The ability to predict mortality was compared in terms of discrimination by Harrell's C (HC) index and calibration using graphical comparison among the GOLD (Global Initiative for Chronic Obstructive Lung Disease) 2011, GOLD 2017, GOLD grade, BODE (BMI, Airflow Obstruction, Dyspnea, Exercise), updated BODE, BODEx (BMI, Airflow Obstruction, Dyspnea, Exacerbation), e-BODE (Exacerbation and BODE), ADO (Age, Dyspnea, Airflow Obstruction), COPD prognostic index (CPI), and simplified/optimized B-AE-D (BMI, Acute Exacerbation, Dyspnea) indexes.
Five clusters were identified based on three PCA components, which accounted for 60% of variance of the data.Importantly, couch potatoes (i.e. the most inactive cluster) were characterised by higher BMI, lower FEV<sub>1</sub>, worse dyspnoea and higher ADO index compared to other clusters ( p < 0.05 for all).