Anemia and Bariatric Surgery: Results of a National French Survey on Administrative Data of 306,298 Consecutive Patients Between 2008 and 2016

BACKGROUND: Bariatric surgery (BS) has grown exponentially in France, and long-term anemia due to micronutrient deficiencies has become common. OBJECTIVES: The objective of this study was to assess the long-term risk of anemia after BS and to investigate the factors associated with the occurrence of this complication. MATERIALS AND METHODS: Data from the French National Health Service database on patients who had undergone gastric bypass (GB), sleeve gastrectomy (SG), or adjustable gastric banding (AGB), between 2008 and 2016 were extracted. Only patients with a primary intervention were considered. RESULTS: Data from 306,298 patients (143.733 SG, 79.188 GB, and 36.413 AGB) were analyzed. Overall, 12.930 of them (5.0%) had a diagnosis of anemia due to micronutrient deficiencies as main diagnosis or related diagnosis at time of a hospital stay between 2008 and 2016. In multivariate analysis, GB surgery, female gender, age younger than 52 years, and 25-OH vitamin D deficiency were positively associated with the occurrence of anemia whereas hospital procedural volume was negatively associated. The risk to be diagnosed with anemia after BS was 13.0% after a GB, 5.6% after a SG and 4.0% after an AGB (Log-rank p < 0.0001). The hazard ratio for anemia after GB compared to SG was 2.0 (95% CI 1.9-2.1), adjusted for age and gender. CONCLUSION: In France, between 2008 and 2016, 5% of patients had anemia after BS. The risk to develop anemia was 2-fold higher after a GB than after a SG. Young women should be particularly aware of this long-term risk.