Predictors of Anemia Recovery in Patients with Pre-existing Anemia Undergoing Metabolic Bariatric Surgery: A Retrospective Cohort Study.

BACKGROUND

Although studies have explored the development of postoperative anemia after metabolic bariatric surgery, little is known about the effect of metabolic bariatric surgery on anemia recovery in patients with pre-existing anemia. Therefore, the objective of this study was to determine the prevalence of anemia recovery six months after metabolic bariatric surgery and predictors associated with recovery.

METHODS

This was a retrospective cohort study of 1,664 patients with pre-existing anemia aged 18-80 years who received a primary metabolic bariatric procedure between January 2010 and June 2020. The primary outcome of interest was the percentage of patients who recovered from anemia as defined by the World Health Organization thresholds at six-months post-metabolic bariatric surgery.

RESULTS

Of the 1,664 patients identified with preoperative anemia, 952 (57.2%) recovered six-months post-metabolic bariatric surgery. Female sex (OR 1.93, 95% CI 1.42-2.61, p < 0.001), age between 45-54 years vs. under 35 years (OR 1.48, 95% CI 1.08-2.05, p < 0.05), and receiving sleeve gastrectomy vs. Roux-en-Y gastric bypass (OR 1.41, 95% CI 1.06-.86, p < 0.05) were associated with significantly higher odds of recovery. A preoperative hemoglobin of 11-20 g/L below normal as compared to 0-10 g/L below normal (OR 0.52, 95% CI 0.40-0.69, p < 0.001) was associated with significantly lower odds of recovering from anemia.

CONCLUSION

More than half of patients with preoperative anemia undergoing metabolic bariatric surgery recover from anemia after their procedure. Age, sex, preoperative hemoglobin, and surgery type all influence recovery. The total body weight lost after six-months post-surgery conferred no significant effect.