Depression, but not sleep disorder, is an independent factor affecting exacerbations and hospitalization in patients with chronic obstructive pulmonary disease

Background and objective: Patients with chronic obstructive pulmonary disease (COPD) may experience depression and sleep disorders, which can adversely affect their health-related quality of life (HRQOL). The aim of this study was to investigate depression and sleep disorders among 85 COPD patients and 46 control subjects, aged 40 years and over. Methods: Patients underwent spirometry and arterial blood gas analysis, self-completed St. George's Respiratory Questionnaire and were assessed on the Center for Epidemiologic Studies Depression (CES-D) and the Pittsburgh Sleep Quality Index (PSQI). The frequency of exacerbations among COPD patients was prospectively monitored for 12 months. Results: The prevalence of depression and sleep disorders was significantly higher among COPD patients than control subjects. The relative risks (95% confidence interval) of depression and sleep disorders were 7.58 (1.03 to 55.8) and 1.82 (1.03 to 3.22), respectively, in COPD patients compared with control subjects. Among COPD patients, there was a correlation between CES-D and PSQI. Lower body mass index, more severe dyspnoea, poorer HRQOL, lower partial pressure of arterial oxygen and higher partial pressure of arterial carbon dioxide were significantly associated with the incidence of depression and sleep disorders. Exacerbations and hospitalizations were more frequent among COPD patients with depression than those with sleep disorders alone or those without depression or sleep disorders. Conclusions: Depression and sleep disorders are very common co-morbidities among COPD patients and significantly reduce activities and HRQOL among these patients. Depression, but not sleep disorder, is an independent risk factor for exacerbations and hospitalization among COPD patients.