Bidirectional associations between clinically relevant depression or anxiety and COPD

Background: The longitudinal associations between depression or anxiety and COPD, and their comorbid effect on prognosis, have not been adequately addressed by previous reviews. We aimed to systematically assess these associations to inform guidelines and practice. Methods: We searched electronic databases for articles published before May 2012. Longitudinal studies in adult populations that reported an association between clinically relevant depression or anxiety and COPD, or that reported their comorbid effect on exacerbation and/or mortality, were eligible. Risk ratios (RRs) were pooled across studies using random-effects models and were verified using fixed-effects models. Heterogeneity was explored with subgroup and metaregression analyses. Results: Twenty-two citations yielded 16 studies on depression or anxiety as predictors of COPD outcomes (incident COPD/chronic lung disease or exacerbation) and/or mortality, in 28,759 participants followed for 1 to 8 years, and six studies on COPD as a predictor of depression in 7,439,159 participants followed for 1 to 35 years. Depression or anxiety consistently increased the risk of COPD outcomes (RR, 1.43; 95% CI, 1.22-1.68), particularly in higher-quality studies and in people aged ≤ 66 years. Comorbid depression increased the risk of mortality (RR, 1.83; 95% CI, 1.00-3.36), particularly in men. Anxiety (or psychologic distress) increased the risk of COPD outcomes/mortality in most studies (RR, 1.27; 95% CI, 1.02-1.58). Finally, COPD consistently increased the risk of depression (RR, 1.69; 95% CI, 1.45-1.96). Conclusions: Depression and anxiety adversely affect prognosis in COPD, conferring an increased risk of exacerbation and possibly death. Conversely, COPD increases the risk of developing depression. These bidirectional associations suggest potential usefulness of screening for these disease combinations to direct timely therapeutic intervention.