Introduction: Patients with COPD have decreased exercise capacity and low oxygen consumption (V̇o2) during formal cardiopulmonary exercise testing, and lower scores on health-related quality of life questionnaires. When isolated, these three variables show different correlations with COPD mortality. The multidimensional BODE (body mass index[BMI], airflow obstruction, dyspnea, and exercise capacity in COPD) index, which comprises four variables including the 6-min walk test (6MWT), predicts survival in COPD.
Objectives: To evaluate the degree of association between the values of the BODE index using the 6MWT with the BODE index using maximal V̇o2 (V̇o2max) obtained in a maximal incremental test.
Materials and methods: Fifty patients with mild-to-severe COPD (average age, 63.5 ± 9.9 years; FEV1, 65.3 ± 23.6% of predicted) [± SD] had BMI, spirometric function (FVC and FEV1), and dyspnea status (Medical Research Council) evaluated. Two BODE index scores were then completed: one with the 6MWT, and one with the V̇o2max obtained during maximal incremental testing on a treadmill.
Results: Correlation between BODE index and V̇o2 in milliliters per minute per kilogram (r = − 0.41) was weak; the correlation was moderate (r = − 0.64) when V̇o2 percentage of predicted was used. The BODE index modified by replacing the 6MWT with V̇o2 showed excellent correlations with V̇o2 in milliliters per minute per kilogram (r = 0.92) and V̇o2 percentage of predicted (r = 0.95).
Conclusion: The excellent correlation between the conventional BODE index and the modified BODE index with V̇o2 replacing the 6MWT enables us to reach the conclusion that the original BODE index is very effective in the evaluation of COPD patients.