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

BACKGROUND:Despite the known positive correlation between exercise and weight loss after 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. OBJECTIVE: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 4 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 of 39.0 ± 4.5 kg/m2 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 1 year. Pearson's correlation showed that pre-Hb correlated positively with post-Hb (r = 0.778, P < .001) and %WL (r = .237, P < .001) at 12-month follow-up but not at 24 months (r = .145, P = .331). Multiple linear regression analyses including baseline variables of age, sex, preoperative body mass index, and diabetes revealed that pre-Hb, age, and preoperative body mass index were independent predictors of %WL. There was no evidence of multicollinearity among these variables. CONCLUSION:The present study showed a potential positive relationship between pre-Hb and postoperative weight loss. More well-designed, large-scale studies are warranted to clarify the effect of hemoglobin level on postoperative weight loss in this patient population.