 % CI 1.02-2.27), and those with a history of fracture (adj. HR 1.84; 95 % CI 1.29-2.63), and cerebrovascular diseases (adj. HR 6.31; 95 % CI 3.53-11.28). In contrast, a decreased risk of fracture was found in subjects using antidiabetic drugs (adj. HR 0.41; 95 % CI 0.18-0.91). Conclusion: This is probably the first and largest study that estimates risk of fracture after bariatric surgery as compared to controls. Our data did not find an overall association between bariatric surgery and risk of fracture. However, fracture risk assessment may be considered among patients who have undergone bariatric surgery, and who have a history of fracture, cerebrovascular disease or who are 60 years or older.