Prognostic value of multidimensional indices in ambulatory COPD patients

The Global Initiative for Chronic Obstructive Lung Disease (GOLD) advocates the use of multidimensional prognostic indices for staging, monitoring and guiding decision-making in chronic obstructive pulmonary disease (COPD) [ ]. The previous severity staging based on airflow limitation has been substituted for a grading (ABCD) system that also includes exacerbations and symptoms [ ]. On the other hand, comorbidities are frequent in COPD, and patients often die from other diseases than COPD. De Torres et al. found that the Body mass index (BMI), Obstruction, Dyspnea, Exercise (BODE) index had better long-term survival prediction than the GOLD ABCD categories system [ ]. Also, they found that combining the BODE index with a COPD-specific comorbidity index, improved outcome prediction [ ]. However, BODE index requires a six-minute walk test (6MWT) and exercise tests are personnel- and time-consuming. Therefore, this index is difficult to use in some settings, like primary care medicine. The Spanish COPD guidelines recommend the BODEX index, which replaces 6MWD with the registry of previous severe exacerbations, at least for less severe cases [ ]. The CODEX index (Comorbidity, Obstruction, Dyspnea, and previous severe EXacerbations) includes both variables of COPD severity and comorbidity (assessed by the age-adjusted Charlson index) and it does not require performing a 6MWT [ ]. Therefore, it is easy to use in clinical practice. However, it has only been validated in patients hospitalized for COPD exacerbation, and it has not been tested in ambulatory patients [ ]. Our hypothesis was that the BODEX index would have better survival prediction than GOLD ABCD, and that the CODEX index would improve outcome prediction, in ambulatory COPD patients.