Red cell distribution width is a novel biomarker that predicts excess body-mass index loss 1 year after laparoscopic Roux-en-Y gastric bypass

Introduction: Bariatric surgery is the most effective method for producing sustained weight loss, improving obesity-associated comorbidities and reducing inflammation in the morbidly obese population. The red cell distribution width (RDW) is a novel marker of inflammation that is usually reported as part of a complete blood count. In this study, we tested our hypothesis that red cell distribution width might represent a novel biomarker predictive of excess body-mass index loss (EBMIL) following laparoscopic Roux-en-Y gastric bypass (LRYGB). Methods: Five hundred and forty-seven LRYGB patients included from a single institution were individually reviewed, noting both preoperative RDW and percent excess BMI loss at 6 months and 1 year post-LRYGB (%EBMIL180 and %EBMIL365, respectively). Bivariate and multivariate linear regression analysis was conducted between age, gender, initial body-mass index (BMI₀) and RDW and each of the two endpoints, to assess the independence of RDW as a predictor of postoperative success. Results: The median RDW was 13.9 (13.3–14.6) %, and median EBMIL180 and EBMIL365 were 55.4 (45.2–66.7) % and 71.3 (58.9–87.8) %, respectively. After controlling for age, gender and BMI₀, RDW was associated with %EBMIL365 (B = −1.4 [−2.8 to −0.002] %, P = .05), but not %EBMIL180 (B = −0.6 [−1.6 to 0.5] %, P = .30. Upon Kruskal–Wallis analysis, patients with a preoperative RDW > 15.0 % had significantly lower %EBMIL than those in the <13.0 % (P < .001) and 13.0–15.0 % (P < .01) strata. Conclusions: RDW is predictive of EBMIL at 1 year following LRYGB. This represents a novel preoperative biomarker that may provide clinically useful prognostic information.