COPD heterogeneity: Gender differences in the multidimensional BODE index

BACKGROUND The BODE index was recently validated as a multidimensional tool for the evaluation of patients with COPD. The influence of gender on the BODE index has not been studied. HYPOTHESIS The contribution of each component of the disease to the BODE index may differ according to gender. METHODS We evaluated age, forced expiratory volume in one second (FEV1), Modified Medical Research Council (MMRC) score, 6-min walk distance (6MWD), and body mass index (BMI) in 52 men and 52 women with COPD and the same BODE index. We compared the studied parameters between men and women and then performed a multiple regression analysis by gender. RESULTS We found statistically significant differences between men and women in all parameters: FEV1 % (55 +/- 17 vs 63 +/- 18, p < 0.001), MMRC [1 (0-2) vs 1 (1-2) p = 0.03], BMI [28 (26-30) vs 25 (22-30), p = 0.05], and 6MWD [546 (451-592) vs 462 (419-520), p = 0.001]. Multiple regression analysis revealed that each component of the BODE index had different weight (beta standardized coefficient) in men and women respectively: FEV1% (0.74 vs 0.62), MMRC (0.31 vs 0.48), BMI (-0.09 vs -0.17), and 6MWD (0.13 vs 0.10). CONCLUSIONS The contribution of each component to the BODE index differs by gender in subjects with similar BODE scores. Long term longitudinal studies will help determine the significance of our findings.