The CODEX index is based on comorbidity, age, obstruction, dyspnea, and previous severe exacerbations. Its main novelty is the inclusion of the Charlson comorbidity score coupled with one extra point per decade of life. This must be correct as any prediction of mortality disregarding age and comorbidity is probably doomed to failure. The authors have clearly demonstrated its advantages over other indexes, such as the well-known BODEX (BMI, airflow obstruction, dyspnea, and previous severe exacerbations),6,7 DOSE (dyspnea, airflow obstruction, smoking status, and exacerbation frequency),8 and ADO (age, dyspnea, and airflow obstruction)9 instruments over the short to medium term in high-risk patients with severe COPD. The other scoring systems are slightly simpler, and possibly better, in classifying patients with mild and moderate COPD who are mainly seen in primary care, where there is limited time and at a stage in COPD management when patients are not yet at risk for being regularly admitted to hospital for an acute exacerbation.