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 patients without COPD 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 patients with COPD and 35,722 patients without COPD, the prevalence of diagnosed depression prior to the first COPD diagnosis was higher in the population with COPD (23.1%) than among patients without COPD (16.8%). The incidence rate of a new-onset diagnosis of depression after the first COPD diagnosis was 16.2/1,000 person-years (py) in the COPD group, whereas it was only 9.4/1,000 py in the COPD-free comparison group. In the nested case-control analysis, patients with severe COPD had the highest risk of developing depression (odds ratio, 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.