Association of preoperative hemoglobin with weight loss after bariatric surgery: a retrospective study

Abstract Background Despite the known positive correlation between exercise and weight loss following bariatric surgery as well as the established association of hemoglobin level with maximal aerobic power and endurance performance, the correlation between preoperative hemoglobin concentration (Pre-Hb) and postoperative weight loss remains unknown. Object This study aimed at assessing the association of Pre-Hb with postoperative percentage weight loss (%WL) at 3, 6, 12 and 24 months after surgery. Setting A single tertiary referral center Methods Outcomes of 282 patients undergoing laparoscopic sleeve gastrectomy at the four timepoints within a 24-month follow-up period were assessed. The primary study endpoint was the relationship between Pre-Hb and postoperative %WL at 12-month follow-up. Results The 282 patients had a mean preoperative body mass index (Pre-BMI) of 39.0 ± 4.5 kg/m 2 with a slight female predominance (57.4%). Follow-up data were available for 221 of 282 (78.4%) patients (mean %WL: 30.9 ± 6.6 %) at one year. Pearson’s correlation showed that Pre-Hb correlated positively with Post-Hb (r=0.778, p p p =0.331). Multiple linear regression analyses including baseline variables of age, sex, Pre-BMI, and diabetes revealed that Pre-Hb, age and Pre-BMI were independent predictors of %WL. There was no evidence of multicollinearity among these variables. Conclusion The present study showed a potential positive relationship between preoperative hemoglobin concentration and postoperative weight loss. Further well-design large-scale studies are warranted to clarify the impact of hemoglobin level on postoperative weight loss in this patient population.