Fracture Risk After Bariatric Surgery: Roux-en-Y Gastric Bypass Versus Adjustable Gastric Banding

Abstract

The long-term consequences of bariatric surgery on fracture risk are unclear but are likely to vary by procedure type. In physiologic studies, Roux-en-Y gastric bypass (RYGB) and adjustable gastric banding (AGB) have differential effects on rates of bone loss. Therefore, our objective was to compare fracture risk in obese adults after RYGB and AGB procedures. Using claims data from a US commercial health plan, we analyzed rates of nonvertebral fractures within a propensity score-matched cohort (n = 15,032) of morbidly obese adults who received either RYGB or AGB surgery between 2005 and 2013. A total of 281 nonvertebral fractures occurred during a mean follow-up time of 2.3 ± 1.9 years. RYGB patients had an increased risk of nonvertebral fracture (hazard ratio [HR] = 1.43, 95% confidence interval [CI] 1.13-1.81) compared with AGB patients. In fracture site-specific analyses, RYGB patients had increased risk of fracture at the hip (HR = 1.54, 95% CI 1.03-2.30) and wrist (HR = 1.45, 95% CI 1.01-2.07). Nonvertebral fracture risk associated with RYGB manifested >2 years after surgery and increased in subsequent years, with the highest risk in the fifth year after surgery (HR = 3.91, 95% CI 1.58-9.64). In summary, RYGB is associated with a 43% increased risk of nonvertebral fracture compared with AGB, with risk increasing >2 years after surgery. Fracture risk should be considered in risk/benefit discussions of bariatric surgery, particularly among patients with high baseline risk of osteoporosis who are deciding between RYGB and AGB procedures. © 2017 American Society for Bone and Mineral Research.

Keywords: FRACTURE RISK ASSESSMENT; GENERAL POPULATION STUDIES; OSTEOPOROSIS.

© 2017 American Society for Bone and Mineral Research.

Figures

Figure 1. Study flow diagram

After applying the inclusion/exclusion criteria, the final study cohort included 7,516 propensity-score matched pairs of obese patients who underwent RYGB versus AGB.

Figure 2. Kaplan-Meier curve for fracture-free survival among the propensity-score matched cohort by surgery type

The numbers of patients at risk and fracture events are shown in the table. The relative fracture risk after RYGB and AGB varied over time, such that the proportional hazards assumption for the primary analysis was violated (p

Figure 3. Hazard ratios (95% confidence interval) for nonvertebral fracture in the propensity-score matched RYGB group versus AGB group (reference) stratified by year

In time-stratified analysis using piecewise Cox models, the hazard ratio of fracture in the RYGB group relative to the AGB group was equivalent in the first two years, but subsequently increased over the follow-up time.