Bone Mineral Density and Turnover After Sleeve Gastrectomy and Gastric Bypass: A Randomized Controlled Trial (Oseberg)

Abstract

Context: Bariatric surgery, particularly Roux-en-Y gastric bypass (RYGB), is associated with an increased risk of osteoporotic fractures. It is unknown whether RYGB or sleeve gastrectomy (SG) have different effects on bone health.

Objective: To compare changes in bone mineral density and markers of bone turnover 1 year after SG and RYGB.

Design, setting, patients, and interventions: Randomized, triple-blind, single-center trial at a tertiary care center in Norway. The primary outcome was diabetes remission. Patients with severe obesity and type 2 diabetes were randomized and allocated (1:1) to SG or RYGB.

Main outcome measures: Changes in areal bone mineral density (aBMD) and bone turnover markers.

Results: Femoral neck, total hip, and lumbar spine aBMD, but not total body aBMD, decreased significantly more after RYGB (n = 44) than after SG (n = 48) (mean [95% confidence interval] between group differences -2.8% [-4.7 to -0.8], -3.0% [-5.0 to -0.9], -4.2% [-6.4 to -2.1], and -0.5% [-1.6 to 0.6], respectively). The increase in procollagen type 1 N-terminal propeptide (P1NP) and C-telopeptide of type I collagen (CTX-1) were approximately 100% higher after RYGB than after SG (between group difference at 1 year, both P < 0.001). The changes in femoral neck, total hip, and lumbar spine aBMDs and the changes in P1NP and CTX-1 were independently associated with the surgical procedure (all P < 0.05) and not weight change.

Conclusions: Roux-en-Y gastric bypass was associated with a greater reduction in aBMD and a greater increase in bone turnover markers compared with SG. This finding could suggest greater skeletal fragility after RYGB.

Trial registration: ClinicalTrials.gov NCT01778738.

Keywords: bone mineral density; bone turnover; gastric bypass; morbid obesity; sleeve gastrectomy; type 2 diabetes.

Figure 1.

Mean percent change in areal bone mineral density (aBMD) from baseline to 1 year after sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB). Bars indicate 95% confidence intervals. P-values were calculated using independent samples t-test.

Figure 2.

Bone turnover markers, vitamin D, parathyroid hormone, and electrolytes after sleeve gastrectomy and gastric bypass during 1-year follow-up. P-values were derived from linear mixed effects models for repeated measures. Bars indicate 95% confidence intervals. Abbreviations: BALP, bone alkaline phosphatase; CTX-1, C-telopeptide of type I collagen; P1NP, procollagen type 1 N-terminal propeptide; PTH, parathyroid hormone.