Validity of Multidimensional Body Mass Index (B), Airflow Obstruction (O), Dyspnea (D) and Exercise Capacity (E), BODE Index as Predictor of Hospitalization for COPD

Background: Patients with COPD have systemic manifestations that are not reflected by the FEV1. These systemic manifestations often correlate with increased risk of mortality and may be considered surrogates of disease severity. We hypothesized that the BODE (body mass index, airflow obstruction, dyspnea, and exercise capacity) index would better predict hospitalization for COPD than FEV1 alone. Study Objectives: The purpose of this study was to test in a cohort of patients with COPD, how well a multidimensional grading system that assessed the respiratory and systemic expressions of COPD would better categorize and predict outcome in these patients. Patients: A total of 150 patients with COPD (ages 45-83 yr; 89% male) recruited from the outpatient clinic of Suez Canal University Hospital were enrolled in 30 months, prospective study and followed-up for a mean period of 12 months from January 2004-June 2006. Measurements: The BODE index was calculated for each patient using variables obtained within 4 weeks of enrollment. The main outcome measure was the number of hospital admissions for COPD during follow-up. The following variables were assessed for each patient: Age, sex, pack years of smoking, FVC%, FEV1%, the best of two 6 minute walk tests done 30 minutes apart, degree of dyspnea, body mass index (BMI). We evaluated the relationship between FEV1%, the level of dyspnea, BMI, the best of two 6 minute walk tests done 30 minutes apart and BODE scores with the number of hospital admissions. Results: After 30 months, 126 patients were available for the follow-up examination (follow-up rate, 84 %). During the follow-up period, 85 (67%) of patients required at least one hospital admission and 6 (4.8%) died. In multivariate analysis a significant effect of BODE score on the number of hospital admissions was found (95% confidence interval (CI), 0.36 to 0.61; p 0.000). In comparison, there was a significant but smaller effect of the pack years of smoking, BMI and BMI score on the number of hospital admissions [(95% confidence interval (CI), 0. 03 to 0.05; p 0.000), (95% CI, -0.32 to -0.09;p 0.01) and (95% CI, -1.6 to -0.12; p 0.05) respectively]. FEV1%, the level of dyspnea, and 6 minute walk test were significant predictors of hospitalization in univariate analysis (p 0.000) but were excluded in multivariate analysis. Conclusions: The BODE staging system, which includes in addition to FEV1 other physiologic and clinical variables, is a better predictor of hospital admissions than FEV1 in COPD.