The Body-Mass Index, Airflow Obstruction, Dyspnea, and Exercise Capacity Index in Chronic Obstructive Pulmonary Disease (BODE Index):
N Engl J Med 2004;350:1005-12.

Chronic obstructive pulmonary disease (COPD), a common disease characterized by a poorly reversible limitation in airflow, is predicted to be the third most frequent cause of death in the world by 2020. The risk of death in patients with COPD is often graded with the use of a single physiological variable, the forced expiratory volume in one second (FEV1). However, other risk factors, such as the presence of hypoxemia or hypercapnia, a short distance walked in a fixed time, a high degree of functional breathlessness, and a low body-mass index (the weight in kilograms divided by the square of the height in meters), are also associated with an increased risk of death. This is a multidimensional grading system that assessed the respiratory, perceptive, and systemic aspects of COPD that would better categorize the illness and predict the outcome than does the FEV1 alone. Data from an initial cohort of 207 patients were used to identify four factors that predicted the risk of death: the body-mass index (B), the degree of airflow obstruction (O) and functional dyspnea (D), and exercise capacity (E) as assessed by the six-minute– walk test. These variables were integrated into a multidimensional index — the BODE index — and validated the index in a second cohort of 625 patients, with death from any cause and death from respiratory causes as the outcome variables.