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

Abstract

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.

Keywords: Bariatrics; Biomarkers; Gastric bypass; Laparoscopy; Outcomes.

Figure 1

Derivation of the 547 patient study cohort

Figure 2

Graphical depictions of the relationship between red cell distribution width (RDW) and percent excess body-mass index loss at one year postoperatively (%EBMIL365) a- Simple linear regression analysis of %EBMIL365 vs. RDW revealed a significant relationship between the variables (P < .001, Pearson r² = .06, n = 547). Linear regression line shown with 95% confidence band b- Box-and-whisker plots of %EBMIL365, by preoperative RDW stratum. Whiskers represent 5^th and 95^th percentiles, box represents interquartile range, median represented by horizontal line within box, outliers represented as individual points. Kruskal-Wallis statistic = 18.6, P < .001, n = 547; **P < .01, ***P < .001.