First, the most important component of the CODEX index (ie, the Charlson index) has several limitations in the context of patients with COPD. Although broadly based, it does not include comorbidities that are relevant to patients with COPD/smokers, such as cor pulmonale, lung cancer, osteoporosis, muscle weakness, depression, and so forth.2,3 Second, it is not clear from the article whether all the comorbidities listed in the Charlson index were actively investigated, or whether the calculation of the index was based simply on patients’ self-reporting or hospital records. The first scenario implies the need for extensive investigations, whereas adoption of the second approach may have allowed several of these comorbidities to have been missed. Last, but not least, this study was designed to develop and validate a model for prognosis, taking associated comorbidities into account, that would perform better than the previous models (BODEX [BMI, airflow obstruction, dyspnea, and previous severe exacerbations], DOSE [dyspnea, airflow obstruction, smoking status, and exacerbation frequency], and updated ADO [age, dyspnea, and airflow obstruction] indexes), which do not include comorbidities. The results of the study showed that the CODEX index has a larger area under the curve in predicting survival at 3 months and 1 year as compared with the other indexes. However, the Charlson index scores of the development and validation cohorts were 3 and 2, respectively, which implies that there were few associated comorbidities present among these patients. This fact becomes more apparent when we consider that all patients would have gotten at least 1 point for the presence of COPD and the rest of the points may have been for the age of the patients, because the mean age of the study cohort was > 70 years. Therefore, we suggest that the previously mentioned points be kept in mind before accepting the CODEX index as an advanced tool for determining the short- and intermediate-term prognosis of these patients.