During admission, all patients were evaluated with a standardized questionnaire. Data collected included time from the first medical diagnosis of COPD, hospitalizations for COPD or other pathologies in the previous year, and home status (family, alone, nursing home). Functional status at baseline was assessed with the Katz index.10 Comorbidity was documented using the previously validated Charlson index, a standard scale with 15 chronic diseases graded for severity of disease.11 For comparative analysis, a point was subtracted from the total score on the Charlson index, as all patients had COPD, which adds a point in this index. Additionally, comorbidity data were collected using a specific questionnaire which included pathologies that were considered relevant, whether included or not in the Charlson index. To calculate the total of comorbidities, one point was added for each one of the following pathologies: ischemic heart disease, heart failure, peripheral vascular disease, cerebrovascular disease, dementia, connective tissue disease, liver disease, kidney failure, diabetes mellitus, AIDS, hypertension, osteoporosis, sleep apnea syndrome, dyslipidemia, presence of psychologic disorders (anxiety or depression), active malignancy (including leukemia and lymphoma), arrhythmia, anemia, and venous thromboembolic disease. Data on medical treatment previous to hospitalization, during hospitalization and upon discharge were also collected. Dyspnea was measured using the modified Medical Research Council (mMRC) scale, and length of stay was recorded. Patients were followed up to 3 months after discharge, and a spirometric test was performed if it had not been done previously. At this time, survival, cause of death, and time between hospital discharge and mortality were collected, and hospital readmissions for COPD or other causes were recorded.