DXA evaluation of bone fragility 2 years after bariatric surgery in patients with obesity

Purpose: The primary objective was to evaluate bone fragility on dual X-ray absorptiometry (DXA) in patients with obesity before and 2 years after bariatric surgery. The secondary objective was to identify risk factors for the development of a bone mineral density ≤ -2 SD at 2 years.

Methods: This descriptive study included patients with obesity who underwent DXA before and 2 years (±6 months) after bariatric surgery. The BMD and the T-score were assessed at the lumbar spine, femoral neck and total hip. Data on body composition on DXA were also collected. The diagnosis of osteoporosis was retained for a T-score ≤ - 2.5 SD at any measured location. Osteopenia, or low bone mass, was defined by -2.5 SD < T-score ≤ -1 SD.

Results: Among the 675 included patients, 77.8 % were women, with a mean age of 49.5 years (±11.1). After bariatric surgery, there were significantly more patients with osteoporosis: 3.6 % vs. 0.9 % (p = 0.0001). Multivariate analysis revealed that the risk factors for developing a bone mineral density ≤ -2 SD 2 years after bariatric surgery in patients with normal BMD before surgery were age and lower lean and fat mass before the surgery (OR = 1.07, 95%CI = [1.03-1.12], OR = 0.83, 95%CI = [0.77-0.91], OR = 1.08, 95%CI = [1.02-1.15], respectively).

Conclusion: There was a significantly higher prevalence of osteoporosis and low bone mass 2 years after bariatric surgery. Older age and lower lean and fat mass at baseline were risk factors for the development of a BMD ≤ -2SD at 2 years.