Nutritional Status in Chinese Patients with Obesity Following Sleeve Gastrectomy/Roux-en-Y Gastric Bypass: A Retrospective Multicenter Cohort Study

Metabolic surgery (MS) is one of the most effective therapies for treating obesity. Due to the lack of multicenter cohort research on nutritional evaluations after surgery in Chinese patients, we explored the changes in nutritional status following MS in Chinese patients. This was a retrospective study of patients (n = 903) who underwent sleeve gastrectomy (SG) (n = 640) or Roux-en-Y gastric bypass (RYGB) (n = 263) for obesity at five different hospitals in China between 17 February 2011, and 20 December 2019. Major nutrients were evaluated at baseline and 1, 3, 6, and 12 months postoperatively. Hb levels decreased, and anemia prevalence increased at 12 months after MS in the premenopausal female group. Moreover, patients with preoperative anemia had an increased risk of postoperative anemia. The ferritin levels (p < 0.001) decreased and iron deficiency increased (p < 0.001) at 12 months after MS among premenopausal females. No significant changes in folate deficiency and vitamin B12 deficiency were found throughout the study. The bone mineral density (BMD) of the femoral neck, lumbar spine, and total hip significantly decreased from baseline to 12 months after MS; however, no new patients developed osteopenia or osteoporosis after MS. Based on 12 months of follow-up, premenopausal females presented a high incidence of anemia after MS. Although we found no differences in osteopenia and osteoporosis prevalence after MS, the BMD did decrease significantly, which suggests that nutrient supplements and long-term follow-up are especially necessary postoperation.