Two-Year Nutrition Data in Terms of Vitamin D, Vitamin B12, and Albumin After Bariatric Surgery and Long-term Fracture Data Compared with Conservatively Treated Obese Patients: a Retrospective Cohort Study.

Introduction: Nutritional deficiencies may occur after bariatric surgery despite supplementation. Fracture risk may also be elevated after bariatric surgery.
Objectives: To compare 25-hydroxyvitamin D [25(OH)D], vitamin B12, and albumin serum concentrations in severely obese patients who had undergone either Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG). Fracture data was compared with data for a conservatively treated group of severely obese patients.
Methods: We considered 253 RYGB and 142 SG performed between 2007 and 2010. At 1- and 2-year control follow-ups, weight was measured and blood samples were drawn. The control group of 199 obese patients received lifestyle intervention and weight was measured at 1 and 2 years post-intervention between 2002 and 2006. We retrospectively collected fracture data for all patients through the end of 2016.
Results: At follow-ups, the mean serum 25(OH)D and albumin levels were within reference ranges and were similar between the RYGB and SG groups. Serum median vitamin B12 level was significantly higher in the SG group compared with the RYBG group, 319 versus 286 pmol/L at 2 years, respectively, p = 0.04. The cumulative risk for fracture was higher in the bariatric groups compared with the control group. The Cox multivariate model showed higher age, bariatric surgery, and lower body mass index (BMI) at the 2-year control increased the risk for fracture after obesity treatment.
Conclusion: Vitamin 25(OH)D, B12, and albumin levels were mainly within recommended levels during the 2 years after bariatric surgery. The cumulative fracture risk was higher in bariatric patients.