Impact of Bariatric Surgery on Bone Mineral Density: Observational Study of 110 Patients Followed up in a Specialized Center for the Treatment of Obesity in France.

INTRODUCTION: Bariatric surgery is used to treat severe obesity. We aimed to investigate the incidence of clinically significant bone mineral density (BMD) loss at 6 and 12 months after bariatric surgery.

METHODS: Observational study performed in a specialized center for the treatment of obesity at the University Hospital of Reims, France. Surface BMD was measured by dual x-ray absorptiometry (DEXA). A reduction of > 0.03 g/cm2 was considered clinically significant.

RESULTS: A total of 110 patients were included. A clinically significant reduction in BMD was observed in 62.1% of patients at 6 months, and in 71.6% at 12 months after surgery. No case of osteoporosis was observed. There were four cases of osteopenia and one fracture post-surgery. BMD loss was related by univariate analysis to the reduction in body mass index (BMI) (p < 0.01), weight loss (p < 0.01), fat mass (p < 0.01), and lean mass (p < 0.01). Multivariable analysis found a significant association between the reduction in BMD and the excess weight loss percentage (odds ratio 1.11, 95% confidence interval (1.05-1.18), p < 0.001).

CONCLUSION: There was a clinically significant reduction in BMD at 6 months after surgery in over 60% of patients undergoing bariatric surgery. BMD loss is persistent over time and predominantly situated at the femoral level, and strongly associated with weight loss. Systematic vitamin and calcium supplementation, as well as follow-up by DEXA scan seems appropriate. Systematic DEXA scan pre- and post-surgery, and annually thereafter until weight has stabilized seems appropriate.