The BODE Index, a Multidimensional Grading System, Reflects Impairment of Right Ventricle Functions in Patients with Chronic Obstructive Pulmonary Disease: A Speckle-Tracking Study

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is not only characterized by chronic airflow limitation, but is also a systemic disease. There is no information about alterations in right ventricle (RV) functions precipitated by systemic manifestations of COPD. Objectives: We aimed to evaluate the relationship between the BODE (body mass index, airflow obstruction, dyspnea, and exercise capacity) index that evaluates systemic manifestations of COPD and RV functions by means of 2-dimensional speckle-tracking echocardiography (2D-STE) in COPD patients. Methods: The study involved 135 COPD patients and 37 control subjects. All patients underwent 2D-STE, pulmonary function tests and 6-min walk tests, and were divided into quartiles according to their calculated BODE index score. Results: COPD patients had impaired RV and left-ventricle diastolic functions compared to controls. There was a decreasing trend from quartile 1 (Q₁) to Q₄ in RV functional parameters, i.e. RV free wall strain (RVFW-S, p < 0.001), tricuspid annular plane systolic excursion (p < 0.001), systolic myocardial velocity (p < 0.001), RV fractional area change (p < 0.001), RV myocardial performance index (p < 0.001) and pulmonary artery systolic pressure (p < 0.001). The transmitral Doppler E wave/lateral mitral annular tissue Doppler E wave ratio was similar in the 4 BODE index quartiles (p = 0.159). Multivariate analysis was performed to find independent predictors of decreased RVFW-S (≤19.06), and the BODE index (in quartiles; OR 4.61 and 95% CI 1.85-11.63) was found to be an independent predictor. In a partial correlation analysis adjusted for forced expiratory volume in 1s % predicted, RVFW-S was correlated with the 6-min walk distance (r = 0.498). Conclusion: The BODE index, which can be easily evaluated in office settings, may provide information about reduced RV functions as well as guiding treatment and helping to predict prognosis in COPD patients.