A comparison of three multidimensional indices of COPD severity as predictors of future exacerbations

Abstract

Background: Prediction of future exacerbations of chronic obstructive pulmonary disease (COPD) is a major concern for long-term management of this disease.

Aim: To determine which of three multidimensional assessment systems (the body mass index, obstruction, dyspnea, and exercise capacity [BODE] index; dyspnea, obstruction, smoking, exacerbations [DOSE] index; or age, dyspnea, obstruction [ADO] index) is superior for predicting exacerbations.

Methods: This was a 2-year prospective cohort study of COPD patients. Pulmonary function tests, the 6-minute walk distance (6MWD), Modified Medical Respiratory Council (MMRC) dyspnea scores, chest computed-tomography measurements, and body composition were analyzed, and predictions of exacerbation by the three assessment systems were compared.

Results: Among 183 patients who completed the study, the mean annual exacerbation rate was 0.57 events per patient year, which correlated significantly with lower predicted forced expiratory volume in 1 second (FEV1) (P < 0.001), lower transfer coefficient of the lung for carbon monoxide (%DLco/VA) (P = 0.021), lesser 6MWD (P = 0.016), higher MMRC dyspnea score (P = 0.001), higher DOSE index (P < 0.001), higher BODE index (P = 0.001), higher ADO index (P = 0.001), and greater extent of emphysema (P = 0.002). For prediction of exacerbation, the areas under the curves were larger for the DOSE index than for the BODE and ADO indices (P < 0.001). Adjusted multiple logistic regression identified the DOSE index as a significant predictor of risk of COPD exacerbation.

Conclusion: In this study, the DOSE index was a better predictor of exacerbations of COPD when compared with the BODE and ADO indices.

Keywords: BODE index; DOSE index; frequency of exacerbation; multidimensional assessment systems.

Figure 1

Flow chart for patient selection. Abbreviations: COPD, chronic obstructive pulmonary disease; DOSE, dyspnea, obstruction, smoking, exacerbations.

Figure 2

Receiver-operator curves for the multidimensional grading systems, GOLD stage, and previous exacerbation rate as predictors of the occurrence of exacerbation during the 1-year follow-up. Notes: The AUC and the 95% CI are shown for each index. The AUC for the DOSE index is significantly larger than for the other multidimensional assessments or GOLD stage (P < 0.001), but shows no difference versus previous exacerbation rate (P = 0.40). Abbreviations: AUC, area under the curve; ADO, age/dyspnea/airflow; BODE, body mass index/airflow obstruction/dyspnea/exercise capacity; CI, confidence interval; DOSE, dyspnea, obstruction, smoking, exacerbations GOLD, Global initiative for chronic Obstructive Lung Disease.