Risk of depression in patients with chronic obstructive pulmonary disease and its determinants

Background: Although it has been repeatedly suggested that chronic obstructive pulmonary disease (COPD) is associated with depression, no conclusion has so far been reached. A study was undertaken to investigate whether depression occurs more often in patients with COPD than in controls. The demographic and clinical variables associated with depression were also determined. Methods: Patients with a registered diagnosis of obstructive airway disease in general practice, aged ≥40 years, forced expiratory volume in 1 second (FEV₁) <80% predicted, FEV₁ reversibility ≤12%, FEV₁/VC ≤ predicted - 1.64 × SD, and a history of smoking were selected. A random sample of subjects without a registered diagnosis of asthma or COPD aged 40 years or older acted as controls. Depression was assessed using the Centers for Epidemiologic Studies Depression (CES-D) scale. Results: In patients with severe COPD (FEV₁ <50% predicted), the prevalence of depression was 25.0% compared with 17.5% in controls and 19.6% in patients with mild to moderate COPD. When the results were adjusted for demographic variables and comorbidity, the risk for depression was 2.5 times greater for patients with severe COPD than for controls (OR 2.5, 95% CI 1.2 to 5.4). In patients with mild to moderate COPD this increased risk of depression was not seen. Living alone, reversibility of FEV₁ % predicted, respiratory symptoms and physical impairment were significantly associated with the scores on the CES-D scale. Conclusion: Patients with severe COPD are at increased risk of developing depression. The results of this study underscore the importance of reducing symptoms and improving physical functioning in patients with COPD.