Chronic obstructive pulmonary disease and the risk of depression

BACKGROUND: Chronic comorbidities are often associated with depression. Most previous studies exploring the association between COPD and depression were rather small and based on a cross-sectional study design. We conducted a large population-based study on the risk of developing an incident depression diagnosis in association with a previous COPD diagnosis. METHODS: We used the UK-based General Practice Research Database to assess and compare the prevalence of a history of depression, and to quantify the risk of developing incident depression in patients with COPD and COPD-free patients between 1995 and 2005. We conducted a nested case-control analysis, matching up to four patients who did not develop depression for each case patient with depression, to further analyze the impact of COPD severity. RESULTS: In a study population of 35,722 COPD patients and 35,722 COPD-free patients, the prevalence of diagnosed depression prior to the first COPD diagnosis was higher in the COPD population (23.1%) than among COPD-free patients (16.8%). The incidence rate of a new onset diagnosis of depression after the first COPD diagnosis was 16.2 / 1000 person-years (py) in the COPD group, while it was only 9.4 / 1000 py in the COPD-free comparison group. In the nested case-control analysis, patients with severe COPD had the highest risk of developing depression (OR 2.01, 95% CI 1.45-2.78). CONCLUSION: This large observational study provides further evidence that patients with COPD are at an increased risk of developing depression.