The incidence of iron deficiency anemia post-Roux-en-Y gastric bypass and sleeve gastrectomy: a systematic review.

Setting: The physiological and anatomical changes that occur as a consequence of bariatric surgery result in macro- and micro-nutritional deficiencies, especially iron deficiency. The reported incidence of iron deficiency and associated anemia after bariatric surgery varies widely across studies.

Objectives: The aim of this systematic review is to quantify the impact of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) on the incidence of iron deficiency.

Methods: Databases including Ovid Medline, Ovid Embase, Helthstar, Scopus, Cochrane (CDSR), LILACS, and ClinicalKey were searched for original articles with additional snowballing search. Search terms included Obesity, nutrient deficiency, iron deficiency, iron deficiency anemia, bariatric surgery, Roux-en-Y gastric bypass, and sleeve gastrectomy. Original articles reporting the incidence of iron deficiency and anemia pre- and post-RYGB and SG from January 2000 to January 2015 with minimum 1-year follow-up were selected. Data extraction from selected studies was based on protocol-defined criteria.

Results: There were 1133 articles screened and 20 studies were included in the final analysis. The overall incidence of iron deficiency was 15.2% pre-operatively and 16.6% post-operatively. When analyzed by procedure, the incidence of iron deficiency was 12.9% pre-RYGB versus 24.5% post-RYGB and 36.6% pre-SG versus 12.4% post-SG. The incidence of iron deficiency-related anemia was 16.7% post-RYGB and 1.6% post-SG. Risk factors for iron deficiency were premenopausal females, duration of follow-up, and pre-operative iron deficiency. Prophylactic iron supplementation was reported in 16 studies and 2 studies provided therapeutic iron supplementation only for iron-deficient patients. Iron dosage varied from 7 to 80 mg daily across studies.

Conclusion: Iron deficiency is frequent in people with obesity and may be exacerbated by bariatric surgery, especially RYGB. Further investigation is warranted to determine appropriate iron supplementation dosages following bariatric surgery. Careful nutritional surveillance is important, especially for premenopausal females and those with pre-existing iron deficiency.