Background: Bariatric surgery increases the risk of anemia, but long-term data from large cohorts are sparse, and it is unclear if certain groups are at higher risk.Objectives: Define factors associated with anemia at five years follow-up after bariatric surgery.Setting: Data from a national quality register. Method:This cross-sectional study uses Scandinavian Obesity Surgery Registry data on primary Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) procedures in Sweden from 2007 to 2020.Hemoglobin and ferritin were analyzed preoperatively, and up to 10 years post-operatively.Factors associated with anemia were evaluated using hemoglobin and ferritin samples five years post-surgery. Result:The study included 73,612 patients (RYGB 80.7%, SG 19.3%).Hemoglobin and/or ferritin data were available for 18,993 patients 5 years post-surgery, of whom 3508 patients (18.5%) had anemia, and 691 patients (27.0%) subnormal ferritin levels.Anemia and subnormal ferritin were more prevalent after RYGB than SG (19.6% vs. 11.3%, adjusted OR=0.58, and 24.1% vs. 15.6%adjusted-OR=0.43).Females had a higher prevalence of anemia than males (20.6% vs. 11.1%,adjusted-OR=0.50).Young age was associated with a higher risk of anemia (31.0%), as was large postoperative weight loss (highest quartile 25.2 %).Results regarding iron supplementation was not conclusive. Conclusions:The prevalence of anemia, likely secondary to iron deficiency, increases up to 10 years post bariatric surgery.Female sex, young age at surgery, large weight loss and undergoing RYGB were associated with an increased risk of anemia, indicating a need for targeted strategies for vitamin and mineral supplementation in these groups.
Spetz et al. (Sun,) studied this question.