Replacement of the 6-min walk test with maximal oxygen consumption in the BODE Index applied to patients with COPD: an equivalency study.
BACKGROUND
Patients with COPD have decreased exercise capacity and low oxygen consumption (Vo(2)) 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.


OBJECTIVE
To evaluate the degree of association between the values of the BODE index using the 6MWT with the BODE index using maximal Vo(2) (Vo(2)max) obtained in a maximal incremental test.


METHODS
Fifty patients with mild-to-severe COPD (average age, 63.5 +/- 9.9 years; FEV(1), 65.3 +/- 23.6% of predicted) [+/- SD] had BMI, spirometric function (FVC and FEV(1)), and dyspnea status (Medical Research Council) evaluated. Two BODE index scores were then completed: one with the 6MWT, and one with the Vo(2)max obtained during maximal incremental testing on a treadmill.


RESULTS
Correlation between BODE index and Vo(2) in milliliters per minute per kilogram (r = - 0.41) was weak; the correlation was moderate (r = - 0.64) when Vo(2) percentage of predicted was used. The BODE index modified by replacing the 6MWT with Vo(2) showed excellent correlations with Vo(2) in milliliters per minute per kilogram (r = 0.92) and Vo(2) percentage of predicted (r = 0.95).


CONCLUSIONS
The excellent correlation between the conventional BODE index and the modified BODE index with Vo(2) replacing the 6MWT enables us to reach the conclusion that the original BODE index is very effective in the evaluation of COPD patients.
Cardoso
Fábio
F
Respiratory Division (Pneumologia/Unifesp), 04023-062, São Paulo SP, Brazil.
Tufanin
Andréa Thomazine
AT
Colucci
Marcelo
M
Nascimento
Oliver
O
Jardim
José Roberto
JR
D015992:Body Mass Index; D001938:Brazil / Q000453:epidemiology; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D016138:Walking / Q000502:physiology*