Comorbidity in chronic obstructive pulmonary disease. Related to disease severity?

Background and objective: Several diseases commonly co-exist with chronic obstructive pulmonary disease (COPD), especially in elderly patients. This study aimed to investigate whether there is an association between COPD severity and the frequency of comorbidities in stable COPD patients. Patients and methods: In this multicenter, cross-sectional study, patients with spirometric diagnosis of COPD attended to by internal medicine departments throughout Spain were consecutively recruited by 225 internal medicine specialists. The severity of airflow obstruction was graded using the Global Initiative for Chronic Obstructive Lung Disease (GOLD) and data on demographics, smoking history, comorbidities, and dyspnea were collected. The Charlson comorbidity score was calculated. Results: Eight hundred and sixty-six patients were analyzed: male 93%, mean age 69.8 (standard deviation [SD] 9.7) years and forced vital capacity in 1 second 42.1 (SD 17.7)%. Even, the mean (SD) Charlson score was 2.2 (2.2) for stage I, 2.3 (1.5) for stage II, 2.5 (1.6) for stage III, and 2.7 (1.8) for stage IV (P=0.013 between stage I and IV groups), independent predictors of Charlson score in the multivariate analysis were age, smoking history (pack-years), the hemoglobin level, and dyspnea, but not GOLD stage. Conclusion: COPD patients attended to in internal medicine departments show high scores of comorbidity. However, GOLD stage was not an independent predictor of comorbidity.