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

Abstract

Takashi Motegi,1,2 Rupert C Jones,3 Takeo Ishii,1,2 Kumiko Hattori,1,2 Yuji Kusunoki,1,2 Ryuko Furutate,2 Kouich Yamada,1,2 Akihiko Gemma,1 Kozui Kida1,2 1Divisions of Pulmonary Medicine, Infectious Disease, and Oncology, Department of Internal Medicine, 2Respiratory Care Clinic, Nippon Medical School, Tokyo, Japan; 3Respiratory Research Unit, Peninsula Medical School, Plymouth, UK 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: frequency of exacerbation, multidimensional assessment systems, DOSE index, BODE index