Fracture risk following bariatric surgery: a population-based study

The effects of bariatric surgery on skeletal health are poorly understood. We found that bariatric surgery patients are more prone to fracture when compared to the general population. While further studies of fracture risk in this population are needed, bone health should be discussed in bariatric surgery clinics.

Bariatric surgery is an increasingly common treatment for medically complicated obesity. Adverse skeletal changes after bariatric surgery have been reported, but their clinical importance remains unknown. We hypothesized that bariatric surgery patients are at increased risk of fracture.

We conducted a historical cohort study of fracture incidence among 258 Olmsted County, Minnesota, residents who underwent a first bariatric surgery in 1985–2004. Relative fracture risk was expressed as standardized incidence ratios (SIRs), while potential risk factors were evaluated by hazard ratios (HR) obtained from a time-to-fracture regression model.

The mean (±SD) body mass index at bariatric surgery was 49.0 ± 8.4 kg/m², with an average age of 44 ± 10 years and 82 % (212) females. Gastric bypass surgery was performed in 94 % of cases. Median follow-up was 7.7 years (range, 6 days to 25 years), during which 79 subjects experienced 132 fractures. Relative risk for any fracture was increased 2.3-fold (95 % confidence interval (CI), 1.8–2.8) and was elevated for a first fracture at the hip, spine, wrist, or humerus (SIR, 1.9; 95 % CI, 1.1–2.9), as well as for a first fracture at any other site (SIR, 2.5; 95 % CI, 2.0–3.2). Better preoperative activity status was associated with a lower age-adjusted risk (HR, 0.4; 95 % CI, 0.2–0.8) while prior fracture history was not associated with postoperative fracture risk.

Bariatric surgery, which is accompanied by substantial biochemical, hormonal, and mechanical changes, is associated with an increased risk of fracture.