Association of increased depressive symptoms and lung health in participants with pre-COPD: A population-based study.
BACKGROUND Depression is a common comorbidity of chronic obstructive pulmonary disease (COPD) and is associated with worse prognosis. However, its association with lung health in individuals with pre-COPD remains unknown. We examined associations of increased depressive symptoms with respiratory symptoms, pre-COPD, and mortality. METHODS We analysed data from the National Health and Nutrition Examination Survey (NHANES 2007-2012). Non-COPD individuals with available spirometry and Patient Health Questionnaire-9 (PHQ-9) data were included. Pre-COPD phenotypes included small airway dysfunction (SAD), preserved ratio impaired spirometry (PRISm) and nonobstructive chronic bronchitis (NOCB). Logistic and Cox regression models assessed associations of increased depressive symptoms with respiratory outcomes and all-cause mortality, respectively. RESULTS Among 10 941 participants, increased depressive symptoms were associated with higher risk of PRISm (adjusted OR (aOR) [95% CI] 1.41[1.07,1.85]), NOCB (aOR [95% CI] 1.90[1.49,2.42]), cough (aOR [95% CI] 2.17[1.72,2.73]), phlegm production (aOR [95% CI] 2.86[2.23,3.67]), exertional dyspnoea (aOR [95% CI] 2.53[2.04,3.13]) and wheeze (aOR [95% CI] 1.86[1.51,2.30]). A one-unit increase in PHQ-9 score was also associated with higher risks of respiratory symptoms and pre-COPD. Additionally, increased depressive symptoms were independently associated with higher all-cause mortality risk among participants with pre-COPD, including SAD (aHR [95% CI] 2.85[1.02,7.95]), PRISm (aHR [95% CI] 2.02[1.01,4.01]) and NOCB (aHR [95% CI] 2.45[1.24,4.84]). Similar associations were observed across depression scores and pre-COPD populations. CONCLUSIONS Increased depressive symptoms were associated with a higher risk of pre-COPD phenotypes, respiratory symptoms, and mortality. Increased depressive symptoms may be a treatable trait that can help mitigate adverse outcomes in participants with pre-COPD.